Abstract: A transceiver has digital transmitting capability. The transceiver includes an antenna having an input for transmitting signals applied thereto. Signal generating means generate first and second signals having first and second frequencies, and transmission means selectively couple the first and second signals to the antenna input in response to first and second micro commands respectively. A processor receives manually chosen messages for transmission comprised of a series of binary encoded symbols. In response thereto, the processor sequentially generates for a predetermined time interval the first micro command for each one bit and the second micro command for each zero bit to be transmitted.

Abstract: A system for determining the position of a ship in relation to predetermined positions on the ocean floor is disclosed. A plurality of first acoustic addressable transponders and a plurality of second acoustic addressable transponders are respectively located at first and second sets of predetermined positions on the ocean floor. Each of the acoustic transponders transmits an acoustic ranging response and identification signal in response to receipt of an acoustic ranging interrogation signal. First and second buoy communications systems are located on first and second buoys respectively moored to the ocean floor in the vicinity of the first and second pluralities of acoustic transponders.