[amsat-bb] Expectations...

PA3GUO pa3guo at upcmail.nl
Sat Jan 3 21:01:33 UTC 2015


Hi Kelly,

Regarding APRS via the ISS;

A busy channel ...
When I use 100W into my 2x6 elements antenna (with doppler correction) I can always get over the ISS APRS station.
When lowering to 5W I get a problem, likely due to many many stations in Europe all transmitting at the same time.
Note: I don't run often with 100W, in fact I rarely use APRS at all.

So, it's a busy channel, see also here: http://www.ariss.net/index2.cgi
00:00:57:07 : WB3FKP]CQ,RS0ISS*,qAR,KB3KBR-15::K8OE :35F here in Alden , PA - UR 599 today via ISS !
00:00:57:10 : W3MAT]CQ,RS0ISS*,qAR,KB3KBR-15::WB3FKP :QSL Good Copy
00:00:57:12 : WB3FKP]CQ,RS0ISS*,qAR,KB3KBR-15::Heard :K0HCV-9,NX9G,WB8JAY,W3MAT,K8OE,KB1CHU
That is 3 transmissions in 5 seconds (up and downlink means 6 transmissions in 5 seconds I believe).
But it does show the satellite (ISS) hears MANY stations at the same time.
Watch the footprint, pick your time, eg when it is over a more quiet area but still in range for you.

Antennas:
The ISS turns and its construction sometimes blocks/shield the antenna's.
You can see that during school contacts, when APRS and Voice run simultanious:
https://www.youtube.com/watch?v=RfNM3bzRW_E
Signal strengths varies independently on the 2 stations (watch the waterfall).
In fact I believe that compared to ~8 years ago, the fading due to the ISS construction itself has increased enormous.

A lot of fun though!
Even if nobody responds, if you hear your packet re-transmitted by ISS, you 'have been in space' already !!

Success & have fun!
Henk, PA3GUO


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