Group for Earth Observation

The Independent Amateur Quarterly Publication for

Number 15

Earth Observation and Weather Satellite Enthusiasts

September 2007

Inside this issue . . .
GEONETCast: Read about
the development of thisworld-wide system forsharing geostationary
weather satellite data
Rob Hollander theorises
over how Reflections ofElectromagnetic Waves canaffect reception with eventhe best antennas
Peripatetic APT: Francis
Bell describes the delights
he has experienced when
taking a minimal APT
system to unusual locations
around the globe
Meteosat-8 has started anexperimental rapid
scanning service—David
Taylor explainsIf you have struggled to set
up your own PC network,
Mark Edwards' article
provides a certain guide tosuccess
The Strait of Dover. In thesecond part of his article,
John Tellick describes what
can be seen from orbit on
the French side of the
ChannelPlus many morefeatures ...

Keep up to date with the latest WXsat News every Month
Radio and Communications Monitoring Monthly (ISSN 1749-7809) aims to be themagazine of choice for all serious radio enthusiasts and to serve all the specialist areasof the hobby. ‘I am pleased to say that all our regular columns provide more information
than any current or former alternative’, commented Editor Kevin Nice.
The magazine provides a regular 4-page Weather Satellite column, “Satellites' View”, byLawrence Harris. In addition, the May 2007 wxsat ‘special’ issue included a feature on
the WS2300 Weather Monitoring System, a review of some of David Taylor’s less wellknown MSG software, ‘“Round the World in 100 minutes with MetOp”, plus a review of
the new R2ZX APT wxsat receiver from Holger Eckardt.
Radio and Communications Monitoring Monthly is available from most good newsagents
as well as direct from the publishers.
Subscriptions are available world-wide. For more information contact Nice One Publishing
Ltd, Tel: +44 (0)1202 862690 or visit the website:www.monitoringmonthly.co.uk

MANAGEMENT TEAMT

he first thing you will have noticed about this issue of GEO
Quarterly is it’s size: we have included an additional eight pages
this quarter, many of them in colour, to provide you with a flavour of
GEO’s visit to EUMETSAT HQ in Darmstadt last July. An event overtwelve months in the planning, this visit drew enthusiasts from acrossthe length and breadth of Europe together for what proved to be theultimate in educational and social experiences. Our report, compiled byJohn Tellick and David Taylor, starts on page 19.
ohn Tellick has also been busy with a follow-up to his Strait ofDover article, this time providing a guide to what can be seen on the
French side of the Strait. He also looks ahead to GEONETCast, asystem that promises, before very long, to bring continuous world-wide
DVB access to images and products from all the world’s geostationary
weather satellites.
ave you ever tried to network two or more home PCs but failed.
Your Editor certainly has! But armed with Mark Edwards’ stepby-step guide, it was simply a piece of cake. If you really would like toshare information between your PCs, just turn to page 34 to discover
how easily it can be accomplished..
ecently, the weather satellite community bade farewell to a
stalwart of many years, NOAA-14. Our front cover bears testimony
to well over a decade of service by reproducing the satellite’s final
image over western Europe, captured by Lawrence Harris on his direct
reception HRPT system in Southampton. Although more modern
NOAA satellites now grace the skies, NOAA-14 was one of the last ofits generation of WXsats. You can read its story on page 9.

J

HRPublic Relations
Francis Bell,
Coturnix House, Rake Lane,
Milford, Godalming,
Surrey GU8 5AB
England.
Tel:
01483 416 897
email: francis@geo-web.org.uk

General Information
John Tellick
email: info@geo-web.org.uk

GEO Quarterly Editor
Les Hamilton,
8 Deeside Place
Aberdeen AB15 7PW
Scotland, UK.
email: geoeditor@geo-web.org.uk

Membership and Subscriptions
David Anderson,
35 Sycamore Road,
East Leake,
Loughborough LE12 6PP
England, UK.
email: members@geo-web.org.uk
Tel:+44 (0) 01509 820 067
Fax:+44 (0) 01509 277 220

Meteorological Consultant
Peter Wakelin
email: meteo@geo-web.org.uk

Technical Consultant (hardware)David Simmons
email: tech@geo-web.org.uk

Webmaster and Website Matters
Ray Godden
e-mail: ray-geo@lescharriols.eu

Education Coordinator
David Painteremail: education@geo-web.org.uk

GEO Shop Manager
Clive Finnis
email: shop@geo-web.org.uk

Contents
GEO Report
Jet Stream Shift across Europe
Strait of Dover - a personal view - part 2
Cloudspotter’s Guide (Book Review)
Radioactive Show
Freak Storms batter Australia
End of an Era: NOAA-14 Decommissioned
A Word of Caution concerning USB Hard Drives
Radar Satellites - part 4: Radar Altimetry
Cover and Full Page Images
GEONETCast
Meteosat-8 Rapid Scanning Service
Streamline Your EUMETCast reception
GEO Visits EUMETSAT HQ
Earth Imaging NewsInternational Liaison

Francis BellJohn Tellick
Clive Finnis
Roger Reeves
Les Hamilton
A Van Belle, D Taylor
Peter Wakelin
John Tellick
David Taylor
Fred van den BoschJ Tellick, D Taylor
Peter Wakelin

2
3
4
6
7
7
9
10
11
13
14
16
18
19
25

GEO Shop
NOAA Satellite Predictions for the UK and Western Europe
Helplines and Internet Discussion Groups
Copy Deadline for December issue
GEO Membership Renewal Form

i
ii
iii
iii
iv

Reviewing Historical Weather Satellite Images
Reflections of Electromagnetic Waves
Symposium 2007 - Report and Pictures
China’s ASAT Attack destroys Feng Yun-1C
Setting up a Local Area Network
Script Snippets
Extend your EUMETCast Options with 3 PCs
Peripatetic APT
Ice Jam on Russia’s Ob River
Software Showcase
In Tray - Readers’ Letters etc.
Trialling the R2ZX APT Receiver

27
28
31
33
34
40
41
45
47
49
50
52

M Righini and G Rossini
Rob Hollander
Francis Bell
Celestrak
Mark Edwards
David Taylor
Alan BanksFrancis Bell
NASA Earth Observatory
Douglas Deans
Lawrence HarrisPeter Green‘Hollowtree’
Eggesford
Devon EX18 7QX
Tel:
01769 580 700
email: international@geo-web.org.uk
Nigel Evansemail: nigel@geo-web.org.uk

PublisherGroup for Earth Observation Ltd.
The Group for Earth Observation Limited is acompany in England and Wales limited byguarantee and not having share capital. Company
number 4975597.
The registered office is Coturnix House, Rake
Lane, Milford, Godalming, Surrey GU8 5AB

Printing
Advent Print Group,
19 East Portway Industrial Estate,
Andover,
Hampshire SP10 3LU.

Responsibility for Constructional
Projects and Software
Every effort is made to ensure that the technicaland constructional articles published in thisQuarterly are correct. However, the ultimate
responsibility is with the reader to ensure thesafety of constructions and for any interfacingwith other equipment. GEO cannot accept liability
for shortcomings in any published design or any
constructions carried out by members or otherthird parties.

Copyright GEO © 2007
The contents of this Quarterly remain theintellectual property of the Group for Earth
Observation Ltd. and its contributors. Copying oftext or images, either from the printed Quarterly
or from any electronically stored source, isforbidden without permission from the editor.

GEO Quarterly No 15

Group for Earth Observation

September 2007

Francis Bell
Visit to EUMETSAT
I am writing this brief report having justreturned from GEO’s visit to EUMETSAT HQ
in Damstadt. 42 GEO members
attended,representing seven countries. This
was a comfortable number making theadministrative effort by both GEO andEUMETSAT worthwhile.

As always my thanks to our talented
membership for sharing their skills andknowledge with us both via GEO Quarterly
and on-line. A reminder that the editor isalways happy to receive copy about any
aspect of Earth observation.

If the comments from our members wereanything to go by, the whole visit was a great
success. We toured three sites involved in thetechnical aspects of instrumentation, satellite
control, data acquisition, processing,dissemination and archiving, and also enjoyeda number of demonstrations. Less technical,
but perhaps more important, were the personal
interactions between GEO members and the
EUMETSAT staff. This included the Director
General, who took the time to speak to us at
the beginning of our visit and at the end of the
day and all the User Services staff, our escorts
to Usingen and everybody else we met on the
tours. All were pleased to talk to us andexplain the facilities we visited.

GEO will attend the AMSAT colloquium in
Guildford on July 20-22 and on September 7-8
will have a stand at the Leicester AmateurRadio Show. Please tell your friends that GEO
will be at this rally—it is our first time at thisevent and we would like it to be worthwhile,with many visitors to our stand.

When you interleave the above with the socialside of technical and personal conversations,meal-times in our hotel, filling local restaurants
with GEO delegates in the evenings and
EUMETSAT's canteen by day, it generated an
outstanding experience for all those who
attended. You will find numerous photographsof the occasion included in the six-page report
prepared by John Tellick and David Taylor on
page 19.

Future Events

GEO hopes to be represented at the
EUMETSAT conference in Amsterdam
between September. 24-28.
Finally, in early November, GEO will have anenlarged stand at the London radio rally at
Kempton. The exact date will be intimatedwhen known.
I will not take up too much space with thesenotes because of the report relating to our
AGM last May which gives an overview of ourgroup’s financial and membership position.
Please read this report. However, I will as
usual urge our existing members not to forget
to renew their membership when it becomesdue. We need the membership income toremain financially viable. Please encourageothers to join, a few hundred additional
members would generate financial security.

Image
I recently received my latest copy of Image
from EUMETSAT. As usual I read this 8-pagepublication from cover to cover. I find it very
interesting and the back page particularly
informative because it lists all current weather
satellites and those planned for launch in thenear future. This publication is available online but if you want a printed copy then writeto:

GEO Quarterly tries to cater for a wide
spectrum of interests but if there is anything
additional you would like included please let
the editor or myself know and I’m sure we canrespond in a positive way.

I received a number of correct answers but
chose the winner as Andreas Lubnow, astudent in Germany. He receives a copy of
Storm Dunlop’s book ‘A dictionary of Weather’kindly donated by the publisher, Oxford
University Press.

This Quarter’s Question
The background to this question relates to myrecent visit to Ecuador. A guide was showing
us around the capital city of Quito. During thetour we stopped at a viewpoint overlooking thecity in the valley below, with the Andes
mountains in the background. Among thosemountain peaks was the beautiful conicalsnow-covered volcanic peak of Cotopaxi, thesummit of which is 5896 m.
The guide said that the summit of Cotopaxi
was the closest point on the earth’s surface tothe sun [1] Of course, Cotopaxi is high, andless than one degree off the equator so thestatement was beguiling. I nodded politely but
decided within about two seconds that thiswas only intermittently true. The Earth’s
highest mountains are outside the tropics, forexample Mount Everest. However, does thecurvature of the earth away from the suncancel out the increased height of a mountainoutside the tropics.

The question is this:On an annual cycle, which single point on
Earth comes closest to the sun? Email youranswer to me. Do not submit your calculations
in full just the answer for your chosen spot on
the earth’s surface. The prize: recognition ofyour geographical and mathematical skills.
I will not be visiting this point—wherever it is.
My compromised breathing when crossing thewestern Andes by road at a height of 4130 m
was affected enough to suggest that I washigh enough for one day: perhaps for a
lifetime.

EUMETSAT User Services
Am Kavallerisand 31
D-64295 Darmstadt
Germanyor email ops@eumetsat.int
and ask to be put on the mailing list.

From Last TimeMy thanks to those who responded to mymystery photograph, taken from an aircraft
while flying over Canada. The most likely
explanation came from Mike Jupp suggestingthat the feature was a linear clearing throughthe trees to accommodate power-lines from amajor hydroelectric scheme at Churchill Falls
carrying electricity to Quebec in the south. The
dimensions of the 700 foot wide clearing
accommodates huge V-type 170 foot highguyed towers carrying three 730,000 volt
overhead lines. This scheme does seem to fit
my observation and my thanks to Mike for his
explanation.

The previous quarterly question wasstraightforward mathematics. It related to thetheoretical fall from orbit of a weather satellite
if it abruptly ceased its forward motion roundthe Earth from its altitude of 800 km.

2

The answer is 400 seconds, making theanswer, to the nearest minute, 7 minutes.

Neglecting the Earth’s atmospheric drag andassuming a constant gravitational accelerationof 10 ms-2, the equation relating the variables
iswhere s = 800 000, a = 10 and t = time.
You should be able to do this in your head!
Divide 800 000 by 5 and take the square root.

www.geo-web.org.uk

September 2007

It’s been a summer of extremesso far across Europe this year!
In the UK, a record-breaking,warm sunny month of April was
predicted to herald a long, hotsummer: but it was not to be.
June and July have both been
the wettest ever. Many regions
have suffered unprecedented
flooding as the rain simply
refused to stop falling as Britain
experienced its worst ‘climatechange event’ in living memory.
On one single day, July 20,
Brize Norton experienced
126 mm of rain, equivalent to
3 months summer precipitation.

Group for Earth Observation

During a ‘normal’ northernhemisphere summer, the jetstream lies over the northAtlantic and acts as a barrier
which directs Atlantic
depressions towards Icelandand northern Scandinavia. But
this year a persistent kink in the
Jet Stream has resulted in it
flowing several hundred
kilometres farther south than isusual, ushering a continuous
flow of depressions across the
British Isles.
At the same time, eastern
Europe was experiencing near-drought conditions as aheatwave sparked countless
wildfires throughout Hungary,
Romania, Italy and the Balkans.
Temperatures soared to record
levels, frequently into the midforties Celsius, and in Hungary
over 500 people, many of themelderly and infirm, died from theeffects of the heat during July.
Farther west, on the French
Riviera, 300 residents were
evacuated from the district
when fire destroyed 25 hectaresof forest close to the seaside
village of Escalet, near St
Tropez.

GEO Quarterly No 15

It was a similar story in the
Puglia region of southern Italy
where brush fires forced
holidaymakers to flee fromcampsites and hotels to thesafety of the seashore to await
rescue by sea and air.
Over 20 000 hectares of forest
and farmland were destroyedby fire in Bulgaria where
temperatures were the highest
since records began. Forests
were also ravaged by fires
throughout Bosnia, Serbia,
Macedonia, Bulgaria, Italy,
Greece and Turkey.

This is a composite image created by combining data from two successive passes of Metop-A on July 22, 2007. The image highlights
the contrasting weather conditions across Europe. While the Balkans were suffering drought conditions, England was drowning.
Image: NOAA CLASS Archive (www.class.noaa.gov/)

www.geo-web.org.uk

3

GEO Quarterly No 15

Group for Earth Observation

September 2007

John Tellick
Bienvenue à France! I hope you had a good journey either over orunder The Channel. It’s time now to describe the French side of theStrait of Dover as depicted so vividly in a high-resolution ASTER image,originally acquired on March 14, 2001 by NASA’s Terra Earthobservation satellite. The image is far too large to reproduce in its
entirety, but interested readers can locate it at:
http://asterweb.jpl.nasa.gov/
gallery-detail.asp?name=tunnel
Credit: NASA/GSFC/METI/ERSDAC/JAROS and U.S./Japan ASTER Science TeamOn the French side of the Channel, the town and major port ofCalais can clearly be seen and the inset image shows the Calais
region at full resolution. Wide sandy beaches, many backed by tallsand dunes, extend all the way through Belgium and Holland andon into northern Germany and Denmark. The sandy islands off the
Dutch and German coast, the Waddenielanden and theOstfriesische Inseln, show up well in our high resolution Meteosat9 HRV and NOAA/Metop AVHRR images (figure 1).The coast andcountryside to the east of Calais right up through Holland is‘famously’ flat: kilometre after kilometre after kilometre of it!
To the west of Calais there is an area of tall cliffs facing theircounterpart in Kent. These cliffs give way again to sandy beaches
backed by lower cliffs, part of the rolling hills with forests, farms
and villages that extend inland as the coastline turns south to
Boulogne and the famous wide sandy beaches of Hardelot-Plage,
Le Touquet and Berck-Plage.
The cliffs rising at Sangatte offer great views of the Channel and
Kent with viewing points at Cap Blanc-Nez and Cap Gris-Nez—thepointed bit where the coast turns abruptly south. It was from thesesites that one of history’s more recent and most infamous
characters, along with his second in command, surveyed the jewel
in his would be crown. But it was not to be!
Just southwest of Calais, the French Channel Tunnel terminal at
Coquelles can be clearly seen along with the massive (white) Cite
Europe shopping complex. The Channel Tunnel—Le Tunnel sousla Manche in French—is, at 30 miles long, the second longest rail
tunnel in the world but claims the worlds longest undersea tunnel
section at 24 miles. The rail link is a vast continuous loop
disappearing into two tunnels beneath the Channel: the end of theloop can be seen circling the French terminal together with theseveral platform access bridges and the engineering area. The
layout is similar at the Folkestone terminal with another loop,
except that it loops from right to left in France but from left to rightat Folkestone. This has nothing to do with the different sides of theroad on which we drive. It’s just to maintain equal wear on the
shuttle’s wheels!

Figure 1 - Sandy offshore islands at low tide
NOAA AVHRR - Image © EUMETSAT 2007

vessels travel through it daily, not to mention the many ferries
travelling across the shipping lanes—and the odd swimmer or two.
Thank goodness for radar! Given this narrowing, the tides bringgreat currents of water flowing though this bottle-neck. Near to thecoast the water looks milky due to the chalk sediment coming fromthe cliffs on either side.
But, it wasn’t always like this!
For several hundred thousand years, parts of Britain have been
joined to the continent. The land area changed with the varying ice
ages but, at its fullest extent, the edge of the land area stretchedfrom Yorkshire to Denmark and from Brittany to Ireland. What is
now the southern North Sea was then a vast fertile plain with rivers
while the English Channel was a great basin where the rivers
Rhine, Thames and Seine (all several miles wide) joined together
to flow out to sea between present-day Cornwall and Brittany.

The total journey time is 35 minutes, platform to platform. Eurostar
and rail freight services only join the loop to pass through thetunnels. Noticeable on both sides of the Channel is the patchworkof fields showing the similar agricultural use of the countryside.
The Strait of Dover itself is the narrowest part of the English
Channel, or La Manche as the French call it, which connects theNorth Sea with the Atlantic Ocean (figure 2). The Channel is one of
the busiest shipping arteries in the world; over 400 commercial

4

Figure 2
The Strait of Dover, English Channel and southern North Sea

www.geo-web.org.uk

NOAA AVHRR - © EUMETSAT 2007

GEO Quarterly No 15

Group for Earth Observation

September 2007

Dutch fishermen have for many years trawled up animalbones which show that, at varying times, woolly mammoths,
hyenas, lions, sabre-toothed tigers, elephants, hippopotamus,
red deer and wild boar all lived on what is now the southern
North Sea.
More exciting is the fact that flint implements from the
Neanderthal period have also been found, indicating that early
man lived and hunted there.

Clive Finnis

Later more sophisticated tools have also been discovered,showing that ‘modern man’—our own ancestors—lived andhunted here around 12,000 years ago on the North Sea plains
which archaeologists now call Doggerland.
But the last great climate change saw temperatures rise about
seven degrees in as little as 15 years and sea levels began torise as the ice caps started to melt: and kept on rising. It isestimated that up to 200 metres of coastline begandisappearing per year. Yes! Per year! Around 11,000 to 9,000
years ago, Doggerland began to shrink as it became flooded
by the North Sea until it finally joined up with the flooding
English Channel as Britain and Ireland became islands off
Europe.
The two areas we’ve visited are often quite ignored as holidaymakers ‘rush to the sun.’ But there is much to recommend
them. In Kent, sleepy Downland villages and scenery, ‘thegarden on England,’ dozens of stately homes, some castles
and many traditional pubs serving real ale, plus the walled cityof Canterbury with its vast cathedral: and great walks andvistas along the Downs and cliffs.
On the French side it is mostly an unspoilt area that time andthe developers (till recently) forgot. More sleepy villages,
interesting old towns, wonderful sandy beaches, uncrowded
roads, good food and a real feeling of ‘being abroad’—yet so
close to home. It even smells different!
Within an easy day-trip there are several typical Flemish
towns well worth visiting: Veurne, Diksmuide and Ieper (better
known to us as Ypres). All possess wonderful gabled buildings
surrounding their town squares.
If passing near Ypres, you must visit one of the many
beautifully tended and poignant WW-I cemeteries that aboundin this area. The Last Post is played by the local fire brigade,every day of the year, at ‘sunset’ under the Menin Gate in
Ypres in memory of the fallen. Impressive Bruges and Gent
are around an hour and a half’s drive from Calais.
In France it is well worth visiting St Omer, the fortified town of
Bergues and Boulogne with its ‘ancient quarter’:there, a visit toNausica is a must. And fashionable Le Touquet and Berckplage shouldn’t be missed with their excellent wide beaches.
For the British on their way home there is a big bonus here,
the hypermarkets, wine and beer warehouses around Calais,
including Tesco and Sainsburys (where you can use your UK‘points cards’), and where where you’ll see more English
people than French. This is hardly surprising since beer andwine are half the price here compared with the UK, as aremany grocery and DIY items. The choice is just out of thisworld. Fill up the car too—fuel is also cheaper.
So, what was a nice image from space has I hope turned intoa journey of discovery? By using the various spectral channelsof Meteosat HRIT and NOAA/Metop AVHRR you can continue
this journey of discovery. Albeit at lesser resolution, you can
explore features throughout Europe—towns, rivers, mountains
and forests; as well as ‘weather,’ snow and sea-ice.
The Straits of Dover—vive la difference: but long live theentante cordiale.

6

The Cloud Spotter’s Guide
Author: Gavin Pretor-Pinney

Whilst browsing through the local bookshop desperately looking for
inspiration for my wife’s birthday present I was drawn to the multicoloured jacket of a book ‘The Cloudspotter’s Guide’ by Gavin
Pretor-Pinney. Although unsuitable for my wife I realised that it
would make an excellent present for me instead – and so I
purchased it on the spot!
The book is divided into
four sections, ‘The Low
Clouds’, ‘The Middle
Clouds’, ‘The High
Clouds’ and a fourth
section which theauthor describes as ‘Not
Forgetting’ but isbasically ‘other clouds’.
Each section devotes anentire chapter to one
particular cloud type,for example cumulus,
stratus, cirrus etc. In
all there are thirteen
chapters and a total of
320 pages.
The book is written inthat rare way that puts
across what could so
easily be a dry,technical subject in alight hearted and witty
way. But the subject
matter is there, and isclearly described with
illustrations and photographs. The author’s regular excursions into
tales and anecdotes related to the particular cloud in question,
makes for an easy read that I found difficult to put down.
The centre section of the book is in colour and is a set of questions
leading to your ‘Cloudspotting Diploma’! All other illustrations are
monochrome, and lead to my only slight criticism in that they tend
to be grey and white rather than black and white, although they
are generally quite legible.
Mr. Pretor-Pinney is clearly an ultra dedicated cloudspotter, andthe story of his 12000 mile trip to, literally, the middle of nowherein Australia to observe a particular cloud type is one of myfavourite sections of the book. I almost felt like ringing the travel
agents to book my own flight to Australia to follow in his footsteps!
All in all a thoroughly readable book which I can recommend
whole-heartedly.
The version I bought was hardback, published by Hodder &Stoughton, ISBN 0 340 89589 6 priced £12.99, although I believe it
has now been released in paperback.

www.geo-web.org.uk

September 2007

Group for Earth Observation

GEO Quarterly No 15

A warm, sunny day welcomed almost 1,000 visitors to the first
RadioActive Show held on the last Sunday in April, where over
90 stands of both traders and exhibitors provided a large crosssection of amateur radio products to satisfy even the mosteclectic tastes and requirements. Visitors travelled from as far
afield as Aberdeen, Swansea, Londonderry and Truro to enjoy
the bright and airy Cheshire venue of Nantwich Civic Hall
where, in addition to the profusion of items on offer andexcellent catering facilities, they were also entertained by talks
and demonstrations given by specialist groups and clubs.
Upon arrival, every visitor received a copy of the Show
programme that also served as the spring edition of Broadcast,the quarterly journal of the Mid-Cheshire Amateur Radio
Society (MIDCARS), the event organisers. Broadcast contains
many interesting articles to suit all levels of differing aspects ofamateur radio, written by a variety of experts. Many visitors
confirmed that it was a worthy addition to their reference
library and an excellent primer for those new to the hobby.
Roger Reeves M0ROJ of MIDCARS said that they were
overjoyed with the visitor numbers and with the many positive
comments received during and after the Show by both visitors
and traders alike. ‘It’s certainly a great reward for all the time
donated and effort made by Club members in arranging theShow and far in excess of our expectations. Many of the traders
have already made reservations for the 2008 RadioActive Show,
which we plan to be even larger and more appealing. We hope
the Show will become one of the premier annual events in theamateur radio calendar.’
RSGB President Angus Annan MM1CCR took advantage of theRadioActive Show to publicly present Arnold Matthews G3FZW
with the RSGB Founder’s Trophy for his outstanding work inpromoting amateur radio.

RSGB President, Angus Annan MM1CCR, presenting theFounder’s Trophy to Arnold Matthews G3FZW, along with
MIDCARS Chairman, Simon Chettle G8ATBThe Mid-Cheshire Amateur Radio Society (MIDCARS) wasestablished over 40 years ago and is an extremely active club foramateur radio enthusiasts. They meet every Wednesday
evening at the Cotebrook village hall, located on the A49 near to
Tarporley in Cheshire, where they have a variety of permanent
amateur radio facilities for all members to enjoy. A programmeof talks and demonstrations is held throughout the year.
The 2008 RadioActive Show will be held on Sunday, February
3, 2008. More information about MIDCARS and the RadioActive
Show can be obtained by contacting Roger Reeves M0ROJ byemail to:info@RadioActiveShow.co.uk

cut power to more 130,000
homes while fifteen thousand
residents had to be evacuatedafter large sections of
Newcastle were flooded withroads cut and trees toppled
over roofs
The most severe storms to hit
the southeast Australian stateof New South Wales for two
years struck during a four day
spell between June 9-12 thisyear. The splendid falsecolour NOAA-18 APT image
sent to us from Australia by
Ken Morgan and reproduced
inside the front cover of thisissue, graphically illustrates
the situation.
Savage 90 kph winds of nearcyclonic proportions swept
through the region, removing
roofs, downing trees andpower lines, while theaccompanying rainfall caused

the worst flooding for 36
years. In the Newcastle
suburb of Wallsend, 200
millimetres of rain fell in just a
few hours.
The gale-force winds whichlashed the NSW coastline
caused ocean swells as highas 18 meters and grounded acoal freighter, the Pasha
Bulker, on a sandbank off
Newcastle. The ship’s 21
Philippino crewmen had to be
winched to safety.
The storm, created by low
pressure systems converging
off the state's mid-north coast,

On Sunday, June 11, some
5,000 residents in the Hunter
Valley, 200 kilometres north of
Sydney, were ordered toleave their homes because offears that the Hunter Riverwould burst its banks. The
Hunter River rose some 10.7
meters overnight, only 70
centimetres below its peak
overflow level.
In the aftermath of the storms,
power crews from New South
Wales and Victoria state had
their work cut out as they
battled to restore power to the
network following its worst
damage in 30 years.

www.geo-web.org.uk

Useful Links
Fred van den Bosch has compiled a
Web Page listing many useful Internet
links. Topics covered include• Weather Satellites• User Groups• Imaging and Processing software• Hardware suppliers• Organisations• Weather satellite home stations• Weather Groups and Forums• University links
You can consult this list at:
http://www.fredvandenbosch.nl/
links.html

7September 2007

Group for Earth Observation

GEO Quarterly No 15

Les Hamilton
An old friend departed from the wxsat airwaves on May 23 this year when the ageing
NOAA-14 satellite was finally taken out of service. This was a sad blow for the dedicatedband of amateurs who still monitored its transmissions, particularly as, even on thisfinal day in service, it was producing some absolutely splendid images. Our front coverimage shows the historic final HRPT image sent down by NOAA-14. This was monitoredby Lawrence Harris from his station in Southampton, and the colour composite image
was produced from raw data he supplied using David Taylor's HRPT Reader software.
NOAA-14 had taken to the skies at aparticularly troubled time for amateur
weather satellite enthusiasts. Readerswith long memories will recall thetroubled saga of the NOAA afternoon(ascending) APT satellites during the
1990s. When NOAA-11 (launched in1988) became due for replacement,
NOAA-13 took to the skies in August
1993 and excellent imagery was received
from the new satellite by enthusiasts
around the world. Then suddenly, just
two weeks following its launch, NOAA-13
completely lost all power and it soon
became apparent that this satellite was
irrecoverably 'lost'.
NOAA swung into action to make readyits successor, NOAA-J, as expediently as
possible and this became NOAA-14
following its successful launch on
December 30, 1994. The NOAA-13
disaster was responsible for breaking thenumbering sequence for the afternoon
satellites: traditionally these had allborne odd numbers; NOAA-14 was thefirst of the even numbered ascending
orbiters which has continued to thepresent.
NOAA-14 has been around for a longtime and endured as the sole reliable
American afternoon APT satellite until
July 2004..
After functioning well for almost double
its design lifetime (nominally 3 years),
NOAA-16 was deployed to take over fromNOAA-14 as the primary ascending
satellite; but after just a few months, its
APT transmitter failed and although
NOAA-16 did become the primary
afternoon satellite, it disseminated only
HRPT.
NOAA-14 was left to carry the flag for
the APT service and was effectively thesole APT afternoon satellite between May
1995 (when NOAA-11 was placed instandby mode—essentially switched off
for all but emergency requirements) and
April 2004, a spell of almost nine fullyears. Figure1 (opposite page) is a colour

composite APT image from NOAA-14,
dating from August 8, 1998. Notice how
dark the land features are compared withthe more modern NOAA satellites! Thisis due to a modified algorithm called
Dual-Slope Gain Transfer which has
been employed in the subsequent NOAAKLMN satellites [1] in order todiscriminate land features more
effectively.

Figure 2
HRPT telemetry dating from June 29, 2005
showing the complete absence of AVHRR imagery
Telemetry file:NOAA CLASS Archive

In mid-October 2001, degraded imagery
from NOAA-14 suggested a problem withthe satellite's AVHRR scan motor. The
following month, the scan motor started
to exhibit anomalies: drawing an
unusually high working current anddisplaying synchronisation problems.
This was alleviated somewhat byintroducing a daily resynchronisation
procedure, but intermittent sync.
problems persisted throughout the yearthat followed although HRPT continued
to be disseminated, albeit with varying
degrees of distortion in its images.
Matters came to a head on April 14, 2004
when, in an effort to resolve thecontinuing high scan motor currents andassociated loss of synchronisation, NOAA
decided, contrary to the manufacturer’s
recommendations, to try and switch off
the motor (which was still working but
with high torque etc) and then reactivate
it.

Figure 3
Imagery starts to return to the NOAA-14 HRPT
telemetry stream (04:02 UT on July 17, 2005)
Telemetry file:NOAA CLASS Archive

But when they attempted to switch it
back on again (the first time such a
procedure had ever been attempted) the
result was the worst possible scenario—
because the motor simply would not restart. With the scan motor now seized upcompletely it was assumed that thisrepresented the final end to imaging fromNOAA-14, and the APT data stream was
switched off, ostensibly for good.
Nevertheless, HRPT telemetry continued
to be relayed to the NOAA Class
Archive [2], where it remains on file tothis day. Interested readers can still
download HRPT telemetry files from thisperiod though processing (with HRPT

www.geo-web.org.uk

Figure 4
Image synchronisation returns to NOAA-14
HRPT telemetry (19:31 UT on July 17, 2005)
Telemetry file:NOAA CLASS Archive9

GEO Quarterly No 15

Group for Earth Observation

September 2007

Reader) reveals no actual imagery
to be present. Figure 2 shows asection from such a telemetry filedating from June 29, 2005.
Then, completely out of the blue
and without human intervention,
NOAA-14 unexpectedly started toshow signs of imagery once moreon July 16, 2005. Perhaps cyclesof heating and cooling as thespacecraft continued orbiting the
Earth had released whatever was
jamming the scan motor. Soon,the motor current andsynchronisation were clearlyrecovering and partial imagery
was restored. Figure 3 comes froman ascending NOAA-14 pass over
Alaska early on July 17 andclearly displays detail from both avisible and an infrared channel
although the synchronisation is
askew. On a descending passmuch later the same day, imagery
is perfect and synchronisation is
spot-on (figure 4).
In the wake of this turn of events,
NOAA actually reactivated the
APT stream for test transmissions
between July 28 and August 2,
though, unusually, these
consisted of a pairing of two
infrared images from channel-3
and channel-4. APT was thenswitched off, presumably because
NOAA-18 was by this time
providing afternoon APT.
Since that time, NOAA-14 hascontinued to provide some superb
HRPT images, though continuing
to alternate between spells ofsynchronisation loss. But with
NOAAs-12, -15, -17 and -18 plus
Metop-A all currently providing
high-quality HRPT, it wasapparently decided that the time
had come to remove NOAA-14
from service. Accordingly, thesatellite was successfully
decommissioned on May 23, 2007.
This involved turning off
transmitters, de-programming theCPU, disconnecting the battery
charge paths and moving thesolar array away from the sun,which, collectively, should ensurethat there is no sporadic
interference with the other APT
satellites (as has been recorded
from TIROS-N, NOAA-6 andNOAA-9).
Acknowledgement
Thanks to Douglas Deans forhelpful discussion in the
preparation of this article.
References
1 NOAA-12 Reborn, Les Hamilton,
GEO Q4, December 2004, p 20.

2 http://www.class.noaa.gov/

10

Arne van Belle and David Taylor
Last issue we published an account from Mike
Stevens relating to problems he experienced
when attempting to set up a RAM Drive for his
EUMETCast system and how he had devised aworking solution using an external USB hard
drive. Mike’s efforts produced considerable
interest, but two of the leading exponents in thefield expressed concerns that, in the long term,
this approach could face future pitfalls. There are
doubts that a USB drive, which is inherently
slower than an internal hard drive, will be able tokeep pace as the EUMETCast data stream
continues to burgeon in the months and years
ahead. There is also a known problem that USB
drives which run continuously are notoriously
short-lived. Arne van Belle and David Taylor, bothof whom have tested the AR Soft RAMdisk
extensively, comment below.
Arne van Belle
The article from Mike Stevens surprises me. I feelvery sorry that Mike lost his complete Windows
configuration after setting up a RAMdisk. But
based on his report I am sure that this was notcaused by the AR Soft RAMdisk. I feel that thiswas most likely due to manually editing theregistry in such a way that Windows judged it tobe corrupt and reverted to the status after its first
install! It’s really a pity that Mike did not mention
any of this problem on the lists as I could havegiven him advice on restoring his lost registry andimproving his system.
The AR Soft RAMdisk does suffer from one or two
well-documented issues on XP and Vista. You
have to disable System Restore for the RAMdisk
and if you set the slider too high, it will not load or
produce a RAMdisk that is smaller than set. I havedone many, many tests involving the AR Soft
RAMdisk, from Windows 2000 up to and including
Vista, and only once have I found Windows failingto load properly. And even that case was easily
resolved by booting into Safe Mode and selecting
a smaller size for the RAMdisk.
I am almost 99% certain that Mike’s problem iscaused by the fact that AR Soft will behave
strangely when you have less memory (Mike has 1
GB) and try to set a large RAMdisk (over 73 MB).
The RAMdisk will simply fail to load at all (andTellicast will immediately abort after a reboot as
Mike describes—but Windows is unharmed) or
create a Z: drive that has less capacity then that
set with the slider.
If you don't check the created RAMdisk size you
will get lost segments as Tellicast restarts, when it
can no longer write to its expected size. Of course,with a backup of his Registry, as described in
GEO, Mike would have been able to restore
everything. You should always create a Registrywww.geo-web.org.uk

backup before editing your Registry.
And do not install the RAMdisk on
Windows XP or higher without applying the
System Restore fix first.
If you are not confident about editing theRegistry you could consider buying a
RAMdisk like Superspeed or Qsoft, neitherof which requires Registry editing. But nomatter which RAMdisk software you use,always verify the free space on the
RAMdisk after creating it. Only then can
you set the correct file database size inyour recv.ini file
The inventive way Mike chose to receive
without using a RAMdisk is unfortunately afar poorer solution. He uses an external
USB disk which will lead to more problems
than the default EUMETCcast installation
which doesn’t use a RAMdisk. I am
amazed that, despite of this, he is able toget good results. Even the fastest USB 2.0
portable disks can only reach about half the
speed of a built in IDE disk. For MetOp weneed the best performance a disk can give.
Whilst Mike’s solution works for him, myadvice (and that from EUMETSAT)
continues to be to use a RAMdisk where
possible as a performance enhancement
technique for coping with he very high data
volume now seen on EUMETCast.
Based on multiple cases at my work, I
have to warn against this use of USB
disks. We have had multiple crashes ofthese disks (manufactured by Seagate
and Maxtor) with total loss of all data.
Many external drives do not provide
enough cooling to the disk. In particular,when you run these external disks formany hours continuously, you can ‘cook’
the hard drive. And we find that glitcheson the USB bus are happening far more
frequently than with internal drives.
David Taylor
I completely support Arne’s comments. We
have developed the RAMdisk solution over
the years and I have complete confidence
in it: I’m using it on three PCs here. There
are one or two well-documented issues,
although they aren’t apparent here.
The last thing most people should be doingis tampering with a working system. Rulenumber one is: ‘If it works, leave it!’September 2007

Group for Earth Observation

GEO Quarterly No 15

Peter Wakelin

This final part in the series looks at how radar altimetry works:
the improvements made since the Skylab mission, Envisat’s
radar altimetry system, and finally a look at some of the results
derived from radar altimeters.
Basic Principles
A radar altimeter on a satellite, typically orbiting at an altitudeof 800 km, transmits pulses vertically downward and measuresthe me taken for an echo from the Earth’s surface to return tothe satellite. This interval can be measured to a high precision
and, as the pulse travels at the speed of light, the distance
between the satellite and the surface can be determined withgreat accuracy.
Although the speed of light in a vacuum is precisely known,
radar pulses passing through the atmosphere are retarded veryslightly and not always to the same degree. Dry air effectively
increases the satellite/surface distance by about 2.3 metres but
atmospheric moisture can increase this further by up to 30 cm.
Ionisation in the upper atmosphere also slows the pulse by avariable amount depending on the time of day and solar
activity, and also on the radar frequency used. However, byusing two radars operating at different frequencies, the error
from this cause can be accurately compensated for.
The ultimate aim of radar altimetry is to measure altitudes ofsea, ice or land surfaces relative to a terrestrial reference frame.
It is not sufficient to know only the surface-to-satellite distance;a precise knowledge of the satellite’s position is also essential.
This reference frame may be the ellipsoid (figure 1), which
would equate to mean sea level if there were no gravitationalvariations around the globe. These irregularities in Earth’s
gravitational field cause the actual mean sea level, the geoid, todepart from the ellipsoid by around ± 100 m. The geoid itself isdistorted by topography, dynamic forces such as tides, winds
and ocean circulations caused by the Earth’s rotation to form
the actual surface.
Modern altimeter-carrying satellites also carry equipment toaccurately determine the spacecraft’s orbit to a high precision.
For example, DORIS (Doppler Orbitography andRadiopositioning Integrated by Satellite) and PRARE (Precise
Range And Range-rate Equipment) instruments enable theposition of the altimeter to be determined to within a few
centimetres. Many satellites also carry a small corner reflector
enabling laser-ranging techniques to determine distances tobetter than one centimetre but with few laser ranging stations,which can operate only in clear sky conditions, thesemeasurements are mostly used to calibrate the other
instruments.
Thirty Years of Evolution
The first radar altimeter was flown on the massive 70-tonne
Skylab 1 orbiting laboratory launched on May 14, 1973. It
demonstrated that radar altimetry from orbit was not only
possible but that the precision achieved exceeded expectations(even though the accuracy in those days was no better than one
metre). The first scientific altimeter mission was flown on the
Geodynamic Experimental Ocean Satellite (GEOS-3) launchedon April 10, 1975. This demonstrated that flat land and ocean

Figure 1 - The ‘Ellipsoid’ Reference frame

could be profiled but, at 50 cm, the accuracy was too low forserious scientific work. Accuracy improved to 30 cm when
SeaSat was launched on April 10, 1978 but this spacecraft
failed after operating for little more than three months. A
similar accuracy was achieved by the US Navy’s Geophysicaland Geodetic Satellite, GEOSAT, which was launched on
March 13, 1985 and remained operational for about four years.
The real breakthrough in accuracy
came in the 1990s with the launch ofEurope’s ERS satellites and the
US/French Topex/Poseidon mission
followed later by Jason-1.
The Russians took an interest in
geodesy very early in the space age,probably due to the need to know
precisely the location of their missile
launch sites. Initially they used
simple triangulation bysimultaneously photographingsatellites from two or more locations,and it was not until Cosmos 1589
was launched in 1984 that an
operational radar altimetry
Figure 2
programme began. Most Russian
Russia's GEO-IK spacecraft
launches were given a cover-all
Cosmos number in an attempt to hide their role and it was
many years later that Cosmos 1589 was identified as GEO-IK 1.
This satellite operated for 15 months and was followed by eight
more in the following 10 years. Surface measurements were
accurate to about 60 cm. All the GEO-IK craft orbited at about
1,500 km altitude, far higher than other radar altimeters.

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September 2007

Figure 3
The radar altimeter being installed on Jason-2.
Launch is scheduled for June 2008.

Not only has the hardware improved over thirty years but so
has the ability to analyse and interpret the returned echoes. For
example, it was soon realised that, when measuring sea surface
heights, more of the return echo came from the troughs of the
waves than the crests. Revised algorithms now enable heights
in quite rough seas to be measured almost as accurately as incalmer conditions. More recent developments now permit theheights of quite small lakes and even rivers to be measured
accurately with obvious benefits.
Envisat’s Altimetry System
ESA’s polar satellite for environment monitoring, Envisat, waslaunched on March 1, 2002 and follows the very successful
ERS-1 and ERS-2 satellites. ERS-1 was launched in 1991 andoperated until a year after ERS-2 was launched. ERS-2 is stillworking and has now passed 10 years of flawless operations.
Data comparisons during these operational overlaps enable any
small calibration discrepancies to be quantified andcompensated for.

Figure 5
Envisat's Laser Retro-Reflector
Credit: Aerospatiale

The RA-2 is a dual-frequency altimeter operating at 3.2 GHz
and 13.575 GHz. The pulse repetition frequencies are 448.83 Hz(for S-band) and precisely four times that for Ku-band, allowinginterleaved operation. Over oceans the high-precision
measurements are used to determine the surface topography,
thus supporting studies of ocean circulation, bathymetry,gravity anomalies and marine geoid characteristics. Processingof the radar echo power and shape enables the determination ofwind speed and significant wave height. RA-2 is also able tomap and monitor sea ice and polar ice sheets. New features ofRA-2 enable it to extend its measurements of altitude andreflectivity over land. It also includes an auto-adaptive tracker
capable of switching to any one of three bandwidths to achieve
improved accuracy at the highest resolution. To further improve
the accuracy, Envisat carries a microwave radiometer to enable
corrections to be applied to compensate for the effects ofatmospheric water in the path of the altimeter signal.
Envisat carries DORIS, a microwave doppler tracking systemfor precise orbit determination (figure 4). DORIS accurately
measures the doppler shift of radiofrequency signals
transmitted from beacons on the ground. Two frequencies areused so that propagation delays in the ionosphere can be

12

Figure 4
DORIS omnidirectional antenna

Figure 6
Global sea-level rise since 1992

Credit: CNES

Credit: CLS/LEGOS

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September 2007

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GEO Quarterly No 15

determined and corrected for. Doppler shift measurements are
made every few seconds enabling orbit determination to an
accuracy better than 5 cm in altitude.
Envisat also carries a laser retro-reflector (LRR) to support
laser-ranging altimeter calibration (figure 5). Situated near thealtimeter antenna, its array of precision-made corner-cubesreflect a pulsed laser beam back to the originating laser-ranging
station where the round-trip time is measured.
Some Results from Radar Altimeters
It will come as no surprise to learn that ice and sea surface levelmeasurements make up the bulk of data derived from radar
altimeters. Accuracies have improved to such an extent thatchanges to ice and sea levels are easily detected over shortperiods of time. The Topex/Poseidon mission was the first to
have sufficient accuracy to detect the variation in sea level due
to seasonal temperature changes—which amount to several
centimetres between spring and autumn in temperate latitudes.
The diagram shows changes in global mean sea level since
October 1992 after the removal of seasonal effects andcorrections applied for atmospheric pressure variations. An
average annual rise of almost 3mm has occurred over the last
15 years.
The Aral Sea, bordering Kazakhstan and Uzbekistan, has been
drying up for the past 50 years since large-scale extraction ofwater from the two main rivers feeding it has been used toirrigate cotton-growing areas set up in the region. Being mostly

Figure 7
The Aral Sea is drying up
Credit: CNES/LEGOS

shallow, the drop in water level has reduced the surface area
dramatically and divided the sea into the Big Aral and Little
Aral. The town of Aralsk, once on the shore, is now nearly
30 km from the water. Topex/Poseidon measurements show thatBig Aral’s surface has dropped by almost 7 metres since 1992.

Cover and Full-Page Images
Front CoverThis is the historic NOAA-14 AVHRR image acquired by
Lawrence Harris on May 23, 2007 during the satellite’s final
pass over Britain prior to being decommissioned. Read moreon page 9.
Image: Lawrence Harris

Inside Front CoverKen Morgan from Victoria, Australia sent us this breathtaking
NOAA-18 APT image of eastern Australia, acquired on June 6
this year, which shows the storm which caused the severe
flooding of the Hunter River, its valley and the city of
Newcastle.
Back Cover
Anthony Lowe from St Helens, Merseyside acquired thissuperb APT image from the 12:34 UT NOAA-18 pass on May
2, 2007. Equipment used was an AOR 5000 scanner with acrossed dipole antenna mounted at approximately 5 metres.
WXtoImg was used to capture and process the signal. The
image dates from the long spell of high pressure that broughtsummer early to much of Great Britain but shows thepersistent haar (sea-fog) that bedevilled the east coast for dayson end.
Page 30
Keith Fraser of Buffalo, New York sent us this NOAA-12 APT
image dating from 22:44 UT on June 19. A low pressure area
centred on James Bay had generated a cold front which wasjust passing overhead at his location at the time of acquisition.
New York city and the East coast were in the firing line of aline of violent thunderstorms which left trees and power lines
down.
Page 33
The lower course of Russia’s Ob River is captured in this
MODIS (Moderate Resolution Imaging Spectroradiometer)
image from NASA’s Terra Earth observation satellite. You canread more about this scene on page 47.
NASA image courtesy Jeff Schmalz (MODIS Rapid Response Team)

Fires on the Balkan peninsula on July 25, 2007, as captured by the MODIS
instrument flying on NASA’s Aqua satellite (see page 3).
Image: MODIS Rapid Response Team at NASA/GSFC

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September 2007

John Tellick

Figure 1 - The current GEONETCast Service Areas

Readers may recall the failure during early commissioning of
one of MSG-1’s solid state power amplifiers (SSPA) in October
2002. An enquiry board investigating the failure decided inearly January 2003 not to risk failure of the other SSPA's (theimaging downlink was operating correctly) by disseminatingprocessed data via the satellite as direct read-out services.
EUMETSAT were therefore obliged to seek an alternative
method to disseminate the 12-channel SEVIRI data from thisnew generation satellite.
The Origins of EUMETCast
EUMETSAT had already been evaluating data dissemination
via a commercial TV satellite during 2003, transmitting NOAAATOVS (Advanced TIROS Operational Vertical Sounder) data,and it was proposed to experiment using this same downlink for
MSG data. Tests, adding MSG-1’s HRIT data to the ATOVS
stream on this Ku-band downlink from the Hot Bird-6 satellite
began in April 2003, using the DVB (Digital Video Broadcast)industry satellite TV format.
These data transmissions could be received with cheap off-theshelf satellite TV equipment on a computer (PCI card or USBbox) fed from an 85 cm offset satellite TV dish with Universal
LNB, across most of the European footprint. A 1.8 metre dishwas required for the easternmost European areas, the Middle
East and western Russia (figure 1).
Tests, which ran throughout 2003, and in which many GEO
members took part by feeding useful logistical and operational
information regarding reception experiences on differing set-ups

14back to EUMETSAT, were a tremendous success. During thetest period more and more data were added to the stream which
proved its expandability, ruggedness and reliability, and
EUMETCast went operational in January 2004.
The rest—as they say, is history and the Ku-band European
service now disseminates some 55 gigabytes of data daily.
Extending EUMETCast Coverage
The first generation Meteosat satellites operated a 2 channel
L-band direct read-out service providing PDUS and WEFAX.
The footprint was of course hemispheric as seen from 0°, as
would have been the footprint for MSG’s 2-channel HRIT and
LRIT direct read-out services. Africa and much of SouthAmerica would therefore be without the new 12-channel
SEVIRI data following MSG-1’s SSPA failure and thecurtailment of direct read-out dissemination. These regions didof course at that time still have direct read-out PDUS andWEFAX services from Meteosat-7.
EUMETSAT are obliged to provide meteorological data services
to Africa. Indeed, the EU had already equipped African nations
with HRIT/LRIT reception equipment under the PUMA
agreement (Preparation for the Use of MSG in Africa), so had toconsider yet another means to provide them with MSG’s newhigh resolution digital data. The Ku-band service footprint fromHot Bird-6 covers only Europe, the Middle East and parts ofwestern Russia (figure 1).
Owing to the frequent heavy rain storms over many parts ofAfrica, Ku-band transmissions would suffer badly from rain-

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GEO Quarterly No 15

Figure 2 - The GEONETCast/EUMETCast System Overview

fade; so C-band transmissions had to be used—and a satellitewith a large C-band footprint over Africa identified..
The C-band Services
EUTELSAT’s Atlantic Bird-3 stationed at 5°W was chosen andtests which began in late 2003 proved successful. The Africa
service became operational during 2004.
The C-band footprint for this service covers a very large area,
resulting in lower signal levels which require much bigger
dishes than for the Ku-band service. EUMETSAT recommend aminimum 2.4 metre dish although a GEO member is South
Africa has achieved good quality and consistent results using a
1.8 m dish with this service.
With the termination of Meteosat-7’s PDUS/WEFAX services
following the successful launch and commissioning of MSG-2,
South America would have lost its access to direct ‘Meteosat
Atlantic data’—as would parts of the eastern seaboard of theNorth America. So, another link in the EUMETCast service was
set up, a C-band service covering the whole of South America
and much of North America, from the New Skies satellite
NSS-806 situated at 40.5°W. This C-band service also requires
a dish between 1.8 m and 2.4 m depending on the receiving
location within the NSS-806 footprint.
The EUMETCast Data Chain
The data chain for EUMETCast services (figure 2) is as follows:• EUMETCast-Europe is uplinked from Usingen, Germany(Deutsche Telekom) to Hot Bird-6.
• This service is received by EUMETSAT’s Fucino groundstation in Italy and an Africa-specific subset of the data is
uplinked (Telespazio) to Atlantic Bird-3 for transmission of
the C-band EUMETCast-Africa service.
• The Hot Bird-6 Ku-band European service is also received
by a ground station in Madrid and relayed to a groundstation in Paris where an Americas specific subset of thedata is uplinked (Globecast) to NSS-806 for the
EUMETCast-America C-band service.
GEONETCast
The extensions to EUMETCast are Europe’s contribution to the
GEONETCast system, instigated in 2005 by the Group on Earth
Observations (GEO) and to be completed in 10 years. This will
be a global meteorological data dissemination service,disseminated via commercial satellites; it will provide roundthe-clock continuous, reliable global data to end-users justminutes following acquisition, and ‘requiring only off-the-shelfsatellite receiving equipment and standard personal computers.’
The Chinese Meteorological Administration (CMA) has begun a
pre-operational service called FengYunCast, their contribution
to GEONETCast via the AsiaSat-4 satellite at 122°E, also on
C-band in DVB format. Its footprint covers a wide area: thewhole of Asia, part of the Western Pacific and into the Middle
East and most of Russia (figure1). It relays data from FY-1D,

FY-2C, NOAA, MODIS on Terra and Aqua, and MTSAT.
America are currently developing a GEONETCast-Americas
DVB service which will cover both North and South America
Regarding EUMETCast-America and GEONETCast-Americas, I
received the following details from EUMETSAT in early May:
‘GEONETCast-America and EUMETCast-Americas are at
the moment complementary to each other, since they coverdifferent kinds of data. NOAA is currently not intending toinclude/cover the data on EUMETCast-America in theirplanned GEONETCast-Americas system but focusesinstead on products only in particular, the nonmeteorological society benefit area ones. The continuationof the operation of EUMETSAT’s EUMETCast-America
service beyond the initial period depends on EUMETSAT
delegate body decision.’
As to the ongoing data content of the expanding GEONETCast
services:‘Data exchange between the three GEONETCast Network
Centres (GNC) (NOAA, EUMETSAT, CMA) is currently
being discussed with a view to cover all nine societal
benefit areas as defined by GEO.’
It seems that GEONETCast was destined to happen anyway?
This form of distribution of meteorological data via commercial
satellites had been suggested by CGMS (the World
Meteorological Organisation’s Coordination Group for
Meteorological Satellites) for many years. But it was
EUMETSAT who, through adversity, pioneered the way to a
new multi-cast data distribution system and proved it to bereliable, rugged and expandable; and the big bonus for the user
community is being able to utilise inexpensive, off-the-shelfdomestic satellite-TV reception equipment.
Acknowledgements
I should mention T-Systems, Deutsche Telekom and Telespazio
who also played a part in this development and the provision of
the service links plus, of course, David Taylor for his brilliant
suite of processing and display software and Rob Alblas for his
free XRIT2PIC processing/display software.
The EUMETSAT website at www.eumetsat.int has a full page of
GEONETCast information regarding the various providers andservices as well as links to further relevant documents. Just
enter ‘geonetcast’ in the ‘Search’ field and click ‘GO’.
Thanks also to EUMETSAT for help in preparing this article.

References
1 Group on Earth Observations
http://www.earthobservations.org/

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GEO Quarterly No 15

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September 2007

David Taylor

During May and June 2007 we bade goodbye to an old friend, only
to welcome it back again shortly after. Meteosat-8, which waslaunched in 2002, has been providing operational data for the 0°
European and African sector since 2004 (and before that,commissioning data since April 2003 as ‘MSG-1’). For many of us,
this was our first introduction to EUMETCast—the highly
successful, low-cost dissemination system adopted after one of
the MSG-1 power amplifiers failed. What good fortune thatturned out to be!
Well, all good things come to an end, and with the successful
launch and commissioning of MSG-2 (Meteosat-9 in production),
it became time (in May 2007) for MSG-1 to become a hot standby
0° satellite, in case of faults with MSG-2. Figure 1 opposite shows
the final image disseminated by MSG-1 on that date.
However, it turned out that EUMETSAT had other plans for
MSG-1. The Convective and Orographically-induced
Precipitation Study (COPS) has procured a three month periodof 5-minute rapid scans from Meteosat-8. These rapid scans are
made possible by reducing the scan vertically so that a region
smaller than the whole globe is covered. Figure 2 shows thevery first Rapid Scan image from Meteosat-8 (processed to falsecolour with the GeoSatSignal software).
You can see the cessation of full-scan MSG-1 data at the middle
of week 19 in figure 3. The same EUMETCast throughputmonitoring graph also shows the start of the rapid-scan MSG-1
data in week 22, immediately following the red line whichmarks the start of June. This particular PC receives both
MSG-1 and MSG-2 data, as well as EARS AVHRR data, hence
the approximate halving of the data throughput while MSG-1
data was not being disseminated.
What Software is needed for the new Rapid Scan Data?
You need no new software, although you may need the mostrecent updates. You will need to ask EUMETSAT to be added tothe service (if it is still running at the time of publication).
TelliCast software
The only change required for the TelliCast software is the
addition of a line to the recv-channels.ini file to allow receptionof EUMETSAT Data Channel-5. Here are before and after
examples:Before:[EUMETSAT Data Channel 3]target_directory=D:\ECast\received
After:[EUMETSAT Data Channel 3]target_directory=D:\ECast\received[EUMETSAT Data Channel 5]target_directory=D:\ECast\received56

16

Of course, your directories will differ from the examples I give
above, but I hope you see the idea. You must point the new data
to a different directory than that used for existing data.
Processing software
Although the MSG Data Manager software had been aroundsince the very early rapid-scan tests during the commissioning
phase of MSG-1, my other software had not; so an early task
was to update the MSG Animator software to handle the more
frequent scans. This was done as soon as the new data wasavailable, which means that many enthusiasts have been
enjoying the super-smooth animations which the 5-minute scansmake possible. A beta version of the new MSG Animator
software may be downloaded here.
http://www.satsignal.eu/ => Software, Beta Versions

Look for version V2.5.8.187 or later. This may even be areleased version by the time you read this.
To handle both the production Meteosat-9 and the Rapid Scan
Meteosat-8 data on the same PC requires that you run two
instances of the MSG Data Manager (so that the files andsettings don’t get mixed up).
Copy all the files from a working MSG Data Manager directory
to a new directory (I suggest you name it MsgDataManagerRS).
Rename the MSG Data Manager files in that directory to, forexample:MsgDataManager-RS.chm
MsgDataManager-RS.ESN.lng
MsgDataManager-RS.exe
MsgDataManager-RS.FRA.lng
MsgDataManager-RS.ITA.lng
MsgDataManager-RS.ntv.lng
MsgDataManager-RS.RUS.lng
Now you can run the renamed MSG Data Manager and set it up
to point to the new source directory for the channel-5 data, andselect the HRIT channels you want to process.
Processing all twelve HRIT channels requires about 250 MB ofmemory for the second MSG Data Manager instance, but you
can reduce that footprint by processing fewer channels.
For further information on COPS see
http://www.uni-hohenheim.de/cops/

Reader’s Letters
Remember, we are always pleased to receive readers’thoughts, comments and queries for our ‘In Tray’ letters page.
Forward these to the editor or any member of theManagement Team. Contact details appear on page 1.

www.geo-web.org.uk

September 2007

Group for Earth Observation

GEO Quarterly No 15

Figure 1 (Top)This was the final
primary transmission
from Meteosat-8,
received at 09:48 UT on
May 10, 2007,
immediately prior to thesatellite being
designated the standby
0° satellite.

Figure 2 (centre)

This is the first rapid
scan frame received from
MSG-1 at 09:55 UT on
June 1, 2007.

Figure 3

This is a ‘monthly’ graphof throughput (two-hour
averaged) showing theperiod when MSG-1 was‘silent’.

www.geo-web.org.uk

17

GEO Quarterly No 15

Group for Earth Observation

September 2007

Fred van den Bosch
Since the end of May this year, thenumbers of missing MSG-segments andMetop chunks I was receiving had
decreased greatly:• MSG: from 2 to 15 per quarter-hour
to 0 (zero!)• Metop: from 5 to 20 per day toalmost none (a maximum of just 1-2
per day)
I explain below what I have done, which
has also appeared in a number ofmessages on the MSG-1 forum [1]. Someobservations by David Taylor [2] and Arne
van Belle have been included in what
follows.
Reasoning and Adaptation
While testing the reception of Metop
HIRS, MHS etc. I was experiencing someproblems and Arne van Belle provided
me with a copy of his own
recv-channels.ini file for comparison. I
found a number of small differences andadapted my own file to match Arne’s. The
differences were:

My old file:• I used 2 folders for all reception:‘received’ and ‘received-AVHRR’• I saved the files in ‘C:\Program
Files\ T Systems\BusinessTVIP\received’. This file contained
only ‘target_directory=received’ so
did not contain the complete path.
• ‘allow_execute=1’ was active
The new file
• Each type of Metop file has its own
folder. I did likewise for MSG-1 datachannels 1-3. MSG Data Manager
has accepted this since v 1.3.4(March 2004) and it has been
documented in its Version History.
• The Target folder is now‘C:\Ecast\xxxx’, where ‘xxxx’ is, forexample. DWDSAT, EPS10 etc. I
have used the full path.
• A ‘#’ symbol has been placed before‘allow_execute=1’ (commenting out
the command). Both David Taylor
and I doubt whether this commandhas any influence.
ExampleTo indicate how the new file looks,
figure 1 shows part of my recv-

18

channels.ini file. The complete version
can be obtained under ‘General Files’
from the download page of my website [3].
Some Observations
Files which are sent with a lower
frequency all go into one folder, like the
SAF data, for instance. Files with ahigher frequency, like MSG datachannels 1, 2 etc, get their own folder.
Personally, I have chosen to use the full
path. The advantage of this is that you
see rapidly where the file has been
written. It is also possible to use only thename of the folder in ‘target_directory’;e.g. ‘target_directory=EPS-3’. To do so, aline with ‘tmp_directory= C:\Ecast’ must
be incorporated into the recv.ini fileunder [Parameters].
Saving files in ‘\Program Files\’ is, forseveral reasons, a bad idea:• it can cause problems when you
upgrade to Windows Vista• if Windows crashes, all your data
will be lost.
The best solution is to put all data on a
separate hard disk and not on separate
partitions. For example,[EUMETSAT Data Channel 1]
target_directory= F:\Ecast\MSG\Data Channel 1

The advantage of this solution is that theread/write head will always stay in theneighbourhood of the data and therefore
does not have to move so much. The more
movement, the greater the delay inreading the data.
The second best solution is to place alldata on separate partitions, the only
solution if just one hard drive is present
in your PC. Personally, I have not done
this for the Tellicast data, which is saved
on my C\: drive. My main idea here wasthat should Windows crash, I would losea lot of data for a longer time—so those
few segments would be of little
importance. All other data is of course
saved on D:\.
Arne for instance, receives 40+ GB per
day on a 3 GHz Pentium-4 using only asingle 250 GB SATA hard drive divided
in a C:\ partition of 20 GB and a D:\
partition of 230 GB.

www.geo-web.org.uk[EUMETSAT Data Channel 1]
target_directory= C:\Ecast\MSG\Data Channel 1[EUMETSAT Data Channel 2]target_directory= C:\Ecast\MSG\Data Channel 2... ditto 3 & 4[SAF-Europe]
target_directory= C:\Ecast\MSG[SAF-Americas]
target_directory= C:\Ecast\MSG... ditto Africa[DWDSAT]target_directory= C:\Ecast\MSG# [EPS-1]# target_directory= C:\Ecast\EPS - 1[EPS-2]target_directory= C:\Ecast\EPS - 2[EPS-3]target_directory= C:\Ecast\EPS - 3... ditto 4 to 18

Figure 1 - Part of the recv-channels.ini file

I have a 2.67 GHz Pentium-4 with a
250 GB hard disk divided into a C:\
partition of 15 GB and a D:\ partition of
235 GB.
Finally
I had never expected that these small
modifications would have such a large
impact. Should you modify your own‘recv-channels.ini’ file, please do so insmall steps and let us know the result. I,
and undoubtedly many others, are very
interested as to which of the above points
really ‘do the trick’. And finally a note
which has appeared most often on the
different forums:‘If your system is working well,please leave it well alone!’
References
1 MSG-1 forum, messages 9799– 9803
http://tech.groups.yahoo.com/group/
MSG-1/
2 David Taylor, http://www.satsignal.net/
3 Fred van den Bosch,
http://www.fredvandenbosch.nl

September 2007

Group for Earth Observation

John Tellick and David Taylor
Earlier this summer, over twelve months of preparation finallycame to fruition when forty-two delegates from throughout
Europe and the UK assembled for a meeting at EUMETSAT’soperations headquarters in Darmstadt, Germany. The party
was warmly welcomed by Dr Lars Prahm, Director General of
EUMETSAT, who praised GEO’s contribution to furthering theamateur use of EUMETCast. Throughout the hectic two-day
programme of activities, staff and officials at both EUMETSat
and Usingen showed genuine appreciation of GEO’s role in theweather satellite sector and could not have been more friendly
and helpful. John Tellick and David Taylor have prepared thefollowing illustrated report covering the GEO party’s
adventures in Germany.
It’s not often that you enjoy the opportunity to meet so many
fellow enthusiasts from across Europe, people you have come toknow well over many years—but only through the medium of
e-mail. Equally, it’s rare to be afforded the chance to visit theheart of Europe’s weather satellite operations and space
missions. Imagine the thrill of being able to do both: that’s justwhat GEO members did in July 2007!
We met up in the Ibis Hotel (photo 3) in Darmstadt on the
Wednesday afternoon, where Carol Finnis handed everyone
their GEO name badges so that we could put faces to names
hitherto known only from e-mails. This was followed by aconvivial meal at a nearby Greek restaurant (photo 4)—’A tablefor 25, please’ in our best schoolboy German: or was it inholiday Greek?
EUMETSAT Headquarters
Thursday morning dawned damp and dismal but the spirit of
the group was high as we set off on the 20-minute walk to
EUMETSAT Headquarters, the impressive building we werefamiliar with from many photos (see masthead illustration). As
we were congregating outside the building, our cameras clickingaround the life-size models of MSG and Metop satellites, therain finally ceased. On entering the impressive atrium,
complete with a stream containing carp running through it(photo 5) and a large screen display welcoming GEO (photo 6),
we were greeted by Sally Wannop, who impressed us so muchwith her presentation during last year’s GEO Symposium inLeicester.

GEO Quarterly No 15

GEO and its members have made—and continue to make—infurthering amateur use of EUMETCast. EUMETSAT has foundthe technical involvement and feedback from GEO members
and our colleagues from Werkgroep Kunstmanen in the
Netherlands most useful, and it is very much appreciated.
The opening session began with a new video dealing with all
aspects of EUMETSAT operations. Once it concluded, Sally
Wannop brought us up to date with current operational status:
this included investigations into a recent incident where
Meteosat-8 appeared to have suffered a collision from afragment of space debris and news of some exciting new
products and services to comein the not too distant future.
A coffee break in the atrium(photo 14) was followed by afascinating illustrated talkfrom the enthusiastic Jochen
Kerkmann (photo 1), entitledGetting the most out of MSG.
In his talk, Jochum dealt withthe use of RGB formats for
Photo 1 - Jochen Kerkmann
detailing and highlighting
Photo: David Taylor
various meteorological andenvironmental phenomena. There exist both well-known,
operationally used RGB combinations, and some other esotericones that are more experimental in nature. For any RGB
combination, there will be occasions when the precise colour
does not turn out as expected; this means that human skill isstill required for interpretation. However, RGB does offer muchgreater analytical potential than simple single-channel
greyscale images.
EUMETSAT Operational Facilities TourFor many, the highlight of the day was the much-anticipatedtour of EUMETSAT’s operational facilities. The party was split
into three groups because of the large numbers, and we visited
three areas in turn.
We were allowed into the most impressive MSG control room
(photos 2, 9) which contains banks of monitors detailing all
aspects of the MSG satellites’ parameters,operations andOn our seats in the hallowed ground of the EUMETSAT Council
Chamber we each found a goody-bag packed with technicalpublications and brochures for the day ahead. This included asplendid Metop image of Europe and the UK, specially printed
with the heading ‘To commemorate the visit of the Group for
Earth Observation to EUMETSAT on 5th July, 2007’.What a
start! As we settled in, we were welcomed by Francis Bell(photo 7) before Sally Wannop officially opened our visit byintroducing EUMETSAT Director General, Dr Lars Prahm.
Dr Prahm welcomed us most warmly (photo 8) with some highly
complimentary remarks about GEO: the quality and content of
GEO Quarterly, which he reads, plus the important contribution

Photo 2 - The EUMETSAT MSG Control Room
Photo: Arne van Bellewww.geo-web.org.uk

19

Photo 7 - Francis Bell welcomes delegates within the EUMETSAT Council Chamber
Photo: David Taylor

Photo 3 - The Ibis Hotel
Photo: David Taylor

Photo 4 - Wednesday dinner at the Greek
Restaurant ‘Poseidon’.
Photo: Arne van Belle

Photo 8 - Director General, Dr Lars Prahm welcoming GEO
Photo: David Taylor

Photo 5 - The Stream
Photo: Cecilia Taylor

20

Photo 6 - ‘Welcome to GEO’

Photo 9 - The MSG Control Room

Photo: Cecilia Taylor

Photo: David Taylor

Photo 10
photo: EUMETSATGEO Quarterly No 15

Group for Earth Observation

imagery. There, Justin Larkins described how EUMETSAT
were currently checking the charging on Meteosat-8 andMeteosat-9’s batteries in preparation for the upcoming eclipse
season. A familiar display (David Taylor’s MSG Data Manager)
was visible on the large monitor above operations.

September 2007

Julia’s talk was followed by François Montagner’s presentation,
Metop: Products and Applications (photo 16). Many GEO
members are already familiar with the high-resolution images
provided by the AVHRR/3 instrument, but Metop offers muchmore, through, for example its GRAS and IASI instruments.
GRAS is a radio occultation sounding instrument whichmonitors the signals from GPS satellites as they rise and set
over the Earth’s horizon to measure vertical atmosphericprofiles for humidity and temperature. IASI, the most advanced
instrument aboard Metop, is an 8000-channel infrared sounding
interferometer, which establishes temperature and water
vapour profiles throughout the troposphere and lower
stratosphere, as well as determining concentrations of tracegases such as ozone, methane and carbon monoxide.
François concluded by touching on areas of interest to the
AVHRR user: the challenge of handling so much data (Metop
dumps a full orbit’s worth of data each time it flies overSvalbard) and the resultant delay in supplying data to end user
stations. Metop direct read-out services are currently notavailable and it is unlikely that the VHF-band LRPT service
can ever be restored. It is possible that the L-band AHRPTservice may be restored (although an attempt to do so during
our visit proved unsuccessful). Nevertheless, there is every
intention to provide these direct readout services on future
Metop satellites.

Photo 11 - The EPS Control Room (Photo: Arne van Belle)

In the EPS control room, which deals with the Metop polarsatellite (photo 11), Gareth Williams guided us round anotherarea replete with monitors carrying information about the
Svalbard ground station and various Metop services. We wereprivileged to have unprecedented access and time for questions
at both control rooms.
Finally, in the Archive Facility, Marc Jenner showed us where
the terabytes (even petabytes) of downloaded data are now dealt
with, and where orders for electronic, digital and photographic
copies of EUMETSAT products are processed (photo 15).
The EUMETSAT building includes a most excellent dining
facility where we broke off for lunch. Not only was the foodexcellent, with a superb choice of quality hot and cold items anddrinks, but the conservatory-like seating area had a really lightand airy atmosphere—with tables reserved for GEO! What agreat opportunity this provided to sit down with fellow
delegates to discuss the morning with EUMETSAT staff andask those questions we forgot during the presentations.
We regrouped for the afternoon session when the opening
presentation came from Julia Figa (photo 12), and was entitled
Jason-2: Measuring Sea Surface Heightfrom Space. Although the considerable
satellite observation data of the atmosphereand land surfaces now available areinvaluable to the meteorologist and forclimate studies, since 70% of the Earth iscovered by oceans, more precise data about
these would add enormously to ourknowledge of their role in climatic
Photo 12 - Julia Figadevelopments.
Photo: David Taylor

Julia explained that some oceanographic data had been
available for several years through the TOPEX/Poseidon
mission and outlined their data services. Jason-2 however, a cooperation between CNES and NASA, will provide unparalleledhigh-precision oceanographic data which will help with
understanding the ocean's role on weather, climate change,
ocean currents and, of course, sea level changes. Julia outlined
the various services to be disseminated by Jason-2 and detailed
her area of involvement, sea surface height measurement, andhow the satellite measures this. Following the launch of
Jason-2, scheduled for 2008, some of this satellite’s data will bedisseminated via EUMETCast.

22

PhotographFollowing a short break for refreshments, all the delegatesmade their way to the atrium for a group photograph (photo 10,
page 21), in which we were privileged to be joined by Director
General Dr Lars Prahm. A full-size version may be downloadedfrom
http://www.satsignal.eu/group-photo.html

After the end of the formal sessions, a small meeting (Photo 18)
was convened between Klaus-Peter Renner and team membersof the EUMETCast system, and some GEO members who had
been participating in system hardware/software testing andproblem solving. This was most useful and productive for allconcerned, with EUMETSAT taking onboard our comments andsuggestions with the possibility of incorporating some of them infuture system upgrades and modifications.
There are some great characters at EUMETSAT, including Phil
Harvey, who suggested the Darmstädter Ratskeller
Hausbrauerei restaurant in the Altes Rathaus (old Town Hall)for dinner on Thursday (photo 19). This is a typical vibrantGerman establishment where they also brew their own beer! We
were delighted to be joined by several EUMETSAT staff, andboth technical and non-technical discussions continued long into
the evening. Nevertheless, we all made the 07:30 start the next
day to board the coach to the Usingen ground station a
few kilometres north of Frankfurt.
Usingen
The weather en-route was at times atrocious and it didn’t lookvery encouraging for our visit. However, as we left the autobahn
and headed into the pleasant fir-tree clad rolling hills leading
towards the picturesque town of Usingen, with its church atop asmall hill, the rain stopped and the sky started to brighten.
Then, through the trees, we got our first sight of lots of dishes: achange from all those computers at EUMETSAT HQ!
As we alighted from the coach, sunny periods began to develop
and skylarks were singing high above the grassy clearings in
the forest where the dishes were located. But ominous slategrey clouds were never far away, providing a dramatic backdrop to the bright white dishes (photo 17).
The visit to the ground station was again brilliant, withcomplete access to the dishes and control room facilities at aleisurely pace. We started off at the two large Meteosat-8 and -9

www.geo-web.org.uk

September 2007

Group for Earth Observationcommand and control dishes (photo 20) and were surprised
when, every now and again, the dish actuators switched on witha clunk. Although a fixed dish is normally used for reception
from geostationary satellites, there is actually enough shortterm movement in these satellites’ orbits to necessitate trackingof these high-gain, narrow beamwidth dishes. The sounds that
we heard were that tracking taking place in real time. Note how
the photo shows the two dishes to be pointed in slightly
different directions. This is not an illusion because Meteosat-9,
the primary operational satellite, is located exactly at 0°,
whereas Meteosat-8 is currently located at about 3.5° west.
We were guided by Phil Harvey and Mohamed Kamel fromEUMETSAT who described the operations at the T-Systems
ground station, where the MSG dishes and facilities are totally
under the control of EUMETSAT via links from the adjacenttransmission tower. The two control rooms house the data
receivers and dish control systems, being split into the Primary
Ground Station (PGS, photo 21) and the Backup Satellite
Control Centre (BSCC). The BSCC is a smaller version of theControl room at EUMETSAT and can, in an emergency, be used
to take control of the satellites when the Main Control Room is
down.
We moved on to another clearing where the T-Systems
EUMETCast uplink dish is located (photo 22). As this uplinkfrequency is 13.827 GHz, the antennas are not especially large;
but as we know, the uplink from this dish to Hot Bird-6
occasionally suffers rain-fade when Usingen experiences
exceptionally heavy downpours, resulting in temporary loss of
the Ku-band EUMETCast service.
The visit completed, we headed back to Darmstadt for lunch,
after which Phil, with the help of some GEO members (finding
the right socket for the plug) actuated the life sized model of
MSG (photo 23) to set it in rotation—though not at the fulloperational speed of 100 rpm!
Tour of ESOCIn the afternoon we were treated to an interesting tour of ESOC
the European Space Operations Centre, where we were split
into two tour groups. The very friendly Dutch lady who guided
us round (photo 24) was impressed by our space-related
knowledge and pleased to meet the large number of Dutch

GEO Quarterly No 15

Welcome Address to theGroup for Earth Observation GEO
by Dr Lars Prahm
On behalf of EUMETSAT, I am very pleased to have theopportunity to welcome GEO members to the EUMETSAT
Headquarters and Operational Centre.
EUMETSAT, through its provision of meteorological satellites
represents a key component of the Global Observing System.
EUMETSAT as a European satellite operator and data provider
plays a crucial role in the delivery of environmental data which isused for all forms of meteorology and climate monitoring. In atime where we more frequently see the impact of climate change
in our every day lives, the GEO members’ contribution, inbringing Earth observation data to the man-in-the-street is mostwelcome. GEO has made a significant contribution to thesuccess of the low cost EUMETCast reception station - I knowthat many members of GEO swell our ever increasing numbersof private users of Meteosat and Metop data and products. Your
interest, enthusiasm and passion for satellite imagery and allforms of Earth observation data is clear to see.
I regularly receive and read your Quarterly journal and I findmany articles both interesting and informative. The quality of the
input from a non-funded, voluntary organisation, such as GEO is
to be highly commended. My colleagues and I also appreciate
the many positive comments you attribute to EUMETSAT and oursatellite missions in the many articles you prepare.
I trust the Agenda prepared for you today will allow you to gain
further insight into our planned activities and additionally, I hopethat you will go away today with a greater understanding of theuse and application of some of the data and products
EUMETSAT provides to the user community at large. The tour of
our Control Centre facilities will allow you to experience at firsthand the nerve-centre of EUMETSATs operational activities.
I see that you are using your time in Germany wisely—I am very
pleased to learn that you have organised a visit tomorrowmorning to the Usingen Ground Station and that you intend to
round off your trip to Darmstadt with a visit to ESA-ESOC.
Once again, thank you for your interest in visiting EUMETSAT
and your continued commitment to the promotion of Earthobservation data for the amateur user. It only remains for me towish you a very successful and enjoyable visit.

Photo 13 - The ESA Control Room
Photo: Arne van Bellemembers in our party! She began with the history of European
space operations and the eventual forming of the European
Space Agency (ESA). A video detailing ESA operations wasfollowed by a visit to the ESA control room (photo 13), from
where European satellites are controlled following theirlaunches from Kourou or Baikonur. As there were no launches
in progress the control room was not manned. We were,
however, able to view the busy control rooms for several active
European satellite projects in operation.

At the end of the ESOC visit it was time to say goodbye to somedelegates who were travelling home that same day. Those of us
remaining enjoyed a splendid dinner in the vast Khan’s
Mongolian restaurant—Chinese and Thai style food. Set meals
were available from the menu or, for 15 (about £10), you could
have the ‘eat as much as you like’ option with a choice of morethan twenty pre-prepared dishes. Alternatively, you could selectyour own choice of ingredients and have them cooked in front of
you on a large griddle (photo 25).
Homeward Bound
Saturday dawned sunny and warm, and we all said our
goodbyes after breakfast. Some of us took the opportunity for afurther look around Darmstadt while others made an excursion
to Heidelberg before heading off to nearby Frankfurt airport.
Everyone agreed that it was a most successful, enjoyable andinformative trip.

www.geo-web.org.uk

Report concludes on page 39 .... more photos on page 24 ...

23

Figure 21 - Primary Ground Station
Photo 14 - Refreshment Break

Photo 18 - Meeting of Hardware/Software Testers

Photo: Cecilia Taylor

Photo: David Taylor

Photo: David Taylor

Photo 22 - EUMETCast Uplink Dish
Photo: Arne van Belle

Photo 15 - David Taylor in the Archive Facility

Photo 19 - Darmstädter Ratskeller Hausbrauerei

Photo: EUMETSAT Staff

Photo: Cecilia Taylor

Photo 23 - Rotating MSG Model
Photo: Arne van Belle

Photo 16 - François Montagner with Sally Wannop

Photo 20 - MSG Command and Control Dishes

Photo: David Taylor

Photo: David Taylor

Photo 24 - Our Dutch Guide
Photo: David Taylor

24

Photo 17 - Dark Clouds at Usingen

Photo 25 - Khan’s Mongolian Restaurant

Photo: Ruud Jansen

Photo: David Taylor

September 2007

Group for Earth Observation

GEO Quarterly No 15

Peter Wakelin

Envisat Images Sargassum Seaweed
The Medium Resolution Imaging Spectrometer (MERIS) on
Europe’s polar satellite for environment monitoring, Envisat,
has, for the first time, detected sargassum, the often dense
vegetation famous in nautical lore for entangling ships. MERIS
uniquely incorporates a 709 nanometre band and it is thiswavelength that has enabled researchers at the Canadian
Institute for Ocean Sciences and at the University of South
Florida to differentiate between Sargassum and other floating
vegetation. A more detailed account of this discovery can befound at:http://www.esa.int/esaCP/SEMHO6ARR1F_index1.html

PMCs over the Arctic imaged by AIM
Credit: Cloud Imaging and Particle Size Experiment dataprocessing team at the University of Colorado Laboratory for
Atmospheric and Space Physics

China Launches Radar Imaging Satellite
China’s recent launch surge continued with the orbiting of its
second SAR (synthetic aperture radar) remote sensing satellite,
Yaogan-2, on May 25. From the northern launch site at
Jiuquan, the CZ-2D rocket lifted off towards a sun-synchronous
642 km orbit and achieved China’s 100th successful satellite
launch since their first orbital mission on April 24, 1970. Somesources claim that the Yaogan series also has a military role
under the codename Jianbing-5. A tiny satellite weighing lessthan 1 kg, developed by Zhejiang University, was also launchedon this mission.

Lines of sargassum in the western Gulf of Mexico
Credit: ESA

AIM Successfully Images High-Level Clouds
The successful launch of NASA’s AIM spacecraft (Aeronomy ofIce in the Mesosphere) was reported in the previous issue(page 23) and within a month the first images of this season’s
Polar Mesospheric Clouds (PMCs) were observed to the north ofEurope. These clouds form at an altitude of approximately
84 km, only in the summer, and only at high latitudes where
mesospheric temperatures are as low as -170°C.
All three instruments on AIM are working perfectly and it isanticipated that early results from the AIM mission will bereported at a major international conference on PMCs and otherhigh altitude layered phenomena to be held in Fairbanks,
Alaska in August.
Further information on NASA’s AIM mission can be found at:
http://www.nasa.gov/aim

Just six days later, another Chinese launch placed Sinosat 3, aC-band domestic communications satellite into geostationarytransfer orbit. It was geostationary over 125°E by June 15.
Much of this information has come from Jonathan McDowell’slaunch reports which are renowned for their accuracy and canbe found at:
http:// www.planet4589.org/jsr.html

Imaging Radar Launched for Italy
United Launch Alliance used a Boeing Delta II to launch thefirst of four COSMO-SkyMed radar imaging satellites for Italy
on June 8. COSMO- SkyMed (Constellation of Small Satellites
for Mediterranean basin Observation), funded by ASI (Agenzia
Spaziale Italiana) and the Italian Ministry of Defence, carries
X-band SAR (Synthetic Aperture Radar) equipment forenvironmental as well as defence and security applications. The

www.geo-web.org.uk

25

GEO Quarterly No 15

Group for Earth Observation

September 2007

COSMO-1
credit ESA

1,700 kg spacecraft will operate in a sun-synchronous orbit atan altitude of 620 km.
TerraSAR-X Launched
The fifth imaging radar satellite to be launched in the past year
took off from Baikonur, Kazakhstan on a Dnepr rocket on
June 15. The 1,346 kg German TerraSAR-X spacecraft iscarrying an X-band synthetic aperture radar imager and wasdeveloped jointly by EADS Astrium GmbH and the German
Aerospace Centre (DLR Cologne).
In addition to the usual ‘stripmap’ mode TerraSAR-X canoperate in ‘spotlight’ mode when a 10 x 10 km scene can beimaged at a resolution of 1-2 metres. This high resolution will
enable scientists to study soil characteristics and even identify
different arable crops, and will also improve the mapping ofurban areas.

The first image from TerraSAR-X radar showing
the River Don near Volgograd
Credit: DLR/EADS

mode, demonstrating a new, promising capability that can
extend portions of a DMSP mission even when critical gyro data
are not available.
concluded on page 44

TerraSAR-X
Credit: EADS Astrium

TerraSAR-X incorporates the Tracking, Occultation andRanging Experiment (TOR) which consists of a dual-frequency
GPS as well as a laser reflector unit to assist in maintaining aprecise orbit. It was developed jointly by GeoForschungsZentrum,
Potsdam and the Center for Space Research at the University ofTexas.
Just four days after launch, and even before the final operating
orbit was achieved, the first test image was received. The image
appeared, to loud applause, on the monitors of the DLR Space
Operations Centre in Oberpfaffenhofen, near Munich, just 30
minutes after receipt of the data by the Neustrelitz groundstation.
DMSP Successfully Operated Without Gyros
The 15th Defense Meteorological Satellite Program spacecraft
has operated successfully for 24 hours in a gyroless navigation

A DMSP satellite
Credit: Lockheed Martin

26

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You can download a PDF version of these predictions from: http://www.geo-web.org.uk/predictions.pdf

September 2007

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Perhaps the best image of the area we have ever acquired is thatshown in figure 3 because, on that May day in 1996, theatmosphere was very dry; all the details a NOAA can see are clear
and sharp. The course of the river Po is visible from the western
Alps to the Adriatic Sea where it drains into a wide delta to thesouth of the Venice lagoon.
Marciano Righini, I4MY and Giampaolo Rossini, IW4CSG

Lake Nasser
When we receive an image of Egypt from a satellite, we areaccustomed to seeing a widening in the course of the river Nile
south of Aswan. The construction of the huge Aswan dam
converted a long stretch of the river upstream into a reservoir.
Figure 1 is a first generation Meteosat HRI VIS image which showsa long lake which is named after President Nasser. The lake isrelatively recent, more recent than the earliest weather satellites.
Have a look at Figure 2: this is a frame from ITOS-1 taken in 1970.
Yes, there is a small lake created by an old dam built in 1902, but
the big Aswan dam was still under construction. It was finished in1971 just in time to avoid the damage of the great drought of 1972.

The picture shows not only the structures of Nature, but also thework of man. A NOAA satellite flying over a flat area always showscities and towns as gray spots, and in this image there are a lot
because the broad plain is densely populated. But we want to callyour attention to an interesting feature: a long straight road running
northwest at the foot of the Apennines, from Rimini on the Adriatic
to Piacenza, for 283 kilometres. This is the Via Emilia (or AemilianWay), a highroad constructed in 187 BC by the consul M Aemilius
Lepidus, whence its name. The road also gives its name to theregion it crosses. Today, parallel with it, are both a railway and a
motorway. The sensor in the satellite can see it because there area lot of built-up areas along the road : factories, stores, houses,
etc.
Figure 4 is a winter IR image where the warm Via Emilia stands
out against the cold countryside. The largest spot is Bologna, thecapital of the region where we live, but Ravenna, our home town,
is not on the Via Emilia; It is located in splendid isolation, ‘Far from
the Madding Crowd’.

Figure 1
Egypt showing Lake Nasser in the course of the Nile (Meteosat HRI visible)
Figure 3
NOAA-10, HRPT, CH.2, 29 May 1996, 16:07 UT.

Figure 2 -A frame from ITOS-1, taken in 1970, before theconstruction of the big Aswan dam.

The Basin of the River Po
Most of northern Italy is occupied by the basin of the river Po, abroad plain whose boundaries are the Alps, the great chain of theApennines stretching from the gulf of Genoa to the Adriatic and the
Adriatic Sea.

www.geo-web.org.uk

Figure 4
NOAA-15, HRPT, CH.3b, 23 February 2003, 17:38 UT.

27

GEO Quarterly No 15

Group for Earth Observation

September 2007

R W Hollander
Reflections of EM-waves play animportant role in the reception ofsatellite signals. It is possible to havevery poor reception with an antenna that
performs very well at another location.
One part of the game is to construct anantenna that is tolerant of reflections;the other part is to find a location wherereflections are minimal.
In calculations regarding reflections of
EM-waves on a surface S, e.g. ground,from a transmitting antenna T, it is often
convenient to introduce a mirror antenna
M (figure 1).

complex reflection coefficient Γ [1],with, for horizontally polarised waves(where, if T is a dipole antenna then T isparallel with S,

and for vertically polarised waves (where,
if T is a dipole antenna then T isperpendicular to S,

where
is the complex relative electric
permittivity:

Figure1
Geometry of the antennas
and the reflecting EM-wave.

A receiving antenna R ‘sees’ the direct
wave TR from T and a reflected wave
TPR, also emitted from T, which seems
to come from M. The result is that R‘sees’ the vector sum of both waves. Thissummed wave seems to come from a
direction somewhere within the angle α.
At the reflection point P, both theamplitude and the phase of the wave willchange. When we calculate the vector
sum of the direct and reflected wave wehave to take into account this change in
amplitude and phase. The phase of thedirect and the reflected wave is not only
different because of the reflection; thedifference in path length also introducesa phase difference.
When the receiving antenna R is very far
away compared to the height h of thetransmitting antenna above thereflecting surface S, then the angle α
becomes very small and the path
difference becomesθd = 2h cosθThe phase difference due to this path
length difference is∆ϕ = 2ππd/λwhere λ is the wavelength.
The change in amplitude and phase at
the reflection point P is expressed by one

28

andthe normal relative electric
permittivity of S,
the absolute electric
permittivity of S, σ the conductivity of Sand
ω = 2ππfthe radial frequency.
Until now, the mirror antenna M is onlyused to simplify the calculation of thephase difference ∆ϕ and to find the
direction of the reflected wave. The
physics of the reflection at P iscompletely contained in Γ.
The reflection of EM-waves is also
described in ARRL [2]. The problem thereis that part of the physics of thereflection in P is incorporated in theproperties of the mirror antenna M. In
particular, a phase change of π radians(180°) is introduced in M, but only in thecase of a horizontally polarised field.
There are good theoretical reasons to doso, but the formulae for Γ have to bechanged as well to account for this πradians phase change of M relative to T.
The phase change is incorporated
correctly in the reflection coefficient by
ARRL.
However, the explanation of what
happens at the reflection point (thephysics of the reflection) is rather
difficult to understand in ARRL.
There are contradictions between text
and figures, and between the descriptionof the reflections of EM-waves inchapter 3 (pp 14-17) and chapter 27(p 47). These problems arise from the fact

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that the model in which a mirror antenna
M is used with properties, which include
the effect of the reflection, is meant forcalculations. If you use this model toexplain what the phase changes are atreflection, especially for horizontally
polarised waves, you end up with a messwhen you try to explain the physics ofthe reflection using formulae intended foruse with a mirror antenna in which
already a π radians phase change isintroduced.
What happens with horizontally
polarised waves; e.g. from a horizontal
dipole above ground? In this case, theE-vector is always parallel with thereflecting surface S, independent of thereflection angle ψ. In the case of a perfectground (a good conductor, no losses) the
E-vector in the plane of the conducting
ground plane at point P has to vanish.
The amplitudes of the incoming wave andthe reflected wave are the same (nolosses).
The E-vector can only be zero at P when
the phases of the incoming and thereflected waves are opposite (have aphase difference of π radians). By
convention, the phase of the reflectedwave is -π radians relative to theincoming wave. If the ground conditions
are not perfect, then losses occur onreflection. The amplitude of the reflectedwave is smaller than the amplitude of
the incoming wave and the phase change
is not exactly 180°.
H-polarised waves have their E-vector at
P completely in the reflecting plane S.
V-polarised waves only have one
component of their E-vector at P in thereflecting plane S; the other component isperpendicular to S. The ratio of thesecomponents depends on the reflection
angle.
For the horizontal component, the same
story applies as described for H-polarised
waves. The vertical component of theE-vector has to be ‘continuous’, whichmeans that the electric field component
perpendicular to a surface is the same
before and after the reflection. The
surface will reflect (part of) the verticalcomponent of the EM-wave if thereflecting surface is conducting. If the
conduction is poor, then most of the wave
will penetrate the ground and only asmall fraction will be reflected. The
vertical component of the E-vector of theincoming wave has to be the same as theSeptember 2007

Group for Earth Observation

GEO Quarterly No 15

Figure 2

Figure 3

sum of the vertical components of theE-vectors of the reflected wave and theground penetrating wave at P. If the
conduction is good (perfect ground) thenthe vertical component of the incoming
wave’s E-vector has to be the same as thevertical component of the reflected wave’s
E-vector at P.
Since V-polarised waves havecomponents of the E-vector in the S-planeand perpendicular to the S-plane (withdifferent properties for reflection, which
moreover, depend on the conduction andpermittivity of the reflecting plane S),
this results in the reflection coefficient Γv
for vertically polarised waves showing
complex behaviour as a function of thereflection angle.
Figure 2 shows Γv as amplitude(modulus) and the phase of the reflectedwave relative to the incoming wave as afunction of reflecting angle ψ for ‘realistic’ground conditions at a frequency of
137.5 MHz.
σ = 5 mS
= 13
Figure 3 shows ΓH for horizontally
polarised waves under the same
conditions.
For vertically polarised waves there is areflection angle, the Brewster angle, forwhich the amplitude of the reflectedwave is minimal and the phase change is
90°. This Brewster angle is about 16°
under the conditions used (137.5 MHz
and realistic ground) and is very small
for a ‘perfect’ ground like sea water. For
reflection angles larger than thisBrewster angle, H-polarised waves arereflected with a 180° phase shift andV-polarised waves are reflected without

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any phase shift. This difference in phaseshift means that, in the case of circularly
polarised waves, the sense of the circularpolarisation is reversed. Antennas which
are only sensitive for the sense ofpolarisation emitted by the satellite areblind for the reflected waves. With theseantennas, noise bands caused by thedestructive interference of the direct andthe reflected wave will be absent fromthe satellite images.
For the effect of reflections on signal
reception, read about the comparison ofantennas for 137 MHz in the December
issue.
References
1 Electronic Engineering Handbook, Dorf,
p.844
2 The ARRL Antenna Book, 20th impression,
chapter 329

September 2007

Group for Earth Observation

GEO Quarterly No 15

Francis Bell
This was GEO’s fourth annual
symposium, again held at the National
Space Centre in Leicester. There was aslight change in format this year withless time being devoted to presentations,hence leaving more time for workshops,
demonstrations and personal
interactions. It still proved to be a busy
day.

with some hints on how to fine tune your
PC to handle these new data. I wasamazed to learn of the wealth of satellite
data which is now readily available to
GEO members. During the lunch break,David complemented his talk by giving
demonstrations, offering advice andrunning workshops to some of themembers.

First thing in the morning there was ahive of activity as stands were set up andlive EUMETCast signals were routed totwo computer systems. This year,
because Storm Dunlop was our keynote
speaker, and he is the author ofnumerous books on the subject of clouds
and weather, some of his publications
were on display and available forpurchase. One of his publishers,Oxford University Press, had
publicity material on display andthe book shop in the NSC also hadpromotional displays relating theStorm’s books. During the day,
Storm signed a number of copies
for delegates. The GEO Shop waswell supported with sales during
the day. BNSC literature
mentioned in GEO Q14 was on
display and available to anyone
who preferred to pick up copies on
the spot rather than write to the
publisher.

The break during the middle of the day
was very productive and was filled withworkshops, discussions and practicalactivities. These included dish alignmentfor EUMETCast, visiting Internet sites
and tutorials on handling EUMETCast
software.

The Symposium commenced with awelcome to the delegates andspeakers together; there was aspecial welcome to David Anderson,
GEO’s new Membership Secretary.

but did offer an opportunity for any
member to introduce a topic for general
discussion.
The financial report indicated that theGroup is just financially viable provided
that membership levels do not decline. It
was stressed that GEO should try not tolose members by the default justforgetting to renew. The company has
constantly underwritten the financial
security of the group but membershipincome is the life-blood which supports
the main expenses of Quarterly
publication and its distribution.
Members of the management team gave
their own reports to the meeting. The
shop made a worthwhile profit for
the Group over the past year. Thereis an encouraging amount ofbusiness, with the new pager
resistant R2FX being a popularitem.
The membership secretary indicatedthat membership was about 500. He
is going to introduce a membershipcard to remind forgetful readersthat they are members of GEO andanticipates that it will generate asense of belonging to the Groupbeyond the Quarterly publication.
John Tellick reported oncorrespondence and othercommunications with national
authorities, particularly Ofcom. He
also reported about experimentation
with a new faster USB interface box
for EUMETCast reception, which should
be available in a few months time.

As usual, the GEO Shop was at Leicester and proved a very
popular attraction for delegates who were able collect items andsave on the normal post and package charges.

Storm Dunlop made the opening
presentation, speaking about cloud
observations both from Earth and space.
The examples and explanations that
Storm gave to the images he showed leftme feeling quite inadequate. I’m
supposed to be interested in theseobservations but I felt just like beginnerwhen faced with Storm’s commentary. He
suggested that, if you could recognise ten
different makes of car or ten different
species of trees, there is no reason why
you should not be able to recognise ten
different cloud types together with thelikely weather which they foretell.
David Taylor was next to take the floor
with an update on the newly launched
Metop-A satellite, its sensors, and data
dissemination methods. The data arefreely and easily available to amateurs
such as GEO members. David concluded

Photo: David Taylor

Ferdinand Valk, visiting from theNetherlands, was our afternoon speaker.
He illustrated the effects of global
warming on our planet’s polar regions.
Covering the history of polar explorationand the establishment of polar scientificstations, he continued by showing
dramatic satellite images to illustrate thesteady decline of ice coverage at the poles
in recent years. He pointed out that aspart of the International Polar Year2007-2008, hundreds of scientific surveys
will be made relating to our polar
regions. With the current recognition of
the polar regions as important indicatorsof climate change, it is not surprising just
how many projects and studies areplanned take place in this IPY.
AGM
It was very encouraging that almost all
the 40 delegates remained for the AGM.
The business was quite straightforward

www.geo-web.org.uk

The open discussion related mainly to thesuggestion that it may be appropriate for
GEO to register as a charity. With theGroup’s commitment to self training,education and non commercial objectives,a charitable status may be appropriate. It
was noted that if this happened there
would be financial benefits relating to tax
refunds. No decision was taken except toresearch the idea.
There was also some discussion as to thelocation for the next GEO Symposium,
and any suggestions will be welcome
although we have a provisional booking
for Leicester once more, on May 10, 2008.
The meeting ended with the drawing of
the popular well supported raffle. And
thanks for the SatSignal meter I won!

31

GEO Quarterly No 15

Group for Earth Observation

September 2007

Keynote Speaker Storm Dunlop
Photo: Clive Finnis

David Taylor holds a Software Workshop
Photo: John Wiggins

John Tellick demonstrates Antenna Alignment
Pjhoto: John Wiggins

David Taylor Discussing his Software
Photo: Ferdinand ValkGEO Company Secretary Nadine Bell
Photo: Clive Finnis

John Tellick demonstrates Antenna Alignment
The GEO Shop Table

Ferdinand Valk speaking on theInternational Polar Year

Photo: Clive Finnis

Photo: David Taylor

Symposium 2007 Group PhotographFrancis Bell32

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Photo: John Wiggins

September 2007

Group for Earth Observation

GEO Quarterly No 15

This article has been compiled, withpermission, from material on the
Celestrak website

As reported by Peter Wakelin [1] in ourMarch issue, China implemented an antisatellite weapon test on their ailing Feng
Yun-1C polar orbiting weather satellite on
January 11, 2007 in what turned out to be
by far the largest debris-generating event
ever recorded. During the following threemonths well over a thousand orbiting
fragments, in addition to the remains of theoriginal payload, had been assigned
NORAD [2] catalogue numbers. It has been
estimated that the breakup created morethan 35,000 fragments larger than acentimetre across.
Clearly this armada of space shrapnel
poses an ongoing threat to existing
communications and Earth observation
satellites and recently a report on Dr T S
Kelso’s CelesTrak website [3] delved further
into this matter. By propagating the 2-line
elements of the fragments back in time hecreated AGI Viewer images and animations
showing the distribution of debris along theorbital path of Feng Yun-1C. Figure 1
illustrates the fated satellite’s final orbit
above the Xichang Space Centre (in red)with the positions of the debris fragments(in green) added as they would haveappeared a mere five minutes following theattack. Readers who possess the free AGI
Viewer software [4] may also download
animations of the event which show the
spread of the resulting debris cloud.

Figure 1 - The Feng Yun-1C orbit and debris cloud 5 minutes following impact (january 11, 2007)
STK-generated image courtesy of CSSI (www.centerforspace.com)

Further analysis indicated that the debris
cloud lay in a polar orbit that stretchedbetween an altitude as low as 200 km all
the way to 4000 km, posing a threat to
many operational satellites. In an average
7-day period it could be determined that
there were over 2500 ‘near-miss’ events
when a piece of Feng Yun-1C approachedwithin 5 kilometres of an operational
satellite payload in low-Earth orbit (LEO).
Figure 2 illustrates the risk to other LEO
satellites, including the International Space
Station (ISS). The population of LEO
satellites (including payloads, rocket
bodies, and debris) which could be affected
is plotted in green. The debris cloud isshown in red and the single green trackshows the path of the ISS.
A detailed analysis of the lifetime of thedebris catalogued so far shows that only
about 5% of it (62 pieces) will havedecayed within ten years.
Almost 85% of this debris will still
remain in orbit 100 years from now.

Figure 2 - The Feng Yun-1C debris cloud in context with existing LEO satellites (early April, 2007)
STK-generated image courtesy of CSSI (www.centerforspace.com)

The majority of the debris from this single
event will therefore remain a hazard for
centuries to come.
References
1 Earth Imaging News, GEO Q13, page 23(March 2007).

www.geo-web.org.uk

2 NORAD - North American Aerospace
Defense Command, the body responsible
for monitoring man-made Earth orbiting
objects.
3 http://www.celestrak.com/
4 http://www.agi.com/products/viewer/

33

GEO Quarterly No 15

Group for Earth Observation

September 2007

Mark Edwards
So you’ve bought a new computer withthe hope it can process data fromEUMETCast better than your old one.
After reviewing the specification you findit has a 10/100 mbps network card built
in—but what does this mean?
Well essentially, a network card willallow you to do many things with yournew computer: sharing files, sharing
printers and sharing a single Internet
connection are just some of the manythings you can do with a networked
computer.
This guide hopes to give you an idea of
how to set up a local area network inyour house.

• It is a modem, so it can replace that
old USB ADSL modem that you haveplugged into your computer. It also
has the advantage that it can stayconnected to the Internet when you
turn your computer off—a big help
when you have more than one
computer sharing the same Internet
connection.
• It can further enhance yourcomputer’s security as it has its own
built in firewall, similar to what Linuxand Windows systems haveincorporated into them.
• Finally it is a router. Routers are
responsible for letting two or morecomputers talk to each other and theInternet at the same time.

Figure 1 - A router, or a broadband modem with router built-in.

The Equipment You Require
Before you can begin to set up yournetwork, you will need a router (or abroadband modem with a router built in),a network cable (typically CAT5e) andcomputers, each with a network interface
card present (figures 1, 2, 3).
These items will give you the essentials
for setting up the most basic of networks.
With a network, it is always best to startwith a basic setup. You can expand it
later as you need to add more computers.
This guide also assumes that you
have broadband internet access,either cable or (A)DSL, and areusing Microsoft Windows XP.
Now let’s look at the above components
in more detail
Broadband Routers
In my network I use a Netgear DG834
ADSL Firewall router. I know that is amouthful but, when you break it down, it
is quite simple. Essentially it is one
device that can do the job of three.

34

Figure 2 - Network ‘Patch’ Cable

All-in-one devices like this used to be
expensive but as they are now becoming
more commonplace the price has fallen.
Devices such as the Netgear DG834 canbe picked up for around £30-£60.
Other advantages in using a device likethis to construct your network are its
built-in web interface and setup wizards.
These take all the hassle and most of thework out of setting up a network.
Network Cabling
There are two types of wiring
arrangement in network cables, crossoverand straight.
• Cross over cable is used to connect
one computer directly to anothercomputer• Straight wired cable is used toconnect a computer to a router,switch, access point or any othersimilar network device.
Network cable also comes in various
types. CAT-5, CAT-5e and CAT-6 areamong the most common types.

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For home networks, any of these is fine
but the most favoured is CAT-5e. Network
cable comes in various lengths and can besupplied up to a maximum of 100 metres
before it becomes too lossy. This meansthat computers can be connected to theInternet or to each other wherever you canlay 100 metres of network cable. If you
need to connect a computer to anotherone, or to the Internet, over a greater
distance, you will need to use fibre optic
cable, which supports a range of up to two
kilometreswithout
amplifiersor
repeaters.
Network Cards
Network cards are responsible fortransferring the data on your computer

Figure 3 - Network Interface Card

into packets and then sending thesepackets over the network cable to thedesired destination. Most computers
today come with network cards alreadyinstalled. If your computer does notalready have a network card it is not too
hard to buy one and install it yourself.
Most network cards are reasonably
priced and install easily into a spare PCI
slot. This is a similar installation to thatfor the Technisat Skystar-2 card. Let’s
now look at the various steps involved insetting up a network:
Setting up a Broadband Router
Most broadband routers will come with
documentation that explains the processof setting them up—or at least shows you
how to access the web interface, whichcontains a setup wizard (or provide
further documentation to guide you
through the setup procedure).
Most routers also provide a short lengthof CAT-5e cable (also known as a patch
cable) to allow you to connect yourcomputer’s network card to it.

September 2007

Group for Earth Observation

GEO Quarterly No 15

An ADSL router has a telephone
connector on the back to allow you toconnect it to a micro-filter and then into
your ADSL-enabled phone line. If you
have a cable modem, most cable
companies provide these with a network
port on the rear, allowing you to connect
a router to it with a network cable. If you
already have a cable modem you willneed only a router, not an ADSL modem
router.
The documentation with a router for acable modem will give setup instructions
and wiring diagrams. In figure 4, you canclearly see the ports on a typical ADSL
modem router: from left to right thepower connector, four network ports andthe telephone socket—connected to a
micro-filter which then plugs into your
ADSL-enabled phone line.

Figure 4 - Rear connections to the Router

Once you have connected your computer
to a network port on the back of therouter (and have powered on bothcomputer and router) it will issue yourcomputer with a network address known
as an IP address. As long as the drivers
for the network card on the computer are
correctly installed, and if your computeris running Microsoft Windows XP orlater, this all happens automatically.
The IP address is used to identify yourcomputer to other computers on the
network. Each networked computer has
to have its own unique IP address. Even
the router will have its own IP address.
Accessing the web interface of an ADSL
router is simple. Open your Internet
browser and type in the IP address of the
ADSL router; which is commonly either
192.168.0.1 or 192.168.1.1

If neither of these works, consult the
documentation provided with your router.
This will provide the correct IP address.
Once connected, you will be promptedwith a username and password box. The
username and password details will also
be found in your router’s documentation.
Note
Most of the newer routers now come witha CD which, in addition to
documentation, also contain a setup
wizard which can be run on yourcomputer to configure the router for you.
This means that you can avoid the webinterface if you don’t feel comfortablewith it.
Once you run the web interface, you arepresented with a wide range of options,Figure 6 - Connecting multiple Computers to a Router

many of which you may not need totouched (as they are often either alreadyconfigured or for advanced users only). At
this point I do recommend following yourrouter’s documentation as setups varyquite significantly from one router toanother. But basically, what you areaiming to do is to configure the router toconnect to the Internet. This is easy to do
as you will probably only have to enter
your username and password details asprovided to you by your Internet service
provider (ISP). A setup wizard is also
included in most web interfaces, which
can aid you in configuring your router.
Once you have entered your Internet
settings so that the router can connect tothe Internet, you have almost completed
the router setup. Most routers will comewith a default setup for networking; if
not, you can consult the documentationthat comes with them to configure therouter as required for networking.
To test that your broadband router isworking, enter a website address into
your Internet browser. Hopefully, yourchosen site will be displayed.
If so, congratulations! You have now
successfully networked your computer toyour broadband router.
Connecting Additional Computers
Now that you have successfully connected
one computer to your router it’s time to
add a second one. This is where theadvantage of using a router starts toshow. All you now need do is connect the
2nd computer’s network card to the routerwith a network cable and the router willassign it an IP address (provided the
network card drivers are correctly
installed on the 2nd PC). This computercan now access the Internet at the sametime as the original one; and the twocomputers connected to the router can
now also ‘talk’ to each other.
Since most routers have 4 or 5 ports on
the back you can have up to 4 or 5
computers connected at any one time
without additional equipment. If you
need to connect yet more computers, youwill need to buy a switch unit. This unit
is a device which ‘switches’ the

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connections between 4 or 5 networked
devices. By doing this, more computers
can be added into the network. It is a lot
more basic in comparison with a routerand there is no setup required. With aswitch you simply plug it into your routerthen plug the computers into the switch
and/or the router and they can thencommunicate with the Internet and eachother. Figure 6 is a block diagram
showing how six computers could be
operated from a 4-port router.
Configuring the Computers
Nowadays, Microsoft Windows™ will do a
lot of the setup without your input, whichmakes the task much easier. But there
are still one or two things you need toknow about in order to make yournetwork easier to operate.
If you want to share printers and files on
your network, you first need to set up a
workgroup. Fortunately, with Windows,
there is a Setup Wizard to make thiseasier for you. Here’s what to do.
Note
If you are running your Windows XP
computer under the Classic interface,
you will not be able to access themenus that follow. Make sure that you
are running the Windows XP theme(or a variant).
Open Windows Control Panel to reveal
the Pick a Category screen and click thesecond option down on the left, named
Network and Internet Connections.
This opens the Pick a Task screen. Selectthe option Network Setup Wizard whichappears near the foot of this screen.
You will now be presented with thesequence of screens illustrated on
page 36 (overleaf). Work through thesescreens, row by row, following the
instructions below each to complete
configuring your network.
You will have to run this wizard fromevery computer that you intend to run on
the network. Remember: you must use thesame Workgroup name but a different
computer name to enable the network to
identify the respective computers.

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September 2007

This is the opening screen of the Network Setup
Wizard. It simply indicates what you will haveaccomplished once you have completed it.
Just click ‘Next’ to start your setup.

You don’t have to review the checklist (as it isgeared more towards advanced network setups).
Make sure all steps are completed, and when the
wizard states ‘connect to the internet’ this reallymeans ‘make sure your router is powered on andconnected to the telephone line’.

If you haven’t connected your network card to therouter the wizard will prompt you to do so. Many
newer computers have more than one network card:
if both are not connected this message can appear. If
you are sure your network card is connected to therouter and is powered on, check the ‘ignore
disconnected hardware’ box and proceed.

This screen may or may not appear depending on
your previous setup. If it does, it is best to ignore
the recommendation it gives and choose ‘No’.

On this screen select the middle option. This will
configure your computer to always connect
through the router rather than try to dial up aconnection of its own.

This screen allows you to choose a name for yourcomputer. This is the name that will be shown toother computers on the network to help you identify
it. Each networked PC must have a unique name.

This is one of the most important steps in the
wizard. The Workgroup name defines which
computers can work together to share resources.

This step in the wizard is equally important. Make
sure that you select the top option. This will enable
file and print sharing services in Windows andopen the ports on the firewall in Windows to allow
this to happen.

This screen is a summary of all the settings you
have just made. It enables you to double-checkthe settings you made to ensure they are correct
before applying them. If the settings appear to becorrect you can move onto the next step.

You can create a network setup disc for use on anyof your PCs that lacks this wizard. If all your PCs
possess this wizard, select ‘Just finish the wizard’.

You have finished the wizard on this computer. Next,
you will have to run it on all the other computers thatyou intend to run on this network.

The name you select here must be the same forevery computer on your network—otherwise thecomputers will not be able to ‘see’ each other.

The wizard is now configuring Windows for you.
As it says ‘This process may take a few minutes’.

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GEO Quarterly No 15

Resident Firewalls
There is one important consideration before moving on. If you
have a resident firewall installed on your PC (e.g. Norton
Internet Security), make sure that you set it up so that it‘knows’ that you are using a network. Most firewalls block theports Windows uses for file transfers. As a result, you cannot‘find’ the other computers on the network, even though they areconnected and set up. You may require to consult the
documentation that came with your firewall software should
problems arise.
Using Networks
In Windows you can browse through the computers on yournetwork as easily as you can browse through folders and files ona single computer. To do this you just need to know where to
look. If you open the My Computer window and look at
Other Places you will find a link to My Network Places (figure 7).
Alternatively if you select the drop down box at the top where
My Computer is displayed you can select My Network Places.
Figure 7 - The My Computer Window

When you follow this link, you will be presented with a windowthat should show a collection of folders headed Local Network(figure 8). This folder holds links to the Shared Document
folders on all the computers you have networked.
Whenever you choose to share a folder
on a computer it will appear here.
To see which computers are currently on the network, or to get abetter view of which computers have which files on them, selectView Workgroup Computers under Network Tasks from the lefthand panel. Now you can see each computer on the network listed(figure 9). By selecting one of these, you can see all the files andfolders available on that specific computer.
How to Share Folders and Files
If you can’t find a particular file or folder on the computer you
are browsing the chances are you haven’t shared it. Windows
will not display files or folders on a network unless they havebeen designated for sharing as a security precaution.
A single file can be shared in two ways. Firstly you can copy thefile into the local computer’s Shared Documents folder. This willallow every other computer on the network to see it underneaththe Shared Documents folder for that remote computer’s name.
The second way in which you can share the file is to share thefolder the file is in. Note: if there are other files in that folder
they will also be shared. The folder you have shared will be
displayed alongside the Shared Document folders in the My
Network Places window.

Figure 8 - The ‘My Network Places’ Screen

To share a folder, browse to it, right click over it and choose
Properties from the menu. On the window that pops up, selectthe ‘Sharing’ tab at the top and you should see somethingsimilar to figure 10 on page 38.
If you are setting up a network for the very first time on thatcomputer, you may be presented with a slightly different
window that explains the risks of sharing folders and files. You
can acknowledge the risk message by clicking the link and thenfigure 10 will appear.
Selecting the Share this folder on the network option will
unblank the ‘Share name’ box and allow you to type the sharename for that folder on the network. Choosing a different sharename to the folder name will still leave the folder with its
original name on the computer where it is located.
The Allow network users to change my files option will allow you,from another computer on the network, to edit, rename anddelete the files remotely. Be careful, as all other computersconnected to the network can also do this.
You should now see this folder in the My network Places windowon all other computers on the network and be able to access the

Figure 9 - The ‘View Workgroup Computers’ Screen

sub-folders and files. It is also shown under the relevant
computer under your chosen workgroup name.
Creating a Network Drive and Configuring Software
A network drive allows you to create a virtual hard drive on
your computer from a folder on another computer. It is,essentially, like a shortcut—to save you having to visit
My Network Places or workgroup window every time you wish toaccess a folder on a remote computer.

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GEO Quarterly No 15

The following describes how to create a
network drive and configure David
Taylor’s satellite software to process data
across the network.
Network drives are displayed in the
My Computer window under ‘Devices withremovable storage’If you want to use the twin-PC setup that
EUMETSAT describe, creating a
Network drive is the best way to go if you
are using processing software on anothercomputer.
In this example we will assume that a
reception computer has been set up toreceive the data from EUMETCast using
MSG Data Manager, while a second
computer has been set up to run
MSG Animator, GeoSatSignal and Metop
Manager.
To begin with, we will create a network
drive from the folder where all the datathat MSG Data Manager processes isstored. If you haven’t changed the default
setup, this is found in the following
location:
C:\MSG-1

You will need to enable sharing of theMSG-1 folder on the reception computer.
If you want to be able to edit or delete
the files in this folder remotely be sure toenable ‘Allow network users to change myfiles.’ Once you have done this on thereception computer, head over to theprocessing computer and open
My Computer and select <Tools → Map
Network Drive>.
You will now be presented with a window
similar to figure 11. If you don’t alreadyhave a drive Z: on your computer, this iswhat will most likely be displayed. Any
drive letter is fine but, with network
drives, it is best to start from the end of
the alphabet and work back.
Next to the ‘Folder’ drop-down box, select‘Browse’. You will be presented withanother window allowing you to search
for the folder you just shared, on thereception computer. This computer will
have its name displayed under the
workgroup name; the default is‘MSHOME’. The folder will then be foundunder the computer’s name.
Select the MSG-1 folder and two further
folders will be displayed, typicallyRaw Data and Images. This is fine, so
make sure the MSG-1 folder ishighlighted and select OK. Make surethat Reconnect at logon on the Map
Network Drive window is checked as thiswill reconnect the drive after a computer
restart.

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September 2007

If you return to your My Computer
window you should now see, under a newheading of Network Drives, ‘msg-1 on[your computers name] (Z:)’ This name isa bit long and, if you are like me andthink it looks a bit messy, you canrename it to something simpler such as‘MSG-1.’ To do this, right-click on the
network drive and in the menu select‘Rename’. You will now end up with‘[your chosen name] (Z:)’—a lot shorterand easier to read. Network drive
shortcuts can also be created on yourdesktop.
Finding the MSG Data
Now you need to tell MSG Animator and
GeoSatSignal where to find the data. Let
us start with MSG Animator. When you
have launched MSG Animator in thesystem tray, right-click and select<Options → Set Image Data Path>. As you
will find, it is really easy to do this now
that you have a network drive. You don’t
have to browse through My Network
Places any more. Simply select ‘MSG-1’
and then, as the program says, select the‘Images’ folder above the ‘HRIT’ folder.
Now MSG Animator is configured andyou can use it just as before (figure 12).
For GeoSatSignal it is a very similar
process. When the program is open,
select <File → Browse EUMETCAST> then,in the window that opens, select<File → Open Folder>. A Browse for folder
window will open, very similar to the one
for MSG Animator and you are looking torepeat the process you did for that
program. Select the ‘Images’ folder abovethe ‘HRIT’ folder. Once this has been
selected the program will remember thislocation. To perform a test selection, click‘Browse Latest’. You should see theimages start to appear as the programpulls the data across the network.

Figure 10 - Sharing a Folder

Figure 11 - Mapping a Network Drive

Finding the Metop Data
The process for the Metop data is fairly
similar to what we have justaccomplished for MSG. Firstly we need tocreate another network drive, but thistime for the location where the Metop
data is stored.
This next step will depend on the folder
structure you are using with the Tellicast
software. I have my folders set so that inthe ‘Received’ sub-folder of‘C:\Program Files\T-Systems\BusinessTV-IP’
I have the following folders:
Data Channel 1
Data Channel 2
Data Channel 3
Data Channel 4
METOP
In the METOP folder, I have the‘AVHRR’ and ‘Messages’ folders whichallows me to easily find where therelevant data is stored. I suggest sharing
the ‘Received’ folder in the default
location of:www.geo-web.org.uk

Figure 12 - Finding the MSG Data

‘C:\Program Files\T-Systems\BusinessTV-IP.’
This way you can access whatever folders
and files you need regardless of yourfolder structure.
Once you have shared the ‘Received’folder you will need to create a Network
Drive for it. On my system I use theDrive Y:.
Now you have set up the Network Drive,
open MetOp Manager. You will need toopen the ‘Setup’ tab and then the‘AVHRR’ tab.

September 2007

Group for Earth Observation

In the Tellicast EPS AVHRR global received files path box you willneed to enter the location where the AVHRR files are stored. To
do this, browse for the network drive you have just created andthen select the folder where your AVHRR files are stored. All
that is left now is to repeat the process for all the data you
receive and wish to process with Metop Manager: ASCAT,
GOME, etc.
Congratulations! You now have a networked two-computer
EUMETCast system.

GEO Quarterly No 15

Continued from page 23 ...

Our reception from EUMETSAT was outstanding and further
cemented the already excellent working relationship between
GEO and EUMETSAT. It was good to renew old acquaintances,put faces to names we regularly deal with and to make newfriends. Hopefully, EUMETSAT enjoyed the visit as much as we
did.
Acknowledgements
On behalf of the delegates, we express an enormous vote of
thanks to Dr Lars Prahm, Director General of EUMETSAT,
Sally, Debbie, Pamela and the many others who made us sowelcome and organised such a packed, informative and friendly
event.
References
Jason 2: http://www.jason.oceanobs.com
http://topex-www.jpl.nasa.gov/mission/ostm.html

What our Members Thought - Letters
May I, through GEO Quarterly, thank everyone who made the trip
to Darmstadt a success. Not just those who went on the trip, but also
those who worked silently behind the scenes to make it perfect: theorganisers within GEO, the staff at Eumetsat, ESOC and all theplaces which were linked with our visit. I had the time of my life.
I had to make a decision:whether to upgrade my PC or to fly out toDarmstadt. Without a doubt I made the right choice. I met many old
friends and made many new ones. The atmosphere was very positive,
and as for EUMETSAT—let's just say the hospitality andfriendliness, as well as the kindness and understanding, far
exceeded my expectations. I really didn't expect to see so much as we
did. The girls from OPS are really nice people and Phil, who showed
us around Usingen ground station, not forgetting Conchita, my new
Spanish friend, all really did everything to make our visit a success.
I felt an emptiness when it was time to leave. As the words from Lou
Read's song read ‘Such a perfect day, You made me forget myself, I
thought I was someone else, Someone good’.
It was an International visit with people from many different
nationalities and cultures; but yet we were all one. There were somany languages in my head I couldn't choose the right words tospeak. It was a laugh! I’ll look at everything and everyone differently
now. The visit certainly made a difference in my life so I'm sureothers had a similar experience. An Unforgettable few days.

Figure 13 - Selecting the AVHRR Folder in Metop Manager

Some Final Points to Bear in Mind
• If you turn the processing computer off and leave thereception computer on, the data for Metop will graduallybuild up as there will be no local space management. MSG
data is usually managed by MSG Data Manager, so thatshouldn’t have a build-up of data if correctly configured.
• Networks via cable run at a speed of 100 mbps. This means
it will take approximately 3 seconds to transfer each
28,123 kB AVHRR Metop file.
• Wireless networks are not recommended for transferring
MSG or Metop data as they are currently too slow anddon’t provide adequate stability• When running a router with a built-in firewall, you have tobear in mind that you may have to open ports to allow
connections to certain programs from the Internet. This is
no different from the firewalls that Windows already has
incorporated into it. To open a port I suggest reading the
documentation that came with your router as it will vary
between different routers.
By following this guide you should have a trouble-free,
networked system providing a fluid flow of data processed fromthe raw data received from EUMETCast. Enjoy!

Thank you my friends, Rob Denton
What a welcome they gave us all at EUMETSAT Headquarters. The
first day we were taken to every part of this immense HQ building,from the main control centre, right down to where all the data has
been stored since records began, by many back up systems andwhich can be retrieved at any time for the use of media etc. We hadtalks on all aspects of satellite research, and the purposes and theuse of satellites in air sea rescue. When we went to lunch theycertainly knew how to look after us. The meals were very very good.
On the second day we had a coach trip through some very pleasantsmall German towns until we reached Usingen, from where
headquarters monitor and control their many satellite systems. Thishas certainly come a long way since Arthur C Clark foretold thegeostationary satellite ‘way back in 1945. The final afternoon was
spent at the European Space Centre, where Mars Explorer and muchother space-related research is done.
There was a great deal of time and effort, done by many people, tomake this trip the success it was. From Valerie and myself, a very big
thank-you for being such good company on this momentous occasion.
Kindest Regards, Valerie and Eric Deanwww.geo-web.org.uk

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GEO Quarterly No 15

Group for Earth Observation

September 2007

David Taylor
This is the first of what may become an occasional series ofarticles describing the use of a rather neglected feature of
Microsoft Windows - the Command Language. If you find thisarticle relevant and interesting, and would like to read more on
this technique, do please get in touch and let us know.
The Problem
Users who regularly collect data from the Internet or from the
EUMETCast data stream often find find that their hard disks
rapidly fill up with data—unless they take steps to prevent thishappening! Of course, many applications that regularly handle
large quantities of data, like my MSG Data Manager and Metop
Manager, already possess built-in facilities for controlling thedatafiles: but what if you want a more refined degree of control
or you need to manage data that you obtained or createdyourself?
The Solution
To solve this program, I wrote a small program called TrimTree
whose sole function is to delete files beyond a specified age, andof a specified filetype, from a given folder.
By making use of the Command Language, it is possible toimplement two or more runs of TrimTree, each of which uses
different parameters (these are arguments that follow the
program name and determine how it will behave). These
multiple runs of TrimTree are achieved by running a single
command file.
Running TrimTree Once
To run TrimTree, the program takes three arguments, eachfollowed by a space character, as illustrated below:
TrimTree [n] [p] [w]

Of course, you may wish to have different retention periods fordifferent file types, and you certainly don’t want to have to typethese long command sequences every time you run TrimTree!
So what you need to do is to place the commands into acommand file, which you can run simply by double-clicking on it
whenever you need to implement that particular set ofcommands.
Making a Command File
Using Notepad, create a file named TrimFiles.cmd. Just as.DOC is the extension for a document file, so .CMD is the fileextension for a command file (sometimes called a ‘batch’ file).
In the file TrimFiles.cmd, enter these lines.
TrimTree 2 C:\MSG\images\ *-msg-ch06.* *-msg-ch07.*
TrimTree 10 C:\MSG\images\ *-msg-ch02.* *-msg-ch09.*
The first line removes files for MSG channels 6 and 7 once they
are more than 2 days old while the second line does likewise forthe channel 2 and 9 files, but only when they are older than
10 days. I find the channels 2 and 9 to be particularlyinteresting, and consider it worthwhile retaining them for alonger period.
You can run this command file either by placing a shortcut to it
in your Startup folder, or by scheduling it to run overnight.
Future Script Snippets will cover these options (and may be
written by others).
Indeed, any reader who regularly makes use of command files
and who has scripts that might interest other GEO members is
welcome to contact us (Ed].
How to Obtain the Program
TrimTree can be downloaded fromhttp://www.david-taylor.myby.co.uk/software/disk.html#TrimTree

[n]
[p]

- Files older than ‘n’ days will be deleted- The full pathname to the folder containing
the files to be managed/deleted[w] - The filetype wildcard

Unzip the TrimTree.zip archive into your\Windows\System32\ folder so that it can be called without
having to specify its full path name.

Consider this typical command line,
TrimTree 2 C:\MSG\images\ *-msg-ch06.* *-msg-ch07.*
This means that, for any files which are• more than 2 days old and• in the folder ‘C:\MSG\Images\’ and below,
TrimTree will check all filenames containing ‘-msg-ch06.’ and‘-msg-ch07.’ Those that are more than two days old will bedeleted while any more recent files will be retained.
Note that the final argument to TrimTree can consist of morethan one wildcard, each delimited by twin ‘*’ characters andseparated from each other by a space character.

Windows Operating Systems
Windows NT and its successors (Windows 2000, Windows XP
and Windows Vista) all feature greatly expanded command-linefunctions compared with Windows 95/98, and all Script Snippets
assume you are running one of the the newer Windows
operating systems.
If you plan to use command language methods under Windows
9X, you must create a command file with extension .BAT (i.e. abatch file’ rather than .CMD;
i.e. in this case you would save your file as
TrimTree.bat
and not as
TrimTree.cmd.

40

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September 2007

Group for Earth Observation

GEO Quarterly No 15

The PC System

Alan Banks - alanjamesbanks@yahoo.co.uk
I recently described my Home EUMETCast Receiving Station
on my web pages and asked David Taylor to give it a critical eye
as I discuss his software in some detail. It was he whosuggested I write for GEO Quarterly and describe my thinking
and conclusions while assembling this home system. I will notdescribe the software side of things in detail as that has been
covered extensively in earlier Quarterlies, although I will
however address some software issues.
I have been involved in Amateur Astronomy for about sevenyears and have been an active member of Macclesfield
Astronomical Society for the same time. As we used to hold all
our meetings at Jodrell Bank, radio astronomy is therefore
always prominent in our meetings. We only meet there for ourmonthly ‘workshops’ since the Planetarium was demolished.

Having read the FAQs on David Taylor’s website and articles by
Arne van Belle and others, I determined on a 2-PC system.
However, I eventually ended up with a 3-PC system. I had
upgraded my original PC in January 2006 but decided to
improve it further: this has evolved as data rates havecontinued to increase. For my second PC I bought an off-theshelf ’student’ model, for reception only, and then brought into
use my son’s PC (my 3rd), an essentially home-built PC in a newcase. This allowed me to reconfigure my system as described
below. I honestly think a 3-PC system is highly desirable,
especially if you do a lot of computing other than EUMETCast
reception. At present the total data received by my system is of
the order of 31 gigabytes (GB) per day.
Available Data
Data from EUMETSAT is received via a TV broadcastingsatellite, Hot Bird-6 at 13°E. The service is called EUMETCastand is provided by a tq®-TELLICAST server. EUMETCast
services provided by EUMETSAT now include Meteosat-9(MSG-2), FSD, AVHRR and Metop-A data.
• Meteosat-9 (MSG-2) is a second-generation geostationary
weather satellite for Europe, providing twelve spectral
channels.
• Meteosat-8 (MSG-1) is, as I write this, sending
experimental rapid scan data of Europe every 5 minutes.
• FSD - foreign satellite data - includes hourly images fromgeostationary satellites around the world, such as the
GOES-West and GOES-East stationed over the Americas,
Meteosat-7 provides the Indian Ocean Data Coverage(IODC), and MTSAT-1R covers Asia and Australia.

I missed a talk on ‘Radio Meteor Detection’ but was fascinatedby the principles and had a go myself. One needs a scanner, adipole aerial and a computer running free software available on
the web. The data is fascinating, especially when one cancorrelate visual sightings with radio detection. However, thesystem becomes automatic and I wanted to go further.

• EARS-AVHRR provides high-resolution 5-channel HRPT
image data from the AVHRR scanner on NOAA-17 and
NOAA-18. Data from several ground stations (CanaryIslands, Northern France, and Svalbard, north of the
Arctic Circle) is combined to give Europe-wide coverage.
The data has a 1km per pixel ground resolution.

Two years ago I discovered the RX2 weather satellite receiverand various sites describing home-brew quadrifilar helicalantennas. By January 2006 I was operating a reliable APT
system with a homemade QFH in the roof space and the RX2. I
then discovered the GEO website (and joined) and all the talk of
EUMETCast. By August 2006 I had my licence, EKU andsoftware and started to receive images.

• EUMETCast is the main dissemination mode for data from
the Metop-A satellite, launched in October 2006. Thissatellite provides high-resolution continuous round-theworld coverage, with data at 1km per pixel resolution.

My System
My system starts with the 80 cm dish and LNB purchased from
GEO shop and is mounted on a fence in the front garden. The
fence posts not being absolutely rigid, an additional pole has
been driven into the ground. I initially thought that movementin the fence adversely effected my reception: however the
problem turned out to be the neighbour’s trees overhanging theline of sight, especially worse when raining. I have completely
cleared the trees to give much better reception although it isstill degraded when I mow the lawn and by the occasional very
high-sided vehicle. I am looking at ways of mounting the dishon the end wall of the house. Unfortunately the ideal mounting
wall has a telephone pole right in the line of sight.
My workstation (figure 1) looks a bit crowded but works well. I
use a KVM (keyboard, video, mouse) switch to move between
two of the PCs and VNC Viewer to access the third. This meansthat I only need one keyboard and one mouse to control
everything. All PCs are attached via Ethernet cables to awireless router/modem. The wireless is only used by my laptop.

Figure 1 - The workstation, showing the three PCs.

All the PCs have names associated with Astronomy. Naming
the PCs makes networking much simpler. The default names
can be pretty horrendous. If you load Windows yourself, you get
the option to name the PC during installation. In Win XP it canbe changed in Control Panel, though best done before
networking.

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GEO Quarterly No 15

Group for Earth Observation‘Kepler’ is the Receive Only PC
A TechniSat DVB PC-TV-Star PCI card installed in this PC
receives the signal. I initially used a TechniSat Skystar USB
box but it wasn’t able to keep up with the vast amount of data
provided after the Metop-A launch. Also installed is the EKU(Electronic Key Unit), supplied by EUMETSAT at €40, and thenecessary Tellique software package costing a further €60.
These are both obtained direct from EUMETSAT and allow
access to the data.
Kepler is an HP Pavilion computer, intended mainly forstudents, fitted with an with AMD Sempron 1800 MHz
processor. 80 GB hard drive, 1 GB RAM and Windows XP
Home. I added another 1GB RAM and a second 200 GB SATA
hard drive. I was planning to add two additional SATA drives
and run them in RAID 0, but unfortunately XP Home doesn’t
support RAID, so I stuck with one drive.
This hard drive has the TelliCast software and received data
folders only. It doesn’t get anywhere near capacity as the raw
data is removed by data management software almost
immediately. I switch off the processing PC at night, so onlyaround 7-8 hours of data tends to accumulate.
Finally, I added a Q Soft 320 MB Ram Drive and changed thecase cooling fans to something quieter. This PC runs
continuously 24 hours a day.
‘Galileo’ is the Processing PC
I built this PC myself using parts
purchased in early 2006 and upgraded it tocope with EUMETCast. It contains an
AMD Sempron 1833 MHz processor, 2GB
RAM, 40 GB and 120 GB hard drives plus
twin 200 GB SATA hard drives in RAID 0.
There are lots of cooling fans, mainly byZalman, a Zalman copper CPU heat sinkand fan and Zalman fanless cooling for thegraphics card. This PC runs very quietly
and critical temperatures are never morethan 10°C above ambient. The operating
system on this computer is Windows XP
Pro.
This PC runs all David Taylor’s software
for about 16-18 hours per day.

September 2007

originally my son’s PC and contains an AMD Sempron 1.7GHz
processor, 1.25 GB RAM and a 72 GB hard drive with
Windows XP Home. I have re-cased this PC, added better
cooling and soundproofed it. Newton runs 16-18 hours a day.
I operate the System as follows.
Kepler receives EUMETCast continuously. Apart from systemprocesses, the only software running is Setup4PC, TelliCast,
Filezilla Server, VNC Server and MRTG monitoring (covered
below). There is no anti-virus or anti-spyware running, though I
do complete the monthly Windows update.
An essential part of the setup, to minimise data loss, is a RAM
Drive. This is a virtual hard drive that speeds up the writing to
disk process that the data rates demand. In the Tellicast
configuration one sets up a folder in this drive where data canbe held temporarily before it is written to the hard drive. A filecalled 0.fsy is created.
Virtual Network
I can only access this PC by virtual networking from either ofthe other two PCs: for this I use RealVNC, available at:
http://www.realvnc.com/products/free/4.1/download.html

The download is less than 1 MB and is quick and easy to install.
Some conflicts between TelliCast and RealVNC have beenreported but I have experienced no such problem. I initiallyinstalled Real VNC so that I could connect remotely from mylaptop when setting up the dish and LNB. I could then monitor
signal quality wirelessly. Occasionally, I have to connect Kepler
to the keyboard and mouse for setting up. However, most tasks
can be completed via the virtual network.
MRTG
I need to be able to monitor various factors on this PC. I use
MRTG 2.15.0 (Multi Router Traffic Grapher), a clever piece ofsoftware that allows many processes to be checked every few
minutes. David Taylor has been posting his results for sometime and, towards the end of 2006, was encouraging others to do
the same so that EUMETCast reception could be monitored
Europe-wide.
Consulting

Figure 2 - ‘Galileo’

http://www.david-taylor.myby.co.uk/mrtg/EumetcastEurope.html

allows one to check whether poor reception is local or general.

‘Newton’ is my Do Everything Else PC
Newton is not associated with EUMETCast and is used for.
Internet browsing, email, word processing, PowerPoint,
Photoshop etc. It also runs FTP software, regularly downloading
data from Kepler and uploading it to my web pages. This was

Setup4PC allows Signal Quality (%), Signal to Noise Ratio (dB)and Bit Error Rate (ppm) of the SkyStar card to be recorded. I
measure total SkyStar traffic activity in Bytes per second.
I measure network activity between the receive and processing
PCs. The TelliCast software records missed and recovered data
packets; this data is monitored.
Finally the temporary file ‘0.fsy’ is monitored. If the file
overfills, usually because of corrupt data in bad weather, one
can take appropriate action (delete it).
All this information is held as html files and .png images in afolder called C:\myweb\documents.

Setting up MRTG
To set up MRTG on a Windows XP computer, first enable
SNMP by going into Control Panel → Add/Remove Programs →Add/Remove Windows Component, and make sure Management
and Monitoring tools is checked.
One also needs, if not already installed, Active Perl, which canbe downloaded from:http://www.activestate.com/Products/ActivePerl/

Figure 3 - ‘Kepler’ and ‘Newton’

42

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September 2007

Group for Earth Observationand MRTG_2.15.0 available from:http://oss.oetiker.ch/mrtg/

Go to Downloads → Stable Release and select mrtg-2.15.0.zip.
Download this file then unzip and install it. Go back to thewebsite and click on ‘Documentation’, select ‘mrtg-nt-guide’ andfollow the instructions for building a configuration file. You will
have to add extra lines to your configuration file, plus some perl
scripts, to monitor the various parameters you require. These
all need to be placed in the ‘mrtg-2.15.0/bin’ folder. The
program b2status.exe needs to be added to the ‘bin’ folder.
Once mrtg.cfg has been correctly configured, you should be able
to run it by typing the commandperl mrtg mrtg.cfg

to start MRTG from the Windows Command Shell. If it isworking correctly, results files should start building up in the
directory you have specified.
For extra information and examples of files needed see:• my website:
http://www.alanbanks.org.uk/EumetsatReceivingStation.html• David Taylor’s website:www.satsignal.eu

From there select EUMETCast under Network Statistics• Fred van den Bosch has a full set of files on his download
page athttp://www.fredvandenbosch.nl/downloads.html• and I have put a zip file to download them at
http://www.alanbanks.org.uk/MRTGSetup.html

Galileo, the processing PC, is switched on first thing in themorning and all the relevant software runs automatically. It
takes an hour or so to catch up with the overnight downloads,
the MSG data taking the longest.
At the moment I am running the following software from David
Taylor.
• To manage and decode Meteosat-9 (MSG-2) data, I use
MSG Data Manager.
• To manage and decode Meteosat-8 (MSG-1) rapid scandata, I use a second copy of MSGDM. I start this manually
after the first copy has processed MSG-2.
• To manage and decode Metop-A data I use Metop Manager
and to do likewise for the NOAA 17/18 data I use AVHRRManager.
• To make real-time animations from Meteosat-9 or Foreign
Satellite Data, I use MSG Animator. I am currently
running two copies; the second for the rapid scan MSG-1
data.
I use the following as needed• To make false-colour images, remap to standard map
projections, or animate the images from MSG data I use
GeoSatSignal.
• To make false colour corrected images from Metop-A andNOAA AVHRR data I use HRPT Reader.
• Kepler Manager (satellite orbital information)• For satellite tracking - WxTrack• To geometrically map images - GroundMap
Defragmenting
I run anti-virus and anti-spyware software and also use mst
Defrag, which continuously monitors and defragments all the

GEO Quarterly No 15

drives on the PC. The huge volume of write/rewrite operations
that occur with all the data would need daily (or at the most,weekly) manual defrags . I found Windows Defrag used a lot of
resources and took quite a long time. Mst Defrag runs in the
background and uses little in the way of resources.
The Tellicast System
Data is transmitted from the various spacecraft to Earthstations in Germany (Meteosat 8 and 9), Svalbard (Metop-A)
and the Canary Islands, Northern France, and Svalbard (NOAA
17/18 AVHRR). Meteosat 9 data is refined, compressed andencoded as HRIT and LRIT files which are added to the
EUMETCast data stream and sent up to the Hot bird-6 satellite
as small ‘packets’ of data tagged with a packet identifier called
the PID. Other packets of data for AVHRR, Metop-A andForeign Satellite Data (FSD) are also sent up to Hot bird-6, butwith different packet identifiers (PIDs).
At the receiver one uses the setup for the DVB card to choose
which PIDs the card should handle. The data is sent from the
DVB card to the TelliCast receiving program as an IP multicast
stream and is now further divided into different channels. A
single PID may contain a number of different streams, but eachstream will have a different multicast address.
The multicast address of the ‘Announcement channel’ stream isfixed, and that channel ‘talks’ to the TelliCast program stating
what data is available. The TelliCast program is configured toaccept particular data channels (by editing the recv-channels.ini
file in the TelliCast software).
When a data stream becomes available the DVB software andthe TelliCast software interact with one another, the former
verifying that Tellicast can handle the data; only if it can (andthis may involve an authorisation check through your eToken),will the DVB software actually process the stream and make itavailable. The data is then written to the configured target
drive using, as a temporary folder, the file ‘0.fsy’ on the RAM
Drive.
Finally, I make use of MSG Data Manager software to convert
these files into a usable format for producing images.
Newton - the Utility PC
This is the third PC, which I use for all my other computer
needs, including email, browsing, writing this etc.
Those tasks relevant to the EUMETSAT images are as follows:

1 Image enhancement
using Adobe Photoshop. Most of the images received warrant
further manipulation. I know our editor prefers the raw image
when publishing, providing him with no lost data. Generally theimages I use are either for presenting at Astronomy workshops
or publishing on my web site.

2 File Transfer using AutoFTP Pro
My setup here is as a result of wanting to have my own home
web server using the third PC. I have a full copy of my website
on this PC, which allows me to check the functionality of thesite. AutoFTP downloads the MRTG data from ‘Kepler’(C:\myweb\documents) every 5 minutes. Also in that folder are
the saved results (downloaded with the MRTG data) ofscheduled jobs from GeoSatSignal working on the processing
PC. AutoFTP then uploads MRTG data every 10 minutes to mywebsite and each of the results of the GeoSatSignal jobs once
per day. Other uploads, such as page updates and new images
are sent manually.

3 Web PublishingThis is not so difficult as it may seem. I first tried to set up a
web server at home but my ISP wouldn’t allow this. It is
probably much more secure not to have a web server at homeanyway. I bought some web space from Streamline.net, whichcost me about £29 for two years with a ‘.org.uk’ domain name.

www.geo-web.org.uk

43

GEO Quarterly No 15

Group for Earth Observation

All the software you need is free and I eventually found stuff
easy to load and use although I did have a few false starts.

Finally, you require Active Perl. This can be downloaded fromhttp://www.activestate.com/Products/ActivePerl/. Just install it

Although I haven't built a web server at home you need somemeans of checking what you're doing and building a complete
copy web site at home before uploading to the web is in my view
essential.
Setting up your Web Server
Open Windows Control Panel → Add/Remove Programs →Add/Remove Windows Components. If you have a line that says
‘Internet Information Services (IIS)’, uncheck it.
You now need to install an application called AppServ, which isavailable at http://sourceforge.net/project/.
To obtain the latest win-32 version, type AppServ in the ‘Find’
field then click ‘Downloads’. On the following page, download
the file marked ‘Appserv Open Project’. Install AppServ. On the
opening screen, select ‘Apache HTTP Server’. When it asks for‘Server Name’ insert your server’s Internet URL; when it asksfor ‘Administrator’s email address’, insert your email address.
You will find that the folder ‘c:\Appserv’ has now been created,
containing a subfolder called ‘www’. This is where all the web
documents you create must go.
Next, you require the web authoring package NVU, which canbe downloaded from http://www.nvu.com. Once you have installed
NVU you can start using it to build web pages, which you mustsave, along with any images you have included, into yourc:\appserv\www folder. I learned the bare bones of NVU byborrowing Build Your Own Website by Kyle MacRae from thelibrary [1].
Once you've got all that sorted you will need web space andsome means of uploading the files to it. For file uploading, youwill need something like AutoFTP, which can be downloaded
from http://www.primasoft.com/ftp.htm.

September 2007

and forget about it. There is lots on the web about building yourown website. Give it a go.
So there you have it, three PC's under one desk in almost
constant use. I've stuck with Windows for all three. I have triedLinux on Newton, but networking is not so easy and I wasn't
using the full capacity of the PC.
I post my MRTG monitoring on the web every 10 minutes. I post
Met-9 images of 0600, 1200 and 1800 UTC. I regularly add
interesting images to the site front page. The whole exercise has
been a steep learning curve. The MRTG in particular drove me
to distraction over Christmas 2006. As was said recently on ayahoo group "Nothing is obvious until it is obvious to you".
Final Thoughts
A three-PC system may seem extravagant. However, I believe it
is a cost effective solution to an upgrade path. One PC I alreadyowned, and I upgraded it by local and Ebay purchases. The
second was a cheap all inclusive deal—there always seem to begood deals on last year’s model. The third was effectively free.
I'm sure many GEO members have family gamers who arealways upgrading to the latest model, so grab their cast-off’ gear
when you can. Apart from EUMETCast, David Taylor's softwareand Photoshop, all other software I have used is free. The KVM
switch was less than £20. There are KVM switches for 4 or more
PC's; the cheap ones don't work and reliable ones are expensive.
If your single-PC EUMETCast system is struggling, adding abasic specification second or even third PC is effective. The only
downside I have is that the 'office' can get a bit warm insummer!
1 Build Your Own Website - The complete step-by-step guide tocreating a website, by Kyle MacRae is published by the Haynes
Group (ISBN: 9781844251162).

... continued from page 26

The DMSP team has developed newcontrol modes requiring fewer than thetwo gyros normally needed for attitudecontrol. Using its Earth and sun sensors
along with an innovative software
estimate of yaw error, DMSP 15 was able
to maintain proper, stable attitude
without any gyro inertial information.
Formerly under military control, the
DMSP spacecraft are now operated by
NOAA. Their imaging system is quite
different to the familiar AVHRR andincludes a low-light capability.
Israel Launches Imaging Satellite
A Shavit rocket lifted off from Israel’s
Palmachim launch site south of Tel Aviv
on June 10 carrying the imaging spy
satellite Ofeq-7 to an eccentric
340 x 575 km orbit. To avoid dropping
spent rocket stages on its neighbours,
launches are made in a westerly direction
thereby losing the benefit of the Earth’s
rotation.

44

Japan and Korea imaged at night by a DMSP satellite. Note theabsence of lights over North Korea

www.geo-web.org.uk

September 2007

Group for Earth Observation

GEO Quarterly No 15

Figure 2 - A NOAA-18 image obtained from Morocco

Figure 1
My mobile APT station on location in Morocco

Figure 3 - The subsequent NOAA-18 image obtained from
Morocco showing cloud eddies around the Canary Islands

Figure 4 - A NOAA-18 image obtained from Los Angeles

www.geo-web.org.uk

Figure 5
Turnstile Antenna located on a Hotel Stairway in LagfunaBeach, USA.

45

GEO Quarterly No 15

Group for Earth Observation

September 2007

Francis BellI have been travelling abroad recently,
perhaps a little more frequently than in thepast. The reasons are various: family to bevisited, holidays and sometimes with asemiprofessional purpose. If I judge thepracticalities to be worthwhile I often takeone of my APT satellite systems with me onsuch expeditions.
At home of course, I have a EUMETCast
system as well as APT equipment but toattempt to take a EUMETCast mobile
system with me on travels would be apointless exercise. In any case, the locationof three out of the five places I haverecently visited lie outside the Ku and C
band coverage of EUMETCast.
It still gives me a thrill to receive live APT
signals, particularly when I am receiving
them with equipment I have built myself.
Second-hand reception via either
EUMETCast or the Internet, however
technically challenging—and recognising
the stunning quality of the retransmitted
images from around the whole world—is
not quite a substitute for receiving live
signals from a satellite, in real time, withsimple equipment. This may be true forother GEO members too because I notethe steady demand from our shop for thelatest APT receivers. I also note thatmembers are upgrading their APT systems
to cope with the pager problem which is
unique to the UK. So APT is alive and well!
Endlessly experimenting, I wanted to knowhow portable I could make one of my APT
systems. Also in the back of my mind wasto try for reception while at sea. Could I
take a portable system to sea, something I
had not done before? I’m not familiar withonboard reception, either on a small orlarge vessel, so this was an extra incentive
for me to try these locations. Perhaps small
boat owners are not familiar with APT
reception so my experiences may be auseful trial.
The equipment I used on my latest travels
consisted of a home-brew turnstile
antenna, a Dartcom preamp, a ten year old
RX2 receiver which I had constructed
myself, a Dell Inspiron 1100 laptop
computer running Windows XP and a
12-volt rechargeable battery. I used
WXtoImg capture and processing software.
The laptop runs for about two hours before
needing recharging. I’m not sure about theneed for the preamp in the system

46

Figure 6 - This NOAA-18 image shows the Philippines. Luzon island and the capital city, Manila are at thevery centre of the image. At upper left you can see the southern part of Guangdong province, China.

because, when on location, my cable runs
tend to be quite short. In future I plan
experiment without the preamp.
The antenna I used was the lightest I could
reasonably take bearing in mind that it had
to fit into a suitcase for air transport. I
carefully used the dimensions taken fromthe turnstile antenna sold by the GEO
Shop, copying the lengths of the elements,
their spacing and the length of the phasing
co-ax between the elements, all to thenearest millimetre. The antenna consistedof a support mast made from plastic watertank overflow pipe which I drilled to accept
wire elements cut from 2.5 mm galvanised
fence wire which I had in the shed. The
wire was strong enough to be selfsupporting yet flexible enough to be bent
and fitted into a suitcase. The total weightof this antenna was 0.4 kg.
Since January this year I have operated
this equipment from the following fivelocations away from home.
The South China Sea
I was a passenger on a cruise ship whichsailed between Hong Kong and Singapore.
The itinerary for the cruise was port
intensive but there were occasional days at
sea which gave me the opportunity of
establishing my APT station on a little-used
corner of an upper deck where I taped theantenna to the ship’s railings. The view ofthe sky was mainly favourable but to one
side there was a obstruction because of the

www.geo-web.org.uk

ship’s air-conditioning system which was
also very noisy. I received several good
images of the South China Sea showing
the Philippine Islands and the coast of
China. The two small problems I
experienced related to the physicalenvironment in which I was located. The
noise from the air conditioning system wasso loud it was difficult to hear the audio
output from the receiver. I find it helpful tolisten to the audio signal in addition towatching the ‘S’ meter during a pass. Also
the bright ambient light level, especially insunshine, made it very difficult to see thelaptop’s screen display. I finished up using
towels to shroud the screen and thenplacing my head beneath this to view thescreen. Undignified but practical.
California
Academic issues dispatched me to LA in
March and during my stay it was great tomeet Ed Murashie and Lynn Grant again.
Ed is a GEO member and came to the UK
in 2005, stayed with me, then gave apresentation at our Symposium.
The hotel where I was staying was at
Laguna Beach, about 40 km south of LA,
and conveniently overlooked the beach. It
was a complex of small buildings
connected by walkways and stairs. Being
resourceful, I discovered a quiet stairway
where I taped the antenna to railings. Thislocation gave a good view of the sky but
was close enough to allow a direct cablerun to my room; this enabled me to operateSeptember 2007

Group for Earth Observation

discretely with the bonus of having accessto mains power rather than relying on
batteries. I was very pleased with theimages I received, which showed thecoastline of the western United States and
Mexico to the south (figure 4). Why is Baja
California part of Mexico and New Mexico
part of the United States? History, I guess!

officer picked up my APT receiver, lookedat the front for about five seconds then at
the back for five seconds, shook it gently
and then put it back in my case without
comment. The process did just register withme that carrying unusual electronic items
on an aircraft could be judged suspicious. I
always carry a GEO Quarterly with me
while travelling, so if I am ever challenged I

MoroccoAn expedition to Morocco was also
accompanied by my APT station. A hotel in
Fès where I stayed had an under-used roof
terrace. There were only a few guests in
the hotel so I had the roof to myself. There
was an excellent view of the sky andrearrangement of the plastic furniture andtape provided an excellent location for theantenna, receiver and computer. I was very
pleased with the NOAA 18 images I
managed to log (figures 1, 2, 3).
The Solent
Colin Cox, a good friend and GEO
member, invited me for a day out on the
Solent. Planned timescales were such that
we would be at sea during NOAA 17 andNOAA 18 passes. I thought it would be
worth taking my APT station and trying for
an image from a small boat.

GEO Quarterly No 15

concluded on page 50 ...

NASA Earth Observatory
Figure 8
The author’s mobile APT station in the Amazon
basin, showing tropical rain forest in the
background, the Napo river and part of the small
boat exploring the area.

The outstanding image reproduced
overleaf (page 48) dates from June 29,
2007 and was acquired by the Moderate
Resolution Imaging Spectroradiometer(MODIS) flying aboard NASA’s Terra
Earth observation satellite.
The image depicts the lower reaches andestuary of the Ob River—at 3650 km in
length, the fourth longest in Russia—
which follows a twisting northwesterly
course from its source in the Altai
Mountains to the Gulf of Ob, before
emptying into the Kara Sea..

Figure 7 - The APT antenna mounted on Colin
Cox’s boat while sailing the Solent.

Again the antenna was taped to railings
with the receiver and computer in thecabin. I received two images showing the
UK and Europe. The images were not very
different to those I receive at home but thecircumstances were different, that is,
reception using portable equipment while atsea. in a small boat.
EcuadorThis was what I really wanted to do! Having
reduced the weight and bulk of my station,
could I really take it to any part of theworld? I have always had the ambition tovisit the tropical rain forests of the Amazon
basin. I booked a holiday which included afour day cruise on a small river boat which
was based on the river Napo, about 20 km
from the town of Coca in Ecuador. Thisriver joins the Amazon further downstream
but because of the river’s smaller scale itprovided easy access to smaller side
waterways, lakes and forest areas which
would have been more difficult to reachfrom the main Amazon river. The captain of
the boat readily agreed to me setting up my
APT station and took a genuine interest inwhat I was doing. Again, I taped theantenna to the ship’s railings and operated

Figure 9
An APT channel-2 image showing Ecuador,
Colombia and Venezuela

by battery. Because of our busy itinerary I
only had the opportunity to receive twosatellite passes. Disappointingly bothcontained slight interference patterns when
the satellite was at a low elevation. I justdidn’t have the time to sort out this small
problem. However, I was still very pleased
with the images I did receive, whichshowed the pacific coast of South America
to the west and the Amazon basin with its
rivers to the east (figure 9).
The captain was interested in what I had
been doing so I left him a copy of
GEO Q14. For my part I was profoundly
impressed with the knowledge anddedication of the people operating this four
day cruise, together with their commitment
to maintaining and documenting their rain
forest and river environments.
Security
Having just returned from Ecuador, one
experience did just highlight a possible
security issue. On international departurefrom the airport in Ecuador, my luggage
was opened by the police in my presence.
There was no problem but the inspecting

www.geo-web.org.uk

Frozen over for several months during
the winter, the onset of summer brings athaw that creates a heavy runoff frommelted snow, which transports vastquantities of ice floes towards the Arctic.
The result is an ice jam downstream fromthe thawed portions of the river. At thetime this image was obtained, the thawof the Ob was nearing completion.
The scene is typical for early summer.
South of the ice jam, the Gulf of Ob isswollen with pent-up run-off; farther
upstream from the jam, the river iswidened as well. Unable to carve throughthe still-frozen terrain, the Ob has little
choice but to overflow its banks.
This image also depicts sea ice retreatingfrom the Kara Sea into the Arctic Ocean
and a lingering line of snow coversnaking its way along the Ob River, tothe west. And while the land to the south
appears lush and green, farther north itis barren and brown. Near the mouth of
the river and bordering the Kara Sea, theland consists of cold-adapted tundra
where a short growing season permits
the growth of only diminutive plants. The
tundra itself had yet to thaw at the timeof this image, hence the region’s lifelessbeige appearance.
NASA image courtesy Jeff Schmalz(MODIS Rapid Response Team)47

September 2007

Group for Earth Observation

GEO Quarterly No 15

Douglas Deans - dsdeans@tiscali.co.uk
As is usual over the summer months,
software updates are in short supply andindeed I am now finding that many of ourbetter known programs are not regularly
updated. I suspect that the digital era hassomething to do with that. Of course, asever, the exception to the rule is the suiteof programs written by David Taylor.
Those are updated on a regular basis,
mainly to accommodate user suggestions.
The latest versions of those programs areshown in the GS1 table list below. In
addition Patrik Tast's excellent APT
Decoder software has had quite a major
update and a short summary of that is
also included. So again, whilst things area little quieter, I take the opportunity toremind readers, particularly those new to
GEO, about the CDs being offered in the
showcase.
CD GS4This CD contains a selection of highresolution images taken from Landsat 7,
the Space Shuttle, MODIS, weather
satellites and a collection from NASA's
Earth Observatory.
The original thought behind this CD wasprimarily to be able to offer those with aslow Internet connection, or perhaps noneat all, the ability to enjoy large, highresolution images. With the huge increasein the use of broadband, and indeed very
fast broadband, there is probably lessneed for this. Nevertheless the CD is fullof fascinating imagery and comes as ahandy composite package with image
descriptions. There are endless Internet
sites now offering new high resolution
imagery on a day-to-day basis but the
subject of the images supplied on GS4
have been chosen not only for theirinterest but also their timelessness. The
CD is available from the GEO Software
collection as detailed below.
Satscape
Readers may recall that I made mentionof a new version of Scott Hather's
Satscape software (GEOQ 13). Scott has
been planning a JAVA option since, as heputs it, 'Quite simply because it can bejust as good as the Windows version,
hopefully run better, but will run on any
operating system, Windows, Linux, Mac
OS X etc.'
The Java version is now in early
development but is not yet a replacement
for the Windows software. Nevertheless,Scott has released an early alpha version
for people to try and to specifically reportbugs and problems. This will not
overwrite your existing Windows version
but will be kept side by side with it.

Indeed those trying it are encouraged touse both editions. If anyone is interested
in trialling the Java software it isavailable for download from the Satscapesite. Go to http://www.satscape.co.uk/ andfollow the links on that page. Once thesoftware is at a more advanced stage I
will report further and make it available
on CD2 where the current Windows
version is still included..
APTDecoder v 2.0.4.76
APTDecoder, already an excellent
composite program, has just got betterwith the addition of mapping features. I

have reviewed this program briefly before
and Les Hamilton provided an in-depth
analysis of the program in GEO Q8(December 2005). For those new to theprogram I strongly recommend reading
this article as it is an excellent guide tosetting up the software and getting togrips with the basic functions as well as
the more advanced options.
The latest update now offers new
mapping features and includes :• The ability to project an image in various
projections.
• Create a daily composite image.

All D avi d Taylor's weather satelli te programs and li brari es, i ncludi ng the current releases of WXtrack,
GS1 Satsignal, HRPT Reader, GeoSatsignal, GroundMap, RX2 PassControl and many other program extras.
This disc also contains a large quantity of sample files, many of high-resolution data, for use with these
programs.
AVHRR Manager
Processes and manages the files for HRPT via EUMETCastv 1.3.6
GeoSatSignal

Manipulates Geostationary weather satellite images

GRIB Viewer

Viewer for GRIB format files

v 6.1.0
v 2.1.4

GroundMap

Rescales satellite images

v 2.0.6

HRPT Reader

Converts raw HRPT data files into images

v 2.7.0

Kepler Manager

Organises files of 2-line element data

v 1.2.8

Metop Manager

Processes and manages AVHRR files from Metop satellites

v 1.1.4

MSG Animator

Automatic animation of MSG images following reception

v 2.5.8
v 2.5.8

MSG Data Manager

Processes and manages MSG data files

RX2 PassControl

Computer control program for the RX2 receiverv 3.1.0

SatSignal

Creates images from wave files

v 5.0.6

WXtrack

Satellite Tracking Programv 3.6.4

A wi de range of software for all aspects of weather satelli te recepti on, i ncludi ng tracki ng, recei vi ng,
GS2 monitoring and image manipulation. Content is detailed below but many other extras are provided. Titles
correspond with folder names. * implies a DOS program.
Collection D02
Recall (wave file recorder), Palette (modifies Wxsat colour palettes).
Scanner recorder v 1.8 (wave file recorder), *NOAA95/*FENG99 (software
Collection D03
for the NOAA 95 HRPT project)
Wxsat (wave file recorder/decoder), Satmon (wave file
Collection D04
v 2.59recorder).
AGSatTrack
Satellite tracking programv 1.33
APTDecoder

Program for capturing APT audio and processing images

CirkitDocuments for the Cirkit Wxsat receiver and the UOSat receiver (PDF)

v 2.0.4.76

Element Manager

2-line element manager

Footprint

Satellite tracking programv 1.59v 2.24

Irfan View

Image/slideshow viewer

v 3.80v 1.40 pre

JVcomm32

Evaluation version (APT/FAX/SSTV decoder)Macintosh kepler editor

Edits verbose AMSAT format elements. Mac OS X and OS9 only.

NeoPaint

Image processing program (30 day evaluation)

v 4.60

OrbitronSatellite Tracking Programv 3.70

Paintshop Pro

Image processing program (30-day evaluation)

PhotoFiltre

Image retouching program with many extras

v 6.1.5

Satscape

Satellite tracker and wave file recorder

v 2.02

Space-Track TLE Retriever Generates TLE files in 'Celestrak' style from'Space Track' data sets
Xrit2Pic

Processes MSG and Metop data

Splitter

Utility program for splitting and reuniting large files

WXtoImg

WAV file recorder/decoder program with many options.

v 2007.03
v 2.7.3

3DEM Package for 3D Terrain Visualisation
GS3 This CD includes the full set of GLOBE Tiles to allow you to produce excellent images and flybys from
HRPT inages. Also included is a selection of Mars MOLA files, sample images and helpful guides by Ed
Murashie.
Image CD
GS4 A wide selection of high-resolution remote images from a range of satellites, including stunning imagery
from the Space Shuttle missions. A full description and source if provided for each image.
Mars Rover Panoramics
GS5 A chronological account, in panoramic images, of the NASA Mars Rovers' progress across the MartianTerrainwww.geo-web.org.uk

49

GEO Quarterly No 15• General settings now includes anoption to show image after
processing.
• Improvements for those using theICOM PCR 1500.
• Improved sharpen and contrast
options in Settings.
• A number of bug fixes.

APTDecoder v 2.0.4.76 isavailable on GEO software CD,
GS2 For further information or to
download the program go to :-Symposium 2007
As a new member of GEO, can I say how
much I enjoyed the Symposium at the
National Space Centre.

http://wap.ptast.com/apt/
decoder/index.html

All my questions were answered withenthusiasm by other members and I now
have an APT system up and running. The
next step is to install the dish and PC card
RX for MSG reception.

How to Purchase CDs

Best Regards
John Wiggins, Newcastle Under Lyme

Write to the address below
requesting GS1, GS2, GS3,
GS4 or GS5. Prices are £5 forany single CD, 2 for £8, 3 for£11, 4 for £14 or all 5 for £17.
Please enclose cash or cheque(made payable to Douglas
Deans - not GEO please) for
the appropriate amount.
Nothing else is required.
The cost includes CDs,
packaging, posting and a small
donation towards the cost ofoverheads. No fee is asked
from overseas members
although an exchange ofsoftware or interesting satellite
images is always welcome.
Orders are normally dispatchedon the day of receipt.
Order your CDs from:
Douglas Deans, 17 MontroseWay,
Dunblane, Perthshire FK15
9JL, Scotland.

Peripatetic APT... concluded from page 47

can illustrate that my activities are ascientific, educational hobby with nosinister dimension.
The Future
I am going to try to make myportable antenna system a little
more visually appealing and quicker
to assemble. I will use the muchlighter R2FX receiver instead of myhome-constructed one andexperiment without the use of thepreamp. In due course I will reportmy findings.
Further details
If anyone is interested in following
my journey on the River Napo
through the adjacent rain forests
just email me and I will forward thetravel contact points to you.
francis@geo-web.org.uk

50Group for Earth Observation

Mysterious Feature (GEO Q14, page 30)
This could be the right of way for the
Churchill Falls 735 kV Power lines toQuebec. The right of way is 710 feet wide.
Here is a link that shows some of it—scroll
down the page a bit to see the photograph.
http://www.ewh.ieee.org/reg/7/
millennium/churchill/cf_history.html

Cheers....Mike G1HWY

Super Delivery
Just to let you know my GEO Quarterly
arrived in record time here in Bulgaria. It
had the Southampton postmark of May 31
and on June 2 my neighbour came to visit
me on his bicycle. He told me that the postlady here had called him and that there
was interesting post for the Englishman!
Only 2 days. How’s that for service!
By the way, they came to install mywireless Internet yesterday, via a remote
microwave link. The installation was
successful but they forgot the paperwork!
This means I have to wait for information
on setting up my mailbox for sending
emails. But I still receive OK on mydomain address (rob@wxsat.org)
I’m hope to meet you all in Germany on the
Eumetsat trip. Sorry I couldn’t make it tothis years Symposium. We have had severe
floods in Plovdiv with up to 2 feet of rainon the motorways this week! Averagetemperature here is about 30°C.
Best Wishes from Bulgaria,
Rob Denton

Etna
Very many thank's for the latest issue of
GEO Quarterly and as always an excellent
publication.

www.geo-web.org.uk

September 2007

As a follow-up from the latest issue, I am
enclosing an image of Mount Etna in
Sicily, with steam and smoke coming fromit (opposite page). This lasted about anhour. This image was received on the May
24, 2007 at 13:15 UT. I hope your readers
find it of interest. As a further point ofinterest, you can see the islands of Malta
and Gozo to the south of Sicily.
Eric Dean, Maidstone, Kent, England

GEO Visit to EUMETSATExactly a week before July 4, I came to the
GEO Homepage and there read of the big
event in my neighbourhood. I have been an
enthusiastic weather satellite amateur(APT) for 15 years, and therefore I thought
this unique chance shouldn't go away
without me.
I wrote Peter Green an email and was
surprised and happy to receive his welcome
the very next day. My chief gave me twodays holidays without problems.
I met with many people from different
neighbouring countries and we chatted
about our hobbies and other interests (goodto refresh my English knowledge) .
Thanks to EUMETSAT's superior
programme for GEO, I am now up to dateover environmental satellite's and havemade many new friends.
Thank you very much. Best wishes andregards,
Best wishes and regards,
Carsten Arnheiter

My thanks to GEO for all the hard work
which made our visit to EUMETSAT sucha huge success. It was wonderful to havesuch interesting lectures from suchdedicated and senior people. Visiting thecontrol rooms was also something that I
found quite stunning, and I had looked
forward to it ever since the visit was firstmooted.
Speaking to others on the visit I am surethat they enjoyed it as much as I did. We
all had a great time and got on so welltogether. It was a good evening too in the
Ratskeller all doing our bit forinternational relations.
So once again, thank you very much.
Kind regards,
Tim Holdsworth

September 2007

Group for Earth Observation

GEO Quarterly No 15

Having looked through some photos I
took when I last visited EUMETSAT, andhaving an interest in things
Scandinavian, Cecilia recognised staff
member Anders Sorensen from Denmark
while she was having lunch. Quite what
Anders thought when this ‘unknown’ lady
called him across, I don't know, but shequickly explained that her husband washere, and directed him to my table.
Anders and I had a good chat about how
the ideas we had discussed a couple ofyear back had developed—the result had
been the EARS-AVHRR service, by theway.
Cheers,David Taylor
Eric Dean spotted Mount Etna erupting in this clip from Meteosat-9
Image © EUMETSAT 2007

Funnel Cloud
About 15.00 UT on Saturday June 23,
while watching an approaching
thunderstorm, my attention was drawn
to a strange cloud circulation. I grabbed
my camera and watched for about fiveminutes as funnel cloud formed. I thenwatched this for about 8 minutes andtook the photograph below.
The image is through glass, so limited.
As the houses cut off the view I cannot
tell whether it was just a funnel cloud(which doesn't reach the ground) or a
tornado (which does). Whatever, thiswas a rather unique meteorological eventin this part of the world (Dunblane,
Scotland). As I said, I don’t know if it
touched down or not but it was still agreat sight: certainly the first time I haveseen such an event live.
Best regards,
Douglas Deans

A funnel cloud photographed by Douglas Deans last June

After Darmstadt ...
Shortly following the GEO visit toDarmstadt, one of GEO’s continental
members, Guiseppe Cico from Italy
arrived in Edinburgh for a week’sholiday.
During his stay, he enjoyed a lunchwith three of GEO’s Scottish
contingent.
The photograph at right, kindlysnapped by a waitress (using David’s
camera), shows the group enjoying
their meal (left to right: Les Hamilton,
Guiseppe Cici, Cecilia Taylor, David
Taylor)www.geo-web.org.uk

51

GEO Quarterly No 15

Group for Earth Observation

September 2007

Lawrence Harris

I thought that I would write this shortpiece about my experiences with the newpager-resistant APT receiver designed byHolger Eckardt. I originally borrowed an
R2ZX from GEO in order to prepare a
short review for publication in
Monitoring Monthly.
APT receivers are few and far between,
and this is understandable; with newtransmission formats being implemented
by the newer generation of weather
satellites there is little incentive orconcern shown by more establishedmanufacturers to upgrade their products
for the special problems generated a few
years back by the UK frequency
allocations. Holger has become theexception in modifying his previously
issued receiver specially for the UK
market.
Clive Finnis kindly delivered the original
pager-resistant unit to me and I installed
it in my computer room. The a.p.t.
antenna feed from the garden-mounted
QFH had been a little short, so an
extension co-ax was fitted. This has neverworked very well anyway, even when
feeding my long-used Proscan receiver. I
connected the new receiver to it andwaited optimistically. Unfortunately,
virtually every satellite pass was adisaster—filled with powerfulinterference. There had to be a basic
problem here.
Relocation
I decided to move the reception
equipment into the garden observatory to
see whether there was any improvement.
One hour later I was operational. The
cable was now more than adequate inlength, so the feed now connectedstraight to the receiver. My original
receiver was not too bad on all satellites,with the exception of NOAA-18; in thisnew location it was a total disaster.
After running this system for a couple ofdays to establish a 'norm', I switched to
the R2ZX receiver. ‘Wow!’ is all that I
can say. Hearing NOAA-18 rise above
my southern horizon and provide
excellent signals immediately was adelight. Previously, all NOAA-18 passes(on the 137.9125 MHz frequency) had
been punctuated by powerful pager
interference every few seconds.

52

I left the system recording automaticallyfor several hours until I had to lock up
the observatory overnight. Thatexperience allowed me to write myreview notes for Monitoring Monthly.
Having to return the receiver to GEO
was something approaching near-trauma!
For a few weeks I struggled with myoriginal system, until finally giving in! I
ordered my own R2ZX and then not only
installed it permanently into theobservatory, but also drilled a small holein the back wall to take the cable feed. I
have since recorded all passes
continuously, which has of course let me
see the overnight and early morning
passes from every satellite.
Box of Magic
I have been delighted with the resultsfrom this box of magic! My first task eachmorning has been to connect via the
network to the remote computer toexamine the pictures collected overnight.
Figure 1 is a section from an enhanced
early-morning NOAA-18 infrared image.
One unexpected problem here has been
the software. I was using Craig
Anderson's WXtoimg but on every
occasion that I connected to the remotecomputer via the network, the actual
display from the program was missing! I
could not activate any commands or see
the picture because the screen was blank.
I notified Craig of this problem and hehas told me that he is working on asolution. Meanwhile others haveconfirmed my own experience. As a resultof this I have recently been using Patrik
Tast's APTDecoder which works perfectly
at both decoding the a.p.t. signal andproducing a selected enhancement.

Figure 1
An enhanced NOAA-18 IR image
02:22 UT on June 2, 2007

You can just forget about pagers!

My local horizon is now quite reasonable
in the south; the east has sprouting treesthat were not there when we moved in
but have shot up to make my observing
difficult! The northern horizon has sometall neighbour's trees and the west is
broken by the house roofs. This
combination of trees causes severe signal
drops during certain passes - not to be
confused with pager interference.

And finally, to its right, is an earlymorning colour composite from NOAA-12
to illustrate that all the satellites areproducing excellent results.

As in my Monitoring Monthly review, I
can only say that this is a most excellent
receiver. Long may the a.p.t.
transmissions continue!

The coloured image at the upper left on
the opposite page was obtained from a
daytime NOAA-18 pass, a complete
sweep from about two degrees south
elevation until cut off by trees to thenorth of me.

www.geo-web.org.uk

NOAA-12 at 05:35 UT on June 2, 2007
The photograph below shows GEO reader Anthony Lowe in
his qth, Anthony sent in a collection of his NOAA APT images
acquired during April and May, making particular reference to
the NOAA-17 pass illustrated opposite.
Acquired at 10:52 UT on May 23, 2007, this image shows a welldeveloped set of Ship Trails off the southwest coast of Britain, as
well as a regiment of lee wave clouds over the far northwest of
Scotland.

NOAA-18 at 12:45 UT on May 30, 2007