Digital communication signal modulation recognition method based on preprocessing noise reduction

Abstract

The invention provides a digital communication signal modulation recognition method based on preprocessing noise reduction, which comprises the following steps: S1, constructing a modulation signal according to a carrier frequency, a code part rate and a sampling frequency, and carrying out noise adding processing; s2, carrying out noise reduction preprocessing on the signal after noise adding processing by using an adaptive filtering technology; s3, extracting wavelet transform features and high-order accumulation features of the signals after noise reduction preprocessing; s4, inputting the wavelet transform features and the high-order accumulation features into a BP neural network for network training; and S5, recognizing a modulation mode of an unknown signal by using the trained BP neural network. According to the method, a communication signal containing noise is preprocessed by using an adaptive filtering technology so as to improve the signal-to-noise ratio of the signal, then wavelet transform and high-order cumulant characteristics of the signal are extracted, and finally the wavelet transform and high-order cumulant characteristics are input into a neural network classifier, so that a better recognition effect can be obtained in a low signal-to-noise ratio environment.

Description

technical field [0001] The present invention relates to the technical field of communication, and more specifically, to a method for identifying modulation of digital communication signals based on preprocessing and noise reduction. Background technique [0002] With the increasingly complex communication signal system and modulation style, and the increasingly harsh signal environment, the identification of modulation types in non-cooperative communication has become crucial in both military and civilian fields. In actual communication, the signal-to-noise ratio of the signal may be very low. At present, the automatic modulation recognition method of the communication signal under the low signal-to-noise ratio is not effective. [0003] In 1986, Hipp et al. first proposed the method of using the high-order cumulant of the signal as a feature for modulation recognition. Since then, the research on the characteristic parameters of the high-order cumulant has been further deve...

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Problems solved by technology

The patent does not identify the modulation method of low signal-to-noise ratio signals in actual communication

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