Reflecting signals of ISS

Almost thought I got lucky….

This is my first attempt at using ISS as the reflector whilst monitoring a 6m signal.

The image below shows an interesting reflection from ZS6TWB/b, but I seriously doubt that it was due to ISS.

I cannot see a reason for the two strange traces; it coincides pretty much with ISS being directly overhead with Doppler shift at near zero, but once again the issue is clouded with the Bi-static Radar theory.

Coming to think of it working and dealing with Doppler during satellite operation was relatively easy to understand by comparison.

I recon it would be better if the transmitting station was QRO and used a high gain antenna. Ideally both the transmitting station and the receiving stations antennas must be fully Azimuth/Elevation controlled.

ZS6A signals from ZS6TWB/b 6m beacon via ISS refelction?

LoTW – uploading incorrect locator information

I discovered that an alarming number of LoTW users are not sending their locator information during uploads to LoTW. There are also a few that are sending incorrect locator information.

The LoTW system does not use the “locator” info provided in the ADIF file. It uses the information that was provided by the user during the creation of the profile (certificate) used for signing the ADIF file.

The LoTW confirmations with absent or incorrect locator info creates a huge problem for those who are chasing VUCC awards.

I was very fortunate to come across the following info on K2DSL blog site.

http://www.k2dsl.com/2009/12/02/correcting-your-lotw-location-info-in-tqsl/

I am sure you all agree it is very easy to sort out this issue if the above steps are followed.

73

Pierre ZS6A

ARISSat – Last transmissions recorded ??

The chances are good that Eddie ZS6BNE and I were the last to copy signals from the above satellite.

The signals were very poor compared to the last few passes we witnessed in the last few days. The MP3 recording I made clearly indicates when the transmitter switched on at 03:57:48 UTC the SSTV transmission begins some 10 seconds later. A very noisy image was recorded with some fairly strong audio telemetry that followed that end then disappeared into the noise.

According to the Live OSCAR Satellite Status page it was not heard again. Did we have the dubious honour to be the last to hear the satellite before it re-entered and burned out?

http://myhome.mweb.co.za/~pierrevd/ARISSAT_04012012_0358_Final.mp3

http://oscar.dcarr.org/index.php

73, Pierre ZS6A

ARISSat – 3 Jan 2012

I am a little miffed at myself for missing out on a few seconds of the SSTV image below.

The transmissions only begin some 13 seconds after the satellite flies into the sunlit side of the earth. I was flipping between the linear transponder and the FM downlink and I guess I missed out on a few seconds of what could have been an interesting image. I suspect that the transmissions only started part way through the image anyway.

Did manage to have a quick QSO on SSB with Andre ZS2BK, and heard myself clearly on CW as well.

I hope ARISSat will still be operating tomorrow, thus giving us a last chance at capturing the final images. It would be rather cool to witness the last moments before it get destroyed?

Most experts seem to agree that it should re-enter tomorrow the 4^th of January 2012 some time.

ARISSat 3 January 2012 @ 0427 UTC

Voices from space – ARISSat-1

The ARRISat-1 satellite which was launched by hand from the International Space Station - ISS, in August last year (2011) continues to work very well indeed. It is rather unfortunate that it should be re-entering the earth’s atmosphere in the next few days and burn out as it does so.

The satellite only works when sun lit and that limits the opportunity quite a bit. In my case, that means having one pass in the morning and that is it, until the next day.

In the last few days, I have managed to capture a few very nice images from ARISSat, using the MMSSTV program.

The pre-recorded messages (children’s voices) are very clear. I have no doubt that the signals can easily be copied by any normal mobile installation.

Some experts predict it will only be with us until 4 January 2012 +/- 1 day.

Happy New Year to one and all !!

73, Pierre ZS6A

Half Duplex operation via AO-7

Operating Half Duplex via AO-7 and other linear transponder satellites.

This procedure was developed so that we had a system whereby portable stations that are limited to using half duplex radios such as the FT-817, FT-857 and FT-897 are able to operate on the linear transponder satellites, without having to rely on the use of CAT control and still enabling the use of SSB and or CW.

The procedure has been used on a several occasions and has enabled us to work some rare DX entities via AO-7. The system will work with any satellite with a linear transponder, but the frequencies will obviously have to be adapted to suit.

The procedure:

·    The half duplex station must transmit on a fixed up link frequency of 432.145 MHz at all times (don’t change the up link frequency). Any frequency within the pass band could be used, but 432.145 MHz happens to be in the center of the pass band.

·    It is imperative that half duplex station, call’s “CQ” often and repeatedly, pausing only to tune the down link, listening for replies.

·    The portable station will have to tune from 145.940 to 145.960 listening for replies. The portable half duplex station must actively search for stations replying to his CQ, after contact has been made with the calling station only slight corrections of the down link frequency will be required to correct for Doppler.

·    It might be an idea to announce during the CQ that the station is “half duplex, fixed up link” to alert the other users to the fact that they must track his down link and not the last station as we normally do.

·    All the other stations must find the calling half duplex stations down link and net on that frequency and thereafter remain locked to the half duplex stations down link. The first station to respond to the CQ will also have to give fairly long calls until contact has established thus giving enough time for the half duplex station to find the correct down link, thereafter it should be easy, all stations must follow the half duplex stations down link.

·   “Round Robin” QSO’s are not a good idea, after each exchange, the over must go back to the half duplex station so that he (the half duplex station) controls the frequency.

·    The above procedure can only work if we understand that that all stations must follow and net on the half duplex stations down link frequency.

VERY IMPORTANT

·    The normal full duplex stations must not make blind calls to raise the half duplex station as this will only create chaos and should be avoided at all times. The half duplex station is relying on a response to his CQ and in turn this will allow all the users to net on the correct frequency (i.e. the down link frequency of the half duplex station). If anyone chooses to ignore this request they will spoil it for all the other stations wishing to work the half duplex station.

We are all very unfamiliar working half duplex. I have no doubt we can improve on the system and identify new pitfalls.

Your comments and feedback will be appreciated.

73, Pierre ZS6A

Hal Lund ZS6WB - Radio Amateur of the year 2011

Last Wednesday I attended the South African Radio Development Trust awards ceremony to collect an award on behalf of Hal ZS6WB.

Hal was awarded the “Garth Milne Technology Award 2011” This was in recognition of his dedication to technology in Amateur Radio and his contribution to the promotion of amateur radio satellite operation in South Africa.

Hal has done much to promote satellite activity in South Africa. 

Hal IMHO is a very worthy recipient of this prestigious award and I am very pleased to see that his efforts have been recognized by the SARDT.

The award function was very well attended and it was great to meet in person some of the voices that I have worked on many prior occasions.

The guest speaker Stafford Masie gave a most interesting and informative talk on developments in the IT industry especially as it pertains to hand held devices (cell phones) etc.