TECHNIQUE FOR ACQUIRING TIMING AND FREQUENCY SYNCHRONIZATION FOR MODEM UTILIZING KNOWN (NON-DATA) SYMBOLS AS PART OF THEIR NORMAL TRANSMITTED DATA FORMAT

摘要

ABSTRACTA signal processing scheme through which the receivermay, at any time, synchronize or resynchronize itself to thetransmitted data signals that are received over a dynamicdispersive channel. At the transmitter, bursts or sequencesof known symbols are interleaved with unknown data. At thereceiver incoming frames of signals (containing interleavedbursts of known data and unknown data) are processed in amanner similar to the processing of spread spectrum encodeddata. A replica (or respective replicas) of the known signalburst(s) is (complex) correlated with the incoming signal tolocate and lock onto a known (PN) reference symbol burst.Once a known symbol block has been located, a symbol rateclock (bit sync) is adjusted to track out any offset in thetiming used for sampling the received data. This is followedby coarse and fine frequency offset adjustments to enable thelocal oscillator to lock onto the transmitted frequency.48