Research And Implemention Of Radar Signal Modulation Identification

To extract parameters of emitters quickly and efficiently is the premise of the radiationsources identification under the increasingly complex electromagnetic environment.As thedynamic of the parameter of modern radar signal, not only the modulation mode becomesmore and more complex, but also dynamic range and frequency variation become large, thenew radar system can’t be recognized just by the conventional characteristic parameters ofradar signal.Only by analysising and extracting new effective radiation characteristics cannew radar system be identificatied.This paper analyzed the identification method of various radar signals (conventionalsignal, linear frequency modulation signal (LFM), nonlinear frequency modulation signal(NLFM), biphase code signal (BPSK), quadrature phase code signal (QPSK), frequency codesignal (FSK)), which was more focused on the actual hardware implementation. Thesemethod was analyzed by simulation with its error size under different input signal given.Some of these method was finally chosen and realized on FPGA to design a digital receiverwhich can realize real-time frequency measurement and pulse signal recognition. Thisreceiver adjusts to pulse width:200ns~500us, input signal frequency ranges from250MHz to350MHz, input signal dynamic ranges to50dB, can realize fast frequencymeasurement and signal type recognition of frontier and intra-pulse signal.Therefore, the main content of this article is:First of all, the sampling theory, commonly method of digital orthogonal transform andthe extraction of phase difference were given, these were the key technologies of the receiver.Second, several method of fast frequency measurements suitable for short data wasgiven and its error was simulatied. On the foundation, three-point frequency measurementalgorithm based on improved Rife was proposed, and the performance of different frequencymeasurement method were compared on the same input signal condition.This paper analyzed the time and frequency domain properties of radar intra-pulsemodulation in detail, gave the time and frequency field simulation diagram according to thedifferent signal characteristics. Different signal identification method was put forwardaccording to the time domain or domain features, recognition method and recognition conditions were given under multiple input signal. All situation was simulated to proved theeffectiveness of these methods.Again, the three-point frequency measurement algorithm based on improved Rifeproposed above,signal type identification method and the several signal recognition methodwere realized and programmed on the FPGA with its implementation steps introduced indetail. The practicality of these methods were verified by system overall test.