Offset Estimation Techniques In Digital Communication Systems

In the digital communication system, synchronization appears especially important. The intelligence signal transmitted in the digital communication is the coded element sequence, using this sequence to change some or several parameters of the carrier to implement the digit carrier modulation. Usually from enhances the resistance to interference and the frequency band use factor embarks, widely uses phase-shift keying (PSK), smallest frequency-shift keying (MSK), and so on quadrature amplitude modulation (QAM). Usually, this kind of communications system belongs to the phase coherent communications system, when the receiver must provide the coherent carrier.This paper closely conducts the research of carrier synchronization's method, has carried on the preliminary introduction to several classical estimate algorithms. Then theoretical elaboration carrier synchronization and carrier frequency offset estimate elementary theory, including the signal parameter estimate value theory and the carrier parameter estimate value method. Then further thorough introduction has arisen several methods of split-ring carrier estimate in burst communications.This paper proposed one kind of fast Fournier transformation(FFT) & the carrier frequency tracks ring circuit's carrier frequency offset to estimate and to restore the method. Namely uses the FFT carrier frequency offset to estimate that first corrects the big frequency offset, based on this uses the carrier frequency track ring circuit to correct the small frequency offset, serves fast, the precise carrier synchronization purpose by the time.