Hi Adrian,
Modem performance and trade offs like RF bandwidth is something I have
been studying, e.g. this one compares various modulation schemes for
digital voice:
http://www.rowetel.com/blog/?p=4663
and many other posts. There seems to be a lot of "low hanging fruit" in
the area of
QPSK , BPSK etc and its derivatives all look great until you constrain
the bandwidth
There are some practical detection advantage benefits with antipodal
signals like BPSK.
PI/4 DQPSK, all those formats, none of them are free from some linearity
requirement. Constraining bandwidth leads
Glen,
I think the extra perf we're expecting comes from the tone spacing and RRC
filtering in DMR. For ideal non-coherent 4FSK, the tones should be spaced
Rs apart. The tone spacing of DMR is 1296 Hz, as you've said above. David
wrote it up here: http://www.rowetel.com/blog/?p=4650 .
Thanks,
Hi Brady
ahh yes
I think I know where you numbers were- assumption I think is in
correct for dmr radio sensitivity.
They can do quite alot better than your assumption.
But, it is a reasonable start.
Remember also the coding performance