Group for Earth Observation

The Independent Amateur Quarterly Publication for

Number 14

Earth Observation and Weather Satellite Enthusiasts

June 2007

Inside this issue . . .
TQchanSel: software fromRob Alblas to give instantcontrol of your EUMETCast
downloads—completely ‘onthe fly’.
Are you having problems
receiving EUMETCast
using a RAMdisk? Mike
Stevens explains hisalternative method fortrouble-free DVB reception
Are you experiencing too
much clutter with multiplePCs, monitors, mice andkeyboards? Guiseppe Cicodescribes how he operates
several PCs with a single
monitor and keyboard
Reviewed: The R2ZX, thenew, pager resistant APT
weather satellite receiver—available exclusively from
GEO
Peter Wakelin describes thehighly eccentric Molniya
satellite orbit
Alan Banks writes about
this year’s intense Tropical
Cyclone season in the
Indian Ocean
Read David Taylor’s
illustrated description of a
recent visit to the new Met
Office Headquarters in
ExeterPlus many more features ...

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

MANAGEMENT TEAM

A

glance at the panel opposite will reveal a new email address forcontacting the editor—geoeditor@geo-web.org.uk. Recent
increases in Internet spam have meant that scarcely one email per
thousand addressed to the editor has been genuine. It is probable thatthe problem has arisen because Management Team email addresses
had been listed, with direct links, on the GEO website. These have now
been replaced by web forms which conceal the actual addresses fromhackers but still allow members to contact GEO Team members.
lease note that the old email address for the editor will remain valid
only until the end of June. Please update your records now.
ob Alblas, a leading member of Werkgroep Kunstmanen, hasproduced TQchanSel, an ingenious computer program that should
appeal to anyone using EUMETCast. TQchanSel allows you todetermine which type of data (MSG, AVHRR, Metop, ATOVS etc.) is tobe downloaded from the DVB stream and stored on your PC forprocessing. If, on a given day, you only wish to receive Meteosat, one
mouse-click is all that is required to set this up: if you decide to add
Metop—again, a single mouse-click instantly adds that service. You
can discover all about TQchanSel in Rob’s article on page 34.
PT enthusiasts will be pleased to learn that the R2ZX, an upgradedversion of the popular German weather satellite receiver, which
now resists pager interference on the 137.91 MHz NOAA-18 frequency,
has been developed exclusively for GEO’s UK market. You can readabout the new receiver in articles on pages 24 and 28.
inally, it’s nice to conclude with a little unashamed trumpetblowing. GEO Quarterly is highly thought of in the highest echelonsof the satellite industry and recently brought warm words ofcommendation from Claudia Ritsert-Clark, Head of Communication
and Information Services at EUMETSAT. You can read her commentson the ‘Letters’ page.

P
R

A
F

Contents
GEO Report
Currents in the Strait of Messina
Cover and Full-Page Image Details
Toba - Footprint of a great eruption
Cloud Streets
Receive EUMETCast without a RAMdisk
A Morning at the Met Office
Tropical Cyclones in the Southern Indian Ocean
Radar Satellites - part 3: Imaging Programmes

Francis Bell
NASA Earth Observatory
NASA Earth Observatory
Les Hamilton
Mike Stevens
David Taylor
Alan BanksPeter Wakelin

2
4
4
4
7
11
15
17
20

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

i
ii
iii
iii
iv

Earth Imaging News
Peter Wakelin
GEO Shop Update
Clive Finnis
Earth Observing from a Highly Eccentric Orbit
Peter Wakelin
A Simplified Tall, Narrow QFH AntennaAnders Höök
R2ZX - The New Pager-resistant APT Receiver
Les Hamilton
Powerless Revisited
Geoff Darby
The Lunar Eclipse - March 2007
Lawrence Harris
A Novel Approach to Erecting New Antennas
Fred van den Bosch
TQchanSel - Control EUMETCast Channels
Rob Alblas
Controlling Multiple PCs from a single Keyboard and Monitor Guiseppe Cico
Software Showcase
Douglas Deans
In Tray
Readers’ Letters
Intriguing Cloud Phenomenon off Cape Farewell
Keith Fraser

23
24
25
26
28
31
33
33
34
36
41
43
44

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

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

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

Membership and Subscriptions
David Anderson,
35 Sycamore Road,
East Leake,
Loughborough LE12 6PP
England, UK.
email: members@geo-web.org.uk
Tel:01509 820 067
Fax:
01509 559 015

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

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

Webmaster and Website Matters
Ray Godden
e-mail: raychieko@tiscali.co.uk

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

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

International LiaisonPeter Green‘Hollowtree’
Eggesford
Devon EX18 7QX
Tel:
01769 580 700
email: international@geo-web.org.uk
Nigel Evansemail: nigel@geo-web.org.uk

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

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

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

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

GEO Quarterly No 14Group for Earth Observation

June 2007

Francis Bell
Established GEO members will have noticed that we now have anaddition to our Management Team, David Anderson, who is now
actively fulfilling the role of Membership Secretary for us. David is
experienced in weather satellite reception, is an establishedmember of GEO and is very competent with software, data bases
and record-keeping. On the subject of our Management Team, andon behalf of all the membership, a formal thanks to them forrunning GEO, not forgetting their wives, who are also supportive of
GEO. These are all honorary roles: that is, nobody gets paid andthere is no routine coverage of expenses.
Satellites and Earthquake Prediction
GEO activities and travel have kept me particularly busy recently.
There was one evening in London at the London Centre for Social
Studies where I gave a straightforward talk about the noncommercial reception of weather satellite images. There was aconnection for the use of these images in predicting earthquakes
but I did not become involved in that issue as any associatedbackground science here is unknown to me. I just kept to thepractical issues of image reception. I was interviewed by Turkish
TV so next time I’m in Istanbul I may be famous.
Equally as serious as Istanbul, with its earthquake threat, I havejust returned from California USA where my hotel was locatedclose to the San Andreas fault. I did look superficially at the local
geology from my amateur perspective and collected a few rocksamples. Parts of this area are a bit scary. Weather satellite
imaging for earthquake prediction would be a valuable tool for any
part of the world, if it was backed by scientific understanding.
GEO at Rallies
GEO had a stand at the South London Amateur Radio andComputer Rally at Kempton recently. This was well attended by thegeneral public and we had many visitors to our stand. There is areport about this rally in the May edition of the RSGB’s RadCom.
From GEO’s perspective it was judged to be a worthwhile day. We
did get new members joining GEO and some renewals.
A new venue for us was the well-attended Mid-Cheshire ARC Rally
at Nantwich where I gave a talk in the speaker programme and we
had a well presented exhibition stand. Another new event for us
was the British Rocket Oral History Programme (BROHP) three
day conference held in Godalming, Surrey. GEO had a display inthe exhibition area and ran live EUMETCast reception on all threedays.
At this conference, as well as the programme of speakers, there
were a number of exhibition stands in the main hall. I collected
literature from some of the stands and bought a meteorite fromanother. More about this meteorite in our next Quarterly perhaps.
It was the literature from the British National Space Centre ( BNSC)
in the exhibition area which particularly caught my eye. I collected
some papers and read them at home on the first evening. In
conversation next day I commented to a BNSC representative
about the breadth of their influence in the UK space effort. Their
reply was: ‘Yes, not many people understand the BNSC’. One of
their publications, which I found particularly interesting, informative
and well illustrated is titled ‘UK Space Activities 2006’. It’s easy toread in about 45 minutes. If you want to know where the UK’s
public annual budget of £207 million is spent (of which £82 million
goes to Earth observation) then this is a must-read booklet.

2

GEO’s diaplay at the BROHP Conference

I have spoken to BNSC’s London office and they will send copies
to individuals on request. If you do this, also ask for their 18 month
calendar, which is informative and well illustrated. In order to obtaincopies you should make contact• by email - bnscinfo@bnsc.gsi.gov.uk• by telephone to their publications bureau on 0845 0150010• by letter to DTI Publications Orderline, Admail 528, London
SW1W 8YT.
Quote the references URN 06/88 for the ‘UK Space Activities 2006’
and URN 06/ST28 for their calendar. There will be no charge forthese publications. Our European members may also wish toobtain this literature. Although the financial report relates to the UK,
many of the activities and reports transcend political boundaries.
Give your full postal address with any request.
Power Supplies and Standby
I was very interested to read Geoff Darby’s follow-up article to mycomments in GEO Q13 relating to power supplies and theprudence or otherwise of leaving equipment on standby (page 31).
The irony here is that shortly after reading the draft of his article,
one of my computer monitors which I had turned off overnight (andwhich is not left of standby) died the following morning the instant I
turned it back on!
Membership Renewals
Here is the usual reminder about checking your membershiprenewal. We do not wish to lose membership by the default offorgetting to renew. Of course some current members will notrenew for valid reasons but don’t just let it be by omission. GEO’s
financial viability is guaranteed by the company structure but our
financial margins are small and we need to maintain a robust
membership to sustain our activities. On a formal note I regularly
report to Companies House and send them our accounts which area matter of public record. I also take copies of these papers to our
Leicester symposium.
GEO Shop
Our GEO ‘Shop’ is a double edged asset. It provides an
outstanding service to our membership with a ‘one stop’ access towww.geo-web.org.uk

June 2007

Group for Earth Observation

GEO Quarterly No 14

the equipment needed for our activities. It
also makes a small profit for us. If you
need any new hardware, do please buy itfrom our shop, everybody comes out awinner that way.
Several new items have been added to ourstock recently. Keep up to date with thelatest developments by directing your Web
browser towards

http://www.geoweb.org.uk/shop.html
And remember, you can order items fromthe GEO Shop using the Internet, either bycredit card or PayPal.
Atlantic Cruise
Readers may recall my report relating toNadine and myself on a transatlantic cruise(reported in GEO Q12) and our encounter
with hurricane Florence and severe Atlantic
storms. There has now been a legal
development. The lawyers have taken tocourt over the questionable decisionmaking process which endangered all the
lives aboard the ship. Would you believe it!
The travel company blamed the shipowners and the ship owner blamed thetravel company. Well life’s like that!
The ship we were on has now beenrenamed ‘Athena’. I have just learned that,
under its previous name of ‘Stockholm’,
this ship was responsible for sinking the
Italian transatlantic liner ‘Andrea Doria’
close to Nantucket Island in 1958. I don’t
think I will sail aboard this ship again.

The busy GEO Stand during the South London Amateur Radio and Computer Rally, Kempton

The Quarterly Question
Thanks to those who submitted answers to
the last Quarterly question which related tothe calculated distance travelled by
Metop-A in one year. I picked Frank
Skillington as the winner. He submitted thecorrect answer 235 million km. The
calculation goes as follows

At an altitude of say 800 km, where someof our weather satellites orbit, theEarth’s gravitational field is only a little
less than on the surface of the planet.
Satellites orbit because their forward
motion together their falling matches therate at which the Earth’s curved surface
falls away from them.

• take the mean radius of the Earth• add the altitude of the satellite• multiply by 2 x pi to give the distancetravelled in one orbit• next divide the orbital time of 101 minutes
into the number of minutes in a year
• multiply the two products together to givethe answer.

The Question
If a satellite at an altitude of 800 km
suddenly ceased all forward motion, howlong would it take to fall to the ground?
Assume that the acceleration due togravity gravity is constant at 10 ms-2
(metres per second per second)throughout the fall and discount theeffect of atmospheric drag (plus the factthat the satellite would probably burnup). To calculate the answer, whichsurprised me when I worked it out, youwill need the following standard equationof motion:

Now for a new Quarterly Question.
Sometimes, when talking to people, amisconception becomes apparent. Many
people think that objects in space justfloat around because there is no gravity
out there.
This concept is quite wrong!

Send your answers, to the nearest fullminute, to Francis Bell:• by email to francis@geo-web.org.uk• or by post to the address on page 1.
The prize will be a book on the Earth’s
weather written by Storm Dunlop,
generously donated by Oxford University
Press.
The winner will be chosen at random one
week before the copy deadline for GEO
Q15 (Saturday, July 28, 2007).

This post should appeal to a member who
is proficient in document and image
processing on a personal computer andwho would like to be involved in GEO.
Interested parties please contactwheres = the distance fallena = the acceleration due to gravityt = time taken to fall from orbit
www.geo-web.org.uk

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

3

GEO Quarterly No 14Group for Earth Observation

June 2007

Cover and Full-Page Images
Front CoverSnow-covered Iceland, visualised from the 12:15
UT NOAA-17 pass on February 26, 2007, anddownloaded from the EARS-AVHRR stream on
EUMETCast by David Taylor.
Image © EUMETSAT 2007

NASA Earth Observatory(Image on page 38)
Between the island of Sicily andmainland Italy lies the Strait ofMessina, that narrow strip of waterthat connects the Tyrrhenian Sea
in the west with the Ionian Sea tothe east. At its narrowest point this
32-km long channel measures justthree kilometers across.
The Strait widens toward the south
but remains relatively shallow witha maximum depth of only about 90
meters. As the tides ebb and flow,
strong currents flow through theStrait, often ripping seaweed fromthe sea floor, while converging
currents form a natural whirlpool
which may well be the origin of thelegend of Scylla and Charybdis,
the two sea monsters thatthreatened Odysseus and the
Argonauts on their journey insearch of the Golden Fleece.
For such a narrow, shallow bodyof water, the Strait of Messina haslong posed problems for sailors.
The main current runs from south
to north but a smaller current runsin the opposite direction. These
currents alternate every six hours
or so, producing complicated wave
patters that can be seen fromspace.
ASTER, the Advanced
Spaceborne Thermal Emission
and Reflection Radiometer aboard
NASA’s Terra satellite took theimage reproduced on page 38,
showing the Strait of Messina, on
August 11, 2003.
At the time of acquisition, the sun
was at just the right angle toilluminate these waves, whichappear as a series of concentricrings heading southward. At rightangles to them are shallower
waves that give the water a roughappearance.
The dark region at the lower lefthand corner of the image (withwhite puffy clouds hovering aboveit) is Mount Etna.
NASA image created by Jesse Allen, using
data provided courtesy of theNASA/GSFC/MITI/ERSDAC/JAROS, andU.S./Japan ASTER Science Team

4

Inside Front Cover
Maurice Elwell obtained this striking NOAA-17
image of an Atlantic depression hitting the British
Isles on March 4, 2007. In an email to the GEO
Shop Maurice stated: ‘I’m sending you this image
taken today to show how pleased I am with my
new R2ZX receiver’. The image was processedusing WXtoImg, taking advantage of its colourful‘precipitation enhancement’ option. The pass wasreceived using a Paul Hayes copper QFH antenna
on an outside pole 6 metres above ground and a
new R2ZX pager-resistant APT receiver.
Inside Back CoverNOAA 14 is still producing some superb results, as
can be seen in this 09:39 UT pass over frozen
Scandinavia on February 19 this year. The Gulf ofBothnia is completely frozen over as is the pincershaped Lake Onega. But large stretches of open
water persist in the Gulf of Finland and on Lake
Ladoga, Europe’s largest lake.
Image: Lawrence Harris

Below is a February 15 MODIS image from NASA’s
Terra satellite showing the distant Kerguelen
Archipelago in the southern Indian Ocean. The
small population comprises some 50 to 100
scientists (Earth sciences and biology). Since 1992,
CNES (the French government space agency) has
maintained a satellite tracking station there.
Image: MODIS Rapid Response Team

Back CoverNOAA-17 imaged Cyclone George passing over the
Pilbara and the Kimberleys in Western Australia
at 01:17 UT on March 10 with winds in excess of
270 kph. Roofs were ripped off, trees uprooted
while power and phone lines were cut. The storm
caused two fatalities, with some 20 injured.
Image: Ken Morgan

Page 6
Great Britain is almost cloud free in this NOAA-17
HRPT image acquired at 11:08 UT on February 3,
2007, with a wreath of lee cloud fringing northwest
Scotland.
Image: NOAA CLASS Library (www.class.noaa.gov)

Page 18
Tropical Cyclone Favio forms an attractive spiralas it brushes past the island of Madagascar on
February 19. David Taylor submitted this Metop-A
image.
Image © EUMETSAT 2007

Page 39
This fine channel-2 AVHRR image showing
Scandinavia and northwest Russia embalmed in
ice was acquired by Metop-A at 09:18 UT on
February 9, 2007.
Image: NOAA CLASS Library (www.class.noaa.gov)(Image on page 5)
Around 74,000 years ago, the Earthwas rocked by the largest volcanic
eruption to have occurred in the past 2
million years. Over what was probably
a two-week span, thousands of cubic
kilometers of debris spewed from Toba
Caldera on northern Sumatra.
Pyroclastic flows (fast-moving clouds of
hot gas, rock fragments, and ash)buried at least 20,000 square
kilometers around the caldera. As far
away as India, ash from the Toba
eruption lies in layers up to 6 meters
thick; on Samosir Island, the ash layer
reaches a depth of over 600 meters!
Placed in context with the 1980 Mount
St Helens eruption, which expelled justone cubic kilometre of ash, Toba isestimated to have produced 2800
cubic kilometres of ash which coveredat least four million km2—equivalent toalmost half that of the continental
United States.
Following the eruption, the groundcollapsed, creating the 30 x 100 km
caldera imaged opposite, now filledwith water to make Lake Toba.
Samosir Island is a resurgent volcanic
dome, a mound of rock uplifted bypressure from unerupted magma in thechamber beneath the volcano. The
Pusukbukit Volcano on the western
shore of the lake also formed after thecatastrophic eruption.
Looking at the incredibly lush tropicalvegetation that covers much of thelandscape, it is difficult to picture thecomplete destruction of plant andanimal life—including humanpopulations—that would have resulted
from the eruption. Very few creaturesof any kind would have survived acrossa broad part of Indonesia. A ‘volcanic
winter’, caused by the increase insunlight-reflecting particles high in theatmosphere, probably lasted several
years. The rapid global cooling trend
would have had profoundconsequences for life around theglobe.
Although there has been no eruption
from Toba in historical times, theregion, which lies close to the Sumatra
Fracture Zone remains seismically
active, and experienced a major
earthquake as recently as 1987.
This image of Toba Caldera wascaptured by the Advanced Spaceborne
Thermal Emission and Reflection
Radiometer (ASTER) on NASA’s Terrasatellite on January 28, 2006.
Image courtesy ofNASA/GSFC/MITI/ERSDAC/JAROS, and the
U.S./Japan ASTER Science Team.

www.geo-web.org.uk

June 2007

Group for Earth Observation

GEO Quarterly No 14

Les Hamilton
The image opposite depicts a splendid
example of a cloud phenomenon that isfrequently observed in satellite images of
the Arctic and the Antarctic. The parallel
streamers of cloud, often stretching several
hundreds of kilometres, are termed CloudStreets. They arise where a flow of cold dry
air moves from land across a neighbouring
region of relatively warm sea or ocean. In
this particular instance, viewed through the
MODIS (Moderate Resolution Imaging
Spectroradiometer) instrument aboard
NASA’s Terra satellite, high pressure overnorthern Canada is forcing cold, relatively
dry surface winds to spread across thewaters of Davis Strait between Baffin Island
and Greenland, picking up moisture whichforms cloud as it advects southward.
How and Why do Cloud Streets Form?
Cloud streets typically form along the pathof low-level winds which are blowing overopen water which is warmer than the winditself. This flow of air often occurs behind acold front and, as it leaves the land or ice
surface, it becomes modified by the verticaltransfer of heat and moisture from theunderlying warmer water.
The air becomes warmed, picks up water
vapour from the sea, then rises by
convection as it is simultaneously swept
along with the wind. The air is thus subject
to two competing influences: vertical motion(convection) and lateral drift (advection withthe prevailing wind). These two influences
cause the rising air to roll and spin,creating horizontal roll vortices, all lined up
with the wind direction. Alternate vortices
rotate in the opposite sense as illustrated
below.

Figure 2 - Cloud Streets in the Labrador Sea - March 29, 2002
Image NASA’s Terra satellite (MODIS)Figure 1 - Roll Vortices in Cloud Streets

Where the air in adjacent vortices is rising
there is uplift of moist, relatively warm airwhich condenses as clouds. Where the airin adjacent vortices is descending, warming
takes place, causing the cloud to disperse
to form lanes of cloud-free air. Thistransformation of the air mass eventuallyleads to the formation of cumulus clouds
with flat bases and fluffy tops resembling
giant heads of cauliflower, which take theform of cloud streets which develop parallelwith the direction of the low level wind.

Credit Jacques Descloitres, MODIS Land Rapid Response Team, NASA/GSFC

Cloud streets usually form within thePlanetary Boundary Layer, that low-lying
region of the atmosphere where its
behaviour is directly affected by contact
with the Earth’s surface. When the winddirection is relatively constant with height,
cloud streets form as a series oflongitudinal roll vortices. The cloud-free
region between each cloud street istypically about two or three times the depthof the convective layer itself.

www.geo-web.org.uk

The most favourable situation for theformation of cloud streets occurs when thelowermost layer of air is unstable but iscapped by a stable inversion layer. This
often occurs under anticyclonic conditions,when the upper air is subsiding, and is alsofrequently found after radiation fog has
formed overnight. Convection occurs below
this inversion, air rising in thermals beneaththe clouds then sinking again in the air
between the streets.

7

June 2007

Group for Earth Observation

GEO Quarterly No 14www.geo-web.org.uk

9

Cloud streets are usually more or lessstraight but can display vortex patterns
should the wind driving the clouds become
disturbed by an obstacle such as an island.
The result can then be the development ofcloud formations such as von Kármán
vortex streets [1] or ship waves [2].
Cloud streets may also form over land if
relatively unstable air streams over an
obstacle and convection is initiated by
friction or shear (figure 7).
References
1 GEO Quarterly No 2, page 46
2 GEO Quarterly No 11 page 10

Further Examples
Gulf of Alaska
Cloud streets streaking across the Bering Sea andGulf of Alaska are captured in this true-colour MODIS
image from NASA’s Aqua satellite on March 14,
2003. The Aleutian islands interrupt the airflow,
leaving a wake that can be seen at the right-handside of the image (figure 3 - left).
image: MODIS Rapid Response Team at NASA/GSFC

Hudson Bay
Hudson Bay was suddenly covered by a spectacular
set of cloud streets in this November 21, 2005
MODIS image acquired by NASA’s Terra Earthobservation satellite. Lines of clouds sweep off thesurface of the ice along the bay’s northwest edge andhead southeast over the water, billowing out to form
irregular lines of puffy clouds (figure 4 - upper right).
image: MODIS Rapid Response Team at NASA GSFC

Amery Ice Shelf
Antarctica is the coldest, windiest, and (on average)
highest continent on Earth. Dry, frigid, katabatic(down-slope) winds can blow fiercely from the South
Pole toward the Southern Ocean for days on end,setting up ideal conditions for cloud streets.
The Moderate Resolution Imaging Spectroradiometer(MODIS) flying onboard NASA’s Aqua satellite took
this picture on August 14, 2006. The image shows
cloud streets rolling off the Amery Ice Shelf on theeast coast of Antarctica. Immediately east of the ice
shelf’s edge is an area of relatively cloud-free air
exposing the dark ocean surface. Winds flowing off
the ice shelf rapidly pick up water vapour here and,just a little farther east, condensation within therising, warmed airflow has produced an impressive
regiment of cloud streets (figure 5 - lower right).
This NASA image was created by Jesse Allen, using data
provided courtesy of the MODIS Rapid Response team.

GEO Quarterly No 14Group for Earth Observation

June 2007

Figure 6 - Cloud Streets over Lake Superior
Like strokes from an artist’s brush, the sky over Lake Superior and Lake Michigan
was painted with long rows of white clouds on February 5, 2007 when frigid, dry air
from the interior blew across the lake. The clouds follow the direction of the wind as
it gusts over the water. The same process can also cause lake effect snow when thecold, moist air blows ashore on the lee side of the lake. Signs of lake effect snow
can be seen along the southern shore of Lake Superior, which is bright white withlittle sign of darker vegetation poking through.

Figure 7 - Cloud streets over the UK
NOAA 16 at 12:43 UT on March 7, 2002.
Image: SMIS (http://smis.iki.rssi.ru)

10

Figure 8 - Cloud streets off Nova Scotia
In this image, acquired by the Moderate Resolution Imaging Spectroradiometer
aboard NASA’s Terra satellite on January 25, 2004, cold air flowing from northern
Canada can be seen to generate cloud streets shortly after crossing the Atlantic
coastline, where it encounters the warm waters of the Gulf Stream. The white circle
in the top centre of the image is an ancient meteorite impact structure housing theLake Manicouagan reservoir.
Credit Jacques Descloitres, MODIS Rapid Response Team, NASA/GSFC

www.geo-web.org.uk

June 2007

Group for Earth Observation

Mike Stevens (G4CFZ)
Here we are again with another new satellite fromEUMETSAT—and what problems it has produced for theamateur fraternity. I have been following the bulletins on theYahoo Groups website and it really has caused quite a stir—but
one has to say the end results are stunning.
So what have I been up to? Well, with every type of virus thathas descended on me in south Dorset, it’s a wonder I haveachieved anything. But we got through the winter and the worstof the Atlantic Gales and it was good to be able see them coming
well before the weather forecasters got round to telling us.
I decided it was time to look at Metop-A. I almost called it the‘one that got away’: it almost did, and it took a lot ofconcentration and thought before diving into the system todiscover how far I could push my PCs to deliver all theinformation that was now being transmitted via EUMETCast.
I had already applied to David Taylor for the licence to run his
Metop Manager software, so that was in and ready to go. The
next part was to look into RAMdisk and, having read Arne van
Belle’s up-dated article [1], I decided to go ahead and join theYahoo MSG-1 Group and download the AR Soft Ramdisk
software. I did so and, following Arne’s instructions to theletter, installed the RAMdisk. All seemed well. After setting up
the system as per instructions I switched on all the programsand everything started up. Files were coming in fromEUMETCast and the RAMdisk was running ok.
System Changes
It was then a case of looking into David Taylor’s instruction
sheet on Metop Manager to make sure that all the necessarychanges within the Tellicast system were initiated. The
required data was added to the ‘recv-channels.ini’ and ‘recv.ini’files and I also followed the advice to increase the file databaseto 80 000 000 to accommodate the RAMdisk. I then worked
through the Setup4PC data management files to check the
PID’s and also to add ‘510’ to that sequence to ensure receptionof Metop. You can refer to full details of these required
operations in GEO Quarterly No 13 [2,3].

GEO Quarterly No 14

email: Mikeg4cfz@tiscali.co.uk
incoming information. As I had just updated the desktop PC to
1-GB of RAM, I felt that something was not quite right.
Then came the first blow. Switching on the next day, Tellicast
would not start up at all. I looked into the system for any
problems but could not find any, so decided to enter the Registry
to modify System Restore. Just as I was about to carry out thisoperation the PC crashed completely and switched off. I was
stunned by this, as I had never experienced anything like it
before. I immediately switched the PC on again, only to find that
all my satellite programs were gone and I was left with abasic PC—just as I had bought it two years before. It had been
restored back to the configuration when it was manufactured by
E-Machines.
You can imagine my horror at this! What had caused this tohappen? My only conclusion was that the RAMdisk was toblame. In his article Arne does state that, unless System Restore
is modified, it will cause a problem—and it certainly seemed tohave done so most spectacularly.
Luckily, I have all my programs saved on disk along with theirlicence codes so it was a case of reloading them all back into thecomputer. However, I have changed the location of Metop
Manager by placing it on to a separate hard drive just in casethe problem happens again.
If RAMdisk was going to be a problem with Windows XP then it
was too risky to reinstall it: so I replaced all my programs but
did not install the RAMdisk into my PC at all. Now I had towork out an alternative method for receiving Metop, and this iswhere the fun starts.

After all this was carried out I rechecked all the systems andfiles that I had modified before reactivating the Tellicast
software for start up—and away it went! All the files werefeeding into the RAMdisk (to its new position defined in the ‘fsy’file) but on looking at the MSG-1 images I found that I now had
gaps in reception that I did not have before; also, Metop wascoming in with many chunks of information missing.
Nevertheless, I allowed the system to continue running until
the end of the day to see if it would settle.
Registry and System Restore Problems
The next day I planned to go into the PC Registry to modify thesettings for System Restore (as I am using Windows XP) before
looking through all the settings within Tellicast and the rest of
the system to see why I was getting so many gaps in theThis clip from a Metop-A pass over Venezuela on January 31, 2007 clearlyshows Lake Maracaibo and the striking mountain relief of the Cordillera deMérida and Cordillera Oriental.

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June 2007

Receiving EUMETCast without a RAMdisk.
I contacted EUMETSAT regarding Metop reception and as
usual they were full of help and advice. They sent me the latest
version of their Tellique Software (version 5.0), which installs
straight into the PC with no problems except for some software
conflicts, which I removed.
My first experiment was to use two networked PCs, a desktop
model for reception and a laptop for decoding and display. FirstI had to speed up all the ports by going into Device Manager
and changing ‘bits per second’ to the highest setting, asWindows XP defaults to a slow speed. This proved fairly
successful but I still had chunks missing from Metop pictures,
so this was not as good as expected—time for another rethink.
I then decided on a separate external 280 GB Hard Drive
attached to the reception PC through a USB Port. Only the
Tellicast and Metop Manager software were to be loaded on tothis drive (drive ‘F:\’), leaving MSG Data Manager and theother satellite programs on the main ‘C:\’ drive.

The EUMETCast reception system, with the software divided between two
PCs and an additional external USB hard drive. The grey boxes below eachdevics details the software installed on each.

I proceeded to load up the separate system hard drives: on drive‘F:\’ the Tellicast and Metop Manager software and on the main
‘C:\’ drive Geosatsignal, Grib Viewer, MSG Animator and MSGData Manager. AVHRR Manager was placed on the Laptop
along with HRPT Reader. It was then a case of following all the
instructions again to modify the ‘receive-channels.ini’ and the‘recv.ini’ files but, as I now had the latest version 5.0 if the
Tellique software, most were already present. But still check forany changes that are required.
With everything now loaded and rechecked, the PC was
switched on and immediately all the EUMETCast files started
to flood in, including the new Metop AVHRR stream. And guess
what! No gaps in MSG or NOAA AVHRR data. Metop too was

Detail of the Paraná and Uruguay rivers as they flow into their estuary(known as the Rio de la Plata) between Uruguay and Argentina.
Metop-A channel-2 AVHRR image - February 20, 2007

The lakes of the East Africa Rift Valley are prominent in this Metop-A channel2 AVHRR image dating from February 21, 2007 as a tropical cyclone bears
down on Mozambique.

Image © EUMETSAT 2007

Image © EUMETSAT 200712www.geo-web.org.uk

This Metop image was downloaded via
EUMETCast on February 15, 2007.
Image © EUMETSAT 2007

GEO Quarterly No 14Group for Earth Observation

June 2007

operating well, and from a complete orbit dump there were only
two chunks missing, and both these were over the sea. So I now
had a single desktop PC, with an additional external hard disc,running my complete system for reception and data decoding forboth Metop Manager and MSG Data Manager—and it works
brilliantly. The auxiliary laptop PC runs AVHRR Manager and
HRPT Reader and is my back-up for any failures in the system.
Figure 2 above illustrates the system.
Further Points
When making modifications to the Tellicast files, take note thatany line within the ‘receive’ files that starts with a hash (#)
character is inactive. As EUMETCAST state, it is ‘commented
out’. This is also explained in David Taylor’s information within
the Metop Manager instructions.
Also be aware that, having inserted the line ‘[EPS-10]
target_directory=received-AVHRR’, you do not have to generate thefile ‘received-AVHRR’. This will be created by Tellicast as soon
as you start to receive the Metop files from EUMETCast. This
separates the Metop information from the rest of the incoming
data. You then direct your Metop Manager to look into this new
folder for the data.
Required PIDs
The other part of the system that I looked at carefully was thenumber of operational PIDs that I required. I do believe that, as
amateurs, we have to compromise on some things, especially as
we do not all have equally powerful PCs to evaluate all the datathat EUMETCast sends out. I removed those that I did not
require. The operational PIDs that I am using are: 100, 300,
301, 500 and 510, which give me all the required data that I
am looking for.
This channel-2 AVHRR image of ice-bound Hudson Bay, Canada was imagedby Metop-A on February 20, 2007.
Image © EUMETSAT 2007

Signal Strength
Another area to keep an eye on is the signal strength of theincoming data. I live in a windy region and am constantly
checking to see if my signal level has dropped. Anything below
40% and gaps begin to appear in the MSG data. And at thatsignal level, really huge chunks of information go missing from
the Metop data. To monitor this, I leave my signal meter incircuit near the dish so that I can at least see if the level has
deteriorated. The degree of attenuation caused by having themeter in circuit is minimal. Although this gives you some ideaof the incoming signal level, a check on SetUp4PC will give you
the full picture. My average signal level at this QTH is 70% but
it does vary during winter storms. I have recently had to adjust
the antenna as I had a signal loss of 15% which was caused byhigh gale force winds moving the satellite dish.
So there it is—the one that nearly got away. But I am now
enjoying fantastic pictures using all David Taylor’s software,and with very few gaps. If you are experiencing problems with
RAMdisk this may be your alternative. It certainly works forme. Incidentally the cost of the external hard drive was £60.00.
My thanks to Arne van Belle for the excellent articles on
RAMdisk (sorry it did not work) and to David Taylor for his
help and assistance, plus his amazing satellite programs. Happy
weather watch from Portland.
References
1 Using the ARSoft RAMdisk with Windows XP
Arne van Belle, GEO Quarterly No 11, page 39
2 EUMETCast and Metop Data
David Taylor, GEO Quarterly No 13, page 10
This channel-2 AVHRR image was captured by Metop-A during a passdown the eastern coastline of North America on February 23, 2007.
Image © EUMETSAT 200714

3 Modifying your PC to receive Metop Data
Peter Green, GEO Quarterly No 13, page 13

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Group for Earth Observation

GEO Quarterly No 14David Taylor

I had the chance recently to spend a day at the UK Met Office.
Being keen on photography, I took my camera and was allowed
to take a few photos to share with you. The Met Officeheadquarters are now in Exeter, Devon, having moved there in2004 from their previous location in Bracknell, Berkshire. They
are located quite close to
Exeter International Airport.
Buses stop right outside
their purpose-built premises,
showing how important the
Met Office now is as an
employer in Exeter.

mount can have difficulty slewing the antenna fast enough onoverhead passes. The Ku-band dishes come in sets of three(figure 12), and each dish carries a quad-output LNB (figure 10).
The dishes not only receive EUMETCast, but also digital TV tomonitor news and broadcast forecasts.
As you would expect, the rest of the facilities are built in amodern style, with open-plan offices and a central ‘street’ where
you can meet up with folk and have the all-important social
interaction. What better after a hard morning’s work than lunchin the café? Well, you could always nip out to the adjacenthostelry – what excellent planning!

The Met Office supports a
staff of about 1200 at their
headquarters, having
centralised staff from a
Figure 1 - Bus Destination Board
number of field offices,which now take advantage of today’s ability for remote
operation to forward their data. The Headquarters Building ismost impressive from a distance (figure 4, overleaf) andcontinues to impress as one gets closer (figures 5, 6).
Within the Met Office there is an organisational split—between
data gathering and weather forecasting. This is, in part,
because of today’s business environment, where othercommercial organisations may provide forecasts and have theright to the same base data as the Met Office forecasters. Well,it’s something like that, and I’m not going to get into politics
here! Forecasters work in teams and each team may work on
one particular region. Data which is supplied to the forecasters
can include observations from ground stations, rain radar dataand satellite images, in addition to the output from thenumerical weather prediction (NWP) model developed by the
UK Met Office. Here, on a large screen, you can see both rainradar and an infrared satellite image in prominent view for all
the forecasters (figure 7).

Figure 2 - Open Plan Offices

Collecting the data and processing it so that it can bemeaningful to the forecasters (and subsequent processing for
public consumption) requires quite a lot of kit, and there needs
to be considerable redundancy so that the inevitable hardware
failure does not disrupt the flow of data. Of course, conventional
meteorological instruments are used, and the Met Office has anextensive testing area where instruments can be refined and
new instruments developed. Figure 10 shows just a small partof that area where the familiar Stevenson screens can be seen.
However, GEO members will also be interested in the extensive
antenna farm (figure 9) which shows, amongst others, tracking
antennas for NOAA HRPT and MODIS data, direct reception
antennas for the older geostationary satellites and Ku-band
antennas for EUMETCast. It is no coincidence that there seemto be two of everything; the entire reception, processing andcomputing chain is duplicated to provide a high level ofavailability through redundancy, allowing maintenance andupgrades without interruption of the data flow.
There are two antennas for polar orbiter reception, one of which
does not have a radome, and you can see the X-Y mounting
quite clearly (figure 11). This style of mount provides better
performance near the zenith, where an azimuth-elevation

Figure 3 - The Nearby Hostelry

Other aspects of the headquarters show how it was built to beenvironmentally sound.
Their Web site lists:• collecting rain water from the site, treating it with UVlight and then reusing it to flush the toilets• using the large amount of heat from the site’s generators towarm or cool the rest of the building as the seasons andweather dictate

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GEO Quarterly No 14Group for Earth Observation

Figure 4 - Met Office HQ in Exeter

Figure 6 - Met Office HQ in Exeter

Figure 5 - Met Office HQ in Exeter

Figure 7 - Large screen display of rainfall radar and satellite IR

Figure 9 - The Met Office Antenna Farm

Figure 11 - XY-mount Polar Orbiter Antennas

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June 2007

Figure 8 - Stevenson ScreensFigure 10 - A Quad LNB

Figure 12 - Triplet Ku-band Dishes

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June 2007

Group for Earth Observation

GEO Quarterly No 14

Alan Banks
Following the record-breaking 2005
hurricane season, tropical storm activity in
the Atlantic Basin was unexpectedly low
during 2006; not a single hurricane madelandfall in the United States. But as we
explained in a previous issue (GEO Q11),
tropical storm numbers world-wide remain
remarkably constant from season to season.
Recently, thanks to the full-Earth Metop
coverage now available via EUMETCast,
Alan Banks has been monitoring a recent
surge in cyclonic activity in the Indian
Ocean, impinging particularly on the island
republic of Madagascar.
The southern Indian Ocean (SIO) has hada busy Tropical Cyclone season during ourwinter and Madagascar has born the bruntof many of the cyclones in the westernSIO.
I became aware of this fairly late when
Tropical Cyclone Favio developed between
February 14-23, 2007. Favio tracked from
10°S, 70°E, travelling south west, close to
Mauritius and La Reunion before rounding
the southern tip of Madagascar andeventually making landfall on the coast ofcontinental Africa close to Inharrosso in
Mozambique. Favio brought very heavy
rain to both Mozambique and Zimbabwe,countries that were already suffering fromthe effects of prolonged heavy rainfall. The
Zambezi River had already broken its
banks. An image I took from Metop-A as
Favio made landfall (figure 1) shows thelower Zambezi as though it were a lakerather than a river. The full page image on
page 18, sent in by David Taylor, shows

Figure 1 - Cyclone Favio makes landfall on February 22, 2007
Image © EUMETSAT 2007

Favio as an attractive spiral as it brushes past
Madagascar on February 19.

Further study of the Australia Severe
Weather website that monitors activity
throughout the SIO showed that the area
had already been struck by a number ofstorms.
Anita, Nov 29 - Dec 2, 2006
Anita was mainly a Tropical Depression but
did reach typhoon status for a while. Anita
tracked down the strait between
Madagascar and the mainland of Africa.
Bondo, Dec 18-26, 2006
Bondo tracked westward from 9°S, 65°E
around the north of Madagascar thenmoved southwest along the north west
coast of the island bringing very heavy rain
before making landfall close to Mahajanga.

Figure 2 - Cyclone Gamede, which brought record rainfall to Madagascar
Image © EUMETSAT 2007www.geo-web.org.uk

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GEO Quarterly No 14

Clovis, Dec 31, 2006 to Jan 4, 2007
Clovis made landfall close to Mananjary on theeast coast of Madagascar, bringing strong
winds, heavy rains and flooding to the regionof Vatovavy Fitovinany.

Enok - Feb 9-11, 2007
Enok didn't make landfall but again broughtvery heavy rain to the east coast ofMadagascar.

Gamede, Feb 21 - March 2, 2007
This Tropical Cyclone was immense. It didn't
make landfall but passed down the east coastof Madagascar and west of La Reunion. A
Meteo France satellite weather station on theneighbouring island of La Reunion claimed:‘world records of precipitation have been
beaten’ by Gamede, which brought theheaviest rainfall in 27 years. One rainfall
gauge on the island recorded 47 cm ofprecipitation over one 3-day period. Figure 2
shows TC Gamede northeast of Madagascar.

Indlala, March 12-16, 2007
Indlala became the sixth cyclone of the season
to hit Madagascar when it formed off thenortheast coast then tracked slowly west to
make landfall south of Antalaha. It thentracked inland, bringing further misery to thepeople of that island before losing its energy.
According to reports from the Joint Typhoon
Warning Centre, Indlala had winds of 115
knots (210 kph), with gusts up to 140 knots(260 kph). Wave heights were estimated to be
11 metres. The island was still picking itself up
after previous storms, with the governmentand relief agencies already overstretched.
Large areas of the northwest, west andsoutheast had already been flooded bytorrential rains, although harvests in the south
had been devastated by drought. Indlalacaused at least 69 fatalities and rendered
14 000 homeless not to mention the 200 000
whose lives have been affected by storm
damage. More than 3600 buildings were totally
destroyed while over 8000 hectares of ricepaddies were ruined.

Figure 3 - TC Bondo makes landfall
Image © EUMETSAT 2007

Jaya, April 2-4
Tropical Cyclone Jaya, which formed over theocean on March 30, went through an explosive
increase in power from tropical storm toCategory-3 cyclone in just 36 hours.
Fortunately, this cyclone had moderated
considerably by the time it finally made landfallin the northeast of Madagascar in the earlyhours of April 2 ,with winds that still reachedclose to 150 kph, a marked change from the
200 kph just twelve hours earlier.

Summary
The 2006/7 rainy season was the first timethat Madagascar had been hit by so many
cyclones in such a short time and there has
been almost continuous rain during the threemonths since late December 2006. 70% of the
agricultural land on the island—mainly vanilla
farms and rice paddies—has been flooded.
Even before Indlala, the Malagasy government
had launched an appeal to the international
community. with the following assessment at
the end of February:

•
•
•
•

at least 7 deaths
32 000 victims of storm damage
8 thousand homeless
90 thousand hectares of agriculturalland flooded• 125 billion tonnes of rice harvest lost

Figure 4 - TC Indlala makes landfall
Image © EUMETSAT 2007... concluded on page 43

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June 2007

Peter Wakelin
Thirty years ago NASA’s Jet Propulsion Laboratory wasdeveloping the first non-military space-borne radar called
Seasat. This third part in the series describes this and somelater radar imaging spacecraft.
SeasatSeasat was launched on June 27, 1978 into a 790 km circular,
high inclination (108°) orbit and its synthetic aperture radar(SAR) was switched on a few days later. The 1.275 GHz radar
frequency gave a theoretical maximum surface resolution of
25 m over a swath width of 100 km, displaced from the groundtrack by the antenna’s fixed look-angle of 20° from the nadir.
Despite the fixed look-angle and the single polarisation
available (horizontal transmit, horizontal receive), and the factthat only 42 hours of radar imagery were received before amassive short-circuit crippled the spacecraft 105 days after
launch, the mission was regarded as a resounding success.
Although, as the name suggests, Seasat’s primary mission was
oceanographic in nature with swell wave-length and direction
and sea ice observations as the main objectives. Geographers,
geologists, meteorologists and cartographers all realised thepotential of this new observing technique. Seasat data werereceived at several locations around the world including RAF
Oakhanger in southern England.
This early Seasat image of Alaska’s southern coastline near
Yakutat clearly shows several different sea states; the darkarea of smooth sea near the centre, bright lines depicting longwave-length swell waves and much rougher seas in the lower
left part of the image. Note also the prominent glaciers on land.

Figure 1 - Seasat Image of the southern coast of Alaska

Canada’s Radarsat Programme
Canada was one of the first nations to spot the potential
benefits of ice monitoring from space following the Seasat
mission and the Canadian Space Agency (CSA) decided todevelop its own series of Earth observation satellites
incorporating SAR, primarily for ice observation.
Unimaginatively named Radarsat, the first was launched in
1995 into a 798 km dawn/dusk sun-synchronous orbit and washighly successful (figure 2).

Figure 2 - Radarsat Instrumentation

Unlike Seasat, Radarsat could vary the nadir offset angle andcould employ several scanning modes as depicted in figure 3.
Also, it could scan either side of the ground track; normallyoperating at the right side at northern latitudes and switchingover to the left side over Antarctica to image nearer to the south
pole. Resolution varied with mode but ranged between 8 m infine mode and 100 m in ScanSAR wide mode.
In order to improve the interpretation of sea radar imagery, theCanada Centre for Remote Sensing (CCRS), in collaboration
with several other organisations, conducted field experiments in
the Gulf of St Lawrence, just north of Prince Edward Island, inMarch 1996. Ground photographs of several areas were taken tocompare with the radar imagery. In figure 4, the areas marked
A, B and C correspond to ground photographs of three different
ice types. Area A (figure 5), shows new ice termed nilas which isfairly smooth and reflects radar energy away from the satellite,
thus appearing quite dark in the image. Area B (figure 6)
illustrates the next stage of ice development where moving

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Figure 3 - Radarsat Operating Modes

pieces of ice strike each other resulting in predominantly
circular slabs with raised edges termed pancake ice. Due to thesurface roughness and high salinity this ice shows brightly in
the Radarsat image. Area C (figure 7) shows a large
conglomeration of pancake ice but with ‘tears’ caused by wind or
tide which can also be seen on the Radarsat image.

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June 2007

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GEO Quarterly No 14

EnvisatEnvisat is Europe’s latest environment-monitoring satellite andwas launched on March 1, 2002 into the same orbit as its highly
successful predecessor, ERS-2. Amongst its suite of instruments
is the Advanced Synthetic Aperture Radar (ASAR).

Figure 4 - Radarsat Ice Monitoring

Figure 9 - Artist’s impression of Envisat in orbit (Image: ESA)The main focus of the earlier missions was ocean and ice
monitoring and this continues with Envisat but with improved
resolution and more modes of operation of the ASAR. The fivemodes are as follows:
Figure 5 (left)- New Ice (smooth)Figure 6 (centre) - Pancake Ice
Figure 7 (right) - Pancake Ice with ‘Tears’

Radarsat’s ability to switch from the usual right-looking SAR toleft-looking SAR meant it could image right down to the southpole and the first Antarctic Mapping Mission, started on
September 9, 1997, lasted for six weeks, during which time theentire continent was imaged. Ohio State University provided
overall project and scientific direction and provided the final
products. The main objective was to create the first radar imageof the entire continent (figure 8) to serve as a benchmark for
gauging future changes.

• Image mode generates high-spatial-resolution data products(30 m) selected from the seven available swaths with arange of incidence angles between 15 and 45 degrees.
• Wave mode generates 5 x 5 km vignettes spaced 100 km
along-track. The position of the vignette can be selected toalternate between the centres of any two of the sevenswaths.
• Wide-Swath and Global-Monitoring modes utilise the
ScanSAR technique using five sub-swaths and eachgenerates wide-swath products (400 km) with spatial
resolutions of 150 m and 1000 m respectively.
These four modes may be operated in one of two polarisations,either HH or VV (in this two-letter code, the first indicates thepolarisation of the transmit signal—H for horizontal, V for
vertical—and the second indicates the polarity of the receive
signal)• Alternating-Polarisation mode provides two simultaneous
images from the same area in HH and VV polarisations,
HH and HV or VV and VH, with the same imaging
geometry as in Image mode and similarly high spatial
resolution.
The European Space Agency recently celebrated 15 years ofnear-real time data delivery in Earth Observation. The volumeof data processed and disseminated to users has increased
dramatically since ESA’s ERS-1 spacecraft completed its
commissioning phase early in 1992. More recently, near-realtime radar data has been in great demand and in the coming
months scientists will get easy access to large amounts of radar
data, particularly over Europe. The nominal five-year lifetime ofEnvisat expired recently but, given the overall excellent
standing of the satellite, the ESA Member States have agreed tofund mission operations until 2010.

Figure 8 - Radarsat Antarctica Mosaic

Radarsat 2 is almost ready for launch. It is more advanced, withimproved resolution, yet less massive than the first Radarsat
and is now expected in orbit this summer.

A radar mosaic of Europe using 143 images acquired byEnvisat’s ASAR instrument working in the wide swath medium
resolution mode has been made available (figure 10) and a smallpart of it has been reproduced at full resolution (figure 11). The
full image (30 MB) is available at:
http://www.esa.int/esaEO/SEM9QLQ08ZE_index_0.html

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Figure 10 - Envisat Radar Map of Europe

June 2007

Figure 11 - Full resolution section showing cities in the Low Countries

Image: ESA

ALOS
Japan’s Advanced Land Observing Satellite (ALOS), also knownas ‘Daichi’, enhances land observation technologies acquired
through the development and operation of its predecessors.
These were the Japanese Earth Resources Satellite-1 (JERS-1,
or Fuyo) and the Advanced Earth Observing Satellite (ADEOS,
or Midori).
The instruments on board ALOS include the Phased Array typeL-band Synthetic Aperture Radar (PALSAR) which has similar
characteristics and operating modes to those of Envisat’s ASAR.
As the name suggests, ALOS was developed, not for ocean
observation, but to contribute to the fields of mapping, land
coverage observation, resource surveying and disastermonitoring.

Figure 13 - Kolombangara in the Solomon Islands (Image: METI, JAXA)

Figure 14

Figure 12 - Artist’s impression of ALOS in orbit

Raised land level off
Gizo Island following
an earthquake(circled)

Image: JAXA

Image: METI, JAXA

Since its launch on January 24, 2006, ALOS has observed
several areas in the Asia-Pacific region which have been
affected by major earthquakes. Soon after dawn, local time, on
April 2, 2007 a magnitude 8.1 ‘quake struck the Solomon
Islands and ALOS’s routine programme was immediatelyinterrupted in order to image the area. Because of its ability toadjust the nadir offset angle, ALOS’s PALSAR was able toimage the affected area very soon after the earthquake.
Although other sensors on ALOS were able to show areas
devastated by the tsunami created by the earthquake, PALSAR
detected significant changes in land levels in the area. The
larger scale image of the area (figure 13), approximately 70 km
across, is centred just west of the obviously volcanic island of
Kolombangara and was obtained shortly after the earthquake
struck.
The delineated area, close to the epicentre just off the coast ofGizo Island, is enlarged (figure 14) and a pre-quake image
received at almost identical tide levels (figure 15) is shown for

22

Figure 15
The same area off
Gizo Island before theearthquake
Image: METI, JAXA

comparison. Clearly, the land level in the encircled area ‘A’ wasraised significantly by the earthquake (figure 15).
The subject of the final part of this series will be radar
altimetry.

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

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GEO Quarterly No 14

Peter Wakelin
Two Small Imaging Satellites Launched
Kosmotras launched a multiple-payload Dnepr rocket on
April 17 from Baikonur, Kazakhstan. Its 14-satellite cargo
included two imaging satellites. Egyptsat, also known as
MisraSat, was built for Egypt’s National Authority for Remote
Sensing and Space Sciences. Saudisat-3 carries an imager and adata collection and relay payload for the King Abdulaziz City for
Science and Technology Space Research Centre in Riyadh. The
two are in similar 700 km sun-synchronous orbits.
NOAA, NASA Restore Climate Sensor to NPP Spacecraft
A key ozone layer sensor is to be restored to the National Polarorbiting Operational Environmental Satellite System (NPOESS)
programme. The earlier decision not to include the Ozone
Mapping and Profiler Suite (OMPS) Limb sensor on the
NPOESS Preparatory Project (NPP) spacecraft has been
reversed and Northrop Grumman Space Technology will now
include the instrument on the NPP satellite which is now
expected to be launched in 2009. The first NPOESS is notexpected in orbit before 2013.
AIM Successfully Launched
NASA’s Aeronomy of Ice in the
Mesosphere (AIM) mission led by
Hampton University in Hampton,
Virginia, USA, was successfullylaunched on April 25. Strappedbeneath an aircraft flying out ofVandenberg Air Force Base in
California, the Orbital Science’s
Pegasus XL rocket was carried out
over the Pacific Ocean andreleased to begin its flight to orbit.

Haiyang-1A which failed in 2004 after operating for two years.
Designed to perform ocean research, monitor ocean conditions
and support the utilisation of ocean resources, it carries a
10-band ocean colour scanner, a 250 m-resolution CCD imager
and an infrared water profile radiometer. This was China’s
second launch this year and was followed by a third the next
day when a satellite was launched to a 12-hour, circular GPStype orbit.
Another Spacecraft Images MarsThis stunning view, showing portions of the Rosetta spacecraftwith Mars in the background, was taken by the Rosetta Lander
Imaging System (CIVA) on board Rosetta’s Philae lander as it
sped past Mars recently, barely 1 000 km above the surface.

Pegasus rocket ignites sending
AIM on its way to orbit
Credit: NASA

This is NASA’s first mission dedicated to the exploration ofpolar mesospheric clouds (PMCs). ‘The occurrence of theseclouds at the edge of space and what causes them to vary is notunderstood’ said Dr James M Russell, III, AIM’s principal
investigator at Hampton University’s Center for Atmospheric
Sciences. ‘AIM will provide the comprehensive data needed toconfirm current theories for cloud formation or develop newones and allow researchers to build computer simulations that
reproduce the observed changes in these clouds.’

Rosetta swings by Mars
Image: ESA

This was the first time that the Philae lander has operated in a
totally autonomous mode and relying solely on its batteries for
power—as will be the case when it reaches its final destinationin 2014. After gaining energy from the Mars fly-by, Rosetta will
gain further speed in November when it swings past Earth on
the way to a landing on comet 67P Churyumov-Gerasimenko.

These clouds, which are more than 80 km above the Earth’s
surface, form only at high latitudes in both hemispheres andonly during the summer months. They have grown brighter andbecome more widespread in recent years and some scientists
suggest that this may be the result of climate change.
China Launches Oceanographic Satellite
China’s second oceanographic satellite, Haiyang-1B, waslaunched into an 800 km sun-synchronous orbit on April 11, on
a CZ-2C rocket from the Taiyuan Space Centre. It replaces

Japanese Radar Satellite Fails
One of a pair of imaging spacecraft launched by Japan in 2003
has failed due to a power supply problem, according to an
official with Japan’s Cabinet Satellite Intelligence Centre. Twopairs, each comprising an optical and a radar imager, are inorbit and are believed to be gathering information when passing
over North Korea.
Landsat 7 Map of Antarctica Created
As part of its contribution to the International Polar Year, 20072008, NASA and the US Geological Survey (USGS) in Golden,

www.geo-web.org.uk... concluded on page 42

23

GEO Quarterly No 14Group for Earth Observation

Clive Finnis

PayPalThe PayPal on-line payment systemchampioned by Ray Godden andintroduced by him about six months ago
has proved to be extremely popular. I
would estimate that over 80% of all orders
received at the GEO Shop now use thissystem, with cheque payments becoming
something of a rarity. Thanks to Ray for his
work in setting up and refining this system.
R2ZX
The popularity of R2ZX ‘pager hardened’
version of Holger Eckardt's establishedR2FX APT receiver has totally surprised us!
We expected that the first batch would takearound a year to sell but all havedisappeared within just two months! It
certainly is a great receiver for use in theUK, all but eliminating pager interference
except in the very worst ‘pager hell’ hotspots.

At the time of writing another batch is onorder, so hopefully we will only be out ofstock for a few weeks. Thank you all foryour patience if you are one of the unlucky
ones waiting for your R2ZX to arrive. The
original R2FX is still selling well tooverseas locations.
Shop Prices
We have managed to hold GEO Shop prices
stable for quite a time now but, unfortunately,
we have recently seen quite significant cost
increases from several sources. This meansthat we have reluctantly decided to raise someof the Shop prices. The UK Post Office haschanged its pricing policy from one based onweight only to one which takes into accountboth weight and size of parcels. As all Shop
prices include postage this has a direct impact
on our costs of shipping. In January Germany
raised its VAT from 16% to 19%, which affects
the costs of the German built R2FX and R2ZX
receivers, while the world-wide rocketing of theprice of copper has wide-spread implications
for us in terms of the cost of wires, cables andpower supplies. We have also experienced
general increases from our suppliers for MSG
equipment and APT antennas.
The Shop’s main goal is to provide carefully
selected and tested equipment and items atvery competitive prices as a service to GEO
members, but we have to pay our way as well:hence the decision to finally raise some prices.
The R2FX receiver has been increased from£135 to £140 for members to reflect theGerman VAT increase (the R2ZX is
unchanged as the increased VAT rate was24

already established when we started sellingthem in February), the APT turnstile antenna
has increased from £ 37.50 to £42.50 due toincreased prices from our supplier, and wehave also had to pass on some increases on
the Dish and LNB, and PCI cards.

June 2007

operation. Of course a separate GEO Bias-Tee
can be used on the ‘Antenna 1’ connection if
you do not feel confident about opening the
R2FX/R2ZX and shorting the internal JP1
jumper pins. The GEO Bias-Tee comes fully
built and tested in a metal case, so is ready touse straight from the box. Incidentally,
although specifically designed for APT use at137-138 MHz, it has been tested to over
500 MHz, so might well prove to be useful toamateur radio or scanner enthusiasts.

I hope that everyone will appreciate thereasons for these rises and, hopefully,
recognise that we still offer very good value formoney—and that we do our best to provide agood service. Of course, it goes without sayingthat all money made goes directly to GEO—
everyone involved gives their time free ofcharge and no-one receives any personal‘expenses’.
New Shop Items
We are very pleased to be holding stocks ofJohn Silver’s impressive APT mastheadpreamplifier. You can read about it in John’s
article in GEO Quarterly 12. These units are
fully built and tested by John and come fitted
in a rugged metal case—so they are ready for
you to fit as soon as they arrive. Preamplifiers
are generally only needed to overcome signal
losses in long cable runs and will probably not
improve signals on shorter lengths of antennalead.

We have also stocked an optional shortcoaxial connecting cable to connect the GEO
Bias-Tee to the R2FX/R2ZX. This cable is
25 cm long and is fitted with the correct BNC
connectors.
UK Plugtop PSU
After several requests, we are also listing theUK plugged 12 volt regulated power supply
which is ideal for powering the R2FX, R2ZX or
the Bias-Tee. This has only been available
before as part of the R2FX/R2ZX Accessory
Pack.
Skystar USB Box

Indeed, if used with short cable lengths, it ispossible that your reception may actually be
degraded; so only consider these if you feelthat they may help with your particular set-up.
If you do need an APT preamp, then John’s iscertainly one of the best designs available.
If you use a preamp with the R2FX or R2ZX
then do not forget to short out the two pins on
the respective receiver’s printed circuit board
labelled JP1, just behind the ‘AF-OUT’connector. This will route 12 Volts up the coaxial downlead connected to the ‘Antenna 1’
connector, to power the remote preamp.
The GEO Bias-Tee
But what if you want to use the ‘Antenna
Diversity’ function built into the R2FX andR2ZX? If both antennas are connected
through long cable lengths you will certainly
need two preamps, but JP1 only supplies
power to the ‘Antenna 1’ connector: no poweris available for a preamp attached to the‘Antenna 2’ connector.
The answer is the new GEO Bias-Tee. This isa small box which is connected into the
Antenna 2 lead and connects 12 Volts from anattached Power Supply to the remote preamp
without degrading the all-important signal fromthe antenna. The GEO Bias-Tee has several
advanced features, such as an internal
electronic self-resetting fuse and reverse
polarity protection to ensure foolproof

www.geo-web.org.uk

It has been necessary to withdraw from sale
the Technisat Skystar 2 USB Box used for
MSG reception as it is no longer available fromthe manufacturers. We are hoping to have a
new improved version available shortly which
will utilise the far faster USB 2.0 interface.
USB 2.0 will have a much greater capability tohandle the ever-increasing data rates as the
EUMETCast system expands with more andmore services becoming available. Currently
tests are under way both at EUMETSAT andamongst the GEO Management Team toensure that any new USB box will be 100%
compatible and reliable in operation. Watch
this space!
Finally can I say thank you to you all for yourcontinued support of the GEO Shop and foryour kind words of thanks. It is muchappreciated by the hard working volunteer
staff!

June 2007

Group for Earth Observation

GEO Quarterly No 14

Peter Wakelin

Useful Orbits
We are all aware of spacecraft observing the Earth from nearcircular polar orbits, typically 600 to 1000 km above the surface,
and the much higher geostationary satellites orbiting above theequator—but there is a less familiar orbit which has some
useful properties.
Our near-polar weather satellites cross the equator northboundat an angle of about 98° from due east; that is, the orbit
inclination is 98°. It is at this inclination that the Earth’s
oblateness perturbs the orbit sufficiently to cause the orbital
plane to precess eastwards at about one degree per day, or one
complete revolution in exactly one year. The result is an orbital
plane that maintains a constant orientation relative to the sun:the sun-synchronous orbit.
Another effect of the Earth’s equatorial bulge is to cause theperigee, the point where the satellite is nearest to the centre of
the Earth, to constantly move around the orbit. This is of little
consequence for near-circular orbits with similar perigee andapogee altitudes but can be troublesome for the more eccentric
orbits. For example, the classified US ‘Keyhole’ high-resolution
imaging satellites are typically in sun-synchronous orbits
ranging between 300 and 1000 km. The low perigee isadvantageous for improved ground resolution but the highapogee saves propellant by confining atmospheric drag to asmall portion of the orbit. As it takes several weeks for the
perigee to move right around the orbit, it could be a while before
a particular target can be imaged at the highest resolution.

Figure 1 - The ‘Molniya’ Orbit

Soon after the Molniya system was established, Cosmos
satellites started to appear in similar orbits but with theperigee slightly displaced from the usual position forcommunications satellites. These were ‘Early Warning’satellites with one of the two daily apogees well positioned toobserve the Atlantic Ocean and North America. They probably
carried infrared sensors to detect the heat generated by missile
launches.

The mathematical term to derive the rate of motion of theperigee includes the multiplier (1-5cos2i) where i is the orbit’s
inclination. This is zero for an inclination of 63.435 degrees soan orbit with this inclination, whatever its size or shape, would
keep its perigee constantly over the same latitude. The
Russians put this inclination to good use more than 40 years
ago.

Meteorological Sensors in the Molniya Orbit
The continually changing height of satellites in the Molniya
orbit creates problems for routine meteorological observations
but it has been suggested as a way to maintain the flow of winddata from high latitudes. Winds derived from the movement of
atmospheric features in the often-cloudy polar regions are best
obtained from the 6.7 micrometre water-vapour channel which
is not carried on current polar-orbiting weather satellites. This
channel will be incorporated into the later NPOESS satellites
after about 2015 but, meanwhile, only the MODIS instrumentson the Terra and Aqua satellites can be used to derive polarwind information and both are approaching the end of theirdesigned lifetimes.

The Molniya Orbit

US Use of the Molniya Orbit

On August 22, 1964, the USSR launched Cosmos 41 into ahighly eccentric orbit of inclination 66°, perigee 426 km andapogee just above 39 000 km, having a period of just under 12hours (figure 1). This was an engineering test flight of a newcommunications satellite system called ‘Molniya’, the Russian
word for ‘lightning’. Not only does this 12-hour orbit take lessenergy to reach than a geostationary one, it also means that aspacecraft could remain very high in the sky over the USSR for
at least 8 hours in every 12 as long as the perigee was far south.
Just three spacecraft, correctly positioned, would ensure USSRwide communications coverage. With much of the USSR at highlatitudes, geostationary satellites are at low elevations, so the
Molniya orbit permits a much shorter signal path through theatmosphere. The first operational Molniya was launched on
April 23, 1965. To this day, this 12-hour, eccentric orbit inclined
at 63.4° is usually referred to as the Molniya orbit.

American military satellites have been using the Molniya orbit
for communications and early warning sensors for some time
now, taking advantage of the long dwell times over highlatitudes that this orbit offers. The latest American spacecraft
to use this orbit is code-named USA 184 and was launched onJune 28, 2006. Its orbital parameters are used here to better
illustrate this useful orbit. A recent two-line elements set forthis object, derived from hobbyist observations as ‘official’
orbital data are not released, is as follows:
USA 184
1 29249U 06027A 07109.57937305 0.00000623 00000-0 00000-0 0 01
2 29249 63.3450 006.3480 7203746 269.5541 090.4459 2.00588141 01

The mean motion close to 2.006 ensures that the ground track
repeats precisely day after day and the argument of perigee

www.geo-web.org.uk... concluded on page 42

25

GEO Quarterly No 14Group for Earth Observation

June 2007

Anders Höök

For a little more than a year now, I havebeen receiving APT images from the
NOAA 12, 15, 17 and 18 satellites. My
first attempt was with a discone antenna
and my Fairhaven RD500 receiver. I thenreplaced the discone with a QFH
antenna, which of course gave better
images, and in January 2006 I got theR2FX receiver, which gave a tremendous
increase in image quality.

better gain at the horizon. I also wanted
to test the diversity facility of the R2FX
receiver, as I intended to continue using
my old ‘fat’ QFH antenna (Paul Hayes'
design). These two topics are the purposeof this text.

However, I still wanted to see if a better
reception of low satellite elevations was
possible and, on Steve Blackmore's site, I
found something that looked interesting:
the Tall Narrow Quadrifilar Helix
Antenna design. This promised to givewww.qsl.net/n8imo/qha.html

Tall Narrow QFHSteve Blackmore's site does not seem toexist any more, but on of Bob Cash's site
there is a description of Bob's own
modifications of Steve's design. I alsostudied carefully the description of the
PADAT 137 in GEO Quarterlies 9/10 but
decided that it was a bit too complicatedto build. All those construction proposals
were, however, very helpful in trying to
do my own modification. I believe it isunnecessary to stress that this is a very
simple design compared with the
PADAT 137.
My modification keep closely to SteveBlackmore's dimensions (figure 1) but thepractical construction differs dependingon what materials my friend Hed Sintorn(who has a very good hobby workshop)
and I had in our ‘junk boxes’. The
antenna is constructed around a 2-metre
length of 32 mm PVC waste pipe using
8 mm copper tube. But I neverunderstood Steve's solution for the top of
the antenna and Bob Cash's photos of his
construction were quite helpful in thisrespect.
Hed and I used an old 10 mm thickcutting-board for the top of the antenna,probably of a material similar topolyoxymethylene (POM or Delrin). We
cut this board in suitable square pieces,which we screwed together. In the four
lowest squares we drilled a 32 mm holefor the waste tube at the top of the mast
(figure 2).
On top of those four pieces we placed aslightly larger square (a ‘bottom board’)on which we laid the horizontal parts of
the antenna (figure 3). As, hopefully, may
be seen from the figure, we cut out four
triangular pieces from the cutting-board
in order to keep the horizontal copper
tubes in place: these we screwed to thebottom board. In the bottom-board there
also is a drilled hole for the co-axial
cable. Above this we screwed a ‘roof’,
another square from the cutting-board.
As may be guessed from figures 2 and 3,
we had to cut out notches in the bottomboard in order to get sufficient room forthe horizontal parts of the antenna.

Figure 3 - Connecting the co-ax to the QFH

Dimensions

Figure 1 - Dimensions

26

Figure 2 - The top of the QFH, showing the balun

www.geo-web.org.uk

Steve Blackmore’s description states thatthe lengths of the four top horizontal
copper tubes should each be 90 mm.
When Hed and I constructed ourantenna, however, we judged theimportant thing was that the total lengthof each pair of tubes, including theelbows, must be 200 mm to the centres ofthe filar elements. We got this length
more or less through ‘trial and error’
when measuring and soldering. Of course
we calculated how far the tubes could be
pushed into the elbows during thisprocess. The lengths of the two lower

June 2007

Group for Earth Observation

horizontal copper tubes was similarly
200 mm in total, including the elbows,
measured to the centres of the verticalelements.
The total lengths of the vertical tubes(filars) were 915 mm for the short helix
elements and 1012 mm for the long helix
elements. In both cases, this included theelbows, here measured to the centres of
the horizontal elements (and before
bending them). The measurements
900 mm and 1000 mm shown in figure 1
are the vertical heights of the respective
loops of the antenna after the verticaltubes had been bent.
As far as bending the vertical tubes wasconcerned, we didn’t use any special
equipment. These tubes are made of
8 mm soft copper, which is easy to bendby hand, and the amount of curving was
simply ‘judged by the eye’. It may be seenfrom the photos that the curvature is notcompletely symmetrical.
We had some difficulty in finding 8 mm
elbows, so we used instead the nearestthat we could obtain, 10 mm.
Consequently, we used 10 mm copper
tube for the horizontal parts of theantenna. To improve thefitting between theelbows and the 8 mm
vertical (helical) parts of
the antenna, weinserted small pieces of
10 mm tube before
soldering it all together(visible in figure 2). The
somewhat untidy
connection of the coaxial
cable (RG 58) can also
be seen in figure 3.
The lower parts of theantenna also use 10 mm
tube for the horizontal
parts. Drilling 10 mm
holes through the mast
was bound to weaken it,
so we glued strips of
40 mm waste pipe overthe 32 mm tube withepoxy resin before
drilling (figure 4 which
also shows the wholeassembled construction).

GEO Quarterly No 14

material, cut out notches forthe vertical rods, placed
them over the joint thenwired them together. Thisshould be visible from figure
5, taken from the roof.
Finally the top part of theantenna was covered withweatherproof paste.
As can be seen from severalof the photos, the balun
consists of four turns of coaxial cable around the mast.
According to Ruud Jansen(GEO Q9 p 10) this is not
the best solution, but it issimple, so we chose it
anyway, thinking that, if
required, it could be changed
to something better later.

somewhat higher elevations than
expected (say some 15° in azimuth)
around southeast and also aroundnorthwest. I guess that this could be dueto the fact that one (or both) of theantennas is slightly directional, or to thelocation of trees in the neighbourhood.
It is quite fun to look at the two LEDs of
the receiver showing which antenna ischosen. As might be guessed from thedifferent radiation patterns of the twoantennas, the old ‘fat’ antenna is usedmuch more than the ‘tall narrow’ one.
But as far as I can see the two antennas
work quite well together.

Figure 5

However, the initial tests of the antenna
showed that it worked very well, and so
the simple balun is still there.
Diversity Reception
The next step was to climb to the roof, fix
the new antenna to the chimney stack,and connect it to the R2FX receiver towhich the old ‘fat’ QFH antenna wasalready connected. I was quite curious
about how the receiver would choose
between the two antennas.
The result was quite satisfying. On thewhole the receiver chose the ‘fat’ antenna
at high satellite elevations, and the ‘tall
narrow’ antenna at low ones, as expected.
I had feared to get lines over the image
and maybe shifting colour intensity when
the receiver switched between theantennas but so far this has not occurred.
Noise lines over the image, owing to
nearby trees and a power line, seem tohave disappeared or at least decreased.
This could be an effect of the distance
between the antennas, some six metres. I
have to admit, however, that I don't
always understand the choice of antenna
selected by the receiver.
The receiver seems to have a tendency tochoose the ‘tall narrow’ antenna even at

Figure 4
The finished QFH

It turned out later that the stability
seemed insufficient for the wholeconstruction so we slipped a 40 mm
waste pipe over the 32 mm pipe as far as
was possible (in view of the already glued
pieces of pipe). Before this, we wrapped asuitable amount of textile tape aroundthe 32 mm pipe so it was only justpossible to slip the 40 mm pipe over it.
We also wanted to further reinforce thepart of the mast where the lower
horizontal parts of the antenna passed
through the mast. This was done with
50 mm waste pipe: this we cut in two
halves, carved away parts of theIt seems that I can now take lower
elevations to the south than to the north.
To the south I normally get good images
down to about 3°, but to the north I
usually already get some noise below 6°. I
originally thought that this might havebeen be due to the fact that I didn't get
the two masts entirely vertical. However,I have now corrected the alignment of themasts and still have the same noise
below 6°. So it looks as if this is due tothe presence of the trees to the north.
Finally, figure 6 gives an overall view of
the antenna arrangement and thesurroundings (looking to some 10° east ofnorth).
Steve Blackmore’s QFH
For the benefit of readers who may wish
to adhere precisely to Steve Blackmore’s
version of the QFH, precise
measurements and some hints are listed
below.
Mast

1.5 m of 32 mm PVC waste pipe
QFH Elements

Use 8 mm mini-bore soft copper tube
plus 8 copper elbows for the corners• 2 x 190 mm lengths for the lower
horizontal tubes• 4 x 90 mm lengths for the top
horizontal elements• 2 x 903 mm lengths for the short helix
elements• 2 x 1002 mm lengths for the long helix
elements• 4 self-tapping screws for the feed.
• A suitable length of RG58 or UR43 forbalun and feed
• A 32 mm cap to plug top end of mast

Notes
The lengths given for the copper tubing are
cutting lengths, which assume that 90°
elbows are used (not bending the copper
tubes themselves).
Drill four 8 mm holes at 90° to each otherand 25 mm from the top of the mast—thesemust be square and in the same plane.

Figure 6 - Twin antennas for ‘diversity’ reception

www.geo-web.org.uk

Mark and drill the lower holes rememberingthat they are in opposing pairs spaced
100 mm apart.

27

GEO Quarterly No 14Group for Earth Observation

June 2007

by Les Hamilton

Late last August I was fortunate to beallowed to test the prototype of a newenhanced R2FX APT weather satellite
receiver. Poor performance on the
NOAA-18 upper frequency of
137.91 MHz caused by in-band pager
transmissions had always been acontentious issue with most APT
receivers—and the R2FX proved nodifferent. After all, it was designed forpager-free conditions in continental
Europe.

Results were so good that GEO took
the plunge and commissioned a batchof the new receivers, which now see
the light of day as the rebadged R2ZX.
This improved version of the receiver
retains all the great features of theR2FX but adds superb immunity topager interference! Holger Eckardt has
designed the R2ZX specifically for the
UK market—and the only outlet fromwhich the R2ZX can be purchased is
the GEO Shop.

However, since the R2FX consistently
produced such crisp satellite images on
the other APT channels, Clive Finnis
instigated a dialogue with designer
Holger Eckardt on the feasibility of
constructing a ‘pager hardened’ version
specifically for the UK market. As aresult, a prototype was produced,
which was passed round several
members of the GEO Management
Team for testing in a number of known
pager black spots. I tested the receiverin Aberdeen, where bursts of pager
activity are almost continuous. I set up
my own R2FX and the prototype side
by side, allocating my outdoor QFH
antenna to the R2FX and the loftmounted turnstile to the prototype.

Just How Good is the R2ZX?
When I started receiving NOAA APT
images in the good old days of
NOAA-9 and NOAA-10 (the late 1980s)
I had excellent horizons and obtained
images that stretched from deep into
the Sahara to the north of Greenland(Don’t scoff! Remember that I live in
Aberdeen, hundreds of miles north ofthe majority of British GEO readers).
Over the years, neighbours on bothsides have been allowing ornamental
trees to flourish to such an extent thatthey are now almost as tall as the roof
ridge on my house, while my outdoor
QFH is mounted just 6-metres high on
the garage roof. In recent years,
particularly southward, I have suffereda shrinking horizon that rarely gives
much imagery south of Gibraltar.

On any receiver capable of imaging
reasonably successfully from NOAA-18(such as my RX2), I found that pager
intrusion was always at its worst whenusing the indoor turnstile: the outdoor
QFH coped much better. But now,
when as expected, the R2FX/QFH
combination failed miserably on
137.91 MHz (upper image, right), theprototype/turnstile system produced ahighly acceptable one (lower image,right). The entire pass is included here,
including slight pager banding, but thedifference was a revelation.
The prototype then made its way toSurbiton where John Tellick—who gave
up APT a decade and a half ago
because pagers had rendered imaging
impossible—was amazed to find that
he too was obtaining long, pager free
NOAA-18 images using an outdoor
turnstile where other receivers like theProscan, Martelec MSR50 and RX2
totally failed to cope with the pagers.

28

The R2ZX is considerably moresensitive than its predecessor and canmaintain an exceptionally high qualityof imaging even when the signal levelis significantly (but obviously not totally)
attenuated by obstructions. As thefalse-colour NOAA-18 image opposite(dating from April 29) indicates, I am
once again enjoying wider horizons.
This is not a one-off ‘lucky hit’ as all my
images, whether NOAA-17 or
NOAA-18, now show this new-foundlength. Near overhead passes now
rarely provide less than 13-14 minutesof good quality signal from thesatellites. A NOAA-17 image acquiredby Maurice Elwell on March 4 isfeatured on the inside front cover.
I mentioned this to Adrian Chamberlain,
who responded: ‘I have noticed that aswell. I only got the unit a few days ago
and now I can see all the Canaries! No

www.geo-web.org.uk

R2FX (top) and R2ZX (bottom) on same NOAA-18 passat 11:44 UT on August 26, 2006

This NOAA-18 pass was acquired at
13:05 UT on April 29, 2007 using a new
R2ZX APT receiver and APTDecoder.
The image was processed from the WAV
file using SatSignal

GEO Quarterly No 14Group for Earth Observation

June 2007

alteration on the feeder or antenna, but the signal is stronger withno noise. Now I can set my minimum elevation to just 1° rather the
12° I needed before (using the WXtoImg program to control theRX). Well chuffed! A dinky unit with big performance.’
Initial Configuration
I did experience one problem when I started using my R2ZX.
Although I could select the channels by hand the unit refused toenter scan mode. A quick exchange of emails with the GEO Shopsolved the problem.
Like its predecessor [1] the R2ZX comes pre-programmed with thevarious satellite frequencies but also with a default value for thereceived signal strength. If the RSSI (Received Signal Strength
Indicator)turns out to be greater than the Threshold level of an
inactive channel (see figure opposite), the R2ZX interprets this asa valid satellite signal and locks on to the channel. You must
connect the R2ZX to a PC serial port using a 9-pin D-typeconnector and make sure that Threshold setting is greater than the
RSSI value. Scanning will now take place as expected.
Note
If using WXtoImg for controlling the receiver, close the program
down before using the configuration utility program R2FXconfig.exe. When you have finished configuring the receiver, close
R2FX-config.exe before re-starting WXtoImg. The reason for this issimply that both programs use the same COM port on the PC andconflict with each other, which may result in unexpected behaviour.
In general, configuration is identical with that for the R2FX [1]. One
difference of note is that the Antenna Diversity function is now
inactive by default and is activated by software (instead of a
hardware jumper).

The R2ZX configuration screen

Also, the audio level to the PC can now be controlled via software:
just enter a value between 0 and 31 in the Audio level field. This
increments in steps of 10 mV to a maximum of 310 mV).
Reference
1 The R2FX APT Receiver
GEO Q7, September 2005, page 19

Francis BellCan anybody help to identify a feature on
this photograph which I took while flying
over Canada on December 5 last year? It
was the unusual linear feature on the
ground which caught my eye.
The aircraft was flying at about 10,000
metres and the atmosphere was particularly
clear, giving me a clear view of the ground.
At the time we were approximately 53°N
62°W and heading SSW, close to theboundary of the Canadian provinces ofQuebec and Labrador. The camera setting I
used was a slight zoom which would havegiven a focal length of about 70 mm: aslightly longer focus than the human eye,but not by much, so the photograph looks
quite natural.
The feature which had caught my eye wasa white band which stretched for perhaps
100 miles. When I first saw the feature I
thought it was a local cleared approach toan airport, but it just went on and on... The
feature looked white and my guess here isthat trees were absent, allowing the groundto show up white because of a recent
snowfall. The adjacent forested areas
appeared very dark by comparison. My
estimate of the width of the white band wasabout 100 metres.

30

I just couldn't understand what I waslooking at. It didn't seem to start or finish
anywhere significant which I could identify.
Some thoughts went through my mind. Was
it a route for electricity supply, an oil
pipeline, a fire break, a major road, apolitical boundary or a geological feature? I
just couldn't quite understand what I waswww.geo-web.org.uk

seeing. I think from the scale of what I saw
that it is unlikely to be visible using weather
satellite images but other Earth imaging
satellites should be able to show thefeature. Can anybody suggest from theabove description, what I was looking at?
Replies to myself or the editor, please.

June 2007

Group for Earth Observation

GEO Quarterly No 14

Geoff Darby
I was interested to read of Francis Bell’s
research into the power consumption of someof his household electronic items. However, I
would urge caution in terms of interpreting theresults too literally in all cases.

in their equipment just as an effort to ‘jump on
the bandwagon’ as it were. With most modern
equipment there is nothing that needs to ‘warm
up’ or stabilise—so you might wonder why astandby mode is needed at all.

In recent years, under pressure from theenvironmental lobby, most reputablemanufacturers have gone to great lengths toreduce both the active and standby power
consumption of their equipment. A large
contribution to the success of this initiative has
been the replacement of inefficient linear
power supplies with switch-mode types
boasting much higher efficiency levels.
However, there are a number of aspects ofswitchers that make them rather different fromlinears and more difficult to measure.

The answer to this is twofold. Firstly, mostpeople want to be able to switch equipment on
from the comfort of their armchairs, using a
remote control. This means that the system
control micro and the infrared receiver module
both need to be kept powered. The power
consumption of these two items (with the micro
idling in sleep mode) is very small, which iswhy manufacturers have been able to develop
the power supply pulse mode. The second isthat the standby mode may in fact be a ‘mask’for important housekeeping tasks that need to
go on in the background.

Waveform Considerations
The first of these is the current waveformdrawn from the mains, which tends not to besinusoidal, and can be quite asymmetric and‘pulsy’. Secondly, it is hard to efficiently reduce
the output of a switcher for standby purposes
without compromising its regulation andstability. To this end, some equipment uses a
chopper transistor standby drive scheme which
regularly pulses the supply up to full operation
for a very brief period—long enough to keep
the capacitors supplying the rail to the system
control micro and infrared receiver charged. So
when a ‘keep alive’ cycle is active, the power
supply will draw virtually a normal amount of
power from the mains but, in between eachcycle, almost nothing. If you integrate thepower consumed over an entire cycle the final
result is equivalent to a very low average
consumption indeed.
I had a quick look on the Internet at power
consumption for assorted Philips monitors, andstandby is quoted at just one watt for a numberof them.
How the power meter does its sampling (andhow well the algorithm that its software uses tocalculate power performs) when the powerdraw is not sinusoidal, or even further departed
from the norm by being both non-sinusoidal
and briefly pulsed, are both factors which could
lead to substantially inaccurate, and thus
misleading results. I’m not saying that thepower meter Francis used cannot handle theseunusual conditions, but if it is primarily
designed to measure the power consumptionof ‘traditional’ loads, then one should not set
too much store by its displayed results whenmeasuring equipment which utilises a switchmode power supply.

Standby Mode in Context
As well as the figures possibly being
misleading, I would also warn against standby
modes being considered a bad thing in allcases. Manufacturers don’t put standby modes

The Sky Box
The Sky box is a good example of this. It has
to be available to receive, in order that its
software is kept up to date by automatic
downloads from the satellite. Also, its modem
and system need to be able to communicate
with Sky’s control centre in order to fulfil theterms of some of their customer contracts: forexample, where a box has been supplied at avery large discount as part of a viewing
package, there is a requirement to have it
connected to a phone line and be available forinterrogation by Sky. Likewise, with Sky+ multiroom packages, the box has to be connected
to a phone line and available for interrogation
to stop you doing a deal with your next door
neighbour. If for any reason you do not allow
this to happen you receive a letter from themwarning of the consequences, in very shortorder.

Older Equipment
Older equipment may also have a standby
mode for less than obvious reasons. An
example of this might be a VCR. Obviously, it
has a clock on it to allow for timer recordings;
but you might say, ‘well hang on a minute, I
don’t use the thing to timer record, so I’ll justturn it right off when I’m not using it’. Baddecision! The head drum usually has a low
power heater in it to prevent any moisture build
up with changes in room temperature andhumidity. If any moisture does form on thehead drum, the next tape you try to play is very
likely to stick to the drum and become totallywrapped around it. This wrecks the tape, jams
the VCR and almost invariably totally clogs theheads, requiring professional cleaning, or in
extreme cases, even replacement.
Further, many items of older equipment store
their operational and set up parameters—
channel tuning, brightness, contrast and colour
settings etc—in a volatile memory that requires
backup power. This is normally supplied by the

www.geo-web.org.uk

standby power condition. If the unit is switched
off a small rechargeable battery takes over, but
is only designed to last for a couple of hours at
most (to allow for general power failures ormoving the equipment). If you leave the item
for too long without power all of the tuning andsetup data will be lost. As the backup
components age their ability to store power
degrades, and the backup time for which they
can sustain the memory decreases to further
worsen the situation. This is not the case withmore modern equipment which tends to use
EEPROM non volatile storage.

Reliability
Finally, another little spanner in the equation isreliability. Whilst the design of switch-mode
power supplies has advanced significantly
during the past two to three years, they remain
at best highly stressed units, operating as they
do directly from the mains with no intervening
voltage reduction devices such astransformers. This makes them very fickle, andprobably the one item responsible for thegreatest number of failures of modern
electronic equipment.
One thing that these stresses do cause isprogressive degradation of certain
components, particularly on cheaper quality
equipment. These degradations may haveabsolutely no effect on the operation of the
supply as long as it remains powered.
However, when power is removed and thenreapplied some days (or even just hours) later,these failing components may well cause thesupply to refuse to start up again if you’re
lucky—and may even result in total failure of
the supply if you’re not.
Ask anyone who repairs these items for a living
as I do, and they will tell you that thecommonest time for switchers to fail is at
power up, particularly after the owner has been
on holiday for a couple of weeks and the entire
domestic supply has been switched off.
Sometimes these failures can be so
spectacular and devastating that the supply
becomes uneconomic to repair, making
otherwise perfectly functional equipment yet
more landfill. A lot less green than leaving it
running, I think you’ll agree.

In Conclusion
So whilst, overall, Francis Bell’s concerns andinvestigations are valid, anyone reading his
article should be aware that there arepotentially wider issues to be considered.
Everything in the realm of the great god Greenis not necessarily made rosier by efforts tosave power above and beyond what the(generally responsible) manufacturers havedetermined is right and proper for reliable
operation of their equipment.

31

GEO Quarterly No 14Group for Earth Observation

June 2007

Figure 1 - Lunar eclipse at 2140 UTC(80 mm refractor and Toucam Pro webcam)

Figure 2 - Lunar eclipse at 2152 UTC

Figure 3 - Lunar eclipse, near totality, at 2233 UTC

32

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June 2007

Group for Earth Observation

GEO Quarterly No 14

Lawrence Harris
February was a busy month, with telescope testing and literary
efforts, and it was into the third week before I saw a reference tothe forthcoming eclipse of the moon. It took me by surprise, having
forgotten about eclipses for some time, so I checked out thedetails. A total eclipse of the moon can be spectacular—as long as
the weather is OK! The last two partial eclipses have seen poor
weather in southern England, but the forecast was moreencouraging this time.
I have my main telescope, a 30 cm Meade RCX400, set up in agarden observatory and a couple of smaller telescopes (60 mm and
80 mm) available for wider field imaging or viewing. For an eclipse,
the smaller telescopes are much preferred because one can see
the whole spectacle rather than the far more detailed view seen
with a large telescope.
So I decided to mount my 80 mm refractor on its mount next to theobservatory. I am able to set this up fairly quickly and have groundmarks to allow quick aligning for imaging. During the afternoon ofMarch 3 I set the scope up, re-charged the battery and fitted my
Toucam-Pro webcam. This combination is not really very good
because the field of view of the tiny chip is so small. I would
normally use my colour CCD camera to obtain much wider fields,
but I was doing some specialised tests of a new, highly state-ofthe-art telescope guiding system called active optics and did notwant to remove the camera even for the eclipse.
My reasoning also included the fact that millions of photographers
would be taking thousands of pictures of the same eclipse, so I was
happy to do it my way. In fact, during the eclipse, I was aware that
I could actually resume imaging close to the full moon because it
would be dark! Two birds with one stone!
Meanwhile, my EUMETCast Meteosat imaging animation systemprovided me with a first-class view of the entire weather situation. I

could see the cloud front over the southwest and the clear, if a little
misty, skies. We were going to get clear enough skies for at least
the first half of the eclipse, including totality.
When the moon entered the penumbra—the outer part of theearth’s shadow—there was little change that I could see. By thetime that we were near the start of totality the change in brightness
was becoming obvious, so I started to take some images. The
small field of view (FOV) was disappointing (figure 1) and I again
wondered about changing over to the colour camera but decided
not to. In fact the moon was almost dark enough for me to start‘real’ imaging! I took some more eclipse images and then got under
way with the main telescope. I took a series of images of the
Messier galaxies in Leo—just above the eclipsed moon! I wasreally pleased with these 10-minute images, knowing that few
people would think of doing this during an eclipse.
Meanwhile, the mist increased, and there was cloud slowly
approaching. With the channel-9 infrared images coming every 15
minutes from MSG/Hot Bird we have a monitoring facility that could
only have been dreamt about a few decades ago. I remember
many wasted sessions as an astronomer, seeing a television
forecast and then, later, realising the difference between their useof the term ‘clear sky’ and mine!
During the second part of the eclipse viewing conditions
deteriorated to the extent that I gave up imaging and closed down
the equipment. It had been very successful so I sent an image(figure 3) to BBC South Today, which was shown on the Monday
evening after all the digital camera pictures had been shown.
Today’s camera technology enables the lay person to capture
eclipses with ease. I wondered why I had forgotten to use mine!
However, with two telescopes on the go, I think that that wasenough!

Fred van den BoschMy antennas have been assembled on a
7 cm wide cylindrical mast approximately
6 metres tall, which is attached to the sideof the house. When I picked up my new
PADAT antenna [1] at the January
werkgroep meeting I was faced with a small
problem: how to get it up to the top of mymast. My previous APT antenna, a coaxQFH type, had been mounted on top of themast before a number of friends helped me
to raise it into position. Unfortunately, I
didn’t know anyone with a sufficiently longladder to replace the antenna on my own,
and it was too much to expect to be able tosummon sufficient helpers, on a day thatwas calm, dry and not too cold, to help me
to bring it down and up again; so I decided
to do it myself by climbing the mast itself.
I had two old, disused pylon masts three
metres tall (bottom left, page 33) which I
attached to the antenna mast using cross-links at both bottom and top. I had alreadydug out my rock-climbing gear, so I put on
my climbing belt and selected a couple ofslings with which to secure myself to themast and a climbing rope to hang from.
From the top of the mast the rope was letdown through a carabiner so that Minh
could hoist the PADAT up. Assembly waspretty awkward: I had to hold the antenna
upright with one hand while doing all theassembling and tightening with the other. In
this situation it is absolutely essential tosecure yourself well (centre-left, page 33).
With the PADAT in position, my weatherstation anemometer was secured on top ofit.
I also mounted a second dish antenna. This
was a bit harder to mount because theclamps were a tight fit and the dish kept
moving from side to side. But that too was
eventually mounted successfully,www.geo-web.org.uk

whereupon it was time to give my poor
RSI-arms a rest. For this reason I waited till
the following day before mounting theantennas for HF and VHF. Although the
climbing itself was actually quite enjoyable,
all this took a lot of effort but the final result
was well worth it.
With the old APT antenna I used to receive
signals from halfway up Norway. Now they
are already starting to record when thesatellites are well north of Norway. Also,
MSG reception is a bit better: before signal
quality was 28% and now it is above 50%.
To summarise, I am very satisfied with mynew antennas, which you can see in thephotograph at the bottom-right on page 33.
Reference
1 Developing the PADAT 137 by Ruud
Jansen - GEO Q9 p 6, GEO Q10, p 12.

33

GEO Quarterly No 14Group for Earth Observation

June 2007

Updated versions of recv-channels.ini are created by copying thecontents of recv-channels.ini.sav back to recv-channels.ini. All lines
in the file which relate to channels that have been deselected bymeans of the channel buttons in the TQchanSel window will becommented out (i.e. prefixed with the hash character, '#') andtherefore switched off.
So all remaining settings, including comment lines in what is now
recv-channels.ini.sav, will be copied unchanged. If any of thesesettings has to be changed again, then this must be done byediting recv-channels.ini.sav itself!
There are three ways to use the channel selector program,depending on the contents of the original recv-channels.ini file.

Rob Alblas

Assigning Channels and Target Directories
In the past few years the amount of data broadcast by EUMETCast
has grown a lot. Without changing the default settings which comewith the Tellique-software, the files of all receiveable channels are
dumped on the hard disc. This is, in most, if not all cases, notdesired. Channels that are not needed may be filtered out bychanging the recv-channels.ini file, and for a once-only setting this isfine. But if you want to change channels periodically, editing therecv-channels.ini file is not very handy. It is easy to make an error,
which may result in you not receiving the requested data.
To simplify the changing of received channels I have written the
program TQchanSel, which allows each channel to be switched on
or off by means of a simple mouse click.
Selecting Channels
There are three places where received EUMETCast data is filtered
before reaching the hard disc:• In the receiver, where the PID-codes determine which data
are to be processed. These codes must be entered in the
Skystar software. Each PID-code activates a group ofchannels, so this is a rather rough way of selecting channels.
• By the EKU, where EUMETSAT determines what may bereceived (this depends on which channels you requested toreceive).
• By the Tellique software, which uses the recv-channels.ini file
to filter the data. This is the best place for users to decide
what data should reach the hard disc. This is also the fileused by TQchanSel to change channel selection.
This arrangement is illustrated diagrammatically in figure 1.

1 Use only the channels and target-directories listed in theoriginal version of recv-channels.ini
2 Use an internal table for channel selection, but retain any
target-directories listed in the original recv-channels.ini file
3 Ignore all information in the recv-channels.ini file and use thebuilt-in table to set up all channels and target-directories
This built-in table contains the following items for each channel:• full channel name• short channel name• target directory
These short channel names are included to provide clear labellingof the buttons in TQchanSel. For example, ‘[EUMETSAT Data
Channel 2]’ will be shown as ‘HRIT’ (figure 2).
Method 1
This approach uses the information that was present in the original
recv-channels.ini file that existed before TQchanSel was run for
the first time. Consider the example below.
[EUMETSAT Data Channel 1]
target_directory=received_avhrr[EUMETSAT Data Channel 2]target_directory=received#[EUMETSAT Data Channel 3]#target_directory=received
Figure 2 - recv-channels.ini file and the TQchanSel display it produces

These data lines mean that:• Data from Channel 1 (which includes NOAA) will be dumped
in the directory 'received_avhrr'• Data from Channel 2 (HRIT) will be dumped into the directory'received'• Data from Channel 3 (LRIT) is deselected (the '#' comments
these lines out) and will not appear in the TQchanSel window.

Figure 1

TQchanSel first backs up the information within this file torecv-channels.ini.sav and will from now on use this backup versionof the file when updating recv-channels.ini. A window will pop up
containing buttons for (in this example) channels 1 and 2.
Channel 3 (LRIT) is not shown because it was commented out inthe original file (figure 2) . You can now use these buttons tochoose whether to store NOAA, HRIT or both to your hard drive.
If the NOAA button is clicked, recv-channels.ini will be updated asfollows (Note: the raised button means that NOAA is deselected).
#[EUMETSAT Data Channel 1]#target_directory=received_avhrr

Initialising TQchanSel
The first time TQchanSel is run, the recv-channels.ini file will berenamed to recv-channels.ini.sav. This latter file is now used as atemplate from which, in combination with the channels selected in
TQchanSel, new versions of recv-channels.ini can be generated.
Once recv-channels.ini.sav has been created it will not be
overwritten, so your original settings will not get lost.

[EUMETSAT Data Channel 2]target_directory=received#[EUMETSAT Data Channel 3]#target_directory=received

Figure 3 - Modified recv-channels.ini file and TQchanSel display

34

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June 2007

Group for Earth Observation

The only difference between the original and updated files is thatcomment characters have been placed before the first two lines ofthe file in order to deselect NOAA. Only HRIT files will now be
stored on your hard drive.

[EUMETSAT Data Channel 1]
target_directory=Ecast\Data Channel 1[EPS-10]target_directory=Ecast\EPS-10

Note that the lines for channel 3, which were already commented
out, have not changed.

[EUMETSAT Data Channel 2]target_directory=Ecast\Data Channel 2

Method 2
The original recv-channels.ini must consist of the following twolines before TQchanSel is run for the first time:#[EUMETSAT Data Channel 3]#target_directory=Ecast\Data Channel 3[*]target_directory=received

GEO Quarterly No 14#[DWDSAT]#target_directory=Ecast\MSG#[TSL Announcement channel]#target_directory=Ecast\MSG

This means: ‘Receive all channels’ and store all the data into thedirectory called ‘received’. This is the default version of the filewhich comes with the Tellique software.
TQchanSel will now use the internal table (which currently contains
33 channels) to generated a recv-channels.ini file containing data
for all 33 channels. To show buttons for all these channels is a bit
too much, and in most cases not desired, so only the first six are
shown by default. The remaining buttons can be made visible fromthe ‘Show’ menu.
Figure 4 shows the TQchanSel window with its six buttons,
alongside the corresponding entries from recv-channels.ini.

...

Figure 5 - recv-channels.ini file created with the -use_tbl option• -sb_off: Don't show selection buttons at start. Just the menu
is visible, so TQchanSel occupies just a very small part ofyour screen. Using the menu or hot key ‘s’, the buttons
become visible, so you can make a channel change• -chanloc <path>: to define the location of recv-channels.ini(default: C:\Program Files\T-Systems\BusinessTV-IP)• -no_menu: don't show the menu. Note that all menu items
have hotkey replacements.
If you want to use a shortcut icon to start TQchanSel and you needto employ one or more of these startup options, you need to makea batch file. Make a file called ‘tqchansel.bat’ in the same directoryas tqchansel.exe, containing ‘tqchansel.exe -sb_off’ (or whateverstartup command you want). You can now run TQchanSel with thestartup option by double-clicking on the batch file.

[EUMETSAT Data Channel 1]
target_directory=received[EPS-10]target_directory=received

An example batch file is available on my website.

[EUMETSAT Data Channel 2]target_directory=received#[EUMETSAT Data Channel 3]#target_directory=received[DWDSAT]target_directory=received[TSL Announcement channel]
target_directory=received

Figure 4 - recv-channels.ini file and the TQchanSel display it produces

Hotkeys
TQchanSel supports the following hot keys (which are also
duplicated on the ‘Show’ menu).
• s show or hide buttons (see also -sb_off)• a show all channels or jut the first 6 (or as many as definedwith the -n option)• t show content of built-in table• r show current selected channels• h help-text
How to use TQchanSel

The target directory for all channels has been set to ‘received’. In
the example above, the LRIT channel is commented out, as will be
the remaining 28 channels if they are not selected for reception.
Method 3
In this method, all the channel and target directories are assigned
using the internal table. To effect this, TQchanSel must be runusing a batch file containing the line
tqchansel.exe -use_tbl
All the data in the existing recv-channels.ini file is transferred to
recv-channels.ini.sav and a completely new recv-channels.ini file isgenerated containing data for all 33 channels as listed in theinternal table.
Note that, compared with method 2, only the target-directories aredifferent. These directories conform with the ‘unified EUMETCast
installation’ as proposed by Arne van Belle.
The first six entries in the new recv-channels.ini file are shown infigure 5 along with the TQchanSel window. In this example, the top
three entries have been selected and the final three deselected.
Some Startup Options• The number of channel buttons that are visible can bechanged by means of option -n. E.g.: -n 12 (default is 6)• Select the channels to receive.
• Click on Set to make the selection active. At this moment a new
recv-channels.ini file is generated.
• Click on Get to set the buttons in the state conform the recvchannels.ini. This may be handy if buttons are pushed on and off
without clicking Set, to restore the original setting.

Note:• You only need to run TQchanSel if a channel change has to be
made. But the program doesn't consume CPU time at rest, andnearly no memory, so keeping it on does no harm. (On my PC theprogram is always started at boot-time with option -sb_off, to keep it
as small as possible.)• Tellique reacts immediately to a changed channel selection so there
is no need to restart the PC.

The order of channel buttons is the same as in your original
recv-channels.ini file. When you use the built-in table, the tableorder will be used. I have added the most interesting channels at
the top—first those containing AVHRR from the two polar satellites(NOAA and Metop) and then HRIT and LRIT from Meteosat.
If you wish to change this order, here’s how to do it.
• Start TQchanSel with the -use_tbl option• Switch on all channels you might want to use ‘once’• Click on Set. This will generate recv-channels.ini... continued on page 43

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35

GEO Quarterly No 14Group for Earth Observation

June 2007

Giuseppe Cico
I originally started receiving weather satellite images in the
1990s using an APT/WEFAX receiver and one of my first XTtype PCs. Reception was just ‘on demand’ while attemptingsome other hobbies and the system was dismantled whilechanging home.
In 2005 I decided to resume my interest in weather satellites,
being aware of the new digital service on EUMETCast. I set a
new dish on the roof and made some tests using my standard
PC: the same one I used for email, web browsing and so on ...
One of issues while setting up a new PC for 24/7 reception was
to avoid starting a ‘control room’ in the computer corner of myliving room. I had some spare shelf space, so I built a small,
minimal PC (using a micro ATX motherboard in an Antec-Ariacase) that looks just like a cube. This works as an unattended
machine, so a keyboard and mouse are not really necessary
other than for maintenance: and that is achieved with a simple
solution named ‘KVM’.
KVM is an acronym for Keyboard-Video-Mouse and is a
hardware interface used for sharing these three devices on morethan one PC. The KVM set is connected to a box and then threecables are connected to each PC. Switching can be done byturning a switch in older models, or with ‘hot keys’ on a
keyboard on up-to-date ones like mine. A quick press of the‘ScrollLock-ScrollLock-Up’ keys on the keyboard does the job forme, and I’m now switched to the other PC.

Figure 1 - Configuration layout schematic

The receiving PC runs the entire software suite, including
Tellicast, MSG Data Manager and so on. I have a LAN
connecting the PCs, and destination folders are shared with mymain PC through this LAN (which is also used for othercomputing tasks). It is useful to use this LAN to have a look at
the receiving PC while attempting other jobs without switching
the keyboard and so on. This can be done using VNC, a virtual
KVM-over-IP. See
http://www.vnc.com/what.html

where you can download the free version of VNC software.
Just open MSExplorer, connect with the remote PC and you see
the remote screen. When the web page is active and yourmouse is over there, then your keyboard and mouse arevirtually switched to remote system.
The free version of VNC has limited colour resolution and speed
is limited by the LAN, so I find it useful just for one-shotmonitoring while KVM switching is for extensive use. The
receiving PC also has an Internet connection for scheduledwebsite updating.
Figure 1 shows a simple drawing of my configuration, where thethird PC was added during the past few months months while
waiting for Metop. When setting up this new PC I had to decide
how to accommodate it using free space on the shelf. (figure 2).
Upgrading KVM from a 2-PC to a 3-PC configuration was one
way, but expensive because a new KVM was needed. So I
decided to set this new PC up as VNC-only. I installed
Windows XP, VNC and the basic receiving software using aspare keyboard, mouse and monitor—then set the BIOS to a
‘keyboardless-server’ configuration. I would need external

36

Figure 2 - PCs and equipment on the shelf
Included are my old APT/WEFAX equipment, 2x400 GB USB backup devices,
my METOP receiving PC, modem/fax, ADSL modem/router, Ethernet HUB,
MSG receiving PC, film scanner, main PC with 19” LCD display andprinter/scannerwww.geo-web.org.uk

June 2007

Group for Earth Observation

GEO Quarterly No 14

devices to be connected only if a major fault should
occur.
My third PC has been running since October 2006,
in the first instance receiving MSG just for test
purposes—and then Metop from its first day. I canfully manage running and upgrading the software,primarily Metop Manager from David Taylor, using
VNC, with just a few tricks.
Tips for using VNC
First of all, I have to work more slowly than withdirectly connected PCs because sometimes a doubleclick acts like a no-click ... so just don’t be in too
great a hurry.
Use less colour and, for stick with the default
background in Metop Manager (although I use apersonal background from NASA BlueMarble for
WXtrack on other systems).
Anyway, using Metop Manager, and selecting andcombining chunks, is easy and results are placed inshared folders ready to be opened by HRPT Reader
on the main PC. Configuring VNC is quite easy,
following manuals, and in only a few minutes one
can connect from another PC simply by opening
MSExplorer—with Java enabled—and writing
something like:

Figure 3 - A VNC session from the MSG PC viewed on my main PC

http://<pc-name>:5800

as the target address. ‘5800’ is the default VNC port,
a method of IP sub-addressing, which identifies
services from the IP-system.
On my main PC’s MSExplorer I enter
http://192.168.111.112:5800

to connect the MSG system andhttp://192.168.111.113:5800

for the Metop-A. In the same way, I can view the
Tellicast pages using
http://192.168.111.11x:2517

I chose to use the ‘192.168.111.xxx’ addresses for the
LAN as these are defined as private addresses. Your
router may determine which of the three private
Internet address ranges you use. As they are notused by the Internet, you can use
192.168.aaa.bbb or 10.aaa.bbb.ccc

Figure 3 is a screenshots showing my main PC(1280 x 1024 resolution) working with the MSG PC
connected. Figure 4 is another screenshot showing
how I can monitor both of the EUMETCast PCs
from my main processing PC.

Figure 4 - VNC sessions from both the MSG and MetrOp PCs viewed on my main PC

I have shown two different ways of controlling PCs
remotely, one with a KVM switch and physicalconnections and another using the network andsoftware. I have been using this for several months
now, and not only am I being ‘green’ by using lessenergy, I actually have some desk space back!
Appendix - Configuring VNC
VNC can be run either in program mode or service
mode. I chose the second option and modified someof the default settings.
I disabled the ‘Disconnect option by setting it to ‘0’(figure 5) , and set some of the protection options.
External IP addresses can be filtered to allow or... continued on page 43

Figure 5 - VNC connections

www.geo-web.org.uk

Figure 6 - VNC security

37

GEO Quarterly No 14Group for Earth Observation

Powerful currents in the Strait of Messina between Sicily and Italy were imaged by the ASTER instrument aboard
NASA’s Terra satellite in 2003. Read more about this phenomenon in the note on page 4.
NASA image created by Jesse Allen, using data provided courtesy of the NASA/GSFC/MITI/ERSDAC/JAROS, and U.S./Japan ASTER Science Team38

www.geo-web.org.uk

June 2007

GEO Quarterly No 14Group for Earth Observation

June 2007

This beautiful NOAA-18 segment downloaded via EUMETCast by David Taylor on March 15 this year shows superlative details of the peaks and valleys of the
Alps. The image also underlines just how little snow has fallen in this part of the world this winter. So fine is the detail that the course of the River Po across thePlain of Lombardy is clearly visible.
Image © EUMETSAT 2007 - Processing: AVHRR Manager and HRPT Reader software

George Newport
sent us a thebeautiful NOAA-17
colour composite
image at left,
depicting highpressure over GreatBritain, the North
Sea, Denmark andthe Low Countries.
Prominent featuresof the image areextensive banks offog over east andsoutheast Scotland,
and the Midlands ofEngland.
George employs
WXtoImg as his APT
capture software andreceived this passusing his RX2
receiver and a Paul
Hayes QFH antenna.
Final image
adjustments weremade using Paint
Shop Pro.
Details
NOAA-17 at
10:57 UT on
March 27, 2007.

40

www.geo-web.org.uk

June 2007

Group for Earth Observation

GEO Quarterly No 14

Douglas Deans - dsdeans@tiscali.co.uk

The talking point amongst the weather
satellite fraternity continues to be theoutstanding global AVHRR data being
provided from Metop-A through the
EUMETCast system. We can view
anywhere in the world, in five different
wavelengths at 1-km resolution. Quite
remarkable! As expected, David Taylor’s
MetOp Manager has developed further
since my column and full review article
last quarter, and there is some updated
information about this. In addition, I havesome news about completely free software
written by Rob Alblas to decode and viewnot only Meteosat HRIT/LRIT images andsome associated data, but also the Metop
global AVHRR files. More about that
below.
As readers will note from this column, I
normally strive to send out GEO CDs on
the same day as receipt of order. However,the new postal arrangements have madelife a little more difficult, and I now haveto use the local Post Office for weighing
and to have odd value stamps put on the
Jiffy bags (even an empty Jiffy bag will
not comply with the 5 mm thickness rule).
So perhaps on some occasions there will bea minor delay of a day or two.
Nevertheless, and perhaps more
importantly, the cost of the CDs remains
the same.
Xrit2pic v 2007.03
Rob Alblas has written this program
which is freely available to all users. The
program reads HRIT and LRIT files from
the MSG satellites and converts the data
into images. There is also some limited
support for other services such as
DWDSAT, Metop and certain
meteorological products.
For those, including myself, who are used
to the usual visual advantages of GUI
operating systems, this program may takea little getting used to. Nevertheless, it iscompletely free and Rob has to beapplauded for providing the software. The
program allows you to preview images
with zooming and panning, and movies
can also be generated—either using thebuilt in AVI generator or external
software.
There are a number of save format
options. The software is available for bothLinux and Windows and you can also
request it for Sun/Solaris. There are somenotes to give guidance on installation andthey are well worth a read.
Xrit2pic v 2007.03 is available on GEO
software CD, GS2 in both Windows andLinux formats. For further information or
to download the program go to Rob’s web
page at:http://www.alblas.demon.nl/wsat/
software/soft_msg.html

MetOp Manager V 1.1.0
In the previous issue of the Quarterly
there was a full review of this new

software (version 1.0.2), and for those
new to the program this is well worth aread. The fundamentals of the softwareremain unchanged but, as anticipated at
the time of writing, there have been anumber of useful additions andrefinements.
There are too many new options to list
them all here but let me briefly
summarise the more useful of them.

All D avi d Taylor's weather satelli te programs and li brari es, i ncludi ng the current releases of WXtrack,
GS1 Satsi gnal, HRPT Reader, GeoSatsi gnal, GroundMap, RX2 PassC ontrol and many other program extras.
Thi s di sc also contai ns a large quanti ty of sample fi les, many of hi gh-resoluti on data, for use wi th these
programs.
AVHRR Manager
Processes and manages the fi les for HRPT vi a EUMETC ast
v 1.3.4
GeoSatSi gnal

Mani pulates Geostati onary weather satelli te i mages

GRIB Vi ewer

Vi ewer for GRIB format fi les

v 6.0.8
v 2.1.2

GroundMap

Rescales satelli te i mages

v 2.0.6

HRPT Reader

C onverts raw HRPT data fi les i nto i mages

v 2.6.8

Kepler Manager

Organi ses fi les of 2-li ne element data

v 1.2.8

MetOp Manager

Processes and manages AVHRR fi les from MetOp satelli tes

v 1.1.0

MSG Ani mator

Automati c ani mati on of MSG i mages followi ng recepti on
Processes and manages the fi les recei ved from MSG
satelli tes
C omputer control program for the RX2 recei verv 2.5.6

MSG D ata Manager
RX2 PassC ontrol

v 2.5.4
v 3.1.0

SatSi gnal

C reates i mages from wave fi les

v 5.0.4

WXtrack

Satelli te Tracki ng Programv 3.6.4

A wi de range of software for all aspects of weather satelli te recepti on, i ncludi ng tracki ng, recei vi ng,
GS2 moni tori ng and i mage mani pulati on. C ontent i s detai led below but many other extras are provi ded. Ti tles
correspond wi th folder names. * i mpli es a D OS program.
C ollecti on D 02
Recall (wave fi le recorder), Palette (modi fi es Wxsat colour palettes).
Scanner recorder v 1.8 (wave fi le recorder), *NOAA95/*FENG99 (software
C ollecti on D 03
for the NOAA 95 HRPT project)
Wxsat (wave fi le recorder/decoder), Satmon (wave fi le
C ollecti on D 04
v 2.59recorder).
AGSatTrack
Satelli te tracki ng programv 1.33
APTD ecoder
C i rki t
Element Manager

Program for capturi ng APT audi o and processi ng i mages
v 1.0.3.72
D ocuments for the C i rki t Wxsat recei ver and the UOSat recei ver (PD F
format)2-li ne element manager
v 1.59

Footpri nt

Satelli te tracki ng programv 2.24

Irfan Vi ew

Image/sli deshow vi ewerv 3.80v 1.40 pre

JVcomm32

Evaluati on versi on (APT/FAX/SSTV decoder)

Maci ntosh kepler edi tor

Edi ts verbose AMSAT format elements. Mac OS X and OS9 only.

NeoPai nt

Image processi ng program (30 day evaluati on)

v 4.60Orbi tron

Satelli te Tracki ng Programv 3.70Pai ntshop Pro

Image processi ng program (30-day evaluati on)

PhotoFi ltre

Image retouchi ng program wi th many extras

v 6.1.5

Satscape

Satelli te tracker and wave fi le recorder
v 2.02enerates TLE fi les i n 'C elestrak' style from data sets recovered fromSpace-Track TLE Retri ever GSpace Track
Xri t2Pi c
Processes MSG and Metop data
v 2007.03
Spli tter
WXtoImg

Uti li ty program for spli tti ng and reuni ti ng large fi les
WAV fi le recordi ng and decodi ng program wi th many
opti ons.

v 2.7.3

3D EM Package for 3D Terrain Visualisation
GS3 Thi s C D i ncludes the full set of GLOBE Ti les to allow you to produce excellent i mages and flybys from
HRPT i nages. Also i ncluded i s a selecti on of Mars MOLA fi les, sample i mages and helpful gui des by Ed
Murashi e.
Image C D
GS4 A wi de selecti on of hi gh-resoluti on remote i mages from a range of satelli tes, i ncludi ng stunni ng i magery
from the Space Shuttle mi ssi ons. A full descri pti on and source i f provi ded for each i mage.
Mars R over Panoramics
GS5 A chronologi cal account, i n panorami c i mages, of the NASA Mars Rovers' progress across the Marti an
Terrai n

www.geo-web.org.uk

41

GEO Quarterly No 14

Instead of a simple backgroundcomprising geographical outlines, it is
now possible to use your own
background display, and indeed one isprovided with the software. This issimilar to the options provided for
WXtrack and is particularly helpful
for the Browser and World View tabs.
There is now an auto-daylight option
for the images tab.
Comprehensive language support
including French, Italian and Spanish
is now provided, as has a new tab formessages, including weekly reports
and individual updates and news foreach of the instrument’s data. Thisutilises data provided fromEUMETCast channel EPS-18.
Support has now been added for theother Metop data such as ASCAT,IASI, ATOVS, GOME etc. This allows
the files to be moved from the ‘receive’folder into a structured file system
and also offers data retention control.
For users interested in some of theother Metop data sets this isextremely useful.
A right click Google Earth function
has also been provided. There has
been a number of bug fixes and, aswith all David’s programs, work has
started in providing full Vista support.
As I said, there are many other minor
additions and improvements too
numerous to mention but they all add
to the general usefulness of the
program.
MetOpManager v 1.1.0 is available on
GEO software CD, GS1. For further
information or to download theprogram go to :http://www.satsignal.eu/

How to Purchase CDs
Write to the address below
requesting GS1, GS2, GS3, GS4 or
GS5. Prices are £5 for any single
CD, 2 for £8, 3 for £11, 4 for £14 or
all 5 for £17. Please enclose cash or
cheque (made payable to Douglas
Deans - not GEO please) for theappropriate amount. Nothing else isrequired.

Group for Earth Observation

June 2007... continued from p-age 23

Colorado, have woven together more than a thousand images from the Landsat-7
satellite to create the most detailed, high-resolution map of Antarctica ever created.
Researchers at NASA, USGS and the British Antarctic Survey (BAS) have launched a
web site, with support from the National Science Foundation, to offer public access tothe image mosaic called LIMA (Landsat Image Mosaic of Antarctica).
Images will be added over the coming months but the files are typically around
100 MB in size so require a broadband connection. More details of the project andimage files can be found at:
http://lima.usgs.gov

GeoEye-1’s Camera Delivered for Integration
Built by ITT of Rochester, New York, the sensor for GeoEye-1’s camera has beendelivered to General Dynamics Advanced Information Systems in Gilbert, Arizona for
integration into the satellite. When operational, GeoEye-1 will be the world’s highest
resolution commercial imaging satellite. Launch is scheduled for later this year.
GeoEye, headquartered in Dulles, Virginia, was formed last year when Orbimage
acquired Space Imaging to create the largest commercial satellite imagery company inthe world.

... continued from p-age 25(269.5541) shows that the perigee isalmost exactly at the most southerly
point of its track. From the mean motionand eccentricity, the perigee and apogeeheights are found to be about 1050 km
and 39 300 km respectively.

One apogee is spent above western
Europe whilst the other is high above thenorth Pacific Ocean.

The plotted ground track (figure 2) shows
two orbits with time marks spaced at
approximately 10-minute intervals along
it. Few marks appear in the southernhemisphere as the spacecraft speeds
around this half of the Earth in 60
minutes; but it then slows down as it
recedes from Earth, in accordance with
Kepler’s second law, to spend 11 hours
over the northern hemisphere.

‘SBIRS presents a new era of global
surveillance with the ability to detect andreport events that were previously
beyond our capabilities, providing greatly
improved support to our combatantcommanders,’ said General Kevin
Chilton, commander of Air Force SpaceCommand last November, on thecompletion of the spacecraft’s initial onorbit checkout.

USA 184 is believed to carry the first
Space Based Infrared System payload.

The cost includes CDs, packaging,posting and a small donation
towards the cost of overheads. No
fee is asked from overseas
members although an exchange ofsoftware or interesting satellite
images is always welcome.
Orders are normally dispatched on
the day of receipt.
Order your CDs from:
Douglas Deans, 17 Montrose Way,
Dunblane, Perthshire FK15 9JL,
Scotland.
The ground track of USA 184, illustrating its twin apogees above the northern hemisphere42

www.geo-web.org.uk

June 2007

Group for Earth Observation

GEO Quarterly No 14

TQchanSel... continued from page 35

the operation, but I was
stunned by the clarity anddetail of the images. With
the passage of time, I
guess I had forgotten how
beautiful they are.

Lightning Strike
It was two and a half years ago that the lightning
strike destroyed my HRPT, APT, and GOES weather
satellite stations, along with three computers,
numerous antennas and rotators, and virtually every
piece of ham radio gear that I owned.
As astronomers say of a new telescope when it’s
brought on line, today my rebuilt HRPT station saw
first light. I captured horizon-to-horizon images on
several passes of NOAA-18.
It’s been a long, hard, frustrating road, and I still
have a few details to resolve in order to smooth out

Controlling Multiple PCs... continued from page 37

deny access, and further security can be
set with a password (figure 6).
An IP filter can be set by defining rules(figure 5) like
+192.168.111.111/255.255.255.255
which means ‘permit 192.168.111.111
host’,?192.168.111.0/255.255.255.0
which means ‘local user has to approveconnection from network 192.168.111.0’
and- 0.0.0.0/0.0.0.0

I still have somesignificant problems toresolve in my system, themost irksome of which isthat the azimuth rotatorloses track of where it is,
forcing me to recalibrate
its position after every
few satellite passes. The
controller was destroyed
and the rotator damaged in the lightning strike, andit appears that the pulse generating magnetic reedswitch in the rotator is either losing or gaining
counts. At this point it looks like it’s going to be adifficult problem to resolve.
Notwithstanding the work remaining to be done, I’ve
been steadily improving the performance of thesystem as I work out the bugs. Today I tracked avery low, very short pass of NOAA-18, for instance;
the satellite never reached even as high as 1°
elevation (about 0.9° degree at max). The result ,part of which is reproduced above, was that I
captured one of the best, if not the best, images I’ve
ever managed of Nova Scotia and Prince Edward
Island in the Maritime Provinces.
Bill Johnston
New Mexico, USA.

I set just one simple rule to enhance myentire security :+192.168.111.0/255.255.255.0
which means ‘permit 192.168.111.0
network’I have some skill about security on IP
networks so I'm a little paranoid, and oneof my basic rules is to set more filtering,even if some measures overlap eachother.

Latest Developments
The most recent version of
TQcanSel features an
installation package that allows
the user to select any folder ofchoice as the program
destination and also, optionally,
allows the creation of a desktop
shortcut icon.
All the start-up featuresdescribed above, which formerly
could only be carried out bymeans of a batch file, can now
be implemented from within the
program itself using the new<Show → Preferences> menu.
Note that you do, however, haveto close then restart TQchanSel
after any such adjustment tomake the change take effect.

GEO Quarterly
I just got the new GEO quarterly and I wanted tocongratulate you on what I think is a particularly
fascinating edition with some truly stunning imagery.
Of course, I most appreciated the Metop feature....
Just one piece of information in this context— it has
been decided that the name will be Metop-A, withno capital ‘O’, and we have implemented thatchange in our next IMAGE edition. No issue really,
just for your information.
Very best wishes,
Claudia Ritsert-Clark(Head of Communication and Information Services)
EUMETSAT

which means ‘deny any other IP address’.
These are just examples, since in my realconfiguration both PCs connected to theInternet are protected using Norton
Internet Security.

• Stop TQchanSel• Edit recv-channels.ini byplacing the channels in thedesired order. (You may
also change the target
directories, if desired.)• Copy recv-channels.ini
back to recvchannels.ini.sav (or remove
the existing recvchannels.ini.sav)• Restart TQchanSel, without
the -use_tbl option.

Tropical Cyclone Activity... continued from page 19

References• Australian Severe Weather Forum
http://australiansevereweather.com.au/
cyclones/index.html• Joint Typhoon Warning Centre, Meteo France (LaReunion)http://www.meteo.fr/temps/
domtom/La_Reunion/

Further Reading
Tropical Cyclones Ferdinand Valk, GEO Q11 Sept2006

www.geo-web.org.uk

Figure 6 - The Preferences Window

Linux
For Linux users there wasalready a program called
MSGreceive, which can be used
to start and stop Tellique, andwhich shows signal strength etc.
TQchanSel is now a part ofMSGreceive.
TQchanSel and MSGreceive canbe found at:
http://www.alblas.demon.nl/wsat/
software/soft_msgsup.html

where you will also find amanual and installation
instructions.

43

GEO Quarterly No 14Group for Earth Observation

June 2007

Keith Fraser KC2JC sent us this NOAA-18
APT image showing what appears to be a
cloud vortex feature, apparently emanatingfrom Cape Farewell at the south ofGreenland.
Keith wrote: ‘I saw these strange cloudswirls in the Davis Strait, sweeping northwest from Cape Farewell at 16.10 GMT,
this morning (February 3). They look like
von Kármán vortices. I also attach a
National Weather Service fax showing NW
winds of 110 knots, from a low just to thenorth of Newfoundland.

NOAA-18 APT image showing the vortices west ofGreenland on February 3, 2007.

MODIS detail from NASA’s Aqua satellite at 15:50 UT on February 3, 2007
Image:MODIS Rapid Response TeamMet Office Visit... continued from page 15• a fully automatic lighting systemthat responds to occupancy andnatural light levels• providing recycling points across allof our sites• increasing the use of recycled paper,especially in our printed material

44

such as brochures and Christmas
cards• reducing business travel byencouraging staff to utilise videoconferencing equipment provided at
the majority of our sites• encouraging green transport usage,

www.geo-web.org.uk

by operating a car-sharing schemeand providing pool bicycles.
Acknowledgement
I would like to thank the UK Met Officefor permission to publish this article.