CODEC (Code/Decode) for Digital Buoys in a Harsh RF Environment

"In a tactical deployment of ADAR sonobuoys, a number of VHF "wideband" channels are used for the uplink communication between each sonobuouy and a tracking aircraft. In littoral environments close to shore-based commercial and other radio frequencyemissions, the uplink frequency bands are subject to in-band radio frequency interference (RFI). Such RFI can result in a significant probability of failure of an ADAR tactic requiring a certain minimum number, say 8 or 4, of clear channels.Several possible and feasible approaches have the potential of offering substantially improved performance for the uplink communications in the assigned VHF bands for ADAR tactics. Current systems for satellite data links, wireless mobile telephony,terrestrial digital TV transmission, and generally digital data links, successfully deploy a variety of more sophisticated modulation and coding strategies. Under this Phase I effort we propose to consider the applicability of some promising techniques ofmodulation and coding for ADAR deployment, drawing upon the developments in data communications over the last two decades. The proposed improvements can have significant performance advantages for the current ADAR system: Not only will an increase in immunity to RFI interference be possible, but the efficiency and lower BER can also allow for trade-offs in channel assignmentsand use of buoy power. Further, the same techniques apply to future digital sonobu