[amsat-bb] HO-68 FM/Packet Understanding

Peter roi at optonline.net
Fri Dec 25 04:19:37 PST 2009

Luc, John and the Group,

I want to wish everyone a Healthy and Peaceful New Year,  and I hope that
Santa was good to you; I know Santa gave me a terrific Satellite gift.

I asked Alan to give me a better understanding of how signals are processed
with XO-68, I hope his explanation below helps.

Dear Peter,

FM / Digital working principle is that whoever will relay signal to who
should transmit first. the transponder is not torn between the uplink

In other words, if the voice first, open the repeater and talk, this time
where the transmitting packet data is necessary to wait for voice
communication before end of the processing voice. By the same token, if you
are transmitting Packet data into voice link from time to time, the
satellite will continue to transmit the packet data to complete the data
frame, and then process voice request if the request is still active.

On the other hand, if there are a lot of very strong signals transmit to the
satellite at same time, the satellite receiver may be unable to decode 67Hz
PL correctly, so voice will be unable to be replied in that case.

Happy Holiday!

Alan, BA1DU

More information about the AMSAT-BB mailing list