Kosbar, Kurt; Chiaventone, Owen; Avola, Kyle; Tuschhoff, Stetson; Missouri University of Science and Technology (International Foundation for Telemetering, 2017-10)
      This paper describes the design of an inexpensive UHF transceiver which leverages some of the recently developed commercial off-the-shelf (COTS) components. The initial goal is to implement digital voice transmit and receive function, although the design can accommodate a wide range of digital communication and telemetry applications. The handheld transceiver transmits 5 watts of power in the 430-435 MHz UHF band. A 1.2 kHz wide GFSK modulation format is used, generated by a Silicon Labs radio chip. The recently released Raspberry Pi Zero processor implements a low bit rate audio coding which conforms to the Codec2 standard. The transceiver fits in a 3 cm x 8 cm x 14 cm volume. It is powered by two 18650 lithium ion cells, and draws approximately 1 watt of power during receive, and 6 watts during transmission.