Research On Detection Technology Of TDDM-BOC Modulation Signal

With the rapid development of spread spectrum communication technology, DirectSequence Spread Spectrum (DSSS) communication technology becomes the importantcommunication way of the nowadays navigator system, like DSSS communicationtechnology that American GPS, European Galileo and Chinese BD adopt. For the sakeof avoiding the interaction and overlap of civil signals and military signals, AmericanGPS and European Galileo navigator system adopt Binary Offset Carrier (BOC)modulation technology; moreover, in order to further improve anti-interference andtracking precision of the transmission signal, Time Division Data Modulation (TDDM)is adopted based on BOC modulation technology, and generates TDDM-BOCmodulation signal.TDDM modulation technology adopts the strategy that the odd chips aremodulated, the even chips are not modulated for the navigator message. The modulationway that makes the transmission signal be no data has many advantages, like it canmake the transmission signal be a better anti-interference and low probability ofinterception, and can advance the tracking precision of the signal. As TDDM-BOCmodulation signal is applied in the navigator system, its detection technology is muchmore researched.The characteristics of TDDM-BOC modulation signal are thoroughly researched inthe paper, and uses quadrate correlate peak equal space detection algorithm toimplement the detection of TDDM-BOC modulation signal existence. Then, the carrierfrequency is estimated through the correlation accumulation-square multiplefrequencies, the carrier frequency estimated is used to demodulate the receiving signals.And the sub-carrier frequency and pseudo-code speed rate are estimated through thesedetection algorithms, such as peak equal space detection, peak average detection,equation detection and least squares-correlation accumulation detection, four detection algorithms is contrasted and analyzed, with the increase of signal noise ratio and errorcode proportion, the estimation precision of all the parameters is reduced. Simulationresult proves that these detection algorithms are simple, and they can detectTDDM-BOC modulation signal and estimate the carrier frequency, sub-carrierfrequency and pseudo-code rate.