Satgen272      Satellite Profile No1 RS12  by GM4IHJ            11 June 94
BID of this msg is SGEN272  Please use this BID if you retransmit this msg

RadioSport 12  (RS12)
Orbit inclination 83 degrees takes it near each of the poles so that it
gradually sees the whole world several times in the course of each day.
Its mean height is about 1000 kms from where it can provide communication
from UK to the Eastern USA and Canada,on passes west of UK , or on passes
east of UK it can give communications into Asia from UK. The 8 watt
transponder is very powerful for a low altitude satellite so its signal is
a lot stronger and less susceptible to fading than previous oscars. To
send a signal up to it ,the frequency band of the mode K transponder
accepts signals between 21.21 and 21.25 MHz . You can receive it and track
it via its 29.408 MHz morse telemetry beacon and you can hear and talk to
other users by receiving in the downlink band 29.41 to 29.45 MHz
  
Ground station equipment for RS12 two way communication is standard HF
terrestrial equipment. You need an HF transmitter of 25 watts or more
output in the band 21.21 to 21.25 MHz loading a simple wire or dipole
antenna. You use the top half of this band 21.23 to 21.25 for Upper side
band voice, and the lower half below 21.23 for CW communications. Your HF
receiver tuning 29.41 to 29.45 MHz can be fed by a simple wire or dipole
antenna.

Start listening for RS12 by getting used to receiving its morse beacon on
29.408 plus or minus 1 Khz of doppler shift. RS12 makes a little over 13
orbits each 24 hour day, with a sequence of 9 consecutive passes out of 13
being audible/receivable in Northern Europe. Stations nearer the Equator
receive only a restricted set of orbits , firstly getting 3 successive
passes , then a break of 4 or 5 hours, then perhaps 3 more orbit passes.  
THe satellite will come in range roughly every 100 to 105 minutes
depending on the latitude at which you first hear it, during these in
range passes. Once you get good beacon copy , try tuning higher up the
band first to the CW signals then higher up to the Upper sideband voice
signals. Please practise careful tuning , following the doppler shift
which can change the signal frequency by a maximum of about 2 Khz over a
15 minute pass above your station horizon. You do not need directional or
trainable antennas

Then when you are adept at reception, tune up your transmitter on say
21.22 MHz press your transmit key and listen for your carrier signal being
repeated by the RS12 transponder at a frequency roughly 8.2 MHz higher
than your transmitted signal. Make sure you avoid interfering with other
users. Once you hear your own note, send a CW test with your callsign ,
tuning your transmitter if necessary to keep your signal in the same place
on your receiver dial. 

Finally when you are happy with transmit and receive, tune around
listening for someone else. Then try transmitting very very briefly
roughly 8.2 MHz below the frequency on which you receive the other
station. You should hear yourself within 1 KHz of his signal and you can
tune your transmitter to get right on frequency and establish
communications with the other station.
73 de GM4IHJ @ GB7SAN