You need the distinct transmit/receive channels for full-duplex communication. The frequencies often only differ by <10MHz or so, with the uplink band being adjacent to the receiving band so they can share the same antenna an RF circuitry. The RF circuitry isn’t the technical difficulty, it’s in the software/firmware that is controlling the hardware. With some firmware/software changes, cell phones should be able to do some ham-APRS-like protocol.
The Hams have already solved this once using APRS at 144.39MHz, and it’s dumb that we don’t have a similar solution ported to cell phones at a convenient one of their working frequencies when not in reach of an on-line tower.
You need the distinct transmit/receive channels for full-duplex communication. The frequencies often only differ by <10MHz or so, with the uplink band being adjacent to the receiving band so they can share the same antenna an RF circuitry. The RF circuitry isn’t the technical difficulty, it’s in the software/firmware that is controlling the hardware. With some firmware/software changes, cell phones should be able to do some ham-APRS-like protocol.
The Hams have already solved this once using APRS at 144.39MHz, and it’s dumb that we don’t have a similar solution ported to cell phones at a convenient one of their working frequencies when not in reach of an on-line tower.