On 8/14/11 4:34 PM, Jim Cameron "KC9PXZ" wrote:
I have a question, I don't have a SSB rig so I am FM only, wish I could decode telemetry and CW that would be a blast! but as I understand I can't with just FM, or am I wrong?
That's correct. It's just not possible to design a highly power-efficient digital modulation method using a NBFM receiver. That requires a linear channel. A FM receiver is nonlinear; it doesn't respond to the amplitude of the signal, and many have limiters. A SSB receiver is "linear" in the sense that there's no limiter and the stronger the RF signal the stronger the audio output. That's why SSB is used for weak signal work, among other things.
The main drawback to the use of standard SSB receivers is of course the great sensitivity to Doppler shift that requires constant tuning. Ideally everyone will move to software defined radios using hardware front ends that are both linear and wideband. The SDX satellite transponder is itself a software defined radio, and using its full capabilities in a future satellite will require a SDR on the ground.
-Phil