Research On Parameter Estimation Of Phase Modulation Signals Based On FRI

Phase modulation signals are widely used in communication and radar systems because of their advantages such as flexible coding,strong anti-interference ability and easy implementation.Through the estimation and analysis of the parameter of the radar and communication radiant source,it can be familiar with the system and use of the enemy radar and the content of the communication,then it is easy to interfere and attack the communication system.Its importance is self-evident.In order to solve the problem of high sampling rate and high sampling number in the current parameter estimation methods,this thesis proposes methods of the parameter estimation of the phase modulation signal based on the sub-Nyquist sampling theory.The finite rate of innovation(FRI)sampling theory has great advantages in parameter estimation because of its characteristic of parametric sampling.Therefore,this thesis mainly studies the parameter estimation method based on the FRI sampling theory,and proposes a single channel sampling system and two multi-channel sampling systems for the phase modulation signal,The specific contents are as follows:1.The phase modulation signal model is studied.Its parameter characteristics are analyzed,and its parametric modeling is performed,and its rate of innovarion is calculated.The evaluation index of the sampling system to be designed and the parameters to be estimated are confirmed.The basic theory of FRI sampling is firstly analyzed.The concept of FRI sampling frame and sampling process are studied.Taking the periodic pulse train as an example,the sampling and reconstructing process of the FRI sampling theory are introduced in detail.2.The piecewise sinusoidal signal model and phase modulation signal model are analyzed and compared.The FRI sampling method of the piecewise sinusoidal signal is simplified,then a single channel sampling system for the phase modulation signal is proposed by analyzing the relationship between the signal spectrum and the signal parameters.In order to further reduce the equivalent sampling rate,a multi-channel feedback sampling system is proposed.Through the nonlinear processing of sampled data,the modulation information is removed,and the carrier frequency of the phase modulation signal is estimated by the single harmonic signal frequency estimation method.Using the estimated carrier frequency,the phase modulation signal is demodulated to the baseband and transformed into a typical FRI signal,Then the location of discontinuities and phase are estimated.In order to further simplify the sampling structure and reduce the complexity of hardware implementation,a multi-channel cooperative sampling system is proposed.3.the modularized hardware structure that consists of baseboard and signal processing module is put forward,and the schematic diagram and PCB design of the baseboard is completed.The Lab VIEW host computer program is writted to control NI PXIe device to complete analog signal output and acquisition,and host computer reconfiguration and other functions.The effectiveness and performance of the proposed sampling systems are verified by simulation experiments.Aiming at the phase modulation signal whose carrier frequency does not exceed 20kHz,the sampling and parameter reconstruction process are completed in the experimental platform by the multi-channel cooperative sampling system,and the normalized mean square error of the estimated value is less than-20dB.