The article discusses the relevance of the compact, mobile radio modem sup-ports modern interface USB. The result is the development of a half-duplex tran-sceiver is a device that works with a frequency manipulated signal in a license-free frequency band. The radio modem is equipped with interface USB, through which data is exchanged, as well as its food, as antennas used inefficient quarter-vibrators. Increase in radio range is possible by the use of antennas with high directive gain. Experimental studies of two designed devices were carried out in an urban setting. Their aim was to establish the maximum sustainable radio range (with line of sight) at different data rates as error correction at the reception, and without. Experimenter, away from the transmitting radio modem, monitored the received data. The use of error-correcting coding is most effective at high data rates (up to 3 dB) than at low (1-2 dB). Increase in radio range is possible by reducing the transmission speed - this is due to the dependence of the receiver sensitivity of the speed manipulation. It should also be noted that the decrease in device size is possible by structural modification.

Keywords: radio interface USB, mobile radio, radio communication range, noiseless coding, frequency keyed signal, experimental studies.