Waveform Design And Signal Processing Of Discontinuous Spectrum

There are a lot of interferences in HF radar working frequency band, it is difficult to find a continuous spectrum to satisfy the requirement of system bandwidth. Discontinuous spectrum signal avoids interference in frequency domain from the perspective of waveform design to reduce the interference of the outside world, at the same time the use of multiple frequencies can also meet the requirements of system bandwidth.At first, this paper gives the classification of discrete spectrum signal, compares the advantages and disadvantages of the discontinuous spectrum signal blocking in transmitting terminal and receiving part. This paper derives the spectrum expression of the discontinuous spectrum of linear frequency modulation signal and discontinuous spectrum OFDM signal based on some existing theories. Then take the ideal rectangular spectrum for example, the discontinuous spectrum resolution characteristics are analyzed, and discuss the change of signal frequency share name resolution and the influence of the inherent resolution.Then analyses the discontinuous spectrum of linear frequency modulation signal, the signal of the ambiguity function has been derived theoretically, size and band of discontinuous intermittent position influence on the distance spectrum side lobe after the pulse compression are discussed, simulation shows that:the distance spectrum side lobe is higher after the pulse compression if the intermittent frequency band is greater, there exists the greatest band position to make the distance spectrum side lobe lower after pulse compression. This paper analyses the signal processing of discrete spectrum of linear frequency modulation signal, the conventional matched filtering can have higher side lobe as a result of the phase jump, therefore, a mismatch filter is adopted to improve the side lobe suppression, respectively, using the least squares algorithm and iterative least squares algorithm for the solution of the mismatch filter coefficients.Then the discontinuous spectrum OFDM signal is analyzed, the ambiguity function of discontinuous spectrum OFDM signal is derived, peak of OFDM signal than was discussed, Using PN modulation can effectively reduce the peak of OFDM signal. For discontinuous spectrum OFDM signal, disable department will make the molecule carrier signal peak than have certain changes, then discuss the influences of band size and location of the intermittent to the distance spectrum side lobe after pulse compression, simulation shows that:the distance spectrum side lobe is higher after the pulse compression if the intermittent frequency band is greater, there exists the greatest band position to make the distance spectrum side lobe lower after pulse compression. Finally adopt the time domain and frequency domain signal processing to process the.discontinuous spectrum OFDM signal.