A new UHF autotune communications system for ships

A UHF radio system for ship-to-ship and ship-to-aircraft communications has been designed for the Canadian Armed Forces. It is automatically tunable to any of 7,000 channels spaced at 25 KHz intervals from 225 MHz to 400 MHz. Each ship is capable of operating 9 simultaneous links in the simplex mode for plain speech, teletype, digital data or secure speech. This is accomplished using 9 transceivers on each ship feeding into separate multicoupler (band-pass filters) and antenna subsystems for the transmit and receive functions. New techniques of system construction allow the transmitters to operate on "adjacent" channels at frequency separations down to 600 KHz and at the intermodulation frequencies of the same ship transmitters. Omni-directional coverage to the radio horizon has been achieved by making the common transmit and common receive antennas of a 'wrap-round' design. These design considerations may have application in the land mobile radio field for multitransmitter base station design.