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

Robert Bruninga bruninga at usna.edu
Sat Feb 3 15:53:08 UTC 2018

Its more about saving TX power than anything else.
If anything opens the squelch on an FM transponder, it is FULL TX power
from the satellite even if almost nothing is there.

On a linear bird, the oTX power is proportional to the input. so the
spacecraft power is not wasted on wek signals.


On Sat, Feb 3, 2018 at 10:45 AM, Philip Jenkins <n4hf.philip at gmail.com>

> 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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