Acoustic Doppler compensation using feedforward retiming for underwater coherent transmission

This paper presents a Doppler compensation architecture to maintain a reliable communication link at the receiver in highly mobile applications. It can recover both symbol timing and carrier frequency offset introduced by the Doppler effect. The standard feedback timing recovery loop has been modified into a feedforward architecture to achieve fast timing convergence and power efficiency. The timing error is tracked by a Gardner detector through all samples before decimation. Further, a control unit uses the timing error information to dynamically adjust the sampling time as well as the carrier frequency offset such that the Doppler shift is fully compensated.