Signal Performance Analysis Of FMICW

During the near three decades, high-frequency ground wave radar detecting for sea has been regarded for its high performance by many countries. To the principle of single-station high-frequency ground wave detection radar, simple pulse wave was chosen, but this wave has many limitations, so continuous signal wave was preferred. Then to meet the problem of the separate between receiving and transmitting for single-station radar system in continuous wave principle, we introduced frequency modulated interrupted continuous wave(FMICW).In early days,the pseudorandom codes were often used in FMICW.Usually m-sequence is used to intertupt frequency modulated continuous wave. The pseudorandom codes have a good autocorrelation of double-values.In recent years,to solve the problems of anti-interference and the ambiguity of range and velocity,a lot of countries do much research to change the waveform of radar signal.The most important improve is to use symmetrical pulses to interrupt frequency modulated continuous wave(FMPCW).In this thesis, two-dimensional FFT, the basic processing technique of FMICW is introduced first. Based on the analysis of the beat frequency signal,the expression of the beat frequency phase is deduced.The expression indicates physics meanings of quantities to be detected and supplies theoretical bases for detection methods.By using two-dimensional FFT,the range and velocity information of target is got out from the echo.According to the periodicity range ambiguity of symmetrical pulses in FMPCW,the processing method of sliding time window is used. By using the processing method of sliding time window, the problem of the periodicity range ambiguity is solved.Meanwhile,the problem of range ambiguity which is produced because the range of target is biger than the maximum range of radar is also solved by using this method.Then,the pulse width parameter which is the most important in the parameters of FMICW is analyzed.The stricter restrict is given to ensure the range spectrum has only one beat frequency after signal processing.At last this thesis introduces the different signal processing methods of FMPCW and FMICW. Then this paper compares the different time-filter performance of FMPCW and FMICW, and then analyses...