Multiband Public Safety Radio Using a Multiband Rfic with an Rf Multiplexer-based Antenna Interface

Various public safety personnel often cannot readily communicate with one another due to the lack of interoperability in their radios. One of the solutions to this problem is to provide user a multi-band multi-mode radio (MMR). In this paper we present the design of an experimental prototype multiband radio, which operates in public safety frequency bands from 100 MHz to 1 GHz. In our design we use a direct conversion CMOS transceiver RFIC developed by Motorola Research Laboratories, which covers the frequency range 100 MHz to 2.5 GHz and contains multiple receivers and transmitters. Although direct conversion has some significant advantages over superhet-based design particularly due to its low power consumption and cost, there is a significant challenge to achieve performance comparable to existing single and dual-band radios. Furthermore, it is difficult to cover all of these bands using the same type of monopole antennas already in common use. Our design employs a multiband antenna-transceiver interface consisting of an RF multiplexer which yields acceptable overall performance for operation in public safety frequency bands using a simple monopole antenna. An FPGA is used to implement all the digital signal processing and a small Gumstix computer including a touch screen LCD is used as a user interface.