[amsat-bb] Re: Half duplex operation on linear satellites

Andrew Glasbrenner glasbrenner at mindspring.com
Wed Nov 4 04:43:29 PST 2009

Pierre van Deventer wrote:
> Good day all,
> I would like to know if there are *any* stations operating on the satellites
> with linear transponders e.g. on AO-7, that use "fixed uplink, half duplex"
> on a regular basis?
> Is done, is it allowed or is it actively discouraged?
> Feedback will be appreciated.
> Kind Regards.
> 73, Pierre ZS6BB
Half duplex, yes, with care given to run appropriately low power levels.

The fixed uplink part is probably being done, but it is counter to 
preferred and recommended practice on Mode U/V satellites. It likely 
will make little difference where the user load is light, but when the 
transponder gets crowded, a fixed uplink sweeps across ~15 khz of 
passband and can be disruptive to other users.

If someone is restricted to half duplex, computer aided tuning on both 
the uplink and downlink really makes a lot of sense for their ease, and 
for staying out of other QSOs.

73, Drew KO4MA

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