Group for Earth Observation
The Independent Amateur Quarterly
Publication for Earth Observation

LAUNCH ISSUE

and Weather Satellite Enthusiasts

Inside this issue . . .
Register for GEO’s first
Symposium at the
National Space Centre
next May
Read about thedisappearing perennial
Arctic sea ice
Peter Wakelin writes
about India’s Space
ProgrammeDavid Taylor discusses
Meteosat-8 (MSG-1)
reception and answers
your questions on thebest PC configuration touse
Learn about Europe’s
Envisat satellite and its
amazing radar Imagery
Follow our guide tosetting up your own
weather satellite groundstation, and receive yourown satellite images
The Snows ofKilimanjaro - Francis
Bell discusses satellite
imaging of snow in thetropics
Arthur Andrews writes
on the Australian scene
Build a portable,collapsible QFH antenna
and much more ...

Glacier Bay National Park and Preserve, Alaska with Gulf of Alaska in the left foreground and the Brady Glacier behind. The
visualisation was created by draping elevation data from the USGS National Elevation Dataset - predominately 30-meter resolution
elevation data collected by NASA’s Shuttle Radar Topography Mission (SRTM) - over an Enhanced Thematic Mapper Plus (ETM+)
image acquired by the Landsat-7 satellite in August 1999. This true-color image was created by combining the red, green, and blue
wavelengths (ETM+ bands 3, 2, and 1).

Radar interferogram of the Las Vegas area (left) with a digital elevation model for comparison (see article on page 22)

GEO is led by
Francis Bell
Clive Finnis
Les HamiltonPeter Wakelin

Nigel Evans
Ray Godden
John Tellick

CONTACT INFORMATION

W

elcome to your first issue of the GEO Quarterly, the official
magazine of GEO, the Group for Earth Observation. GEO is
a new organisation aimed towards everyone with a keeninterest in weather satellites and Earth imaging.

G

EO has been conceived as a wholly amateur group, which willremain totally independent of any commercial interests in theweather satellite and Earth imaging fields. GEO is totally
dedicated to serving both educational users and the amateur
community.

I

nside this launch issue you will find numerous articles aimed
at newcomers to the hobby. Arthur Andrews reminisces about
how he started out in Australia. Cedric Roberts explains what
fired his interest in the weather. John Tellick traces the
MSG-1 story from its launch in 2002 up till the present.
Francis Bell suggests an Earth-imaging project to test yourskills.

Now turn to page 2 and read Francis Bell’s ‘Mission Statement’on The Group for Earth Observation. Learn of our hopes andaspirations, and the bright future we all see ahead for the
Remote Imaging Community.

General Information
John Tellick
e-mail: info@geo-web.org.uk
Articles and Images for Publication
Les Hamilton,
8 Deeside Place
Aberdeen AB15 7PW
Scotland, UKe-mail: editor@geo-web.org.uk
Membership and Subscriptions
Nigel Evans,‘Eventail’, 7 Gloster Ropewalk, Aycliffe,
Dover CT17 9ES
England, UKe-mail: members@geo-web.org.uk
Meteorological Consultant
Peter Wakelin
e-mail: meteo@geo-web.org.uk

Contents
Introducing GEOGEO Symposium - Leicester - May 1, 2004
The Disappearing Perennial Arctic Sea Ice
Official GEO Internet Discussion Group
Snows of Kilimanjaro (How Band Aid Got it Wrong)
Meteosat Second Generation
Free Amateur and Educational Access to MSG
The Polar Low Phenomenon
Watching the Weather
Unusual Solar Activity
May the FORCE be with You
MSG Update - John Tellick’s Questions Answered
The Indian Space Programme - part 1
European Publications - Free to GEO Readers
Copy Deadline for the Next Issue
Satellite Frequencies and 2-line Elements
Advanced Synthetic Aperture Radar from Envisat
Setting the Correct Time on Your Computer
Cover Images
Comet Training Modules
View from the Other Side
Improved W/V Data from MSG-1
Massive B-15A Iceberg Snaps in Two
Earth Imaging NewsIn Tray - Readers’ Letters and Questions
Satellite Predictions
Joining the Group for Earth Observation
EUMETSAT Operations New Bulletins
Software Showcase
First Steps in Setting up an APT Ground Station
Portable/Collapsible Quadrifilar Helix Antenna

Public Relations and Education
Francis Bell,
Coturnix House,
Rake Lane,
Milford,Godalming,
Surrey GU8 5AB
EnglandTel:(01483) 416 897
e-mail: 100523.1037@compuserve.com

Francis Bell
NASA
Francis BellJohn Tellick
EUMETSATLes Hamilton
Cedric Roberts
Peter Wakelin
Francis BellDavid Taylor
Peter Wakelin
Francis BellDavid Taylor
Peter Bartlett
Arthur Andrews
David Taylor
NASAPeter Wakelin

Douglas Deans
Les Hamilton
Chris van Lint

2
3
4
5
6
7
9
10
13
14
15
16
18
20
21
21
22
25
28
30
31
33
34
36
37
38
39
40
41
42
46

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 4975595.
The registered office is Coturnix House, Rake
Lane, Milford, Godalming, Surrey GU8 5AB
Printing
Toptown Printers, Vicarage Lawn,
Barnstaple, Devon EX32 7BN.
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 designor any constructions carried out by members orother third parties.
Copyright GEO © 2004
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 1

Group for Earth Observation

Launch Issue

Francis BellWelcome to this first publication of‘GEO Quarterly’. In this introduction I
will be as brief as possible because thecontent of the following pages will bemuch more interesting and will relate
to the practical aspects of our interests
in live weather satellite reception.
The background to this new groupstems from a wish to establish anamateur organisation interested in thereception of live weather satellite
images directly from space. The historyof amateur weather satellite reception
goes back over 20 years, to the time
when Muirhead printers and dedicatedframestores were used for recording asection of an image. Today however,with readily available fast computersand sophisticated software, together
with a second generation of weather
satellites beyond APT and WEFAX data
formats, a second look at our interest
group / hobby seemed timely. Hence,
the new group: ‘Group for Earth
Observation’, associated with theappropriate acronym ‘GEO’ and its
quarterly publication.
In the very long tradition of amateurinterests—the best example must be
amateur radio—our intention is toexperiment, free from any commercial
association, and to help other members
interested in direct reception of weather
satellite signals. You may have seen
publicity material submitted to Short
Wave Magazine, the RSGB’s RadComand the National Space Centre’s BNSC
Directory. These published texts areexactly in line with the above
statements of our plans and rationale.
Without wishing to excessively flatter
those people who have agreed to leadthis new group, there is a wealth ofintellectual background within thegroup, embracing disciplines such as
RF, astronomy, computing, meteorology, oceanography, publishing and awide experience of weather satellite
reception.
Page 2

We have decided to make this first
GEO Quarterly publication freely
available, but of course, to maintain ourgroup and cover the costs of thequarterly
publications(quarterly
implies four times a year) we do need asubscription membership. If you have
not yet joined then read this publicationand then judge whether £12 a year ismoney well spent. Visit our web site atwww.geo-web.org.uk which is readily
accessible and will be under constantreview as this GEO Group develops.
Alternatively, write to:
FJB (GEO),
Coturnix House,
Rake Lane, Milford,
Godalming GU8 5AB
England,Great Britain.
for information about joining the GEO
group.
Forgive me if I repeat this but GEO has
a passion for being an amateur based
group. And here comes the big benefit:
EUMETSAT have just written tome stating that amateur andeducational users of theirsatellite services do not have to
pay any license fee for the
reception of their encryptedsatellite data streams. Here I
must express particular thanks
to John Tellick who deserves
most of the credit for making thispossible. For over a decade now,
John has campaigned tirelessly
with EUMETSAT, the Met
Office and other Agencies onbehalf of weather satellite
enthusiasts.
I cannot understate the benefit of thiswhich I and others have worked forwith EUMETSAT. Herewith my public
thanks to the EUMETSAT Council andto our UK Meteorological Office for their
Check www.geo-web.org.uk for all the latest news

support of the amateur and educational
communities who explore the scienceand technology of what is possible forthe reception and display of the newgeneration of weather satellite images.
A cautionary word here. I believe that
GEO is in a privileged position in theamateur community and I ask that thisstatus is not compromised. I ask that
nobody distributes or publishes
material, text or images, where thecopyright resides elsewhere. Most of ourmaterial is directly available in the
public domain so there is no problem,
but it is courteous and perhaps a legal
requirement in some cases to have thepermission of the author or copyrightholder before submitting material for
printed publication or display on theInternet.
GEO will not support any exploitationof the intellectual property owned
outside the public domain or withoutthat owner’s permission.
Judge our first publication by reading it
and then decide whether you wish tojoin us. To join, visit our web site or
write to FJB as shown above.
If you think our new GEO group with its
quarterly publication plus its support
for amateur and educational users is
worthwhile, then please recommend
GEO to your friends and colleagues. We
do need an extensive membership tomake GEO viable and worthwhile.
I cannot finish without expressing myadmiration for the commitment andskills of those people (friends),
responsible for the formation of GEO.
The same goes to contributors to thispublication who have made it soworthwhile. I look forward to thesuccess of the group and the excitingtimes ahead.
Enjoy reading and exploring the rest of
your first GEO Quarterly.

Launch Issue

GEO has secured an outstanding
location for its inaugural one-day
symposium—the National Space
Centre in Leicester. This Centre
is a stunning venue, and well
worth a visit even without thebonus of a GEO meeting. Please
put this date, May 1, 2004, in yourdiary. If GEO is to continue withthese events we do need yoursupport.
From about 9.30 am, in the
exhibition area, we will have on
display live satellite reception:interesting for beginners and theexperienced alike. The hardware
and software will be there,
together with advice on thepurchase of the equipment forweather satellite reception.

Group for Earth Observation

accessible by road or rail. There isa bus service to and from the city
centre to the National Space
Centre. There is a large free carpark at the Space Centre if youcome by car.
As this is GEO’s first symposium,
we do need your support for the
event. It is expected that
distinguished speakers will be
there and every effort will be put
into live satellite reception. Pleasecome if you can to support GEO.
Registration
If you wish to register, please send
your name and address by post to:‘FJB‘ (GEO),
Coturnix House,
Rake Lane, Milford,
Godalming, Surrey GU8 5AB
or email your details to:100523.1037@compuserve.com

marked ‘Leicester Symposium’.

The ‘Rocket Tower’ at the
National Space Centre in Leicester

Invitations have been issued topotential speakers for the day,mainly relating to the latest
developments in weather satellite
reception. Nothing is guaranteed
here because it depends on otherpeople but the track record thus
far is encouraging.
The cost for the day is a very
modest £10 which will include
access to the Centre’s exhibitionarea. This fee does not include
food, travel or accommodation.
These personal details must be theresponsibility of each delegate.
The National Space Centre isabout two miles north of Leicester
city centre. Leicester, almost in
the centre of England, is readily
Page 3

GEO Quarterly No 1

You will be put on the databaseand later, in March, sent details of
Leicester’s local accommodation,
traveldetails,
theday’s
programme and invoiced for £10.
If you are coming from outside theUK you may pay the £10 on the
day or the equivalent in Euros or
US$.
However, because of restricted
numbers it would be much betterto avoid disappointment andregister your details in advance.

An American ‘Gemini’ space capsule, oneof the exhibits on display inside the
National Space Centre.

Finding Your Way to the
National Space Centre
By Car
The National Space Centre is located justoff the A6, two miles north of Leicester City
Centre, and midway between the inner andouter ring roads. Brown signs direct you
from junctions 21, 21a and 22 on the M1
and all other arterial routes around
Leicester. There is free parking for 400
vehicles at the Space Centre.
By Train
Midland Mainline and Central trains serve
Leicester station.
By BusBus route 54 serves Leicester Station, City
Centre, St Margaret’s Bus Station and
Abbey Lane, the latter just 5 minutes walkfrom the Space Centre.
For information on shuttle buses serving
the Space Centre, telephone Leicester
Tourist Information Centre on (0116) 299
8888.
The map below indicates the location of
the National Space Centre (not to scale).

Details of GEO, and in due course
the day’s programme, may befound on our website at:www.geo-web.org.uk

Details of the National Space
Centre may be found at:www.spacecentre.co.uk.

You are advised to consult both
websites if you can.
Check www.geo-web.org.uk for all the latest news

Page 3

GEO Quarterly No 1

Page 4

Group for Earth Observation

Check www.geo-web.org.uk for all the latest news

Launch Issue

Launch Issue

Group for Earth Observation

GEO Quarterly No 1

NASA/Goddard Spaceflight Center
A NASA study finds that perennial sea ice in the Arctic
is melting faster than previously thought—at a rate of
9% per decade. If these melting rates continue for a few
more decades, the perennial sea ice will likely
disappear entirely within the 21st century as aconsequence of rising temperatures and interactions
between ice, ocean and the atmosphere that accelerate
the melting process.
Perennial sea ice floats in the polar oceans andremains at the conclusion of the summer, when the ice
cover is at its minimum and seasonal sea ice has
melted. This year-round ice averages about 3 meters in
depth, but can be as thick as 7 meters.
The study also finds that temperatures in the Arctic
are increasing at the rate of 1.2°C per decade. Melting
sea ice would not affect sea levels, but it could
profoundly impact summer shipping lanes, plankton
blooms, ocean circulation systems, and global climate.
‘If the perennial ice cover, which consists mainly ofthick multi-year ice floes disappears, the entire Arctic
Ocean climate and ecology would become very
different,’ said Josefino Comiso, a researcher at
NASA’s Goddard Space Flight Center, Greenbelt,
Maryland, who authored the study.
Comiso has used satellite data to track trends inminimum Arctic sea ice cover and temperature over
the Arctic since 1978. Since sea ice does not change
uniformly in terms of time or space, Comiso sectioned
off portions of the Arctic data and carefully analysedthese to determine when ice had reached the minimum
for that area each year. The results were compiled toobtain overall annual values of perennial sea ice.
The rate of decline is expected to accelerate due topositive feedback systems between the ice, oceans andatmosphere. As temperatures in the Arctic rise, thesummer ice cover retreats, more solar heat is absorbedby the ocean, and more ice is melted by a warmer
upper water layer. Warmer water may delay freezingin the fall, leading to a thinner ice cover in the winterand spring, which makes the sea ice more vulnerable tomelting during the subsequent summer.
Also, the rise in summer ice temperatures by about
1.2°C each decade could lengthen the summers,
allowing earlier spring thaws and later freeze dates in
the fall, causing further thinning and retreat ofperennial ice.
Comparing the differences between Arctic sea ice datafrom 1979 to 1989 and data from 1990 to 2000, Comiso

found the biggest melting occurred in the western area
(Beaufort and Chukchi Seas) while considerable losses
were also apparent in the eastern region (Siberian,
Laptev and Kara Seas). Also, perennial ice actuallyadvanced in relatively small areas near Greenland.
In the short term, reduced ice cover would open
shipping lanes through the Arctic. Also, massive melts
could increase biological productivity, since melt water
floats and provides a stable layer conducive toplankton blooms. Also, both regional and global
climate would be impacted since summer sea ice
currently reflects sunlight out to space, cooling theplanet’s surface, and warming the atmosphere.
Comiso recently analysed the ice cover data up to thepresent and discovered that this year’s perennial ice
cover is the least extensive observed during thesatellite era. The study appears in the late Octoberissue of Geophysical Research Letters, and was fundedby NASA’s Cryospheric Sciences Program and theNASA Earth Science Enterprise/Earth Observing
System Project.
The two composite images presented opposite provide
a comparison between the minimum sea ice
concentration in the Arctic between the years 1979 and2003 as imaged by the DMSP Special Sensor
Microwave Imager (SSMI). The upper image shows theminimum sea ice concentration for the year 1979, andthe lower one shows the minimum sea ice
concentration in 2003.
Thanks to the National Aeronautics and Space
Administration (NASA) for making this material
available. The original article can be consulted on the
NASA/Goddard Spaceflight Centre website at:
http://www.gsfc.nasa.gov/topstory/2002/1122seaice.html
Images courtesy Scientific Visualizations Studio, NASA GSFC.

Official GEO Internet Discussion GroupGEO has its own, private and moderated on-line
discussion forum, called ‘GEO-Subscribers’.
The aim of the Group is to provide a forum where GEO
members can share information, ask questions and receive
speedy responses.
To sign up, send an email to:
GEO-Subscribers-subscribe@yahoogroups.com

asking to be placed on the list.

Check www.geo-web.org.uk for all the latest news

Page 5

GEO Quarterly No 1

Group for Earth Observation

Launch Issue

Francis Bell

Although it has taken me several months tointermittently commission my new MSG-1 homereceiving station, it is fully working and I am now
receiving strong signals 24 hours per day. The results
are astonishing! All those lovely spectral bands, so
regular and so fast. Take a breath and that’s several
megabytes you have missed. I still consider myself abeginner. Animations, overlays, political boundaries,
colours, combining or subtracting images; these are all
for the future but what I am receiving at the moment is
awesome.
As a total beginner of course, I looked at the newimages in the light of experience with previous
Meteosats and polar orbiters. I was so pleased because
one feature I saw in the MSG-1 visible high-resolution
band I recognised: I had seen something almost
equivalent in an image from a NOAA APT pass I
recorded a year ago. I strongly believed what I waslooking at, using the new satellite, was snow in Africa.
I had previously checked with Peter Wakelin that what
I thought to be snow was correct. Peter confirmed that
it was almost certainly snow which was showing up on
my image. He knew the area which I had imaged andyears before had cycled through some of the mountains
there. From my atlas, spot heights of 4165 m and3797 m are shown. I wish I could cycle in this sort ofterrain! I went back to the image and admired it! I
reopened my atlas and looked up the latitude, longitude
and altitude relating to the image’s area. It seemed tofit but I was still surprised. Africa is supposed to be hot
desert or tropical forest. I discovered that perhaps noteverywhere on the continent is like that.
I thought it would be a challenge to our new readershipto invite submissions for satellite images showing snowin Africa. I think any amateur or educational receiving
station should qualify for an entry. The use of any
satellite and RF modulation format will be acceptable.
No professional SPOT or LANDSAT images please:that’s not quite in the spirit of what I’m suggesting.
Submissions to the editor please within one year fromthis publication. The 23° tilt of the Earth’s axis fromthe ecliptic determines the seasons. So a year gives
everybody time and all the seasons to secure an image
for a potential entry to this publication.
One of the targets is quite easy. Even from my house in
the S.E. of England I have received images of snow in
Africa from two different satellites. Other images ofsnow in Africa are not quite so easy but I know they are
possible using home equipment.
Please accept this challenge. The advent of MSG-1
opens up major new opportunities for us. There is no
Page 6

specific prize: just the satisfaction of having yourimage(s) published in our new-style magazine.
Having posted this challenge, I began to think about
Africa. What area of land constitutes continental
Africa? There are some peripheral island anomalies
and the Sinai peninsula. Eventually I decided Africa
was the contiguous land mass that we would commonly
recognise as Africa, bounded by its coastal outline andlimited to the north east by the Suez Canal. Within thisdefinition please submit as many images as you can ofdifferent areas in Africa showing snow.
From the title of this article I may have given away oneof the permanent areas of snow in Africa which I havepersonally seen.
I have had the double privilege of being in the Amboseli
National Park, Kenya, at 6.00 am one morning andseeing a stunning African dawn with the snow-cappedmountain of Kilimanjaro in the background.
Kilimanjaro is a serious mountain with an altitude of
5895 m. Don’t attempt to climb it without aprofessional guide. Many people have died of acutemountain sickness on this mountain trying! It looks
tropical and beguiling but it is a seriously highmountain.
My second privilege was a chance meeting with the
man / family who hosted Ernest Hemingway while hestayed in the area at the time he was writing his book:‘The Snows of Kilimanjaro’. It’s still in print. My new
friend lived in a village close to the base of Kilimanjaro.
I spent half a morning talking to him and was
impressed with his skilful use of English literature andhis knowledge of the mountain. He had been to the top
twice.
As a starting point for this challenge I will give thefollowingdetails.
Kilimanjaro’s
latitudeisapproximately 4°S, it’s longitude is 47°E and thealtitude of the mountain is 5895 metres. There ispermanent snow here. Please submit your best image. I
have tried imaging the snow on this mountain myself
but at the time of writing I have only managed to image
its cloud cover. But that doesn’t mean it can’t be done!
There is another mountain at zero degrees latitude not
all that far north of Kilimanjaro.
Now for the peripheral areas of non-contiguous Africa.
There were two islands that troubled me - Tenerife andCyprus. I’m going to exclude Tenerife as part of Africa,even though it is very close at only 300 km distance andTenerife does have permanent snow. Although I havenever set foot on the island I have seen it from the sea.

Check www.geo-web.org.uk for all the latest news

Launch Issue

Group for Earth Observation

GEO Quarterly No 1

A deep sea fishing trip (more Ernest Hemingway I’m
afraid: ‘The Old Man and the Sea’, an appropriate
description) brought us close to the island, and a viewof its snow-capped mountain was very clear. The scaleof the mountain was impressive (No I didn’t catch any
fish: and yes, Nadine was sea sick).
Cyprus spooks me a little. In which continent is it
located? Cleopatra would have it as Egypt hence partof Africa: Mark Anthony gave it to her. Rome (ancientor modern), Greece and Britain would have it asEuropean. The Turks, (well at least the northern thirdof the island), would claim it for Turkey, hence Asia. I
take the geological perspective. I have been to theisland more than once and seen the extruded
pillow-lavas forming the Troodos mountains,
indicating the island’s marine origin. A collision of
three continents. So the ambiguities of this island rule
it out of the challenge but it still remains aninteresting target for imaging. I know the Troodos
Mountains in Cyprus and they do have snow in winter.
I have been there and seen the ski facilities.
Fortunately I was there in the summer: T-shirt andriding a motor bike. It was cool as we approached thesummit but no snow in mid summer. However, I did
see an impressive array of large dishes - NATO’s ears
to the east.

NATO’s ears to the east, with the author in the foreground

Images of snow in the Troodos mountains represents
an interesting challenge. What about snow inPalestine? It does happen! Who can image that? I havedeliberately not submitted any of my images to theeditor in anticipation of better entries from ourreadership.
You only have twenty years to accept this challenge.
Peter Wakelin has just informed me that the ice cap on
the summit of Kilimanjaro is melting. In twenty years
time it may have gone!
In starting this article it was not my intention but afurther challenge has come to mind. Can anybody
submit an image of Key West, Florida. HRPT or LRIT
would be interesting. I visited Ernest Hemingway’s
house in Key West about a year ago. I will not makeany friends by saying this—but that will not stop me—
Key West is the only interesting place in Florida.

John Tellick
The dawn of a new era wassignalled with the successful launch of Europe’s
newest geostationary satellite, MSG-1 on August 28,
2002. MSG-1 is the first in
a new series of all-digital
European geostationary
meteorological satellites
which will replace the original Meteosat series which
has been operational since1977.
MSG is a cylindrical,
spin-stabilised satellite,
rotating at 100 rpm around
Launch of MSG-1© 2002 ESA/CNES a principal axis which is
Arianespace/Photo Services
aligned nearly north-south.
Optique CS
The spin is also a necessary
feature for the operation of MSG’s Earth scanningradiometer, the Spinning Enhanced Visible andInfrared Imager (SEVIRI).
This instrument scans the Earth every 15 minutes to
produce full-globe images in eleven spectral channels
ranging from visible light (VIS) through Infrared (IR).
These images have a resolution of 3 km at the subsatellite point (SSP) while a selected area, including
Europe, is provided as a high resolution visible image(HRV) with 1 km resolution at the SSP.
MSG satellites transmit two end-user imaging
channels. High Rate Information Transmission (HRIT)
on 1695.15 MHz* provides all twelve SEVIRI channels
at full resolution every 15 minutes. Low Rate
Information Transmission (LRIT) at 1691 MHz*
contains a subset of five of the SEVIRI spectral
channels at reduced resolution every 30 minutes plus,
in addition, relays of foreign satellite data (GOES-E
and -W, Meteosat-5 IODC and GMS/MTSAT imagery)every 3 hours.
MSG-1 also carries a Geostationary Earth Radiation
Budget (GERB) instrument, the first time this has
been flown on a geostationary satellite. Its data, bothalone and combined with that from SEVIRI, will
provide vital new information on diurnal variations
into the radiative balance of the planet. It will also
have important applications regarding climate studies
and monitoring.

Check www.geo-web.org.uk for all the latest news

Page 7

GEO Quarterly No 1

Group for Earth Observation

Failure of the MSG-1 Power Amplifier
Following its successful launch and placement into
geostationary orbit, MSG-1 commissioning tests began
in late September 2002. But in mid-October, thedownlink under test ceased when the Solid State
Power Amplifier (SSPA) being used unexpectedly
switched off and could not be reactivated. Subsequentimaging tests proved the SEVIRI instrument and theraw data downlink chain to be operating correctly, but
it was eventually decided not to disseminate user
services directly owing to doubt over the remaining
SSPAs.
The EUMETSAT EUMETCast Service
EUMETSAT had already been testing a new data
retransmission service for the Advanced TIROS
Operational Vertical Sounder (ATOVS) data fromsensors aboard NOAA polar orbiting satellites.
Following the SSPA failure, EUMETSAT were obliged
to pursue an alternative means of disseminating theMSG-1 data and trials via EUMETSAT's Multicast
Distribution System (EUMETCast)] began at the endof April 2003. These were transmitted by
EUTELSAT's Hot Bird-6 satellite stationed at 13°E
using the digital video broadcast (DVB) format used bydigital satellite TV. This service was due to become
fully operational as the primary 0° longitude service inlate January 2004 with MSG-1 renamed Meteosat-8
and located at 3°W.
System Hardware Requirements
The main component of the hardware system is theTechniSat SkyStar-2 PCI DVB receiver card. This is afree-to-air digital satellite-TV receiver that is installedinside your computer (there is also a USB version).
The SkyStar unit can also receive data transmissions,
including satellite Internet services. The receiving

The Skystar-2 card (left) and USB unit (right)

antenna recommended by EUMETSAT for most ofEurope is an 85 cm offset satellite-TV dish, provided agood quality standard Universal
digital satellite TV LNB is
employed. Good quality satellite
TV co-ax cable such as CT100 is
required between the dish andthe receiver. Care should betaken when stapling and routing
this cable as digital signals cansuffer losses due to sharp bends A typical 85 cm offset
satellite-TV dishor cable constriction.

Launch Issue

a signal-strength meter which allows you to ‘fine tune’
your dish set-up.
Software Requirements
To receive the EUMETCast service from Hot Bird-6
you also require software called tq®-TELLICAST tohandle the DVB data stream. This software isavailable either from T-Systems in Germany for €60
plus handling charges, or from EUMETSAT, who send
you purchasing details once you have applied for theservice. To be able to purchase this software you mustfirst successfully register with EUMETSAT for MSG
dissemination using the form EUM/OPS-MSG/REG/01
which is available on the EUMETSAT website at:
http://www.eumetsat.de/en/dps/helpdesk/registration.html

Once you have been successfully registered, you will be
issued with the username and password required for
installation of the tq®-TELLICAST software andnotified that you may now apply for the software.
To assemble, save and display the files generated by
the T-Systems software you will also require David
Taylor’s MSG Data Manager software. This can beobtained from David Taylor for £44 at:
http://www.satsignal.net

It is also strongly recommended that you download andread EUMETSAT’s technical document EUM TD 15,
Issue No 3. A link is available from our website at:
http://www.geo-web.org.uk/eumet_docs.html

as it contains much useful information concerning the
EUMETCast service.
The Fully Operational Service
This began in January 2004 and contains the complete
12-channel SEVIRI HRIT data every 15 minutes plus
full LRIT data every 30 minutes, as well as foreignsatellite relays. With the exception of the WMO
requirement of ‘free’ 6-hourly HRIT and LRIT data
sets, this data will be encrypted from March 2004. To
receive the full encrypted data sets an Aladdin eToken
PRO decryption unit (a USB dongle) will be required,together with associated software to control access tothe data in accordance with the EUMETSAT Data
Access Policy and your user category as applied for atregistration. The current price is around £40 for thedongle and software. All users who have applied for the
EUMETCast service will be contacted regarding
application for the decryption unit and software before
the service is encrypted in March 2004.

Aligning the dish to Hot Bird-6 is not too difficult if you
have a sensitive satellite-TV level meter at the dish.
One of the SkyStar installation set-up screens includes
Page 8Check www.geo-web.org.uk for all the latest news

The Ku-band
signal power levelfoot-print for Hot
Bird-6. Most ofcentral Europe and
S and SE Englandlie within the
53 dBW contour.

Launch Issue

Group for Earth Observation

C-band MSG-1 EUMETCast Service
Although Europe is now catered for with the Ku-band
EUMETCast service via Hot Bird-6, EUMETSAT also
have an obligation to supply African States with MSG
meteorological data under the EU-funded PUMA
Agreement, which had equipped African States with
MSG receiving stations.
For technical reasons, C-band transmission waspreferable and, following tests, EUTELSAT’s Atlantic
Bird-3 satellite stationed at 5°W was chosen. These
tests proved successful, and a trial service began latein 2003. The C-band beam covers the whole of Europe
and Africa, all of which, with the exception of parts ofMorocco, southern Algeria, Mali and Niger, lie within
the 39 dBW footprint.

GEO Quarterly No 1

The Atlantic Bird-3 C-band footprint over Europe andAfrica is only 39 dBW compared with Hot Bird-6's
Ku-band spot beam of 53 dBW over SE England andcentral Europe, This means that a significantly larger
antenna will be required to receive this service, and
EUMETSAT recommend a 2.4 metre dish.
The Atlantic Bird-3 C-band EUMETCast footprint also
extends into the eastern part of the USA at reduced
levels and EUMETSAT recommend that a dish size of
3.7 m will be required in most US locations.
* No longer relevant to MSG1 due to SSPA failure.

The format of the C-band dissemination will be DVB
EUMETCast, the same as for the Hot Bird-6 Ku-Banddissemination. The data will be uplinked to Atlantic
Bird-3 via the Fucino ground station in Italy and will
be a re-broadcast of the Hot Bird EUMETCast service.
Access to the C-band EUMETCast trial dissemination
both within and outside EUMETSAT Member States issubject to applications using the same MSG Image
Data Service registration form described above.
The same T-Systems tq®-TELLICAST software will be
required, as will MSG Data Manager to deal with file
management and image viewing.

Footprint diagram for Atlantic Bird-3 C-band transmission

Logo © EUMETSAT 2003
The paragraph printed below is probably themost important paragraph in this publication.
It is reprinted with the permission of
EUMETSAT.
If you don’t understand it at the first reading,
it relates to the availability of satellite datafrom EUMETSAT to amateur users.
EUMETSAT will not charge a license fee
for the reception of their data to a UK
amateur or educational user.
You are sincerely counselled to conformstrictly to EUMETSAT’s licensing conditionsand GEO will be dissociated from any
individual
or
group
who
infringe
EUMETSAT’s licensing agreement. GEO
wish this privilege for our membership to
continue.

The EUMETSAT notice below
released in December 2003

be treated like ‘Educational Users’ for data
licensing purposes.
‘Such users would be required to sign alicense agreement and strict compliance ofthe license conditions for ‘Educational
Users’ will apply. License fees are notcharged for access to data as an‘Educational User.
‘For further information on the licensing
conditions please consult your licensing
authority or refer to the EUMETSAT Data
Policy brochure, EUM BR 12, available on
the EUMETSAT website.’
Regards,
Sally Wannop
User Support Manager
EUMETSAT User Service

was‘The EUMETSAT Data Policy concerning
access to HRIT and LRIT SEVIRI data has
been amended. It is now possible forindividual users (amateurs) who require
access to data for their own personal use to

STOP PRESS - January 7, 2004
EUMETSAT / UK Met OfficeLicense Agreement for Reception of MSG
Data

Check www.geo-web.org.uk for all the latest news

In line with EUMETSAT’s policy for
individuals within member states of the EU
to deal with their own meteorological office,I have just concluded my own licenceagreement with the UK Met Office in Exeter.
I was in the MSG trial, so my details would
have been forwarded from EUMETSAT to
the UK Met Office: hence my early license.
However, there is nothing to stop other UK
resident GEO readers, or any other
European users from registering theirinterests and concluding a licenceagreement for MSG data reception.
In the UK contact:
Colin Cuthbert,
UK Licensing Agent, EUMETSAT,Met Office,Fitzroy Road,
Exeter EX1 3PB
Tel:01392 884678
Fax:
01392 885681
email:
colin.cuthbert@metoffice.com
Francis Bell

Page 9

GEO Quarterly No 1

Group for Earth Observation

Launch Issue

Les Hamilton
When you examine your NOAA
channel-4 infrared images during
the winter months, you may fromtime to time spot what looks like aminiature cyclone in the Barents
Sea or the North Atlantic Ocean.
What you are observing is almost
certainly a polar low.
Just such a phenomenon wasobserved by Ferdinand Valk in
December 2003, and his image isreproduced opposite. The polar low
is the whorl of cloud which fills the
Barents Sea and obscures thesouthern part of the island of
Novaya Zemlya.
What is a Polar Low?
During long Arctic winter nights,
cold air builds up to create what is
known as the polar front, theboundary between cold air to thenorth and warmer air to the south.
A polar low is a small cyclone withwindspeeds near to or above galeforce, which forms in the cold air
far north of the polar front itself.
The European Polar Low Working
Group [1] defines any cyclone to thenorth of the polar front, and which
has a spread of less than 2000 km
across, as a ‘meso-scale cyclone’ or‘mesocyclone’. The classical polar
low is included as a subtype,
restricted to very intense maritime
systems stretching up to 1000 km
and where the near-surface winds
exceed 15 metres per second (30knots).
A polar low forms only over thesea, and exclusively during thewinter months: it arises when apacket of cold polar air moves
across relatively warmer water(such as that provided by theNorth Atlantic Drift as it sweeps
past Iceland and into the Barents
Sea). Typically, these polar lowsshow considerable similarity totropical hurricanes but they are
generally only of the order of 400
to 800 km across: some may span
Page 10Figure 1 - NOAA 17 - 09:14 UT on December 21, 2003 (© Ferdinand Valk)

as little as 100 km. The polar low
illustrated in figure 1 spannedaround 900 km. Figure 2 shows thesynoptic sea-level pressure chart
for the region. The long, trailingcomma-shaped tail seen hugging
the northern coastline of Russia’s
Kola peninsula is a characteristicfeature of the polar low. As thestorm matures, spiral cloud bands,
often with a clear eye at the thecentre of the cloud vortex, look
remarkably similar to a tropical
cyclone and provide the polar low
with its alternative appellation,that of Arctic hurricane.
For many centuries, seafarers in
the north Atlantic and Arctic
oceans have recounted tales offierce storms that seemed to appear
from nowhere, often accompaniedby strong winds and snowfall [3]. It
is highly probable that ships which
disappeared without trace over theyears may have been the victims ofthese unpredictable, short-lived
cyclones. Polar lows show a very
Check www.geo-web.org.uk for all the latest news

Figure 2 - Sea-level isobars
at 12:00 UT on December 21, 2003

characteristic pattern and life cycle
during which they produce severe
weather consisting of heavy
precipitation (usually falling assnow) coupled with strong surface
winds.
Eventually, most polar lows
encounter the coasts of Norway,
Scotland and Denmark where theiractivity rapidly diminishes. In fact,
Northern Scotland bore the bruntof just such a polar low in February
1969 during which a gust of windmeasured during a violent snow

Launch Issue

Group for Earth Observation

GEO Quarterly No 1

shower at Kirkwall airport in the Orkney Islands wasrecorded with a speed of 118 knots (218 km/h) .
It was not until satellite imagery arrived on the scene
during the 1960’s that a better understanding of thesestorms was realised. Because of their northern positionand small scale, and the fact that they appear in thedark winter season, AVHRR-NOAA IR images provide
one of the best ways of detecting polar lows.
Today we know that polar lows are a frequent featureof the relatively warm ice-free waters around thecoasts of the Nordic countries, in the Labrador Sea, theGulf of Alaska and the Sea of Japan. And of course,
they are also a feature of Antarctic polar waters.
Lifespan of a Polar Low
A polar low can brew up and disperse completely again
in a surprisingly short period of time: typically thephenomenon lasts only between 12 and 36 hours.
The illustrations on the right trace the appearance anddispersal of the December 21 polar low. Exactly one
day before Ferdinand Valk spotted this system, a
NOAA-17 channel-4 HRPT segment revealed no signwhatever of any activity of this nature (figure 3)
although there was clear evidence that streamers ofpolar air were heading southwards over the Barents
Sea. Early the following day, NOAA-12 imaged acompact polar low encircling the area (figure 4), butjust six hours later (figure 1) it was already clearly
beginning to show signs of decay. The final image inthe sequence came from a NOAA-16 transmission in
the early hours of the following day (figure 5), by whichtime the storm had all but exhausted itself, leaving
behind only a few isolated fragments of bright cloud toindicate that it had ever existed.

Figure 3 - NOAA 17 - 07:33 UT on December 20, 2003

Figure 4 - NOAA 12 - 02:41 UT on December 21, 2003

Further Examples of Polar Lows
Interestingly, a particularly well formed polar low
appeared in precisely the same region almost exactly
one year ago, on December 20, 2002 (figure 6).
Although polar lows are generally associated with the
Arctic, they can form in the waters of the northAtlantic, in the region between Greenland and Norway
and sometimes, rarely, even as far south as the Faeroe
Islands. Furthermore, a polar low embedded in asoutherly moving airstream may on occasions track
into the North Sea. We need look back only as far as
January 2003 to remind ourselves of one of these
relatively rare visitations when much of Britain andthe Low Countries experienced paralysing blizzards asa polar low made landfall. The culprit coursed down
the North Sea, and is illustrated in figure 7, a
NOAA-17 channel-4 APT image acquired shortly
before noon on that day.
Like their much larger tropical cousins, polar lows
tend to decay rapidly when they reach land, due to the

Figure 5 - NOAA 16 - 00:11 UT on December 22, 2003

loss of the energy supply provided by the relatively
warm sea they are traversing. But before they do, they
can produce severe weather conditions over the land
and this was one such occasion. The cyclone advanced
southwards over the North Sea and caused severe

Check www.geo-web.org.uk for all the latest news

Page 11

GEO Quarterly No 1

Group for Earth Observation

Launch Issue

blizzards over much of eastern Britain as well as overlarge parts of Holland and Belgium (figure 7) [2]. At
some locations on the east coast of England, windspeeds reached force 10!
From that afternoon chaos reigned throughout GreatBritain. Stanstead Airport was closed while thousandsof travellers were delayed at Heathrow Airport asflights were cancelled; the London underground cameto a halt; schools were closed; many workers trying to
make their way home after work found themselves intraffic gridlock for many hours; thousands suffered
power cuts; snowploughs struggled to keep roads open,with many short journeys taking hours and there werenumerous road accidents as up to 15 cm of snow fell inmany places. Yet in the corresponding NOAA-17 image
the following day, only a tenuous streamer, possibly a
remnant of the cyclone’s ‘comma’ tail, remained to tell
the tale (figure 8).
References and Further Reading
1. The European Polar Low Working Group
http://www.meteo.uni-bonn.de/mitarbeiter/GHeinemann/eplwg/eplwgop.htm
2. 'Polar low' boven zuidelijke Noordzee
http://www.knmi.nl/~floor/artikelen/zenit/polarlow/
3. Weather Online
http://www.weatheronline.co.uk/feature/wf261103.htm
4. Cloud Structure (of the Polar Low)
http://www.zamg.ac.at/
docu/satmanu4.0/satmanu/manual/PL/pl1.htm

Figure 6 - NOAA 12 - 04:33 UT on December 20, 2002

ImagesFigure 2
Figures 3, 4, 5, 6

The images were processed using David Taylor’s HRPT Reader, thenconverted to orthographic projection using his Groundmap program,which also added country outlines.

Reproduced by courtesy of the SMIS NOAA HRPT telemetry archive at:

Figures 7 and 8

http://d902.iki.rssi.ru/dataserv/engl/oper_e.shtml

NOAA-17 APT images received by Les Hamilton and processed using
Craig Anderson’s Wxtoimg software

Figure 7 - A polar low brings blizzards to Britain and the Low
Countries (NOAA 17 - 11:08 UT - January 30, 2003

Figure 8 - Next day, the polar low has completely disappeared(NOAA 17 - 10:43 UT - January 31, 2003)

Synoptic chart created with Digital Atmosphere

Page 12Check www.geo-web.org.uk for all the latest news

Launch Issue

Group for Earth Observation

Cedric Roberts M.B.E.
I decided, or rather my health decided for me, to takeearly retirement from teaching at the end of theautumn term in 1986. I had been in full time education
work since 1955 and my current position, in 1986, asHead of the Upper School at the local large mixed
comprehensive had thrown such pressures upon me
that my health was beginning to suffer. So, when I wasoffered a ‘way out’ I did not need further prompting!
Leaving a full-time career that had taken every
moment of my time left me at first feeling like a fishout of water. I had timeon my hands and no
prompting to get things
finished as soon as
possible. So I looked
round for some hobby
that would supplement
my life-long passion forthe ‘weather; a hobby
that had started on
January 1st 1946 withdaily climate readings,
and which continues tothis very day. But what
was I to do?

GEO Quarterly No 1

Midlands conurbation, I was subject to the radio
signals being generated by all manner of people, andsome of these almost blotted out the entire satellite
signal from the satellite. Not being in any way a ‘Radio
Ham’ I was totally unsure about what to do in order totry and eliminate as much of this interference as was
possible. I looked around for guidance and had the good
fortune to make contact with a firm called Spacetech
working from Portland Bill. They proved some of themost helpful people that one could wish to meet andguided my through a whole maze of their new software,plus the installation of a new BBC Archimedes
computer, which enabled me to produce images manytimes more detailed than my earlier attempts.
Consequently I had a year or two of relatively ‘stable’
conditions and collected some excellent imagery fromboth polar orbiting and geostationary satellites using
the Spacetech system.
These
continued
tosupplement my climate
work, which had itself
expanded greatly and now
required a more powerfulcomputer, as well as
improved software, if I
were to get the most fromit. I therefore moved over
to a PC and installed
Windows and Excel toenable me to make full useof the, by now, extensive
files of climate data, and it
was at this point in timethat I came across a firm
called Dartcom working
from Yelverton in Devon.

Much to my pleasure, afriend sent me his copy ofAmateur Radio magazine
in which I found mentionof a new area of study
After brief discussion of
dealingwiththerequirements I moved
An MSG-1 image of Hurricane Isabel, imaged by Cedric Roberts
acquisition and display ofover to the full Dartcom
the weather satellites that were then in their earlysystem, using their own receiver and software, anddays. I decided that this would be an excellent aid tobegan to take even more detailed images than ever.
my work on weather, and set about acquiring,
installing and making operational a simple system in
All of this brought me from the 1980’s to the 2000’s, theuse at the time. This was supplied by a firm in thelast decade or so making use entirely of the Dartcom
south of England, and used a device under the name ofsystem. In 2001, I decided to install the Dartcom HRPT
‘Grace’ to decipher the radio signals transmitted by thesystem, even though it would not be possible to placepolar orbiting satellites. These satellites, then only
the rotator and dish on the roof. As it had to be
recently placed in position, were the American NOAAs
installed at ground level I had to make a very careful
and the Russian Meteors. The initial system waschoice of position if I were to obtain any worthwhile
produced by Martelec and I was thrilled after spending
imagery at all, since I had 3-story houses to the north
several days installing all of the equipment, including
and a very large oak tree to the south. However,a rather unusual antenna termed a ‘turnstile’, tojudicial planning enabled a good position to be foundreceive my first rather fuzzy image of the Earth as thepermitting imagery to be obtained from Iceland in thesatellite sped across the sky.
north to north Africa in the south, and as far east as
the Black Sea on suitable passes.
However, I soon discovered that producing a good
image was not all that easy as I seemed to be getting aThis has continued to provide excellent imagery andlot of noise, not connected with the satellite at all, on
when the new MSG-1 satellite was put into orbit andthe receiver. Living as I do on the boundary of the West
promptly had difficulties with one of the power units, I
Check www.geo-web.org.uk for all the latest news

Page 13

GEO Quarterly No 1

Group for Earth Observation

Launch Issue

opted to go ahead with Dartcom, who installed the
Tellique software and new dish to acquire the signals
from this satellite. David Taylor proved a real godsend
as he provided a massive amount of help in the use of
his software for reading and displaying the signals
from this satellite.

the images can be seen in extreme detail, in false colour
and even in animation, so far has the software
progressed. I have been indebted to all with whom I
have dealt, and especially to David Wright at Dartcom
and David Taylor for his guidance on the use ofsoftware.

A colour composite image of the full Earth disc is shownon the inside back cover of this issue, along with ageometrically rectified segment covering Europe.

I now look forward to even greater things as I am
hopeful of taking receipt of the new Dartcom Softwarefor using with MSG-1 over the Christmas period. The
World of Science moves ahead at an astonishing rate,though I am now beginning to feel that the newer
material is more suited to those who are not quite as
old as myself. Today I do at times feel that I am in
danger of being left behind as the subject races ahead.

Currently I am able to take polar orbiting andgeostationary images, both containing superb detail.
Matters have gone a long way since I looked at my first,
rather blotchy image of the UK and western Europe,
which I then considered the height of excellence. TodayPeter Wakelin

A Powerful display of Aurora Borealis as imaged over Europe on October 29, 2003 by the F-15 DMSP satellite
Image courtesy US Air Force Weather Agency.

The last peak in the 11-year solar cycle occurred earlyin 2001 and the average sunspot count has been
decreasing since then. But in late October 2003 threehuge sunspots appeared: one, named ‘sunspot 486’, wasthe biggest for 13 years. The three spots unleashed 11
X-class flares (the most powerful class) in only 14 days,
equalling the total number seen throughout theprevious year. The effects on Earth were many; radio
communications were disrupted, astronauts and some
air travellers received radiation doses equal to a chest
X-ray and auroras appeared at unusually low latitudes.
Page 14The Operational Linescan System on the US Defense
Meteorological
Satellite
Programspacecraft
incorporates a photomultiplier system enabling it toimage clouds in moonlight. This high sensitivity
permits night-time imaging of auroras as well as thelights of towns and cities as the accompanying image
shows. The lights of North Sea oil installations are also
visible. The auroral glow extends from northern
Britain across to Latvia in this image and exceptionallybright displays were reported in southwest Norway.

Check www.geo-web.org.uk for all the latest news

Launch Issue

Group for Earth Observation

GEO Quarterly No 1

Francis BellIn a recently published journal I invited entries for acompetition relating to the forces experienced by
MSG-1 . The idea was to stimulate an appreciation of
the extreme environment which science, engineeringand technology place upon space satellites.
The inducement for winning entries, was a CD-ROM
containing aerial photography of their local county.
This was sponsored by Getmapping plc. The
competition is now closed but for those who missed thedetails the single question to be answered was this.
What is the G force experienced by the externalsurface of MSG-1? The satellite is in space, it is
3.2 metres in diameter, and spins about its
central axis 100 times a minute.

Below is a list of the people who sent in a correct entry(The first correct entry received came from Les
Hamilton, the Journal Editor - but as he had over amonth longer than everyone else to work out theanswer, he is not eligible for a prize.)
Andrew Thornton

Accrington Lancashire

Des Watson

Ringmer E. Sussex

Ken Barker

Winsford Cheshire

Derek Beales

Bury St Edmonds

Andreas Lubnow

Braunschweig Germany

Bert Harms

Hooghalen Netherlands

John Malos

Brisbane Australia

Jonathan Gudgeon Milton Keynes
Brian Davies

Lingfield Surrey

Paul Telco

Welwyn Garden City

I asked for the answer to be given in the unit of a G:even though it is not an SI unit it is what most of us
experience every day and we are familiar with a forceof 1 G.

Gerry Morgan

Corrandulla Ireland

Rob Hollander

Den Haag Netherlands

John Nixon

Sheffield

I received 16 answers of which I judged 15 to becorrect. The favoured answer was 17.88 G . Rounding
to the nearest whole number generates the answer
18 G. I did allow one answer of 17 G.
A model answer was provided by Rob Hollander andhis entry went as follows:
The Answer is 18 G
Since, in a stable orbit, gravitational forces andcentrifugal forces (due to the orbiting) cancel, we only
have to take into account the centrifugal force due tothe spinning of the satellite. The acceleration isdefined as the ratio of force over mass or as the change
of velocity per unit time. In your case only the directionof the velocity is changing. Then is simply derived that:On the surface of the earth we experience a
gravitational force over mass ratio of 1 G, which
depends slightly on the place on Earth. But in the
Netherlands, 1 G = 9.81 ms–2. So, the answer in G is175.46 / 9.81 = 17.88, close to 18G, which is hugeindeed.
I hope that this answer is correct enough to make me a
candidate for the CD-ROM , and the calculation shortenough not to bore you.
Yours sincerely,
Rob Hollander,
DEN HAAG, The Netherlands.

Chris Ashby

Whitstable Kent

Terry Baldwin

Broadstairs Kent

R. E. Hogben

Dover Kent

I think Rob Hollander’s comment: ‘indeed this is huge’,correctly states the extreme environment in which thissatellite operates. Of course the instruments embedded
close to the axis of rotation experience smaller G forces
but the whole structure must remain intact.
Some CD-ROMs have been sent to winning entries.
Writing this report close to the date of the competition
closing I have not yet arranged for the Getmapping plc
CD-ROM to be sent but I hope this will be possiblesoon.
My thanks to all who took an interest in thecompetition.
A Postscript
Within some of answers I was very diplomaticallytaken to task over some of the terms I used in thecompetition text. Words like ‘constant’, ‘velocity’, ‘force’and ‘acceleration’ seem to be the province of physicists,
not mere mortals like me—a humble biologist.
Okay: Here’s a question for any reader who has only aphysics degree as qualification .
How does water manage to travel from the soil tothe top of a tree which may be 100 m tall?
Here is a hint. There is no physics formula which will
directly generate an answer for you. Answers in lessthan 50 words to me please.

Check www.geo-web.org.uk for all the latest news

Page 15

GEO Quarterly No 1

Group for Earth Observation

Launch Issue

David Taylor Answers John Tellick’s Questions
Q I want a system that acts like a
Meteosat WEFAX system—to
be able to view a European or
global sector every -hour ineither VIS or IR and animate it.
Every-hour would be
preferable but one has to berealistic. Can I do that, andwhat system spec would I
require—one or two computers?
A One dedicated computer (but I
don't recommend that) or two
PCs networked. Spec forprocessing (or single) PC:
1-2 GHz+ processor, 512 Mb1 Gb of memory (1 Gb memory
if you want to use the HRV or
Meteosat-5 visible channel).
Fast hard disks with 2 Mb or
8 Mb buffers. See below forsecond Receiver PC spec.
___________________________Q I want 24-hour full imaging andanimation and want real-time
display of any channel I choose.
Can I do that and what systemspec do I need—two computer I
suspect?
A Same answer as above, withmore emphasis on CPU speed
and memory.
___________________________Q I just want to dip in every now
and again to see ‘what's goingon’ and use the computer forother things at other times. Can
I do that and what system spec
do I need?
A For me, the critical item here is‘use the computer for otherthings.’For example, if you start doing
complex image processing,making panoramas, complex
spreadsheets etc., the CPU load
Page 16that this produces can cause
missing segments. If thisdoesn’t matter, that’s fine. The
500 MHz PC below would dothat, but I would suggest atleast 256 Mb of memory.
___________________________Q What is the most basic
computer spec I can use todownload EUMETCast, accepting considerable downgradingofthesystem’s
possibilities?
A If you don’t mind missing very
occasional segments, then use a
500 MHz Pentium III with
256 Mb memory for data
capture only. Use a separate
processing PC.
In short, if you want to do
everything on a single PC, try
to make sure it’s a good one(1-2 GHz or better, 512 Mb to
1 Gb according to your aims)
and expect missing segments if
you overload the single PC withother tasks. So make it adedicated MSG PC if possible.
Use Windows 2000 or XP. If you
can find a 500 MHz PC for
separate receiver use, most ofthepotential
problems
disappear and you can do what
the heck you like on theprocessing PC. Use Windows2000 or XP.
There’s nothing to stop you
using the single PC solution tostart with, and later migrating
to two PCs as funds allow.
___________________________Q Where should I install the
SkyStar card?
A Locate a PCI slot with no card
to either side of it, remove theCheck www.geo-web.org.uk for all the latest news

back panel blanking plates
from both adjacent empty slots(to improve the air flow over the
DVB card) and install the card.
____________________________Q When will encryption of the
MSG data start?
A The service start date is early
March, 2004.

MSG-1 Transmits its
First Meteosat-5
LRIT Image
On November 25, 2003, MSG-1
added another ‘foreign’ satellite toits FSD (Foreign Satellite Data)
relay on the LRIT data stream.
This time the satellite wasn’t reallyforeign, but an older EUMETSAT
satellite, Meteosat-5, now relocatedover the Indian Ocean. The images
are transmitted every three hours
and comprise thermal and water
vapour data at 2500 x 2500 pixels
and a visible channel at a stunning
5000 x 5000 pixels.
Data at this resolution waspreviously only available to users
with access to the PDUS data
stream. This data may also bemade available over the Internet aspart of the LRIT data service.
The image opposite was processed
through GeoSatSignal-4, using thevisiblechanneltoprovidebrightness information and thethermal channel to provide thecolour component.
Image processing: David Taylor
Image © EUMETSAT 2003

Launch Issue

Group for Earth Observation

Check www.geo-web.org.uk for all the latest news

GEO Quarterly No 1

Page 17

GEO Quarterly No 1

Group for Earth Observation

Launch Issue

Peter Wakelin‘There are some who question the relevance of space
activities in a developing nation. To us, there is noambiguity of purpose. We do not have the fantasy ofcompeting with the economically advanced nations in
the exploration of the moon or the planets or manned
space-flight. But we are convinced that if we are to playa meaningful roll nationally, and in the community ofnations, we must be second to none in the applicationof advanced technologies to the real problems of man
and society.’
The Man
These were the words of Dr Vikram Sarabhai, spoken
more than thirty years ago. His early interests andresearch activities were in theareas of interplanetary physics
andtheEarth’shighatmosphere. It was he who
established India’s programme
for the International Geophysical Year, 1957/58, during
which the USSR launched
Sputnik 1.
Shortly after that he became
Chairman of the newly-createdIndian National Committee forSpace Research and in 1962 setup
India’s
firstrocketDr Sarabhai
Photo: ‘The Hindu’launching facility at Thumba,
in southern Kerala. The firstsounding rocket was launched on November 21, 1963:
the Indian space programme was under way and, quite
rightly, Dr Vikram Sarabhai is regarded as its
architect.
The PlanWith a land area in excess of three million square
kilometres and a population heading inexorably
towards one billion, it was realised very early on in thespace age that communications satellites, and imaging
spacecraft to monitor weather and land usage, would
be of great benefit to the Indian nation. The long- term
aim was to build and launch their own satellites but,initially, much experience could be gained by utilisingother nations’ spacecraft.
By establishing an Earth station at Ahmedabad in
1967, experiments in satellite communications became
possible and in 1975, in cooperation with NASA, theSatellite Instructional Television Experiment was set
up using an American Advanced Technology Satellite,
ATS-6. A ground station was established near
Hyderabad in 1979 to receive imagery from the NOAA
Page 18

weather satellites and also the US and European
Earth-resources satellites such as Landsat, ERS and
SPOT.
Meanwhile, experimental and development work on
their own satellites and launch vehicles was proceeding
steadily.
The Outcome
The
first
Indian-built
satellite, Aryabhata, went
into orbit in 1975 aboard an
Intercosmos rocket launchedby the USSR. A further five
years passed before India
became the seventh nation
to launch its own spacecraft.
Aryabhata
There were delays, setbacks
India’s
first satellite
and some spectacular launch
failures but eventually these problems were overcome.
More powerful rockets were developed and reliability
improved to such an extent that other nations’spacecraft are now being orbited on board Indianrockets.

India’s launch vehicles are not yet capable of launching
their very heavy communications and meteorologicalsatellites to geostationary altitude so they they still
rely on the USA and Europe to launch them but theirmost powerful vehicle did successfully place Kalpana-1
into geostationary transfer orbit in 2002.
2003 was a very successful year with four satellites
successfully launched. Two were heavy spacecraft in
the INSAT-3 series, launched by Ariane-5 rockets from
Kourou, French Guiana, but the other two werelaunched from India. Sadly, Dr Sarabhai did not live to
see his country’s space programme evolve into theremarkable success story that it is today.
This brief overview of the Indian space programme
ends with a chronological listing of significant events
over the last 42 years. Part two will detail the early
achievements in both satellite and launch vehicle
development.
1962 Indian National Committee for Space Research
was formed by the Department of Atomic
Energy and work on establishing the Thumba
Equatorial
RocketLaunchingStationcommenced.

Check www.geo-web.org.uk for all the latest news

Launch Issue

Group for Earth Observation

GEO Quarterly No 1

1963 The first sounding rocket was launched fromThumba on November 21.

March 24. A similar failure occurred 16 months
later.

1965 The Space Science and Technology Centre wasestablished at Thumba.

1988 he first operational Indian Remote Sensing
Satellite, IRS-1A was launched by the USSR on
a Vostok rocket on March 17.

1967 A satellite telecommunications Earth station
was built at Ahmedabad.
1969 The Indian Space Research Organisation(ISRO) was formed under the Department ofAtomic Energy on August 15.
1972 The government of India set up the Space
Commission and the Department of Space onJune 1; the latter taking over ISRO from the
Department of Atomic Energy. The first
airborne remote sensing experiments also took
place in this year.
1975 The first Indian-built satellite, Aryabhata, waslaunched on April 19 by an Intercosmos rocketof the USSR. Experiments in satellite
telecommunications, especially educational
television, were started using the USA’s
Applications Technology Satellite ATS-6.
1979 Bhaskara-1, an experimental satellite for Earthobservation was launched on June 7 by the
USSR. On August 10 the first experimental
launch of the Indian-built Satellite Launch
Vehicle (SLV-3) rocket failed to orbit its Rohini
technology payload.
1980 The second SLV-3 launch from the Sriharikota
launch site successfully placed a Rohini
satellite into orbit on July 18 making India theseventh country to launch its own spacecraft.
1981 Another Rohini satellite was launched by an
SLV-3 rocket on May 31 to conduct remotesensing technology studies. On June 19 APPLE(Ariane Passenger Payload Experiment) was
launched with Meteosat-2. It was acommunications test satellite. Bhaskara-2 wasIndia’s second experimental remote sensing
satellite and was launched from the USSR on
November 20.
1982 The first of four operational INSAT-1 satellites
procured from the USA was launched on
April 10. This multipurpose communications
and meteorological satellite, INSAT-1A, waslaunched by the USA on a Delta launch vehicle
but failed after a few months’ service. INSATs
1B, 1C and 1D followed in 1983, 1988, and1990.
1987 An uprated rocket, the ASLV (Augmented
Satellite Launch Vehicle), failed to orbit its
payload, an advanced Rohini satellite, on

1992 The first successful launch of the Augmented
Satellite Launch Vehicle (ASLV) orbited anadvanced Rohini experimental satellite on
May 20. The first of the Indian-built secondgeneration INSATs was launched into ageostationary orbit on an Ariane-4 rocket from
French Guiana on July 10. INSAT-2A carriedcommunications and meteorological payloads.
INSATs 2B, 2C, 2D and 2E followed in 1993,
1995, 1997 and 1999.
1993 The first launch of the Polar Satellite Launch
Vehicle (PSLV) was unsuccessful and failed toorbit its payload, IRS-1E.
1994 IRS-P2 was successfully placed into sunsynchronous orbit by a PSLV on October 15. P3
and P4 followed in 1996 and 1999.
2000 INSAT-3B, the first in the third generation
INSAT series, was launched aboard an
Ariane-4 rocket from French Guiana on
March 22.
2001 On April 18, the first developmental
launch of the Geostationary
Satellite Launch Vehicle (GSLV)
took place. It successfully placed its
payload GSAT-1, an experimental
communications satellite, into ageostationary transfer orbit.
2002 An improved PSLV placed METSAT-1 into ageostationary transfer orbit on September 12.
The spacecraft, India’s first exclusively
meteorological satellite, was later renamed
Kalpana-1 in memory of Kalpana Chawla whodied in the Columbia accident.
2003 This was a busy and very successful year with
INSAT-3A launched on an Ariane-5 from
French Guiana on April 10, GSAT-2 launchedon a GSLV on May 8, INSAT-3E orbited by an
Ariane-5 on September 28 and finally, on
October 17, ResourceSat-1 was boosted into
orbit by a PSLV.

Acknowledgement
I am indebted to the Indian Space Research
Organisation for making so much information
available on their website:

Check www.geo-web.org.uk for all the latest news

http://www.isro.org
Page 19

GEO Quarterly No 1

Group for Earth Observation

Launch Issue

Francis BellI thought readers would like to know
about a number of other publications
which are available in our interest areaof weather satellite reception.
Below are described three publications
which I receive at home. Each one isavailable free of charge once you haveapplied to have your name and address
added to the publisher’s mailing list. I
think this is a right and proper course ofaction for any of this readership because
these publications are ultimately paid
for from public taxes. You will find thatthe publishers are pleased to extend
their readership to those who are
genuinely interested in their materials.
But it’s up to you to submit you nameand address: GEO will not do it for you.
Here are the details of the threepublication I receive. If any reader
knows of other publications of potential
interest in our field, please let me know.
ESA Bulletin - Space for Europe
This magazine appears four times per
year and ESA describe it as their housemagazine. It covers the high-profile
activities of the European Space Agency.
The Bulletin contains some 100 glossy
A4 pages containing articles about
ESA’s activities, projects, space vehicles
and background science. There arealways a few pages devoted to current
space missions which include weather
satellites. I have been known to read theBulletin from cover to cover but moreusually I read the abstracts and only
read fully those pages of special interest
to me.
Earth Observation Quarterly(Guess the frequency of this publication)
This Remote-sensing Newsletter is also
produced by ESA and usually contains
about 20 A4 pages. The latest edition
covers meteorology, earthnet, remotesensing, solid Earth and future
programmes. It also contains a pictureof MSG-1’s launch but you can’t see
much detail and also includes somestunning Earth images.
Page 20To be placed on the mailing list foreither of the above publications, writeto:
ESA Publications Division,
c/o ESTEC,PO Box 299,
2200 AG Noordwijk
The Netherlands
Image
This is published by EUMETSAT twicea year.
This periodical, which comes directlyfrom EUMETSAT, appears in a 12-page
A4 format and specifically covers thelatest weather satellite news. The latest
edition includes special pages relating toMSG-1 plus other interesting topics anda global satellite update. I think most
GEO readers would be interested in
Image. I usually read it from cover tocover. If you are quick you may still beable to receive the latest edition which I
recommend: but I cannot promise this, it
depends on EUMETSAT’s policy.
To be placed on EUMETSAT’s mailinglist for Image, write to:EUMETSAT User Service
Am Kavalleriesand 31,
D-64295 Darmstadt
Germany
If you decide to request your name andaddress to be added to either of theabove mailing lists, I think it would bequite constructive to give your name andthen in brackets (GEO).
This will have the mutual benefit ofletting ESA and EUMETSAT know theextent of their current readership andgive GEO an influence within theseorganisations should it ever become
necessary in the future.
Postage to Europe is 38 pence but theuse of two second class stamps worth
40 pence may be easier.

Check www.geo-web.org.uk for all the latest news

The front covers ofthese three publications
are shown here together
with our gratefulacknowledgment totheir publishers.

Launch Issue

Group for Earth Observation

Articles
The Editor is always on the lookout for articles andimages relating to all aspects of Remote Imaging forinclusion in the GEO Quarterly. Particularly welcome
are topics, such as:
•
•
•
•
•
•
•
•
•

Technical articles on antennas, receivers andother hardware
Construction projects
Weather satellite images
Reports on weather phenomena
Description of how you set up your own Remote
Imaging station
Activities of overseas members
Reviews of relevant software and hardware
Letters to the Editor
Problems and Queries for our experts to answer

Please don’t be deterred if you have never written for amagazine before. Please don’t hesitate because you
don’t feel you have sufficient expertise to piece anarticle together. Don’t be put off because you feel yourspelling and grammar might not meet ourrequirements.
We will always be happy to help and advise you, to add
the final polish to your contribution, and convert yourdrawings into quality graphics. You will be sent a proof
copy of your article in PDF format so that you can makeGEO Quarterly No 1

final suggestions, additions and alterations prior to
publication.
Contributions should of course be original and, where
possible, should be submitted to the editor in electronic
format (floppy disc, CD or e-mail attachment). But wewill also accept handwritten or typed copy.
Images and Diagrams
Images can be accepted in any of the major bitmap
formats, e,g, JPG, BMP, GIF, TIFF etc. Images in bothmonochrome and colour are welcomed for inclusion.
Line drawings and diagrams are also welcome in
Windows metafile and postscript formats.
Please note that images and drawings must not beembedded within the text of your article, but should
be submitted as individual files.

Submission of Copy
All materials for publication should be sent to the
Editor, Les Hamilton, 8 Deeside Place, Aberdeen,
AB15 7PW, Scotland.
Materials may also be sent as attachments to thefollowing e-mail address:
editor@geo-web.org.uk

Weather Satellites and their Frequencies
Polar Orbiting Satellites

Frequencies

Geostationary Satellites

Location

Frequencies
WEFAX (MHz)

USA

75°W

1691.0USA

135°W

1691.0

Meteosat-5

India

63°E

1691.01698.0

Meteosat-6

Europe10°E

1691.0137.621707.0

Meteosat-7

Europe0°1691.0, 1694.5-

1700.4

APT (MHz)HRPT (MHz)NOAA 12137.501698.0GOES-ENOAA 14137.621707.0GOES-WNOAA 15137.501702.5NOAA 16-NOAA 17Feng Yun 1C, 1D

Where to Download NASA 2-line Elements
Satellite tracking programs require regular updates of the NASA 2-line element sets that they use to calculate
the positions of Earth-orbiting satellites. One of the best Internet sources for these files is Celestrak at:
http://www.celestrak.com

Elements for many groups of satellites are updated daily. Particularly useful are:http://celestrak.com/NORAD/elements/weather.txt (most weather sats)
http://celestrak.com/NORAD/elements/resource.txt (Okean and Sich)
http://www.celestrak.com/NORAD/elements/stations.txt (ISS)

Check www.geo-web.org.uk for all the latest news

Page 21

GEO Quarterly No 1

Group for Earth Observation

Historical Background
On March 1, 2002, the European Space Agency (ESA)
launched its most ambitious Earth observation
satellite, Envisat, into an 800 km orbit from theEuropean spaceport at Kourou in French Guiana. Thisgigantic satellite, the size of an articulated lorry andweighing some eight tonnes, was by far and away
Europe’s most ambitious project to date for thecontinued monitoring and investigation of climate andenvironmental change. Full details of the mission canbe found at:
http://envisat.esa.int

Developed from the European ‘Polar Platform’ project
initiated in 1988 and subsequently renamed Envisat(ENVIronmental SATellite) in the early 1990’s, thissatellite was developed at a cost of 2.3 billion euros.
Powered by a 70 square-metre solar array generatingover 6 kW of electricity, Envisat is the most powerfultool yet devised for monitoring the state of our planet
and the impact of human activities upon it. Envisat
views the Earth with unprecedented detail, andproduces enough digital data every 24 hours to fill thehard drives of 500 desktop PCs.
Introduction
The largest instrument carried aboard Envisat is theAdvanced Synthetic Aperture Radar (ASAR), a highresolution, wide-swath imaging radar. ASAR iscapable of producing high quality images, by both day
and night, of the oceans, coastal zones, polar ice andland regions of Earth, irrespective of weather
conditions or cloud cover.
ASAR collects information on:• ocean wave characteristics• snow and ice extent• sea ice extent and motion• land and surface properties• surface topography• deforestation and extent of desert areas• surface soil moisture and wetland extent• disaster monitoring, e.g floods, earthquakes,
landslides

narrow beam of microwaves directly towards an object
which reflects some of the signal straight back to theantenna. The travel time and signal strength of the
returned microwaves can be used to determine thedistance of the object. This is the type of radar used in
air-flight control operations, and by shipping.
However, this mode of radar lacks the resolution to
produce actual images. For imaging purposes, radar
must project its beam parallel to the antenna, and to
one side of it–what is termed side-looking radar (SLR).
When a beam of microwaves from Envisat’s SLR meetsa smooth surface at an angle (figure 1), most of thebeam is reflected away from the satellite at an
identical angle to that at which it arrived at thesurface. This means that few if any of the reflected
microwaves return to the satellite.

Figure 1
Reflection from asmooth surface

On the other hand, where the microwaves meet arough surface, the beam undergoes backscattering,with radiation reflecting in a multitude of directions(figure 2). Some of these backscattered microwaves doreturn to Envisat’s radar antenna, and modern signal
processing techniques can use these to build up an
image of the terrain below. The intensity ofbackscattered radiation is related to the texture, mostparticularly roughness, of a surface and is directly
related to the ‘brightness’ of the eventual image: therougher the terrain, the brighter it shows on a radar
image.

Figure 2
Backscatter from arough surface

The images presented on the page 24 illustrate thecapabilities of Envisat’s ASAR imager.
Radar Imaging
The microwaves used for radar imaging occupy a nichein the electromagnetic spectrum between light waves
and radio waves. Since both light and radio waves areused for imaging, most notably in astronomy, it will
come as no surprise to learn that radar can also beharnessed for this purpose.
In its simplest form, a radar antenna sends out aPage 22

Launch Issue

Synthetic Aperture Radar
The larger an antenna, the more unique information
can be obtained about a particular viewed object,permitting the creation of a more detailed image. This

Check www.geo-web.org.uk for all the latest news

Launch Issue

Group for Earth Observation

principle is used in modern radio astronomy, where
two dish antennas situated hundreds of kilometresapart can operate in tandem to provide an effective
resolution equivalent to a single dish with an apertureequal to the separation between the two smaller ones.
Modern optical telescopes likewise use ever larger
mirrors to improve resolution of distant deep-sky
objects.
The length of an SLR antenna determines the image
resolution along the direction of travel: the longer theantenna, the smaller the detail that can be resolved. To
achieve its maximum ground resolution of 30 metres,
Envisat would require an antenna several kilometresin length. But it would be prohibitively expensive tolaunch such a large radar antenna into space, so
another option has to be found. By employing a
relatively small antenna and making use of thespacecraft’s forward motion, a much larger antenna
can be simulated. The technique is known as Synthetic
Aperture Radar (SAR).
SAR makes use of the forward motion of a spacecraft tocreate a synthetic ‘aperture’ of (potentially) unlimited
length, thereby narrowing beamwidth and increasing
resolution. The radar antenna aboard Envisat, whichis aligned with the craft’s flight direction, measures
just 1.3 metre wide by 10 metres in length yet has theeffective size of a stationary antenna several
kilometres in length. This arises because Envisat, at
its orbiting altitude of 800 km, travels some 7.5 km persecond between positions ‘X’ and ‘Z’ (figure 3).

Figure 3 - The synthetic aperture

As Envisat flies over this section of its ground-track itemits some 1700 short radar pulses (each just a few
microseconds in duration) towards its viewing swath
each second, and any object over which the satellite
passes returns approximately 1000 back-scatteredresponses to the antenna. All this microwave
information returned while Envisat moves fromposition ‘X’ to position ‘Z’ is stored, and later converted
into images by computers using modern signal
processing techniques.
After intensive signal processing, all the backscatteredresponses are integrated to produce an image thatlooks as though it had been obtained from a large,
stationary antenna. Such Envisat images can have aresolution as high as 30 metres. The synthetic
aperture in this case is the distance travelled by the
spacecraft during the integration time (i.e. while it
moves from ‘X’ to ‘Z’ in figure 3).
SAR provides its own illumination (microwave pulses)

GEO Quarterly No 1

and can thus image independently of sunlight; images
can be obtained with equal effectiveness during bothday and night. Envisat’s ASAR operates in the C-band(frequencies in the 4 GHz - 8 GHz range) which meansan operating wavelength of 3.5 - 7.5 cm. Unlike visible
radiation which is scattered and diffused by the water
droplets in atmospheric clouds, the radar’s longer
wavelengths are relatively undistorted by clouds.
Applications
Envisat is able to respond quickly in the wake of anatural disaster such as the ‘Prestige’ oil spill
highlighted in figure 4 overleaf. ASAR imagery can bea vital tool for risk and disaster management teams
alike, monitoring the extent of flooding, or spotting
landslides in remote and inaccessible terrain.
The Advanced Synthetic Aperture Radar aboard
Envisat can map Earth’s surface to an accuracy of a
few tens of metres in a single pass. And when images
from two orbits are combined using a technique calledinterferometry, Envisat can detect subsidence in a city
street, the bulging of a volcano’s slope, or the sagging
of a glacier above a buried hot-spot, even when the
movement is only a few centimetres. Experiments in
London, Rome and Paris have proved that groundmovement of as little as one millimetre per year can beclearly detected from Envisat’s radar data.
The bottom left image on the inside front cover of thisQuarterly is an interferogram created at the German
Aerospace Centre (DLR) by combining a 1999 SAR
image from the ERS-2 satellite with a recent image
from Envisat’s ASAR instrument. It shows an area ofapproximately 30 x 35 km around the US city of Las
Vegas which can be seen in the centre of the image as
an area of bright colours with its major thoroughfares
appearing as straight dark lines. Each colour cycle in
the image, from blue to red to yellow, represents anelevation change of 8.4 metres, the effect producing
bands of colours showing the topography of the city andsurrounding area. The right hand image is a digital
elevation model showing the area under observation(Image credits: ESA/DLR).
Acknowledgments
All SAR images reproduced courtesy the European
Space Agency (ESA). Much of the explanatory text
accompanying the images is summarised from theEnvisat web pages at:
http://www.envisat.esa.int

Further Reading on the Internet
•
•
•
•
•

http://envisat.esa.int/instruments/tour-index/
http://www.envisat.esa.int/
instruments/alar/index.html
http://www.esa.int/export/esaSA/
ESAGSWTHN6D_earth_0.html
http://southport.jpl.nasa.gov/
desc/imagingradarv3.html
http://www.soest.hawaii.edu/
GG/HCV/NEWSV2N1/mackay1.html

Check www.geo-web.org.uk for all the latest news

Page 23

GEO Quarterly No 1

Group for Earth Observation

Launch Issue

The Prestige Oil Spill

Monitoring Ice Movement

Figure 4 is an Envisat ASAR image that was acquired
five days after the tanker Prestige was badly damaged
in a storm off the northwest coast of Spain on
November 17, 2002 . The dark plume emanating fromthe stricken ship and stretching to the Spanish coast isan oil-slick over 150 kilometres long. The tanker itself
is discernible as a bright white point located about
100 km off the coast. Support vessels are also
identifiable as smaller white points surrounding theship. The ASAR was operating in its wide-swath mode
covering an area approximately 400 kilometres
square, and the illustration is approximately
200 kilometres wide.

Figure 5 is a wide-swath image (150 m resolution)
showing the birth of antarctic iceberg C-19, whichmeasured 200 x 32 km, and was some 200 metres inthickness, shortly after it calved from the Ross Ice
Shelf in the Antarctic. The white swirls surroundingthe ‘berg indicate sea ice. This radar image also shows
clearly difference between Antarctic ice that is restingon land or water: the Ross Ice Shelf at lower right, forinstance, is seen as a smooth surface while at lower left
the image shows the rougher terrain of Antarctic ice
resting on land.
The Arabian Peninsula
In the centre of this wide-swath, 150-metre resolution
radar image (400 km wide) is the Arabian Peninsula,consisting of the countries of the United Arab Emirates(left side) with its main cities of Ajman, Ash Shariqah
and Dubai, visible as bright areas along the coast, andOman (right side and tip of the peninsula).
The group of small white dots off the east coast of
Oman is a fleet of ships. To the north is Iran with its
Qeshm Island and on the mainland the city ofBandar-el Abbas and the Zagros Mountains (left).

Figure 4 - The Prestige oil spill - November 17, 2002
Photo © ESA, 2002

Figure 5 - The newly calved C-19 iceberg - July 18, 2002
Photo © ESA, 2002

Page 24

Figure 6 - Arabian peninsula - June 22, 2003

Check www.geo-web.org.uk for all the latest news

Photo © ESA, 2003

Launch Issue

Group for Earth Observation

GEO Quarterly No 1

David Taylor
Introduction
An important part of any amateur weather satellite
station is time-keeping. Accurate times (and up-to-date
Keplers) are required to predict when a satellite will bevisible and perhaps to steer an antenna to track it
accurately. For most of us that will mean getting thestation computer accurately synchronised to UTC(Coordinated Universal Time). How you do this will
depend on the accuracy you require and whether or not
you are connected to the Internet.
The typical PC clock might have an accuracy of theorder of 100 parts per million, which means that it
could drift several seconds every day. Of course, some
PCs will be more accurate than this and some will beworse! For some purposes, simply setting the PC’s
clock once a day might be adequate, but this would
result in a step change of the time at the instant ofcorrection. This approach is called ‘stepping the clock’.
Some software might not work properly in the presenceof a large time step; in particular the widely used
WXSat uses the 16-bit C run-time library, whichappears to completely ignore such step corrections. A
better approach, and one which eliminates these clock
steps, is to measure the clock frequency error over a
period of time, and then adjust the clock frequency so
as to compensate for any error. This is possible
because, although the hardware clock frequency isfixed, the system timer interrupt frequency is driven
via a software programmable divider from the
hardware clock, and it is the rate at which these timer
interrupts occur that determines the internal time heldby the operating system. Software that adjusts theclock rate or clock frequency, rather than simply
stepping the clock, is therefore to be preferred.
By the way, Windows works in UTC in its internal
operations. What you see presented as a clock time, orfile date and time in Explorer, is derived from theinternal UTC value by the addition or subtraction of
the bias that is appropriate to your Time Zone. Thiscan have some unexpected effects. For example, filedates and times on both CDs and the NTFS (NT File
System used by more recent versions of Windows) are
held in UTC, so that between summer time (daylightsaving time) and standard time there will be a one
hour difference in the apparent file time stamp as
displayed by Explorer. But the FAT file system keeps
its time in ‘clock time’, so that the file time stamp
displayed for an FAT file will stay the same between
summer and winter!
Another issue is the BIOS – there is a CMOS RealTime Clock (RTC) chip included in the BIOS section ofyour PC to store the time and other settings while the
PC is powered off. By convention, the BIOS displays

local clock time, and any operating system must allow
for the difference between clock time and UTC when itboots. Windows will offer to set the BIOS clock forward
or back for you when it discovers a difference in thetime settings from one boot to the next. However, it has
no way of knowing whether the BIOS itself has beenset, so if you boot multiple versions of Windows acrossclock time changes, you will be asked multiple times
whether or not to reset the (BIOS) clock. You should
only agree to do this once, of course. Whether or notbooting multiple versions of Linux does the same I do
not know.
If You Have an Internet Connection
There is plenty Windows software available to allow
you to keep time accurately, and which one you choose
will depend on whether you have a permanent Internet
connection and which version of Windows you arerunning. If you are running Windows NT 4, 2000 or XP
then the obvious choice is the public standard Network
Time Protocol (NTP) server software from thefollowing URL:
http://www.ntp.org/links.html

Basically, NTP works by having a hierarchy of servers.
Servers at the root of the hierarchy are synchronised tovery accurate external sources such as GPS, precision
radio clocks, or atomic standard clocks. Suchexternally synchronised servers are marked as‘stratum-1’ servers. Systems further down thehierarchy are typically synchronised to upstream
servers and then provide synchronisation for clientsdownstream. The NTP software provides both clientand server in a single package. Thus your Internetfacing PC which may be synchronised with a public
stratum-2 server, will itself be operating at stratum-3,
and may also provide time synchronisation services forother PCs on your network which would then operate
at stratum-4. See illustrations on page 26.
If you have more than one Internet-connected PC, you
should designate just one of these as a master time
server for your station. It is good practice to limit the
number of PCs that you connect to an external NTP
time server because this limits the load on theseservers. Your Internet Service Provider (ISP) may
provide an NTP service, or you can choose a stratum-2
server from the list at:
http://www.eecis.udel.edu/~mills/ntp/servers.html

If you are interested in the engineering theory behind
NTP and, in particular the use of both frequencylocked and phase-locked loops, then I recommend thatyou read the papers by David Mills at:
http://www.ntp.org/documentation.html

Check www.geo-web.org.uk for all the latest news

Page 25

GEO Quarterly No 1

Group for Earth Observation

Launch Issue

Accuracies Achieved with NTP
PC Bacchus
233 MHz AMD, 64 Mb
NT4 SP6 - no interactive
Synched from the Internet
PC Hermes
1 GHz Pentium III, 512 Mb
Win2000 Pro SP4 - no interactive
Synched from Bacchus
Peered with Odin and Stamsund
PC Odin
1.9 GHz Pentium 4, 1 Gb
Win XP Pro SP1 - heavy interactive
Synched from Bacchus
Peered with Hermes and Stamsund
PC Stamsund
2.8 GHz Pentium 4, 1 Gb
Win2000 Pro SP4 - heavy interactive
Synched from Bacchus
Peered with Hermes and Odin
These graphs relate to my four network PCs. The reported offset from UTC is plotted, plus a fixed 100 ms offset required because
the graphing tool I used is only intended to plot positive values. PC Bacchus is synched from servers on the Internet. In general, all
PCs are within 10 ms of UTC, with glitches most noticeable on Stamsund, caused by heavy interactive or batch CPU use. It is as if
some timer interrupts are being lost. The PC takes about an hour to recover after such a glitch. As the bottom three PCs are synchedas peers to each other, when Stamsund gets a negative glitch there is a small positive glitch visible on the other two PCs.

These graphs show Bacchus, which is synced off the Internet,
during three different time periods which demonstrate short,medium and long-term errors. The daily drift due to temperature
variations is clearly visible, together with the occasional glitch.
Page 26

These graphs show Hermes over three time periods. There ismuch less daily variation than with the Internet synched PC,
because the clock is synched every 64 s instead of every 1024 s(using 64s polling against an Internet server is considered badpractice).

Check www.geo-web.org.uk for all the latest news

Launch Issue

Group for Earth Observation

Unfortunately if you have Windows 98 or ME, then you
cannot run the public standard NTP software, as it
requires to be run as a service, which is not allowed bythose versions of Windows. An NTP client normallytalks to its upstream servers about once every 20
minutes, so if you have a dial-up connection you may
also have problems with the software. For both of thesesituations, I recommend the Tardis software, which
was written in the UK. Of course, there are many otheralternatives. You can download Tardis from:http://www.kaska.demon.co.uk/tardis.htm

Tardis does have the ability to provide a frequency
adjustment, rather than a simple clock step, undercertain conditions. Please see its documentation for
details. Tardis is shareware, although it is the fullversion that you download. If you continue using
Tardis, do remember to register it!
If You Have no Internet Connection
If you have no Internet connection but are connected toa network that has an NTP server included, then you
can use the NTP software described above. Otherwise,
you will need an external reference source of time.
Suitable sources include a GPS receiver or a time code
receiver working from the LF signals from MSF at
Rugby, England on 60 kHz or DCF77 from Frankfurt,
Germany on 77.5 kHz. Equivalent US (WWVB) andJapanese services also exist.
There are two ways by which a GPS receiver can
provide time. The first method is a serial interface
where the time code is sent in ASCII once a second: theother method is a pulse-per-second (PPS) interface
where there is no time code but simply a regular pulse
occurring once every second. Whilst the PPS interface
can provide an accurate time reference when each new
second starts, it does not provide an absolute timevalue, and therefore must be used in conjunction witha separate time of day reference. The NTP software
mentioned above will accept input from both types of
GPS receiver. A simple Radio Clock receiver has been
a described by Jonathan Buzzard at:
http://www.buzzard.org.uk/jonathan/radioclock.html

but unfortunately the software described is for Linuxand not Windows. Various GPS modules appear on thesurplus market from time-to-time.
Accuracies
What sort of accuracy can you expect to achieve? Well,it all depends on your connection. With a modem
connection, I would expect you to achieve sub-second
accuracy, but if you are using clock-stepping softwarethen the accuracy will immediately degrade after thetime is set.
If you are using frequency adjustment software, thenyou should do rather better in the medium term. Be
aware that the BIOS RTC only holds time to thenearest second, so switching your PC off and on will
introduce a time step even if the clock rate is perfect.

GEO Quarterly No 1

If you have a permanent Internet connection, then you
should get accuracy between 10 and 100 milliseconds
depending on the connection quality. If you are using acable modem, or other connection with anasymmetrical send and receive propagation delay time
between you and your reference server, then you may
end up with a low jitter, but a fixed offset relative toUTC. The NTP software allows you to trim out suchoffsets if you can measure them. With the radio clock,you may expect accuracies of the order of one
millisecond (although you will need to trim out
propagation delay time and receiver rise time), andwith the GPS PPS connection even better than that!
If you are curious, you can see how well (or otherwise)
my PCs are doing at:
http://www.satsignal.net =>Network Statistics, NTP Summary

Conclusions
The requirement for accurate time-keeping at yourstation can be satisfied whether you have a permanentinternet connection or not. If you want your own timestandard then a home-built receiver could be thesolution and a project for the Winter! Software to help
you is readily available.
Appendix I
During the preparation of this article, a number offurther questions on time scales came to mind. These
were presented to Peter Wakelin for his comments, andI am indebted to him for the answers which appear
below.
Which Time Scale is Used in Kepler Data?
UTC without exception. So if a leap-second occurs
between epoch of elements and predicted time, a onesecond correction will be required.
How accurate does my data need to be andhow accurately does my computer need to be
set to track the satellites I receive today andwill receive tomorrow?
If concerned about accurately pointing an antenna at asatellite using a computer-based system then there areseveral considerations:
1. Acceptable pointing error - beamwidth of dish andfrequency. The fact that NOAA satellites near thezenith move about 0.5 degree in a second gives anidea of the overall accuracy needed for acceptable
pointing accuracy.
2. Prediction software accuracy - some (including
Instantrack and Timestep’s Track2) use a crude
spherical Earth model so if you use geographic
coordinates for your site instead of geocentric ones
you are starting off with a location error of around
20 km (in the UK). which equates to more than adegree on an overhead NOAA satellite.
3. Computer clock - from (1) it is clear that 1 or 2
second accuracy is needed.

Check www.geo-web.org.uk for all the latest news

Page 27

GEO Quarterly No 1

Group for Earth Observation

4. The accuracy of the Two-Line element setsthemselves. Errors are rare but not all
perturbations are catered for in the Two-Line data
or in prediction software: but for 850 km satellites
like the NOAAs, updating every couple of days
should be adequate for 1 or 2 seconds accuracy.
Bearing in mind all the above, I decided long ago tocontinue with manual tracking for HRPT reception,
watching the signal strength meter constantly.
How Does GPS Handle Leap Seconds?
There was much discussion on this topic on one of thesatellite forums a year or two back but I didn’t take a
lot of notice. I’m sure an internet search would reveal
much but as I recall GPS uses a modified form ofInternational Atomic Time but offset by an integer
number of seconds so that it equated to UTC when GPS
started back in the 80’s. I also recall that GPS
operators want rid of UTC and everyone to adopt TAI
but astronomers won’t have this so meanwhile GPS isreluctantly ‘corrected’ at some stage to UTC.
Appendix II
Professor David Mills of the University of Delawareteaches courses in computer architecture, computer
networks and computer security. He added thefollowing clarifications to the leap-second debate:“If we ever had to give back a leap-second, it would bea disaster. The WWV/WWVB time code has only asingle bit to signal leap insertion and no way to signal
deletion. The GPS time code has the UTC-GPS offset inseconds, but the GPS receivers I have indicate only

Cover Images
Front Coverleap insertion. From the ERTS data the rate of increase
has flattened out over the past three years, which
certainly gives me the willies; but my professional
friends tell me not to worry about it.”Appendix III
Ton Van Baak provided me with these additionalcomments:“Yes, there is only a single bit in the WWV/WWVB timecode to indicate a pending leap second but the sign andmagnitude of the UT1 correction bits tell you if the leap
second is positive or negative. For WWVB these arebits 36/37/38 for the sign and bits 40/41/42/43 for themagnitude.
“For example, for the 6/30/1997 leap second the UT1
correction was -0.5 before the leap second and +0.5
after the leap second. Similarly for the 12/31//1998 leap
second the UT1 correction was -0.3 before and +0.7
after the leap second.
“When the net change in UT1 correction is +1.0 theleap second will be positive and if the net change is -1.0
it will be a negative leap second. So a separate bit for
positive/negative leap second is not needed in thespecification.
“I’m not saying there won’t be hardware or software
trouble elsewhere if a negative leap second were ever tooccur, but the WWV/WWVB time code specification
itself is not a limitation.”
For further details on these leap second examples see:
http://www.leapsecond.com/notes/ls-wwvb-97.htm
http://www.leapsecond.com/notes/ls-wwvb-98.htm
http://www.leapsecond.com

is a merged data product created fromseveral sources, predominately 30-meter
resolution elevation data collected by
NASA’s Shuttle Radar Topography
Mission (SRTM).

This SeaWiFS image shows smoke
billowing from California wildfires on
October 26, 2003. Flames fanned by
Santa Ana winds generated large
quantities of smoke which covered over
150,000 square miles of the Pacific
Ocean to the southwest.

Image courtesy Landsat Project Science
Office, NASA’s Goddard Space Flight Center

Image courtesy the SeaWiFS Project,
NASA/Goddard Space Flight Center, and
ORBIMAGE.

Top: Colour composite MSG-1 images
from Cedric Roberts

Inside front Cover
Glacier Bay National Park and Preserve,
Alaska, imaged by the Landsat-7
satellite’s Enhanced Thematic Mapper
Plus (ETM+) instrument in August 1999
with elevation data from the USGS
National Elevation Dataset (NED). This
true-color image was created by
combining the red, green, and blue
wavelengths (ETM+ bands 3, 2, and 1).
The resulting image was then draped
over a visualisation of the NED data withno vertical exaggeration. The USGS NED
Page 28

Launch Issue

Inside Back Cover

Foot: Patrick Prokop captured thisenchanting NOAA 12 HRPT image of
Hurricane Isabel on September 17, 2003.
Note the strong sunglint on the waters of
the Gulf of Mexico.
Back Cover
B-15A, B-15J, and C-16 icebergs in theRoss Sea, Antarctica, imaged at 250
metre resolution by the NASA Aqua
satellite at 03:55 UT on November 12,
2003.
Image credit: MODIS Rapid Response Team,NASA Goddard Space Flight Center.
Check www.geo-web.org.uk for all the latest news

Opposite Page
Arne van Belle from s’Gravendeel in the
Netherlands received this MSG-1 image
via the Eumetcast service at 08:44 UT
on May 8, 2003.

The image was decoded using David
Taylor’s MSG Data Manager. Afterremapping, channels VIS006 (blue),
VIS008 (green) and IR016 (red) werecombined into this colour composite
image using GeoSatsignal.

This selection of channels gives,
generally, the most realistic colour
scheme: it can be used to differentiate
ice and snow from water. The high cold
clouds are tinged cyan, as is snow in theAlps.

A striking feature of the image is Cyclone‘Manou’ centred over Madagascar.
MSG-1 Trial Data, © EUMETSAT, 2003

GEO Quarterly No 1

Group for Earth Observation

Launch Issue

Peter Bartlett
For readers interested in gaining a further
understanding about weather forecasting via remoteimaging from weather satellites, I recommend
studying some of the training modules available on theInternet from the Meteorology Education and Training(METED) web-site at:
http://www.comet.ucar.edu/

A list of all the modules available can be seen at:
http://www.comet.ucar.edu/modules/index.htm

A few of the topics on offer are discussed below.
The Remote Sensing ModuleThis unit was developed for students enrolled in an
introductory Earth or atmospheric science course. It is
designed to supplement lecture and textbooks andaims. Its goal is to make you a better consumer ofweather information by providing dynamic graphics,
animations, and science content about remote sensing,satellite imagery, and hurricanes. When you havecompleted this module, you should be able to viewsatellite imagery in a typical weather forecast on TV or
the Web and recognise the importance of somefeatures.

movement and other weather features: some sections
include audio descriptions. Figure 1 is a screenshot on
the theme ‘Clouds and storms on Visible Imagery’ andincludes an animation of Hurricane Opal.
Remote Sensing of Land, Ocean & Atmospherewith Modis ModuleThis presentation focuses on the capabilities of the
MODIS instrument on the Terra satellite platform. It
is divided into short sections and includes an overview
of the MODIS instrument with multiple examples ofimagery products, highlighting applications in the
Earth, oceanic, and atmospheric sciences. Topics
covered include the Modis Launch, Cloud Mask, Land,
Ocean and Atmospheric applications. Figure 2 comesfrom the section that explains how MODIS uses its
many imaging channels to detect whether the land ismasked by cloud cover.

Figure 2 - Cloud mask

Figure 1 - Clouds and storms on VIS Imagery (Hurricane Opal)

The unit contains four sub-topics relating to Remote
Sensing, Satellite Imagery, Hurricane Features andExploring Hurricanes. Here you will learn the basic
principles of remote sensing, what satellite-based
sensors observe, the imagery they create, and how tointerpret these. You will learn the basics about classic
hurricane characteristics and explore three recent
hurricanes through a time sequence. There areopportunities to inquire about phenomena, develop
and test hypotheses, and make calculations. In all, thismodule includes over 30 graphical images, including
movies and flash animation sequences depicting cloud
Page 30

The topic areas described above are some of the 60 plus
modules that are available for viewing on-line. Certain
modules are also available for downloading but some ofthese are 60-80 Mb so can take a while, especially if
you are not using broadband. All modules include large
numbers of detailed graphics, both static andanimated, some with additional voice-overs.
The source of the above material is the Cooperative
Program for Operational Meteorology, Education, andTraining (COMET®), whose web site is hosted by the
University Corporation for Atmospheric Research(UCAR), funded by the National Weather Service at:
http://www.comet.ucar.edu/© 2002 University Corporation for Atmospheric Research
All Rights Reserved.

Check www.geo-web.org.uk for all the latest news

Launch Issue

Group for Earth Observation

GEO Quarterly No 1

Arthur Andrews VK2 AAE
I felt very honoured when I was asked if I would like towrite a regular article for the magazine of the newly
formed Group for Earth Observation. This I will bepleased to do subject to the restraints of the farm andother commitments.
As this is the first of what I hope will be many articles,
I thought I would bore you with some personal details
about how I managed to end up on a small farm on theother side of the world. I was born and raised in
Fareham, Hampshire and educated at St. John’sCollege, Southsea. In 1961 I met and later married mywife Hazel who comes from the little village of East
Dean near Chichester, West Sussex.
In June 1967, taking advantage of the heavily
subsidised migrant scheme, we boarded a plane toAustralia with our two children, Nigel aged 3, andHelen aged 2. Thus we became some of the many ‘Ten
Pound Poms’ to come to this land. Sadly this scheme
was discontinued a few years after our arrival. For themost part of my working life we lived in one of theouter suburbs of Sydney and my job took me to all
States and Territories of Australia which was a great
experience. In 1985 when I turned 50 I decided to takeearly retirement and we purchased a small farm deepin the Central Tablelands of N.S.W. and realised alifelong dream.
Ever since I built my first crystal set when I was about
10 years old I have been interested in radio andelectronics and in 1977 I obtained my amateur
operator’s certificate. About eleven years ago I became
interested in weather satellites, an interest which has
not diminished with time. Like most beginners I
started off with APT and had a lot of fun
experimenting with different types of antennas for
APT and dish feeds for wefax reception. Later I
progressed to an HRPT system which opened up a new
field in image interpretation and manipulation. A few
years ago I was lucky enough to acquire a five-bedroom
demountable which had been used for workers on aremote building site. It was fully wired for power andeven had two air conditioners. I removed four of thefive internal partitions making one large and one small
room and the building was then known by the grandtitle of the ‘Communications Centre’.
In it are housed the HRPT system and dedicatedcomputer: a secondary computer is used for wefax
images from GMS-5, the weather station readouts andthe lightning detector data. My main computer andamateur radio gear are in my study in the house.
Figure 1 shows the ‘Communications Centre’ in all its
glory. The 1.8 metre dish on the left is for GMS-5
reception, whilst the 90 cm offset dish on the roof wasfor HRPT reception but has since become redundant.
The trees behind the building are a bone of contention
between my beloved and me. I’m for chopping all ofthem down to give me a better all-round view but thisis strongly opposed in certain quarters. It wassuggested I move my building instead and I suppose
there is certain logic in that proposal.
Due to some experimental work I am engaged in I
found I needed a larger centre-focus dish sited so that
I had a good view to the east. This turned out to be an
agricultural project. Ideally I wanted a 1.2 metre
centre-focus dish, but try as I might I could not find a
supplier in Australia who stocked them. There wereplenty of offset dishes of that size but they were notsuitable for my requirements. Eventually I decided touse a spare 1.5 meter ex-satellite TV dish I had lying
around. I had decided to site the dish in an adjoining
paddock, (fields are called paddocks in Australia),
about 50 metres from the Communications Centre.
This necessitated the purchasing of a new run of low
loss co-axial cable for the feed and two runs of sixstrand cable for the az/el rotator. The next problem
was how to fix the dish to the rotator.
A talk to Terry down at the village garage solved the
problem. Terry is a true ‘bush’ mechanic and can turnhis hand to almost anything and next day he designed
and welded together a cradle to fix on to the dish,complete with brackets for fixing to the elevation armsof the rotator. As the dish was of pressed steel it waspretty heavy and as Hazel and I are not as young as wewere we found we could not lift it up to attach it to therotator. However, placing the dish on the hydraulicfront end loader of the farm tractor and raising it to therequired height, from where it was then easily fixed
into place, soon solved that. One final problem
remained: how to counter-balance the weight of thedish so that undue strain would not occur to therotator. Farmers world-wide have always followed theadage, ‘necessity is the mother of invention’, and thisfarmer is no different. After a bit of thought, I got
Terry to weld a bracket on to a steel bar, and then apiece of railway track to the bar. This I attached to therear of the rotator but found that it was still out ofbalance. I had some lengths of galvanised pipe lying
around so I experimented with different lengths until abalance was achieved, the pipe lying snugly in thegroove on the side of the railway track. To stop the pipe
sliding out when the dish was raised I used a clamp tokeep it in place and the job was complete. Figure 2
shows a picture of this magnificent invention. It
certainly isn’t pretty, but it works.
During summer I have often had trouble with the LNA
fitted to the feed at the focal point of the dish. I put the

Check www.geo-web.org.uk for all the latest news

Page 31

GEO Quarterly No 1

Group for Earth Observation

Launch Issue

pointing towards or away from the sun. I will let you
know the results of the tests in the next issue.

Figure 1 - The ‘Control Centre’

The new dish and its location now give me a good viewto the east and I can now acquire the satellites at 3° ofelevation. This now allows me to capture good imagesof New Zealand, which I have been unable to do before.
Figure 3 is an image of part of the South Island of New
Zealand captured from NOAA-16 in October andprocessed in false colour by David Taylor’s excellent
HRPT Reader software. The snow lying on themountain ranges can clearly be seen, as can some of
the many lakes that abound in the South Island.
I am always on the lookout for unusual weather
systems when I examine the HRPT data that I havecaptured and Figure 4 is a case in point. This image,again processed by HRPT Reader and received fromNOAA-16, shows a large thunderstorm in Bass Strait
neatly sandwiched between the Victorian coast andFlinders Island.

Figure 2 - My innovative dish support

erratic behaviour of the LNA down to excessive heatradiating from the centre of the dish. Shade
temperatures at my location regularly reach 100°F
during the summer months so I was interested to findout just how hot the LNA got on these days. Most
normal thermometers seem only to go up to about
130°F so were not really suitable. My brilliant wife
suggested using an oven thermometer and bought me
one on her next trip into town. This fits neatly next to
the LNA so now I will be able to see the difference
between shade and dish temperatures. These should
vary considerably depending whether the dish is

Figure 4 - Thunderstorm in Bass Strait

Port Phillip Bay can be seen centre left whilst thenorth coast of Tasmania can be seen at the bottom. The
storm was travelling from west to east and it isinteresting to note the almost straight leading edge
and the large thunderheads poking above the cloudmass like so many pimples. There was no othersignificant cloud within hundreds of miles of thisstorm.
October ushered in the Summer Madness Period again
where Australia’s time zones border on the ridiculous
when the various States and Territories adopt or reject
daylight saving. This stupidity is best understood bylooking at the map (Fig 5). The normal time zone
offsets are shown in bracketed figures, South Australia
being half an hour behind the east coast and West
Australia two hours behind which is sensible enough.

Figure 3 - South Island, New Zealand
Page 32

Check www.geo-web.org.uk for all the latest news

Continued on page 35 . . .

Launch Issue

Group for Earth Observation

GEO Quarterly No 1

David Taylor
compression for the HRIT channel-12 image (HighResolution Visible - 5568 x 11136 pixels) was replacedwith the same lossless wavelet compression used on
the other eleven channels. This resulted in a somewhat
greater data flow, as the files are larger, but no users
have reported problems as a result. The actual images
are now significantly better, with the JPEG artefacts
being replaced by smooth transitions, which isparticularly visible in the darker regions. Whether
Eumetsat will continue with this format is unknown at
the time of writing.

The original LRIT W/V channel relayed at
13:15 UT on October 28, 2003

Eumetsat made the following comment on October 29,
2003: ‘Following the successful introduction of HRV
lossless wavelet compression on October 29, we have
not observed any loss in quality or timeliness to theservices delivered on EUMETCast. In addition, we
have received positive feedback on the improved HRV
image quality from Dissemination Trial Users. As aresult, we plan to continue with HRV lossless wavelet
compression for the foreseeable future.’

One of the most dramatic effects of
the recent transition to the
production
IMPF
groundprocessing software for MSG-1 has
been that Eumetsat took theopportunity to review the gain
settings for the channels, tooptimise the dynamic range andprevent clipping. This resulted in
the gain for the water-vapour
channels
being
increased
substantially, so that the pale
image received from the 12:15 UT
LRIT data (left) was replaced witha much more contrasty image
from the 13:15 UT scan (mainimage, below). This change wasmade on October 28, 2003.
As the LRIT data is transmittedwith lossy JPEG compression,much of the low-contrast detail inthe earlier image was masked by
JPEG artefacts. No such problems
arise with the new gain settings
though! Users of the HRIT dataalso saw the same change.
The next day saw the start of atest where the lossy JPEG

The ‘improved’ LRIT W/V channel relayed at 13:15 UT on October 28, 2003
Check www.geo-web.org.uk for all the latest news

Page 33

GEO Quarterly No 1

Group for Earth Observation

Launch Issue

NASA
A massive iceberg that had been
blocking traditional shipping routes toMcMurdo Station, the National Science
Foundation’s research station in
Antarctica, snapped into two recently.
The iceberg, which is designated B-15A,
appeared intact when imaged by theModerate Resolution Imaging Spectroradiometer (MODIS) aboard NASA’s
Terra satellite on October 7, 2003, but
an image captured just two days later(figure 1) showed the ‘berg to have split
into two. The larger northern section isabout 75 miles long; the shorter one is
20 to 25 miles long. A more recent colour
image acquired by NASA’s Aqua MODIS
instrument appears on the back cover,and shows the split even more clearly.
The B-15A iceberg calved from the Ross
Ice Shelf at the end of March 2000, at
the end of the Antarctic summer melt
season, and has since drifted to its
present location. At that time, itmeasured 170 miles long by 25 miles
wide with an area of 4 250 square-miles,
almost exactly the area of the island of
Jamaica.
B-15A was formed from glacial ice
moving off the Antarctic continent andcalved along pre-existing cracks in theRoss Ice Shelf near Roosevelt Island.
The calving of the iceberg resulted in thenorthern boundary of the ice shelfreceding some 25 miles to the south, aloss that it will probably take the ice
shelf up to 100 years to replace. Cracks
in the Antarctic ice shelf have beenclosely observed since the advent of
remote sensing by satellite and are ofparticular interest to scientists studying
the potential effects of global warming.
The break-off of this iceberg is believed
to be part of a normal process in which
the ice sheet maintains a balance
between constant growth and periodic
loss.
Figure 2 shows the scene as captured by
Terra’s
MODIS
instrumenton
September 17, 2000. The enormous
bergs became locked up in winter sea ice
before they could drift very far that firstseason, but at the onset of the following
Page 34

Figure 1 - Terra MODIS image showing Iceberg B15a on October 9, 2003

Image courtesy Jeff Schmaltz, MODIS Land Rapid Response Team at NASA GSFC.

Figure 2 - Terra MODIS image showing Iceberg B15a on September 17, 2000
Image courtesy Jacques Descloitres, MODIS Rapid Response Team at NASA GSFC.

spring thaw, soon after this image was acquired, they began to drift.
The large, southernmost berg is B-15A, and it eventually drifted
toward Ross Island, seen at the bottom left of the image. The amazing
shadow being cast on the ground south of Ross Island is from Mount
Erebus. An unusual situation arose during the Antarctic summer,
December 2002, when seasonal sea ice in the Ross Sea failed to

Check www.geo-web.org.uk for all the latest news

Launch Issue

Group for Earth Observation

GEO Quarterly No 1

disperse, and blocked the route used bysupply ships bound for McMurdo Station(the National Science Foundation’s
researchstationon
Antarctica).
Normally, the ice dramatically retreats
from Antarctic coastal waters, but thisyear unusually high levels of ice
persisted in the Ross Sea despite theadvancing summer, impeding thepassage to Ross Island.
Figure 3 shows the scene on
December 17, 2002. Ross Island, seen at
the lower left hand corner of the image, isengulfed by the outer reaches of the Ross
Ice Shelf (bottom). The build-up of packice may have been due to the presence of
two large icebergs (B-15A, lower left andC-19, top centre) which had run aground,interfering with the ocean circulation
patterns that melt or carry off theseasonal ice.
The Ross Ice Shelf is a massive field ofsnow and ice that begins on land but
hangs out over the sea. Ross Island
Figure 3 - Icebergs B-15A and C-19 trapping seasonal ice in the Ross Sea
reaches a maximum elevation of
Terra MODIS - December 17, 2002
3 794 meters on Mount Erebus, an active
Image courtesy Jacques Descloitres, MODIS Rapid Response Team at NASA GSFC.
volcano. The fact that parts of the island
appear just barely to rise above the ice
shelf provides dramatic evidence as to just how thickoccasionally giving rise to enormous icebergs like Bthe ice sheet is —1 000 metres in some places. The
15A, while the interior regions are fed by glaciers
shelfundergoesperpetual
demolition
andwhich flow down on to the shelf from the mainland ofreconstruction as its outer portions break off,
Antarctica.
View from the Other Side. . . Continued from page 32

Come daylight saving, Queensland, West Australia andthe Northern Territory stubbornly refuse to adopt it
whilst the remaining States do. This then leads to the
farcical situation of Queensland at longitude 150°E
being half an hour behind South Australia at 135°E.
Equally stupid is South Australia and the Northern

Territory which share nearly the same areas oflongitude, yet the N.T is an hour behind S.A. The mind
boggles. If we have got to have daylight saving andpersonally I don’t see why, I think it ought to be under
Federal control and every State adopts it. This won’t
happen of course, as the States are very jealous of theirautonomy and won’t relinquish any of their powers. It
was once suggested that all Australia had only one
time zone based on the 135°E line of longitude but I
don’t think it was ever seriously considered.
Goodbye for now from the Other Side.

Figure 5
The Australiantime zones

Check www.geo-web.org.uk for all the latest news

Page 35

GEO Quarterly No 1

Group for Earth Observation

Launch Issue

Peter Wakelin
Meteor 3M Redesigned
Meteor 3M N1 was launched more than two years ago but its
successor, N2, to be launched in 2006, will be a very different
spacecraft; it will conform more closely to the standards agreed
by the Coordination Group for Meteorological Satellites(CGMS). Like its western counterparts, it will carry imagers in
the visible, infrared and microwave channels as well as infraredand microwave atmospheric sounders. It will broadcast directly
to user stations in the digital LRPT (137.10 or 137.89MHz) and
AHRPT (1700MHz) modes.
Meteor 3M N2 and the follow-on N3 will be based on the proven
Resurs platform and are intended to demonstrate key systems
and be the precursors of the next-generation purpose-built
meteorological spacecraft. The basic imaging instruments
include the MSU-MR scanning radiometer with six channels
between 0.5 and 12.5 micrometres and having a resolution of
1.0 km and the KMSS high resolution scanner operating in fourchannels in the visible/near-infrared band with a resolution of
100 m but with a reduced swath-width of 100 km.
In addition to the above-mentioned imagers and sounders thesespacecraft will also carry active radar imagers named‘Severjanin’. This instrument is currently under development
and the first one to fly should be on the joint Russian/Ukranian
spacecraft Sich-1M, which may be launched later this year.
Intended for ice monitoring, resolution will be better than 1 km.

ResourceSat-1 image showing part of Washington DC. The
White House is at lower left and the Capitol at lower right.
(Image courtesy Indian National Remote Sensing Agency.)
Japanese Launch Failure May Further Delay MTSAT 1R

India Launches ResourceSat
India’s fourth satellite to be orbited in 2003 lifted off from theSatish Dhawan Space Centre onboard an Indian-built Polar
Satellite Launch Vehicle (PSLV) at 0452 UT on October 17. The
PSLV placed the 1360 kg ResourceSat-1 into an 802 x 875 km,
98.7° sun-synchronous orbit.
ResourceSat-1 replaces two older Earth resources satellites,
IRS 1C and 1D, which have been successfully imaging for morethan 6 years. In addition, ResourceSat-1 greatly enhances data
quality; it carries three cameras:•••

A high resolution Linear Imaging Self Scanner (LISS-4)
operating in three spectral bands in the visible and nearinfrared with 6m resolution
A medium resolution LISS-3 with 23.5 m resolution
An Advanced Wide Field Sensor (AWiFS) with 56 m
resolution.

ResourceSat-1 also carries a solid-state recorder with acapacity of 120 gigabits. This recorder was used to store theaccompanying LISS-4 image of part of Washington, DC, USA on
November 8, which was later read out to a receiving station inIndia.
Page 36

Two Japanese spy satellites were lost during launch on
November 29 when the H-IIA rocket had to be destroyed 11
minutes after launch. Early reports indicated that one of the
10-tonne solid boosters failed to separate from the first stage
less than two minutes after launch as planned, possibly
because leaking hot gas burned through the command wires.
Although the H-IIA is reported to have reached its planned
altitude of 422 km, its velocity at that height would have been far
too low, because of the extra mass carried, and its payload
could not reach orbital velocity.
As the H-IIA will be used to launch MTSAT 1R, a further delay toat least mid-2004 seems likely until the problem is resolved andcorrected. MTSAT 1R is a replacement for the original MTSAT 1
which was destroyed in a launch failure. It will be placed at
140°E to replace the ailing GMS-5 spacecraft.
NPP to test Next-Generation Instruments
The NPOESS Preparatory Project (NPP) is scheduled forlaunch in October 2006 to test four of the critical sensors to be
carried on the next-generation US NPOESS (National Polarorbiting Operational Environmental Satellite System) spacecraft.

Check www.geo-web.org.uk for all the latest news

Launch Issue

Group for Earth Observation

They are:•
Visible/Infrared Imager Radiometer Suite(VIIRS) which is a 22-channel radiometer
having a resolution of 650 m at visible
wavelengths.
•
Cross-track Infrared Sounder (CrIS) which is a
Fourier Transform Spectrometer to determine
the vertical atmospheric distribution oftemperature, moisture and pressure from thesurface to the top of the atmosphere.
•
Ozone Mapping and Profiler Suite (OMPS)
which consists of a nadir-scanning ozone
mapper similar to NASA’s Total Ozone Mapping
Spectrometer (TOMS) and a limb-scanningradiometer capable of much greater verticalresolution than the Solar Backscatter Ultraviolet
radiometer on the current NOAA spacecraft.
•
Advanced Technology Microwave Sounder(ATMS) which is a new cross- track microwave
sounder for deriving temperature and humidity
profiles. It will be far smaller, lighter and lesspower-hungry than the present generation ofsimilar sounders.
There will be no 1.7 GHz data transmissions from
NPP although direct readout will be available on
7812 MHz at 15 Mbps to suitably equipped groundstations.
NOAA-N to be Launched in September 2004
NOAA-N, to be renamed NOAA-18 when operational,is expected to be launched in mid September and will
go into the afternoon orbit replacing NOAA-16. It will
carry two uprated instruments: the High Resolution
Infrared Sounder HIRS/4 will have a much improved
resolution over the HIRS/3 currently in use and
EUMETSAT’s Microwave Humidity Sounder will
replace the Advanced Microwave Sounder Unit
(AMSU-B) on current spacecraft. Imagery will betransmitted in the familiar APT and HRPT modes.
Feng Yun-2C Launch Expected in 2004
China’s third geostationary weather satellite isscheduled to be launched later this year. The
problems experienced by FY-2A and -2B have beenaddressed; in particular, the power supply has been
increased to better manage thermal control during
the eclipse seasons. Like its predecessors it will bestationed above 105°E. WEFAX will be replaced by
LRIT. Some changes have also been made to theinfrared imaging channels to enhance usefulness.
The 10.5 - 12.5 micrometre window has been split
into two to more accurately determine atmosphericwater- vapour content and a 3.7 micrometre channel
has been added to improve surface temperature
measurements. In addition, all IR data will be 10-bit
rather than the 8-bit of earlier spacecraft.

We would like readers to participate with
us by sending us letters and queries
about weather satellite imaging to GEO.
We will of course also respond to these
for the benefit of the readership at large,
and we hope that you will too.
As this is our Launch Issue, Francis Bellhas started the ball rolling with thefollowing submissions to start you
thinking.
______________________________
Dear Editor
I wonder if any of your readers could help
me over a puzzle have experienced overthe last 10 years. Over this period of time
I have been receiving weather satellite
images, mainly direct from Meteosat,
plus the NOAA and Russian polar
orbiters. In addition to this I have also
received the relayed images via
Meteosat of other geostationary
satellites: thus covering most of theworld.
My puzzle relates to hurricanes.
Hurricanes are of course storms notexperienced in this country ( September
1987 in the SE of England was not ahurricane) but they are almost common
in the North Atlantic summer and autumn
when sea temperatures are at theirhighest. What I don’t understand is why
there are no hurricanes in the South
Atlantic. Maybe I have got this completely
wrong and that is why I am asking.
In the Pacific there are typhoons andtropical cyclones which I understand are
the same type of weather system as
hurricanes but just known by anothername. I know these do occur in thesouthern hemisphere. I can recall news
reports of one in Darwin and others
Polynesia with considerable local
damage. But why not in the South
Atlantic? When was the last hurricane tohit Rio de Janeiro or Salvador?
Okay, I know a bit about the oceans Antarctic Bottom Water, Benguelacurrent and the intensification of westernboundary currents. Have you ever tried
swimming in one? They are horrible andcold, at best you need a wet suit. Giveme Hawaii or the Maldives any time!

GEO Quarterly No 1

software in my new and fast computer,curiosity got the better of me when I
configured it to receive Hot Bird's TV
signals. This is one of the biggest : ‘Don’tbothers I have experienced in my life. I
didn't count, but found some 300
channels, 50 of which were TV. The only
channel of any interest was ‘BBC World
Service’ which you can receive on
Terrestrial Digital and Satellite-TV
anyway!
It’s okay if you want Arabic, Italian,
German or other foreign-language TV:
it’s a good service for those users. But
how many radio channels can you listen
to at once?
Here is a very serious conclusion which
may benefit your readers. Do not botherwith the TV transmissions from Hot Bird ifthere is the slightest chance of themcompromising MSG-1 reception. It isn't
worth it!
______________________________
Dear Editor,
I am astonished with the detail revealed
by my new MSG-1 system. As well as theraw images it is also possible to put
detailed political boundary overlays onthese satellite images. I often do this on
the screen for an exact identification ofan area which interests me.
While browsing through some of myimages I noticed coastal outlines forsome Atlantic islands. An atlas revealed
these were the Cape Verde islands..
Lat.15°N Long. 25°W. They caught myeye because of the nearby cloud patterns
which the islands must have been
affecting when the image was taken. I
have seen this before on other satellite
images but for other island groups.
It so happens I have been to the Atlanticislands of Madeira and the Canaryislands. I have also been to The Gambia
which is about the same latitude as theCape Verde islands. However, I know
almost nothing about the Cape Verdeislands.

So why no hurricanes in the South
Atlantic? Or have I got this quite wrong. If
I have please could you send a South
Atlantic hurricane image to the editor
together with some statistics.

Please can any of your readers saywhether they have been to the Cape
Verde islands and what are the island’s
best attributes. The biology, geology,
climate, and political antecedents would I
feel sure be of interest to your readers.
And can I get a package holiday there?

____________________________________________________________

Dear Editor,

Dear Editor,

Would you please allow me to reinforce
the advice offered by David Taylor insetting up his software for the receptionof MSG-1 via the Hot Bird-6 satellite.

Could somebody please advise me about
forward error correction? How can you
correct an error that has not happened
yet? I know MSG-1 uses this system forits data stream, so it must be very clever.
The word ‘forward’ still mystifies me.

I did align my dish with its LNB, andhaving installed the Tellique card andCheck www.geo-web.org.uk for all the latest news

Page 37

GEO Quarterly No 1

Group for Earth Observation

Launch Issue

NOAA 12NOAA 15NOAA 17NOAA 12NOAA 15NOAA 17

Feb 20 04:30 06:10 14:18 15:56
Feb 21 04:06 05:45 15:32 17:12
Feb 22 05:21 07:01 15:08 16:47
Feb 23 04:56 06:36 14:44 16:23
Feb 24 04:32 06:12 14:20 15:58
Feb 25 04:08 05:47 15:34 17:14
Feb 26 05:23 07:03 15:10 16:49
Feb 27 04:58 06:38 14:46 16:24
Feb 28 04:34 06:14 14:22 16:00
Feb 29 04:10 05:49 15:36 17:16

05:55 07:34 17:21 19:02
07:11 08:51 16:58 18:38
06:47 08:27 16:35 18:14
06:24 08:04 16:12 17:50
06:00 07:40 17:27 19:08
07:16 08:57 17:03 18:43
06:53 08:33 16:40 18:19
06:29 08:09 16:17 17:56
06:06 07:46 17:32 19:13
07:22 09:02 17:09 18:49

10:50 12:30 20:38 22:17
10:27 12:07 20:15 21:54
10:05 11:45 21:31 23:13
09:42 11:22 21:09 22:50
10:59 12:39 20:47 22:26
10:36 12:17 20:24 22:03
10:14 11:54 20:02 21:41
09:51 11:31 21:18 22:59
11:08 12:49 20:56 22:36
10:46 12:26 20:33 22:13

Apr 21 04:34 06:14 14:22 16:00
Apr 22 04:10 05:49 15:35 17:16
Apr 23 05:25 07:05 15:11 16:51
Apr 24 05:00 06:40 14:47 16:26
Apr 25 04:36 06:16 14:23 16:02
Apr 26 04:11 05:51 15:37 17:18
Apr 27 05:26 07:07 15:13 16:53
Apr 28 05:02 06:42 14:49 16:28
Apr 29 04:38 06:17 14:25 16:03
Apr 30 04:13 05:53 15:39 17:20

06:54 08:34 16:41 18:20
06:30 08:10 16:18 17:57
06:07 07:46 17:33 19:14
05:43 07:23 17:10 18:50
06:59 08:39 16:46 18:26
06:36 08:16 16:23 18:02
06:12 07:52 17:38 19:20
05:49 07:28 17:15 18:55
07:05 08:45 16:52 18:31
06:41 08:21 16:29 18:07

11:05 12:46 20:52 22:33
10:42 12:23 20:30 22:09
10:20 12:00 20:08 21:47
09:57 11:37 21:24 23:05
11:14 12:55 21:01 22:42
10:52 12:32 20:39 22:19
10:29 12:09 20:17 21:56
10:06 11:46 21:33 23:15
09:44 11:23 21:11 22:51
11:01 12:41 20:48 22:28

Mar 01 05:25 07:05 15:11 16:51
Mar 02 05:00 06:40 14:47 16:26
Mar 03 04:36 06:16 14:24 16:02
Mar 04 04:11 05:51 15:37 17:18
Mar 05 05:27 07:07 15:13 16:53
Mar 06 05:02 06:42 14:49 16:28
Mar 07 04:38 06:18 14:26 16:04
Mar 08 04:13 05:53 15:39 17:20
Mar 09 05:29 07:09 15:15 16:55
Mar 10 05:04 06:44 14:51 16:30
Mar 11 04:40 06:20 14:27 16:06
Mar 12 04:15 05:55 15:41 17:22
Mar 13 05:30 07:11 15:17 16:57
Mar 14 05:06 06:46 14:53 16:32
Mar 15 04:42 06:21 14:29 16:08
Mar 16 04:17 05:57 15:43 17:24
Mar 17 05:32 07:13 15:19 16:59
Mar 18 05:08 06:48 14:55 16:34
Mar 19 04:43 06:23 14:31 16:09
Mar 20 04:19 05:59 15:45 17:26
Mar 21 05:34 07:15 15:21 17:01
Mar 22 05:10 06:50 14:57 16:36
Mar 23 04:45 06:25 14:33 16:11
Mar 24 04:21 06:01 15:47 17:28
Mar 25 05:36 07:16 15:23 17:03
Mar 26 05:12 06:52 14:59 16:38
Mar 27 04:47 06:27 14:35 16:13
Mar 28 04:23 06:03 15:49 17:30
Mar 29 03:59 05:38 15:24 17:05
Mar 30 05:14 06:54 15:00 16:40
Mar 31 04:49 06:29 14:37 16:15

06:58 08:39 16:46 18:25
06:35 08:15 16:23 18:01
06:11 07:51 17:38 19:19
05:48 07:28 17:14 18:55
07:04 08:44 16:51 18:31
06:40 08:20 16:28 18:07
06:17 07:57 17:43 19:25
05:53 07:33 17:20 19:00
07:09 08:50 16:57 18:36
06:46 08:26 16:34 18:12
06:22 08:02 16:11 17:49
05:59 07:39 17:25 19:06
07:15 08:55 17:02 18:42
06:51 08:32 16:39 18:18
06:28 08:08 16:16 17:54
06:04 07:44 17:31 19:12
07:21 09:01 17:07 18:48
06:57 08:37 16:44 18:24
06:33 08:13 16:21 18:00
06:10 07:50 17:36 19:18
05:47 07:26 17:13 18:53
07:02 08:43 16:50 18:29
06:39 08:19 16:27 18:05
06:15 07:55 17:42 19:23
05:52 07:32 17:18 18:59
07:08 08:48 16:55 18:35
06:44 08:25 16:32 18:11
06:21 08:01 16:09 17:47
05:57 07:37 17:24 19:05
07:14 08:54 17:00 18:40
06:50 08:30 16:37 18:16

10:23 12:03 20:11 21:50
10:00 11:40 21:27 23:09
09:38 11:18 21:05 22:45
10:55 12:35 20:42 22:22
10:32 12:12 20:20 21:59
10:10 11:50 19:58 21:36
09:47 11:27 21:14 22:55
11:04 12:44 20:51 22:32
10:41 12:22 20:29 22:08
10:19 11:59 20:07 21:46
09:56 11:36 21:23 23:04
11:13 12:54 21:01 22:41
10:51 12:31 20:38 22:18
10:28 12:08 20:16 21:55
10:05 11:45 21:32 23:14
09:43 11:23 21:10 22:50
11:00 12:40 20:47 22:27
10:37 12:17 20:25 22:04
10:14 11:55 20:03 21:41
09:52 11:32 21:19 23:00
11:09 12:49 20:56 22:37
10:46 12:27 20:34 22:13
10:24 12:04 20:12 21:51
10:01 11:41 21:28 23:09
09:39 11:18 21:05 22:46
10:56 12:36 20:43 22:23
10:33 12:13 20:21 22:00
10:10 11:50 19:59 21:37
09:48 11:27 21:14 22:55
11:05 12:45 20:52 22:32
10:42 12:22 20:30 22:09

May 01 05:28 07:09 15:15 16:55
May 02 05:04 06:44 14:51 16:30
May 03 04:39 06:19 14:27 16:05
May 04 04:15 05:55 15:41 17:22
May 05 05:30 07:10 15:17 16:57
May 06 05:06 06:46 14:53 16:32
May 07 04:41 06:21 14:29 16:07
May 08 04:17 05:56 15:43 17:24
May 09 05:32 07:12 15:18 16:58
May 10 05:07 06:47 14:54 16:33
May 11 04:43 06:23 14:30 16:09
May 12 04:18 05:58 15:44 17:25
May 13 05:34 07:14 15:20 17:00
May 14 05:09 06:49 14:56 16:35
May 15 04:45 06:25 14:32 16:11
May 16 04:20 06:00 15:46 17:27
May 17 05:35 07:16 15:22 17:02
May 18 05:11 06:51 14:58 16:37
May 19 04:46 06:26 14:34 16:12
May 20 04:22 06:02 15:48 17:29
May 21 05:37 07:17 15:24 17:04
May 22 05:13 06:53 15:00 16:39
May 23 04:48 06:28 14:36 16:14
May 24 04:24 06:03 15:50 17:31
May 25 03:59 05:39 15:25 17:06
May 26 05:14 06:55 15:01 16:41
May 27 04:50 06:30 14:37 16:16
May 28 04:25 06:05 15:51 17:33
May 29 04:01 05:41 15:27 17:07
May 30 05:16 06:56 15:03 16:42
May 31 04:52 06:32 14:39 16:18

06:17 07:57 16:06 17:44
05:54 07:34 17:20 19:01
07:10 08:50 16:57 18:37
06:46 08:27 16:34 18:13
06:23 08:03 16:11 17:49
05:59 07:39 17:26 19:07
07:15 08:56 17:02 18:42
06:52 08:32 16:39 18:18
06:28 08:08 16:16 17:55
06:05 07:44 17:31 19:12
07:21 09:01 17:08 18:48
06:57 08:37 16:44 18:24
06:34 08:14 16:21 18:00
06:10 07:50 17:36 19:18
05:47 07:26 17:13 18:53
07:03 08:43 16:50 18:29
06:39 08:19 16:27 18:05
06:15 07:55 17:42 19:23
05:52 07:32 17:18 18:59
07:08 08:48 16:55 18:35
06:44 08:24 16:32 18:11
06:21 08:01 16:09 17:47
05:57 07:37 17:24 19:05
07:13 08:54 17:00 18:40
06:50 08:30 16:37 18:16
06:26 08:06 16:14 17:53
06:03 07:42 17:29 19:10
07:19 08:59 17:06 18:46
06:55 08:35 16:42 18:22
06:31 08:11 16:19 17:58
06:08 07:48 17:34 19:16

10:38 12:18 20:26 22:05
10:15 11:55 20:04 21:42
09:53 11:33 21:20 23:01
11:10 12:50 20:57 22:37
10:47 12:27 20:35 22:14
10:25 12:05 20:13 21:51
10:02 11:42 21:29 23:10
09:39 11:19 21:06 22:47
10:56 12:37 20:44 22:23
10:34 12:14 20:22 22:01
10:11 11:51 20:00 21:38
09:48 11:28 21:15 22:56
11:05 12:46 20:53 22:33
10:43 12:23 20:31 22:10
10:20 12:00 20:08 21:47
09:57 11:37 21:24 23:05
11:15 12:55 21:02 22:42
10:52 12:32 20:39 22:19
10:29 12:09 20:17 21:56
10:06 11:46 21:33 23:15
09:44 11:24 21:11 22:51
11:01 12:41 20:48 22:28
10:38 12:18 20:26 22:05
10:16 11:56 20:04 21:42
09:53 11:33 21:20 23:01
11:10 12:50 20:57 22:37
10:47 12:27 20:35 22:14
10:25 12:05 20:13 21:51
10:02 11:42 21:29 23:10
09:39 11:19 21:06 22:47
10:56 12:37 20:44 22:24

Apr 01 04:25 06:04 15:51 17:32
Apr 02 04:00 05:40 15:26 17:07
Apr 03 05:15 06:56 15:02 16:42
Apr 04 04:51 06:31 14:38 16:17
Apr 05 04:27 06:06 15:52 17:34
Apr 06 04:02 05:42 15:28 17:09
Apr 07 05:17 06:57 15:04 16:44
Apr 08 04:53 06:33 14:40 16:19
Apr 09 04:28 06:08 15:54 17:36
Apr 10 04:04 05:44 15:30 17:10
Apr 11 05:19 06:59 15:06 16:45
Apr 12 04:55 06:35 14:42 16:21
Apr 13 04:30 06:10 14:18 15:56
Apr 14 04:06 05:46 15:32 17:12
Apr 15 05:21 07:01 15:08 16:47
Apr 16 04:56 06:37 14:44 16:23
Apr 17 04:32 06:12 14:20 15:58
Apr 18 04:08 05:47 15:34 17:14
Apr 19 05:23 07:03 15:09 16:49
Apr 20 04:58 06:38 14:45 16:24

06:26 08:06 16:14 17:53
06:03 07:43 17:29 19:10
07:19 08:59 17:06 18:46
06:55 08:36 16:43 18:22
06:32 08:12 16:20 17:58
06:08 07:48 17:35 19:16
05:45 07:25 17:11 18:52
07:01 08:41 16:48 18:28
06:37 08:17 16:25 18:04
06:14 07:54 17:40 19:22
05:50 07:30 17:17 18:57
07:06 08:47 16:53 18:33
06:43 08:23 16:30 18:09
06:19 07:59 16:08 17:46
05:56 07:36 17:22 19:03
07:12 08:52 16:59 18:39
06:48 08:28 16:36 18:15
06:25 08:05 16:13 17:51
06:01 07:41 17:28 19:09
07:17 08:58 17:04 18:44

10:19 11:59 20:08 21:46
09:57 11:37 21:24 23:05
11:14 12:54 21:01 22:41
10:51 12:31 20:39 22:18
10:29 12:09 20:17 21:55
10:06 11:46 21:33 23:14
09:43 11:23 21:10 22:51
11:00 12:41 20:48 22:28
10:38 12:18 20:26 22:05
10:15 11:55 20:04 21:42
09:53 11:32 21:19 23:00
11:10 12:50 20:57 22:37
10:47 12:27 20:35 22:14
10:24 12:04 20:12 21:51
10:02 11:42 21:28 23:10
09:39 11:19 21:06 22:46
10:56 12:36 20:43 22:23
10:33 12:14 20:21 22:00
10:11 11:51 19:59 21:37
09:48 11:28 21:15 22:56

Jun 01 04:27 06:07 15:53 17:35
Jun 02 04:03 05:42 15:29 17:09
Jun 03 05:18 06:58 15:05 16:44
Jun 04 04:53 06:33 14:41 16:19
Jun 05 04:29 06:09 15:55 17:36
Jun 06 04:04 05:44 15:30 17:11
Jun 07 05:19 07:00 15:06 16:46
Jun 08 04:55 06:35 14:42 16:21
Jun 09 04:31 06:10 15:57 17:38
Jun 10 04:06 05:46 15:32 17:13
Jun 11 05:21 07:01 15:08 16:48
Jun 12 04:57 06:37 14:44 16:23
Jun 13 04:32 06:12 14:20 15:58
Jun 14 04:08 05:47 15:34 17:14
Jun 15 05:23 07:03 15:10 16:49
Jun 16 04:58 06:38 14:46 16:25
Jun 17 04:34 06:14 14:22 16:00
Jun 18 04:10 05:49 15:35 17:16
Jun 19 05:25 07:05 15:11 16:51

05:44 07:24 17:11 18:51
07:00 08:41 16:48 18:27
06:37 08:17 16:25 18:03
06:13 07:53 17:40 19:21
05:50 07:29 17:16 18:57
07:06 08:46 16:53 18:33
06:42 08:22 16:30 18:09
06:18 07:58 16:07 17:45
05:55 07:35 17:21 19:02
07:11 08:51 16:58 18:38
06:47 08:28 16:35 18:14
06:24 08:04 16:12 17:50
06:00 07:40 17:27 19:08
07:16 08:57 17:03 18:43
06:53 08:33 16:40 18:19
06:29 08:09 16:17 17:56
06:05 07:45 17:32 19:13
05:42 07:22 17:08 18:49
06:58 08:38 16:45 18:25

10:34 12:14 20:22 22:01
10:11 11:51 20:00 21:38
09:48 11:28 21:15 22:56
11:05 12:46 20:53 22:33
10:43 12:23 20:31 22:10
10:20 12:00 20:08 21:47
09:57 11:37 21:24 23:05
11:14 12:55 21:02 22:42
10:52 12:32 20:39 22:19
10:29 12:09 20:17 21:56
10:06 11:46 21:33 23:15
09:44 11:23 21:11 22:51
11:01 12:41 20:48 22:28
10:38 12:18 20:26 22:05
10:15 11:55 20:04 21:42
09:53 11:33 21:20 23:01
11:10 12:50 20:57 22:37
10:47 12:27 20:35 22:14
10:24 12:04 20:13 21:51

Page 38

Check www.geo-web.org.uk for all the latest news

Launch Issue

Welcome to this first issue of The GEO
Quarterly, the new magazine aimed ateveryone with an interest in Earth
Imaging, Weather Satellites and Weather
Interpretation. Thanks to funding that theGroup has acquired, the first 2000 people
to apply will receive this Launch Issue
absolutely free of charge. We do hopethat you enjoy reading it.
Journey of Discovery
There has probably never been such an
exciting array of satellites orbiting andimaging our planet. The geostationary
Meteosat-8 (formerly MSG-1) is justentering full service, providing highquality images of Earth every fifteen
minutes, while NASA’s Terra and Aqua
satellites have already been providing
amazing high-resolution true-color
images of our planet for someconsiderable time.
Many enthusiasts throughout Europe are
already enjoying near real-time receptionof Meteosat-8 images on their own
home-computer systems and although
Terra and Aqua are as yet out of reach of
the hobbyist, discussions have alreadytaken place on Internet newsgroups
concerning the feasibility of amateur
access to their data streams.
And for the less ambitious, a new APT
satellite, NOAA-N, is due for launch inthe second half of 2004 to join thecurrently active NOAA’s -12, -15 and -17,
providing the complete beginner with theeasiest entry route of all into thisabsorbing hobby.
It is certain that a fascinating journey of
discovery lies ahead as advancing
technology brings these and other yet-tobe launched satellites within the reach ofamateur enthusiasts and educational
users. We hope you will come and share
this journey with us!

Group for Earth Observation

resources to continue distributing all
subsequent issues in this form: as afledgling organisation, funding will
inevitably dictate what we can achieve.
We fully intend to provide another printed
magazine for the November/December
issue (No 4). But a printed medium is themost expensive distribution option, andthe May-June and August- September
issues may well have to be distributed
electronically, on CD-ROM, as Acrobat
PDF documents to reduce overheads.
It is very much up to you, our readers, tohelp us by subscribing to The Group for
Earth Observation. Your contributions will
provide the financial backbone to allow
us to continue serving you.
Magazine Content
We hope that this first issue of The GEO
Quarterly provides a well-balanced andvaried range of interesting articles foryou. We plan to publish spectacularsatellite images, some in full colour; tooutline image processing techniques; toprovide construction projects related tosatellite imaging; to review and detail theuse of developing software packages toacquire satellite transmissions anddescribe how to create create images
from them . . . and much, much more.
We value readers’ opinions in indicating
the paths we should tread. For example,
a veritable armada of imaging spacecraft
has just reached Mars, and the Cassini
mission is due to arrive at Saturn in July.
Would you like to see us devoting someof our coverage to these missions—orshould we stick rigidly to images of ourown planet?
What did you think of this issue? Pleasefeel free to suggest ways in which we
could improve our service to readers bycompleting the response section in theright-hand panel of the membership
application form.

GEO Quarterly No 1

Centre, Leicester last May and we aredelighted to announce that he has
agreed to organise GEO’s first members’
meeting at the same venue on Saturday,
May 1, 2004. As last year, the cost will bea modest £10 for the day, a real bargain,as this includes a ticket to visit the Space
Centre’s Exhibition Halls in addition toadmitting you to our workshops andlectures. Speakers are already being
contacted, and we hope to have aworking MSG-1 reception station in
operation.
Subscribing to GEOThis Launch Issue of the GEO Quarterly
comes to you absolutely free: it is yours
to keep regardless of whether you
choose to join us or not. If you enjoyedthis copy of The GEO Quarterly, and wish
to join the Group, please complete thecoloured Membership Application Form
accompanying this issue. You will thenreceive a further four issues of The GEO
Quarterly during the ensuing 12 months.
Submitting Your Application Form
Please complete your application form
and the readers’ response section thenreturn it, with the appropriate remittance,
to Nigel Evans, at the address indicatedat the foot of the form.
HOW TO PAY
The most convenient way to pay your
GEO subscription is by credit card
(Mastercard, VISA, Switch or Switch
Solo). Additionally, overseas readers may
pay by means of a banker’s draft cheque,drawn on a London (England) bank, with
the London Bank’s address clearly
printed on the cheque. UK Readers may
make payment by personal cheque or
postal order.

The GEO Quarterly Magazine
Symposium
We plan to publish this Group magazine
four times per year. This issue comes as
the familiar glossy A4 colour magazine.
Time will tell whether we will have theMany of you may recall the successful
one-day Symposium organised by
Francis Bell at the National Space
Check www.geo-web.org.uk for all the latest news

All cheques and postal orders must be
made payable to ‘Group for Earth
Observation’.
Page 39

Subscription Rates
United Kingdom - £12

Europe - €22

USA - $32

Rest of World - £19

Please Note
Your subscription is valid for a period of one year from your date of application, and will entitle you to all theprivileges of membership of the Group for Earth Observation, including four issues of The GEO Quarterly.

Please send your completed form to:
Nigel Evans (GEO subs),‘L’Eventail’, 7 Gloster Ropewalk, Aycliffe, Dover CT17 9ES, England, UK.
Please make all cheques and Postal Orders payable to the ‘Group for Earth Observation’.

The Group for Earth Observation Limited is a company in England and Wales, limited by guarantee and having no shares.
The company number is 4975597. The registered office is Coturnix House, Rake Lane, Milford, Godalming GU8 5AB.

GEO Quarterly No 1

Group for Earth Observation

EUMETSAT Operations
News Bulletins
Francis BellThe latest bulletin, ‘Issue 10’, was published in
December 2003. I noticed that my copy of ‘Issue 9’ wasdated exactly a year before. Whether this is an annual
publication or it was just coincidence I don’t know.
What I do know is that it is a very valuable document.
The latest bulletin is 21 A4 pages long and is full oftechnical news, administrative and policy statements.
For those members regularly receiving Meteosat
signals it is almost a must to read. The latest issue isavailable on EUMETSAT’s web site at:http://www.eumetsat.de/en/dps/helpdesk/
documentation/pdf/newsbulletin10.pdf

If you do not have a copy and you are interested in
Meteosat then I recommend that you download thisdocument from EUMETSAT’s web site. On my slow
modem it took about 3 minutes. Then I printed it out.
Most of the contents refer to Meteosat-8, as MSG-1 has
been renamed since becoming fully operational in
January of this year.
For those not able to download the document I willdraw to your attention some very importantparagraphs of news that it contains.
Para. 3.2.1.
This states that, from January 2004, the trial period
will close and routine operations will start. From thisdate direct users will need to conclude a licensing
agreement: or for the 6-hourly data, complete a
Registration Form.
Para 3.2.2
From March 1, 2004, reception will be controlled by the
EUMETCast Key Unit (EKU). This EKU is the USB
decryption hardware used in conjunction with a ‘username’ and ‘user-key’ to restrict data access to anindividual user reception station. The EKUs are only
available from EUMETSAT. A fee of €40 is charged per
EKU. In Europe the licensing authority will be your
National Meteorological Service.
Para 5.4.1
Following the successful introduction of the second
generation Meteosat services on EUMETCast, it has
been decided to continue with this system as thebaseline operational dissemination mechanism forMeteosat-8 and the subsequent MSG satellites. Thisdecision will not only allow for continuity in the data
reception mechanism for Meteosat-8 data users, but it
also increases the full lifetime limit of individual
satellites.
Para 5.4.2
A full complement of Indian Ocean coverage will be
introduced by the end of the first quarter of 2004.
Page 40

Launch Issue

Para 5.5
EUMETSAT will be introducing a payment by credit
card system in early 2004 which will allow users to pay
for hardware and software.
Para 6
Amendment to EUMETSAT data policy. This has
already been covered in this GEO Quarterly on page 9.
Wow! If you have ever read good news this is it.
Amateur users do not have to pay a license fee.
Payments by credit card. Indian Ocean coverage.
And the best news if you didn’t recognise it - reread
Para 5.4.1. The investment GEO members are making
in time, trouble and experimentation in hardware andsoftware for Meteosat reception will be a valuable
investment for at least the next ten years!
Thank you EUMETSAT!

Last December brought unprecedented precipitation to southern
France, vast areas being inundated by over 100 mm of rain
during the 48 hours from 7.00 a.m. on December 1. And on
higher ground in the Ardèche region the figures were even more
severe; 393 mm at La Souche, 380 mm at Loubaresse and 367
mm in Barna—representing more than four times the entire
monthly rainfall in little over two days. In the town of Montpellier,
129 mm fell on December 3 alone.
Rain, coupled with high winds, forced over 9000 people to flee
their homes as the nation’s second largest city, Marseilles, wasdeclared a disaster area: a barge was used to evacuate 1000
people from one of the city’s northern suburbs.
On December 17 an eleven year old Canadian boy had a lucky
escape after a number of fellow school-children rolled a 5 tonne
snowball on top of him. The boy lost consciousness andstopped breathing for a time during the incident at Niagara
Falls, Ontario.
Parts of Australia really sizzled on Christmas day. The
temperature reached a scorching 39°C, some 14 degrees
above the mean December daytime high of 25.6°. By contrast,
Kuri Bay in the north of Western Australia had more than its fairshare of rain as 179 mm fell on Christmas eve, compared witha monthly mean of 150 mm.
Tropical cyclone 03B hit southeast India north of Madras with
70 mph winds on December 16 , leaving thousands homelessand producing at least 45 fatalities. The storm caused
considerable damage to the paddy, sugarcane, tobacco andcotton crops, as well as cutting power supplies and telephonelines.
The town of Agata just north of the Arctic Circle in Krasnoyarsk,
Siberia expects severe winter temperatures, but saw in thisNew Year with a maximum day temperature of only -46.5°C
almost 20° below its mean January average of -27.2 °C.

Check www.geo-web.org.uk for all the latest news

Launch Issue

Group for Earth Observation

GEO Quarterly No 1

Douglas Deans - douglas@dsdeans.freeserve.co.uk
Amateur Earth Imaging relies almost exclusively thesedays on the use of a personal computer to acquire andprocess the data beamed down to us from orbiting
satellites. In this first issue of the GEO Quarterly, I am
presenting a wide range of software, a mixture of
freeware and shareware, that should prove useful toeveryone who enjoys our hobby, from beginners toadvanced users.

GS2

A wide range of software for all aspects of weather
satellite reception including tracking, receiving,monitoring and image manipulation. Content asdetailed below but many other extras are provided.
Titles correspond to folder names. * implies a DOS
program.
Recall (wave file decoder). Palette
Folder D-02
(modifies wxsat colour palettes).
Scanner recorder v 1.8 (wave filerecorder). *NOAA95 / *FENG99
Folder D-03
(Software for the NOAA 95 HRPT
project)
Wxsat v 2.59 (Wave file
Folder D-04
recorder/decoder). Satellite Monitor(Wave file recorder).
Satellite tracking
AGSatTrackv 1.33
programDocuments for Cirkit Wxsat receiver
Cirkitand UOSat receiver. - PDF format.
Provides current weather conditions
e-weathermanfrom the Internet to your computer.
Program to manipulate
Element
v 1.58 NASA 2-line element
Managerdata
Simple satellite tracking
Footprint
v 2.10program
Probably the best
IrfanView
v 3.80 freeware image viewing
software available
APT/FAX/SSTV decoder
JVComm32
v 1.23- evaluation version only
For editing verbose AMSAT format
Mac Kepler
elements. Mac. OS X and OS9
Editoronly.
Image processing
Neopaint
v 4.0
program (30-day
evaluation)
Image processing
Paintshop Pro
v 7.04 program (30-day trial
version)Satellite tracking
Satscape
v 2.00ProgramUtility program for
Splitterv 4.0
splitting and reuniting
large files
WAV file decoding
program - Windows
Wxtoimgv.2.5.5 9.X/ME/2000/XP.
Linux and Mac options
included.

GS3

3 DEM package for 3D terrain visualisation - Includes all
the necessary files to produce excellent images and flybys.
All the Earth GLOBE files are provided along with a large
selection of Mars MOLA files. Many other extras including
sample images and helpful guides.

GS4

Image CD (New) - A wide selection of high-resolution
remote images from a range of satellites, including stunningphotography from the Shuttle missions. A full description
and source is provided for each image.

All the items listed are available on the Internet, butsome are sizeable downloads. To provide these in auser-friendly way, I have collected them on a series ofCDs, which can be ordered from me by return.
CDs GS1,GS2 and GS3 relate to software for decoding
and displaying satellite images, while GS4 is packed
with over 700 Mb of data from a range of satellites,much of it large, high-resolution images that would beconsidered by many to be too large for download.
How to Purchase CDs
Simply write to the address below requesting GS1,
GS2, GS3 or GS4. Prices are £5 for any single CD,
2 for £8, 3 for £11 or all 4 for £14. Please enclose cash
or cheque (made payable to Douglas Deans not GEO)
for the appropriate amount. Nothing else is required.
The cost includes the CD, packaging and posting, asmall donation towards the cost of overheads, the costof overseas orders and the search for new or updated
software. No fee is asked from overseas members
although an exchange of software or interestingsatellite images is always welcome.
Orders are normally dispatched on the day of receipt.
Please apply to the address at the end of this article.

GS1

All David Taylor’s weather satellite programs andlibraries, including the current releases of WXtrack,
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 the programs.
Satellite Tracking
Wxtrackv 3.4.0
ProgramCreates images from
SatSignal
v 4.0.8
wave files
Converts raw HRPT data
HRPT Reader
v 2.5.2
files into images
Manipulates
GeoSatsignal
v 4.0.2 geostationary weather
satellite images
Rescales satellite
GroundMap
v 1.3.6
imagesComputer control
RX2 PassControl v 2.2.8 program for the RX2
weather satellite receiver

Order your CDs from:
Douglas Deans, 17 Montrose Way,
Dunblane, Perthshire FK15 9JL, Scotland.

Check www.geo-web.org.uk for all the latest news

Page 41

GEO Quarterly No 1

Group for Earth Observation

Launch Issue

Les Hamilton
Perhaps you have visited one of the rallies this summer
and seen weather satellite images on display. Maybe afriend with a PC has let you into the secret that you too
can receive such images, in real time, from the skies.
Or you may have discovered the hobby when browsing
the Web. Either way, armed with a personal computer,suitable antenna and dedicated receiver for the
137 MHz band, you could be running your own groundstation in next to no time and for relatively little cost.
The Satellites
There are currently three American satellites
dedicated to the return of so-called Automatic Picture
Transmission (APT) weather images of our planet.
Operated by the National Oceanic and Atmospheric
Administration (NOAA), the NOAA-12, NOAA-15 andNOAA-17 satellites occupy low Earth orbits
840 kilometres in altitude and pass completely roundthe planet once every 104 minutes. As the satellite
orbits are fixed in space with respect to the Sun, therotation of the Earth carries every part of the globe
within the view of any of these satellites at least twice
per day.
Receivers
In order to gain access to the signals from thesesatellites, you require a receiver tuned to the 137 MHz
band. There are several options for European
enthusiasts; the dedicated Proscan II receiver, the RX2(which is only available in kit form) or the Czech
RX137-141 or a scanner. Details can be found at:siren approaches then recedes from you). Receivers
must be able to accommodate this and a bandwidth of
40 kHz is required. Both Proscan and RX2 receivers
were specifically designed to combat this but the
majority of scanners were not.
Consequently, many scanners are totally unsuitablefor weather satellite imagery, and even those that are(e.g. the Icom PCR 1000) produce inferior resultscompared with the Proscan and RX2.
The Antenna
Signals from the NOAA weather satellites aretransmitted with right-hand circular polarisation, andyou therefore require an antenna specificallyconstructed to receive this type of signal. Use of amakeshift antenna will certainly allow you to hear theaudio signal through your receiver, but it will not be
possible to decode it into a satisfactory image.
Most APT enthusiasts utilise one of two basic designsof dedicated antenna, the crossed dipole (turnstile) or
quadrifilar helix (QFH). Turnstile antennas can bebought for around £30. Commercial QFH antennas arenotoriously expensive, but many enthusiasts build
their own from PVC conduit tubing, junction boxes andhttp://www.geo-web.org.uk/hard.html

Fig.3 - A turnstile antenna

Fig.1 - A cased RX2

Fig.4 - A QFH antenna

co-axial cable. Chris van Lint’s popular QFH project,originally published some years ago is reproduced on
page 46, and takes just an afternoon to construct.

Fig.2 - The Proscan II

The fact that these satellites approach the observer,
pass high overhead then recede towards the opposite
horizon superimposes a significant and constantly
varying Doppler effect on to their transmitted
frequencies (the same as you hear when a police-car
Page 42

The antenna should be mounted with clear horizons allaround. The best situation as at the top of your TV
mast (above the TV antenna), but loft-mounted
antennas can give excellent results as can an antenna
mounted on a stake in the garden, just a metre or so off
the ground. So long as there are no obstructions
between the antenna and the satellite, nor large
nearby metallic objects to cause signal reflections, goodresults can usually be obtained.

Check www.geo-web.org.uk for all the latest news

Launch Issue

Group for Earth Observation

GEO Quarterly No 1

The Display Unit
These days, weather satellite images are almost
always displayed on the screen of a personal computer.
But before you can view the weather pictures, youmust first convert the received radio signals into
images, and for this an interface is required. There are
two options: either a purpose-built decoder in the formof a PC card or external unit, or the PC’s existingsoundcard. The simpler option (and also the cheaper) is
the latter, and this is the route described in this article.
Your receiver will possess an audio output and signals
from this must be fed into the PC soundcard, generally
via the line-in socket, though the microphone input isanother possibility—which one you use depends on thesignal level output by the receiver itself. Check whichworks best for your set-up.
Connecting It All Together
Once your antenna is safely mounted where you intend
to deploy it, use good quality screened co-axial
downlead (RG 59 is ideal) to connect it with yourFig.5 - How the units connect

receiver. The receiver in turn must be connected toyour PC soundcard by a length of screened audio lead.
Suitable short audio leads with a jack-plug at each end
are readily available at rallies and computer fairs.
Preparing the PC Soundcard for Recording
First-timers frequently stumble at the very firsthurdle. Although everything appears to have been set
up correctly, no audio signal is heard from the PC
speakers and frustratingly, no images are produced.
This outcome is almost always the result of anincorrectly configured soundcard.
By default, computer sound-cards are configured forplaying back audio through the PC speakers. Often the
card’s recording mode will not have been initialised. Do
this by means of the program Sndvol32.exe which you
can find in your Windows folder. If in doubt as to whereto find this, click on your PC’s START button andselect ‘Find’. Type sndvol32 in the 'Named:' field, 'Lookin:' should be drive C:, then click the 'Find Now' button.
When the filename Sndvol32.exe appears in thebrowser window, double-click on it to open it. Sndvol32
first appears with the words 'Volume Control' in its
title-bar. Click the <Options> menu, followed by<Properties> to reveal the properties screen. Click theFig.6 - The soundcard recording control with theline-in input muted (left) and active (right).

‘Recording’ radio-button, make sure that the ‘line-in’option is ticked in the ‘Show the following volume
controls:' browser, then click OK to reveal the
Recording Control panel (figure 6).
The usual input channel for recording from a wxsat
receiver is line-in, so this must be activated by firstly
checking the 'Select' box in the 'Line balance:' panel,and then elevating the volume control slider to midscale (this will require more careful adjustment later).
However, depending on the input levels of yoursoundcard, you may prefer to make use of the
microphone input channel instead.
Software
The simplest package, but the most popular among
beginners, is Wxsat authored by Christian Bock ‘wayback in 1995. The program’s appeal lies in its ability to
decode the satellite transmissions into images in realtime, while simultaneously recording them on to yourhard-drive in the form of WAV files. Although thegeneration of images requires a degree ofexperimentation and effort by the user, recording WAV
files is relatively straightforward.
Open Wxsat’s <Recording> menu and select the third
item from the foot, labelled ‘Test’. This reveals awindow flanked by a grey line at both top and bottom.
These two lines represent the maximum permitted
amplitude for an incoming satellite signal. Exceed
these levels and the signal will be ‘clipped’, masking
out much of the bright cloud detail as full white. Thislevel must be adjusted during reception of a live

Fig.7 - Wxsat’s recording-level test screen

Check www.geo-web.org.uk for all the latest news

Page 43

GEO Quarterly No 1

Group for Earth Observation

Launch Issue

satellite signal, something which may be accomplishedby adjusting the Sndvol32.exe volume slider position,or by placing a variable potentiometer (volume control)
into the audio line feeding the soundcard. The
maximum amplitudes in the signal from the receivermust not be allowed to break either grey line.
Figure 7 shows part of a NOAA wave sample with apeak-to-peak value of ± 0.7, which is more thanadequate for the production of good images. Figure 8
was produced from the same NOAA-17 signal as thetest screen above. Notice how the image displays a fullrange of tones from brightest white through full blackand that both land and cloud show excellent tonalvariation. Figure 9 shows the same transmission, but
most of the cloud structure in the visible (left) frame
has been lost because of ‘clipping’. For the same reason,
the infrared image (right) is almost devoid of detail.
Although this is an extreme example, for the purposeof illustration, readers do frequently submit images
with very washed-out clouds like those in figure 9.
The main reason for this would seem to be an attempt
to enhance land detail, which is often quite dark, byincreasing the input level. This practice is notrecommended, as it destroys most the cloud detail.
Instead, the balance between light and dark tones
should be adjusted after the image has been created,using the ‘gamma’ feature of an image editing program
such as Paintshop Pro.
The Usefulness of WAV Files
To actually record a WAV file while a screen image
builds up you must select the appropriate decoding
mode. Click the <Parameters> menu to reveal thedefault list of decoding options. Start by selecting the
topmost item from the list; this will produce twin
NOAA images as shown in figure 8, with a visible lightimage on the left and an infrared image to its right.
Other options on the list permit decoding of individual
visible or infrared images, as well as allowing the user
to combine them as a false-colour image.
To

initiatearecordingsession,Fig.9 - NOAA 17 - 11:12 UT on July 13, 2003
This is the same image as shown above. This time the input
level was far too high and clipping has occurred, destroying
tonal detail in the clouds, and washing out the IR frame.

select<Start at Subcarrier> from the <Recording> menu, followed
by <Save Bitmap and Wave> to prime Wxsat to record a

WAV file as it displays the image each time it detectsa NOAA weather satellite APT signal.

The great advantage of saving WAV files as well as theactual bitmap images is that the WAV file may berepeatedly decoded through Wxsat (or another program
such as Satsignal or Wxtoimg). This allows parameters
to be adjusted until you judge that the final image isthe best that can be achieved.
Help With Wxsat
The Wxsat program comes complete with an extensive‘Help’ file extending to more than 350 kb in size. This
contains dozens of pages of information, many withsupporting diagrams and screenshots to help you
Page 44

Fig.8 - NOAA 17 - 11:12 UT on July 13, 2003

Fig 10 - A WXSAT help screen dealing with histograms

customise the program to meet your requirements.
Wxsat may be downloaded from the HF-FAX siteat:
http://www.hffax.de/WX_Satellite/WXSat/inst259e.exe

The splendid NOAA-17 APT image on the facing
page was acquired by Hartmut Schaksmeier ofRemscheid, Germany at 11:33 UT on November 13,
2003 and depicts the first serious winter storm to hit
Great Britain. Northern Ireland and western Scotland
faced the brunt of its power with winds of 120 kph.
The image was processed with the software package
WXtoImg, which will be described in a future issue.

Check www.geo-web.org.uk for all the latest news

Launch Issue

Group for Earth Observation

Check www.geo-web.org.uk for all the latest news

GEO Quarterly No 1

Page 45

GEO Quarterly No 1

Group for Earth Observation

Launch Issue

Chris van Lint
BackgroundIn the past, many articles have appeared in a numberof publications singing the praises of Quadrafilar Helix(QFH) antennas. Those of us who have had an
opportunity to try such an antenna will agree that thisdevice appears to be optimum for APT, since it is truly
circularly polarised, with more gain as compared to theclassical turnstile or lindenblad types. Often thesearticles are accompanied by construction details toallow the home constructor to build a suitable device
themselves. The majority of these articles, however,
employ an infinite balun matching-scheme, which is
not exactly constructor-friendly to the average home
experimenter.

Description
I claim no originality for the antenna I am about todescribe. As mentioned before, there are numerous
descriptions in circulation at the moment. A
fundamental deviation from classical QFH antennas is
the fact that in this design the filars are not supported
directly by the mast but by PVC arms. This relatively
simple but nevertheless brilliant idea came from
Eugene Buck W3KH, who also provided thedimensions. My contribution lies in the idea of using
removable arms and conventional flexible co-axial
cable for the filars and matching line alike, whichallows the filars to be folded against the support mastwhen not in use.

These antennas rely on using copper tubing filars
together with a hard-line co-ax filar to form the balun.
In some locations hard-line co-ax is difficult to obtainand expensive. QFH antennas using this construction
method require that the filars be insulated from the
support and often PVC piping is used for this purpose.
Since the filars have to be shaped into the desired
helical form, they have to be self-supporting and somemeans of anchoring them to the support mast has to bedevised. This is not an easy feat, in addition to which
the shaping of -inch tubing is not as simple as it
seems. The interconnection of the filars has to be done
carefully or the antenna will not work. Construction
details which I have seen so far are rather confusing
and they have put me off building a QFH of the infinite
matching balun type.

This antenna is a -turn, half wavelength device using
a self-phasing big/small loop configuration. Impedance
matching is achieved by an infinite balun arrangementin which one of the four elements is a length of co-ax toproduce a characteristic impedance of approximately
40 Ω. The antenna is constructed from standard 20 mm
PVC electrical conduit tubing for the support arms anda length of 32 mm PVC tube for the support mast. To
accommodate the support arms I used six PVC 2-way
junction boxes. The relevant dimensions can be notedfrom figure 1. The dimensions for individual arms arealways half the total width when measured from thecentre of the support mast. QFH antennas of this typeuse a big and a small loop and this is the reason why,instead of 4-way, two 2-way junction boxes were used,mounted at 90° one above the other. This procedure
creates a (B)ig and (S)mall loop.

Ever since arriving in Hong Kong I have been plaguedby pager interference. Hong Kong uses the 137138 MHz frequency bands for paging applications aswell as various others. In fact there is a pager
transmission on 137.95 MHz. This has made receptionof certain APT frequencies a misery and I can not get
acceptable results on the 137.50 MHz and 137.85 MHz
transmissions. After having tried numerous ideas toovercome the problem, including narrow band-passfiltering, I have decided that the only practical solution
is to change location. This is of course easier said thandone. It is not practical to relocate from my present
abode for a number a reasons, not least of which is thefact that another residential area will not necessarily
offer relief from the interference. The only areas where
one could expect to get interference-free reception
would be the more remote and less populated areas on
the south eastern part of Hong Kong Island and thiswould require some form of mobile set-up. Having
convinced myself that the best possible APT antenna
must be the QFH, I set my sights on constructing a
portable version.
Page 46

Each loop splits into two filars, which are supported byremovable PVC arms B1, B2, S1 and S2. Figure 2
shows the connection of the filars in relation to eachother. Note that the smaller loop is not connected at thebottom and for this reason filars S1 and S2 may be left
joined so that a single length of co-axial cable 221.6 mm
in length is used. The diagram shows connection
details as viewed from the top of the mast, connections
at the bottom and the joining of the feed cable.
Only one filar (one half of the big loop) is used as aco-axial conductor and those filars which do not require
use as a co-axial cable have the centre conductors
soldered to the braid at both ends. I used RG-6U
co-axial cable, not because of its low loss, which is notparticularly relevant at these frequencies, but because
it has a continuous aluminium shield in addition to thebraid: this gives the cable extra rigidity which is usefulfor shaping the filars once the arms are fitted. Since
the APT satellites in which we are interested transmit
their signals using right-hand circular polarisation

Check www.geo-web.org.uk for all the latest news

Launch Issue

Group for Earth Observation(RHCP), the filars must be wound in an anti-clockwise
direction when viewing the antenna from the top down
its vertical axis.
Construction
Start by cutting a suitable length of support mast. In
my case I cut the mast just long enough to allow asocket to be fitted inside the lowest 2-way junction box.
This allows the mast to be extended by inserting
another length of 32 mm pipe. Cut holes in theundersides of the junction boxes. The two junction
boxes are cemented together at a 90° offset angle toform a cross and a total of three sets of such assemblies
are required.

GEO Quarterly No 1

Each junction box assembly will have one pair of shortand one pair of long support arms. Drill holes big
enough to accommodate the co-axial cable on top of,and as close as possible to, the topmost arms. For thebottom set of arms do the same, but below the arms.
Once completed, insert and twist the arms so that theslot slopes from top left down 45° to bottom right. The
arms may now be removed and put aside. It may be
helpful to put marks on the sockets and arms toindicate in which position the 45° angle is achieved. If
the marks on both the sockets and arms are in exactly
the same position there should be no need to put
identifying marks on individual arms and sockets; i.e.
the position marks should be sufficient.
Insert the co-axial cable which forms the smaller loop
into the hole below one of the short arms all the way sothat the cable exits on the opposite side. Ensure thatthe length of cable at both sides is the same. Join thecentre conductors to the braid. Cut two equal lengths ofco-ax which will form the big loop. On one piece only,
join the inner conductor to the braid and insert one end
in the hole above one of the longer arms. Do the samewith the second half-length of co-axial cable, but in the
opposite hole. Solder the four cables in the top junction
box according to the instructions in figure 2. Insert the
opposite ends of the co-axial cables in the holes
situated-turn anti-clockwise on the bottom
assembly.

Figure 3
The completed QFH antenna.

Slide the centre assembly on to the mast, followed by
the top and bottom ones. For the centre assembly, a
suitable hole may be cut in one of the junction box lids
which is than slid over the mast to cover the centre
assembly. Note that no dimensions are given for
positioning the centre assembly, as this is not criticaland should simply be near the centre. Cement theassemblies into place, initially with solvent-based PVC
cement. I find that this adhesive, once a little dry,allows some level of adjustment before it setscompletely. Once you are satisfied that the assemblies
are correctly aligned and the adhesive is dry, apply
generous amounts of an epoxy-based adhesive tocomplete the mast assembly.
Now cut the support arms. The actual length will
depend on the physical dimensions of the junction
boxes used. Make sure that you adjust the final length
on the basis of the arms having been tightly fitted into
the junction box sockets. Remember that the loop
dimensions shown in figure 1 constitute the total widthof each of the two loops, and the width of thecorresponding arms should therefore be half this, andmeasured from the centre of the mast. Allow a little
extra length to accommodate two slots in the support
arms into which the co-axial cable filars can be snuglypressed.

Drill a suitable hole somewhere in the lowest junction
box to accommodate one end of the co-axial feed line,
which should be fitted with a connector of your choiceat the other end. Push this feed-line through and join
all cables as shown in Figure 2.
Cement the top junction box cover and the cover for thebottom junction box assembly into place. Now insert
the arms in their correct positions and adjust the slot
angles. Simply press the co-axial filars into theappropriate slots, moving anti-clockwise from the top,
completing a half turn by the time you get to thebottom.
After a little manual shaping of the filars to form thehelical shapes, the antenna is finished. If the antenna
is to be used as a permanent fixture rather than amobile device, you can drill a small hole through thearms, behind the slots at 90° to accommodate a nylon
tie to secure the filars into the slots.
Performance
I have compared the performance of my prototype
against my other QFH antennas, including acommercial version under dynamic conditions, using a
co-axial relay to switch from one antenna to the other.
I am convinced that the performance of the portable
QFH is a good as my other QFH antennas. There areno noticeable nulls and I get usable signals from AOS
to LOS (on 137.62 MHz, the only frequency I canreceive without interference!).

Check www.geo-web.org.uk for all the latest news

Page 47

GEO Quarterly No 1

Group for Earth Observation

Launch Issue

Figures 1 and 2 - Plan of the QFH antenna, showing dimensions.

If you are plagued by interference from a single source,
you may find the QFH more suitable than other typesof antenna. The QFH produces a higher magnitude ofgain on circularly polarised signals as compared tolinearly polarised signals. This in effect attenuates
linearly radiated signals in relation to the circular ones
and reduces interference.

And Finally . . .
Francis BellDuring field testing I noticed that the QFH appears tohave distinct directivity in relation to linearlypolarised signals. In my case there is a pager
transmitter, which makes reception of signals on
137.5 MHz almost impossible. This interference is notintermodulation and it is there when no signal is being
received from the satellite.
I found that by turning the antenna when not receivinga satellite signal, it was possible to find a very distinct
reduction or sometimes a null in the strength of theinterfering signal. This has enabled me, for the firsttime, to decode NOAA 12 signals on 137.50 MHz. A
similar improvement could be obtained when dealing
with other forms of linearly polarised interference.

Page 48

Well, if you lived in Hawaii and were interested insatellite reception, what would you put in your backgarden?
I’ll bet all Pacific Rim communications come throughthis station

Check www.geo-web.org.uk for all the latest news

Photo: Francis Bell

Cedric Roberts produced this colour composite image of
the Earth from MSG-1 on June 2, 2003
Image © Eumetsat 2003

This is a zoomed section of the full Earth image at the left,
rectified and with country outlines added after processing withDavid Taylor’s MSG Data Manager and GeoSatsignal programs.
Image © Eumetsat 2003

Patrick Prokop produced this spectacular channel-1, -2, -4 colour composite NOAA 12 image of Hurricane Isabel at 5:17 pm EDT
on September 17, 2003. There are over 20 more colour images of Isabel from various NOAA satellites on Patrick’s website at:
http://www.wtoctv.com/Global/link.asp?L=98798&nav=0qq7HyjV