[email protected] wrote: > I'm wondering if anyone has thought about or attempted to modify an > analog repeater to regenerate P25 signalling (C4FM)? I know the easy > way would be to buy a Quantar or similar box, or tying two mobiles > back-to-back for flat-audio passthru. > > I want to find a way to recover the phase-modulated signalling, > passing it to a homebrew "logic" board. This board would stream the > bits into memory and if the NAC is valid, then regenerate the > similiar stream out the transmitter. You could also store-and-forward > this "audio" to other systems or for playback. So I either need to > buy a manual to read the theory or ask here if anyone has tinkered > with this. Maybe I'm missing something here, but isn't > phase-modulation not quite the same as our VCO-modulated direct FM? > P25 as I understand it, either shifts the phase 600Hz or 1800Hz plus > or minus, and based on this generates a two-bit "symbol" at 9600 > baud.
Error: P25 is direct FM-actually true FSK. Phase-modulated transmitters won't work with P25.
