CW beacon in FSK?

  • We can measure uplink and downlink frequency to a high degree of precision and we can measure the doppler (which has a 24h period). The only thing nobody (of the hamradio community at least) has measured is the actual transponder translation frequency. Is is nominal 8089.500 MHz but this is not a GPSDO. So it will have offsets and drifts.

    So even if we uplink on 2400.050 MHz dead on, the CW beacon could be slightly off..

  • DH2VA Yes, I know about the NDA ... (when I reside under an ND(C)A I always say: "I don't know" <-- more polite ; -)

    With the risk getting off topic in my own thread ... ah well ... ; -)

    I'm not sure about your connotation of 'non zero offset', what do you mean with that? What offset, and what is allowed to be 'non-zero' ? (e.g. 8089.5 ?)

    Besides TV Ku/X band transponders, this satellite carries more transponders (like e.g. S/X band ; -) but also Ka band tpx and anti jamming facilities as well as TDOA capabilities (like almost every modern geosat has to pointify jammers/intruders in co-operation with other satellites). In order to do this a precise on board clock is very handy ; -)

  • Offset to nominal 8089.5 MHz can be non-zero. And the clock can be measured from the ground as many of you have already proven, no need to have a super precise clock on the s/c. It just has to be stable enough and I think we can all agree it is.

  • True. It is more than precise enough for our purposes.

    So we leave the discussion concerning absolute frequency accuracy behind us and wait for the outcome of my incentive of this thread : -)