Research On Generation And Detection Technique For The Medium And Long Distance Chirp-ewb Signal

Chirp-EWB(Chirp-Extreme Wide Band) has its own advantages in medium and long distance communication because of its several GHz bandwidth. Compared with general UWB(Ultra Wide Band), Chirp-EWB can increase the communication distance through broadening the bandwidth of the signal and would not interfere with the existing communication system. The detection of the Chirp signal is also easier than that of general UWB. It can further expand the area of UWB application. At present, the Analog-to-Digital Converter can not reach the demand of the generation and detection of the Chirp-EWB signal with several GHz bandwidth. Based on the summary and analysis of the existing methods, the techniques of generation and detection on Chirp-EWB signal are studied in this dissertation, the main achievements are included:1. The generation of Chirp-EWB signalThis dissertation analyzes the existing generation methods of Chirp signal. Particularly, for the method based on VCO, the output signal has the disadvantages of low linearity and the frequency of signal drifting with the change of temperature. To solve the problems, this dissertation proposes one generation method of Chirp signal by using VCO based on combining voltage homing and frequency offset estimation. By homing the primary value of the voltage and using frequency in every period of the signal to estimate the frequency offset, the proposed method can keep the output frequency of both VCO at receiver and transmitter the same and correct the nonlinearity of VCO. The proposed generation method can generate Chirp-EWB signal with several GHz bandwidth and high linearity up to 10-5.2. The detection of Chirp-EWB signal1) To solve the problem of high sampling rate due to the multipath effect when receiving the Chirp-EWB signal, this dissertation proposes one receiving program based on group delay equalization after channelization. The program applies an analog and digital channelized method after completing the active spectrum compression of the Chirp-EWB signal. It can reduce the sampling rate and processing speed of the system. The group delay of the channel would cause distortion to the signal after active spectrum compression, which would influence the performance of the program. This dissertation designs the group delay equalizer to overcome this problem.2) Multipath delay would result in false peaks after active spectrum compression, which would influence the multipath delay estimation result. One method for multipath delay estimation based on two-phase energy accumulation is proposed in this dissertation. The method accumulates the energy of the signal after active spectrum compression in two phases. Simulation results show that the method can eliminate the influence of false peaks and estimate the multipath delay correctly.