non-doppler correction on linear sats
How to deal with signals (CW/SSB) where the other party doesn't seem to do doppler correction? I use an Airspy/IC820H combo to receive (2m) and transmit (70cm) and both are controlled by Gpredict so that uplink and downlink on linear sats stay in tune. However, I hear many stations that apparently don't do this and their signals "walk" up very fast, right out of my passband. Difficult to get their call, let alone have a QSO. So what should be my strategy to deal with this?
73 de Hans
BX2ABT
Hans, The funny thing is that if both stations don't auto-correct for doppler they can stay in QSO for much longer since both will "walk" the satellite's pass band. I guess this is how it worked in the good old days. So, when I faced this situation, I would tune to the calling station then turn OFF my auto-correction and adjust only the uplink slightly to hear myself when transmitting. It worked in most cases. If the calling station puts out a very short CQ, like in FM sats, just TX and ask them to do a longer call. GL es 73! Umesh, k6vug On Thursday, May 9, 2019, 1:08:16 AM PDT, Hans BX2ABT via AMSAT-BB amsat-bb@amsat.org wrote:
How to deal with signals (CW/SSB) where the other party doesn't seem to do doppler correction? I use an Airspy/IC820H combo to receive (2m) and transmit (70cm) and both are controlled by Gpredict so that uplink and downlink on linear sats stay in tune. However, I hear many stations that apparently don't do this and their signals "walk" up very fast, right out of my passband. Difficult to get their call, let alone have a QSO. So what should be my strategy to deal with this?
73 de Hans
BX2ABT
Hello Umesh,
I tried it the other day, but you need to constantly re-tune the receiving signal, while handling your key and the rotator at the same time. During low elevations the drift is minor, but high elevations and you find yourself very busy. It's doable, but it begs for automation of some parts of the system.
The last couple of days not many passes I could be active. Hopefully next week is going to be better for more tries. Cheers for the advice.
Hans
BX2ABT
On 05/10/2019 02:50 AM, k6vug@sbcglobal.net wrote:
Hans,
The funny thing is that if both stations don't auto-correct for doppler they can stay in QSO for much longer since both will "walk" the satellite's pass band. I guess this is how it worked in the good old days.
So, when I faced this situation, I would tune to the calling station then turn OFF my auto-correction and adjust only the uplink slightly to hear myself when transmitting. It worked in most cases. If the calling station puts out a very short CQ, like in FM sats, just TX and ask them to do a longer call.
GL es 73! Umesh, k6vug
On Thursday, May 9, 2019, 1:08:16 AM PDT, Hans BX2ABT via AMSAT-BB amsat-bb@amsat.org wrote:
How to deal with signals (CW/SSB) where the other party doesn't seem to do doppler correction? I use an Airspy/IC820H combo to receive (2m) and transmit (70cm) and both are controlled by Gpredict so that uplink and downlink on linear sats stay in tune. However, I hear many stations that apparently don't do this and their signals "walk" up very fast, right out of my passband. Difficult to get their call, let alone have a QSO. So what should be my strategy to deal with this?
73 de Hans
BX2ABT
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Hans BX2ABT -
k6vug＠sbcglobal.net