Modulation mode identification method based on all-digital receiver

Abstract

The invention discloses a modulation mode identification method based on an all-digital receiver. The method comprises the following steps: 1, carrying out FFT (Fast Fourier Transform) on a measurement and control signal received by receiving equipment, and estimating a carrier frequency and a 3dB bandwidth; 2, completing down-conversion, filtering and resampling by using the estimated carrier frequency; 3, tracking the frequency offset of the orthogonally decomposed low-frequency signal through a phase-locked loop, and distinguishing an FSK signal and AM _ FM and MTONE _ FM signals by using afrequency tracking curve; and 4, carrying out FFT conversion on the frequency tracking curve containing the modulation information to identify AM _ FM and MTONE _ FM signals. The method has the advantages of being simple in calculation amount and easy to achieve in hardware. According to the method, the FSK signal and the composite modulated narrow-band FM signal can be accurately judged in the full-digital receiver, and the recognition accuracy is better than that of a traditional signal instantaneous spectrum recognition method.

Description

technical field [0001] The invention is mainly aimed at signal detection and frequency estimation, and mainly relates to a modulation mode identification method based on an all-digital receiver. Background technique [0002] In the actual electronic reconnaissance environment, the transmitted signal is often accompanied by a mixture of wideband digital modulation signal and narrowband signal, which requires research on the modulation method identification of the received communication signal. And in the case that the various parameters of the signal (signal bandwidth, modulation mode) are unknown, it makes the signal reconnaissance and identification more difficult. [0003] The currently used modulation method identification methods mainly include the identification method research based on signal cyclic spectrum, the identification method research based on signal high-order cumulant, the identification method based on signal constellation diagram, and the identification me...

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Problems solved by technology

These two methods have a large amount of calculation, the calculation process of parameter extraction is difficult, and the real-time online analysis of signals is poor, so it is difficult to apply in actual engineering projects.

[0004] Based on the above analysis, it can be seen that the current modulation identification method is mainly for PSK / QAM signals, and for the identification of narrow-bandwidth analog-digital mixed signals, the identification performance of the current identification method drops rapidly.

Moreover, the current recognition algorithm has a large amount of calculation and is difficult to implement on hardware.

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