Sampling And Adaptive Filtering Of Rada Echo Signal

Signal sampling and direct wave suppression of radar echo signal are researched in this paper. Firstly, paper introduces research background and its sense, as well as international research condition currently. Then the characteristic of FM signal and FM broadcast is analysed. As for the FM broadcast with high frequency and narrow band, the principle and realization of bandpass sampling are researched later. And the effect of bandpass over-sampling to SNR is simulated thereafter.Based on data processing demands for radar signal, two synchronous sampling channels are needed. Besides, the target echo signal is often weak with strong noise, so data acquisition (DAQ) card should sustain high sampling frequency and resolution. PCI9820 of ADLINK is chosen because of good character. It can sample two channels simultaneously. Its SFDR is 75dB and its resolution is 14 bit. Moreover, the maximum sampling frequency it can bear is 130MS/S。Paper analyses the hardware characteristic of PCI9820 in the way of analog inputs, data sampling, data storage, triggering, calibration, multiple cards synchronization etc., and some corresponding resources are chosen for research, which provides foundation for the following software developing.Then sampling software based on C/C++ is designed in VC++6.0 for PCI9820. As for various sampling needs, programs used for auto calibration, specified data count sampling, real-time sampling, mixed sampling of the above two and circle sampling of specified data count sampling are designed. Besides, internal functions used in these programs are also explained. All the program flow charts, as well as running interfaces and core parts of some programs, is showed in paper. These programs are independent one another, used to realize different sampling modes. The design logic is clear and fluent, with pellucid operation method and high-efficiency interface. After debugging, it is used to do lots of experiments in lab, then in radar station. It turns out that these programs run steadily and satisfy real requirements well.Later, sampling software based on MFC is also designed in VC++6.0 for PCI9820. All the independent programs designed before are included. And it possesses friendly interface, which facilitates the input and display of sampling parameters etc. Its running interface and operation manual are given in paper. After debugging, it is used to do lots of experiments in lab before in radar station. It runs steadily, realizes its designing functions and satisfies real requirements well. Users can choose from programs based on different design modes to work for your purpose.Because there is strong direct wave in radar echo signal received by radar target antenna, the direct wave should be suppressed, or it is very difficult to do the following DSP such as Doppler frequency and range estimation etc. So, the LMS adaptive arithmetic is introduced. And the program for it is designed in MATLAB. As for...