DMR, NXDN/6.25 and NXDN/12.5 all have the same "voice compression" and all use the same device, AMBE+2 Vocoder that compresses voice to 2400 BPS. All 3 also use the same technique of 4-level FSK-frequency shift keying to transmit ones & zeros in binary code to send the 2400 voice bits plus other...