[amsat-bb] Question about PL/CTCSS on uplink

Mike Diehl diehl.mike.a at gmail.com
Sat Feb 3 16:48:05 UTC 2018

Think about how SSB changes the pitch of your voice whenever it is off frequency so your tone would be off frequency as well. Most importantly is that linear transponders don’t demodulate anything and are basically a bent pipe. Whatever comes in the passband is mixed with an LO and retransmitted on another frequency. 

Mike Diehl

> On Feb 3, 2018, at 10:45, Philip Jenkins <n4hf.philip at gmail.com> wrote:
> I understand why FM satellites need an PL tone on uplink (to keep out
> land-mobile services, like taxi-cabs, etc), but why is a PL not required
> for the linear sats utilizing the same frequencies? A linear transponder is
> certainly capable of receiving/transmitting an FM signal (albeit not
> successfully demodulating that signal).
> This question came up at a satellite presentation I did, and I had never
> thought about it. ( Moreover, will radios even transmit a PL on SSB/CW
> transmissions?)
> Philip N4HF
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