VK3APC
VK3RMC
Moorabbin and District Radio Club Inc. Club Facilities
Financial Members of the Club can have their own station home page and use the MDRC domain name. Members can built their Station Home pages on sites like QSL.Net or their own Internet Service Provider. The Club will provide a link to these sites. Alternatively you can built your own page(s) and send it to the Club Webmaster who will load the page for you. Direct access to the website is not available. See Links section of the Website for current Members pages.
Conditions. The MDRC Committee of Management has the right to remove any or all of the Members page(s) if it:-
- Deems the pages unsuitable.
- Not consistent with the Purposes of the MDRC Inc.
- If the content brings the Club into disrepute.
The domain name being "MDRC.org.au" can be used
by the Member to promote their station as they see fit.
eg MDRC.org.au/CALLSIGN HTTP://MDRC.org.au/VK3DVO or http://MDRC.org.au/VK3MQ
Assistance and instruction is available to Members as required to develop and build their own page. Contact the Webmaster for information or help
The Weather Satellite Imaging Project.
Progress Report.
The aim of this project was to receive the VHF signals from a polar orbiting weather satellite, decode them using a computer & software, and present the picture or image on the computer monitor screen.
The whole project involved a suitable antenna & special VHF radio, feeding demodulated signals to a computer via the soundcard. Then, using a special software program, further decode the signals to produce a visible light image and an infra-red image on the monitor screen. Further enhancements are available to produce attractive coloured images with overlays showing latitude, longitude, rivers & lakes etc. as required.
It was considered that such a project, encompassing both Radio Principles and Computer Principles would encourage New Members , particularly those already having computer interests. Further, when weather images are able to be created and displayed on a regular basis, such images could be transmitted over ATV for a number of Amateurs to receive.
Good Images would encourage an interest in the weather, and then interpretation of the images. I'm sure there is good info. on interpretation available from the Internet.
The whole process is termed "Automatic Picture Transmission" or APT & is capable of a
resolution of 1 pixel = 4 square kilometers.
The equipment can be made portable.
The equipment could be errected at a school (on an oval, with permission of the School) or at a
Scout Event (with permission) and the whole activity demonstrated and explained.
Combining radio, computers and the weather, it should prove a powerful attraction , and encourage young people to join Amateur Radio and preferably the M&DRC.
On 3rd. Nov. On 3rd. Nov. 2004 the Tuesday Morning Group provided $89 to purchase a kit from PowerHouse. The kit was called " VHF Receiver for Weather Satellites " and was designed by Jim Rowe for Silicon Chip. ( Dec. 2003 ) The kit included a masthead amplifier. (Subsequence experience indicates that the amplifier is very useful ! )
Kit-building was entrusted to Bill Currie, with specialist help in SMD soldering by Mathew Wilson. Commissioning & operation was/is being carried out by Ray Rutledge,while a Quadrifiler Helix Antenna was built by experienced Antenna Constructor , Harley Kerr. Supply of suitable antenna cabling was by Geoff Beadle (have not seen you for a while, Geoff ! ). Design & assembly of bits for the antenna pole by Ken Morgan, with cartage of poles from Radio Parts by Gerard Werner
It is hoped that overall installation at the Club will be under Station Officer, Rosco Hamment.
The new computer that the Club hopes to purchase will have a major role in this project. It should have a soundcard, a decent graphics card with s-video output (to feed into ATV equipment ) and with the ability to display 3D Graphics, as required by prediction program "Satscape". The screen should be big enough for a few "operators" to see the screen activity. The processor should be fast enough to operate Satscape in conjunction with Wxtoimg or one of the other weather satellite APT programs. My computer which has a pentium 3, can just do the job. A Dell portable with a pentium 2 is not suitable.
The Weather Satellite Signals we hope to receive, are those transmitted by the NOAA Series of weather satellites. Operated by the National Oceanic and Atmospheric Administration, there are presently 4 satellites transmitting APT, Noaa-12, Noaa-15, Noaa-17 & Noaa-18. I believe one more satellite ( presently being repaired after a fall from its assembly stand) remains to be put into orbit.
They occupy near polar orbits, the deviation from an exact polar orbit is chosen so that the orbit plane precesses 360 degrees per year.They are some 850 kms in altitude, and pass completely round the Earth in about 102 minutes. Their signals are in the 137 MHz band and are Right-Hand circularly polarised. For best reception, antennas should be specifically constructed to receive this type of signal. Desirable attributes are omnidirectional, resonant at 137MHz band to provide gain & help exclude adjacent signals. Several suitable antennas are the Turnstile, the Lindenblad and the Quadrifilar Helix. My internet research suggests that the best antenna is the QFH.
The antenna must have a clear view of the satellite . The satellite "rises" from either the North or South and "sets" towards the opposite pole. There may be 2 or even 3 orbits during which our antenna will be within the transmitted signal "footprint". Any structure, tree etc. that comes between the Satellite and our antenna during the satellite passage will degrade the final image. Any RF interference also degrades. Desirable receiver-masthead amplifier characteristics are high sensitivity, good signal-noise ratio and immunity to other adjacent signals. A further important receiver requirement is an IF bandwidth within 35 to 50 kilohertz. This bandwidth is required to cope with the change in received signal frequency as the satellite approaches the antenna then recedes from it. ( Doppler effect)
I hope to email several “raw” and “enhanced” images with some explanation to Ian Morris for the M&DRC website.
Gentlemen, the biggest thrill comes when, with all keplers up-to-date, your receiver is tuned to correct frequency and you are watching Satscape on the computer screen. The footprint of the satellite transmitted signal moves and touches your location icon --- then the radio bursts into life !!
Can the predication be that accurate ? It is almost “scary” !
Addresses of a few websites for those interested.
Weather Satellite Decoding program by Craig Anderson. www.wxtoimg.com/images/
Satscape Predication program by Scott Hather. www.satscape.co.uk
Many items including QFH construction details www.pilotltd.net/satellite.htm
Many NOAA Sites, here is one . www2.nedc.noaa.gov/docs/klm/
Group for Earth Observation. www.geo-web.org.uk/apt.html
Remote Imaging Group. www.rig.org.uk/index.html
Ron Alblas. Dutch designer. www.alblas.demon.nl/wsat/index.html
Christian Bock – Writer of wxsat, original program that an Amateur could use.
www.riglib.demon.co.uk/guide.htm
There are many more sites, - navigate using the links.
Another fascinating investigation is The Predication Program. Origin, history & development.
Plus “ The Satellite Equation”
Ken Morgan VK3CEK.
Repeater operated by MDRC -
Picture Gallery