Does anyone periodically perform linear transponder frequency calibration for the Amateur Radio satellites. There often seems to be several 100s or Hz or even a bit more than a kHz of error. I assume due to LO drift or offset. I have done some tests on my own and got some ball park values but wondered if someone was doing it super accurately. My test methods need some refinement to improve accuracy. I need these values to feed into my rig up/downlink Doppler corrections since I use a radio the is cross band but not full duplex so I can’t hear my own downlink. Need to calculated up/downlink frequencies with full Doppler correction to be pretty spot on.
I have been on the linears and fm, and I’d say full duplex is very much worth it. even if the rx is a cheap sdr stick.
IIRC the satpc32 users have some correction tables where you get pretty spot on. You also need to know your own LO to a quite high accuracy in your blind case, else this all falls to pieces.
Your radio LO will be multiplicated, ie the error on 70cm is 3x the amount on 2m, this nonlinearity will probably bite you.
I’d say it’s theoretically possible, but given the reality of satellite communication I’d say it will be really hard to make a lot of qso’s. Some will think you’re just elbowing CQ on a adjacent channel, some will be quick to answer you on your frequency and you will be unable to know where to tune etc etc.
I hope you get a full duplex solution up and running and make many qso’s!
There’s a active telegram group with some ~280 amsat members if you’re interested. There’s a lot of tried solutions out there.
1 Like