Re: [Freetel-codec2] 4FSK modem performance

Thank you very much guys for your responses. I will continue to play with Gnuradio and try to test various modulation schemes over the air as this is an interesting exercise. Cheers, Adrian On 3/7/16, glen english wrote: > Hi Brady > ahh yes > > I think I know where you

Re: [Freetel-codec2] 4FSK modem performance

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

Re: [Freetel-codec2] 4FSK modem performance

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,

Re: [Freetel-codec2] 4FSK modem performance

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

Re: [Freetel-codec2] 4FSK modem performance

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