A Non-coherent Demodulation Method of Baseband 2fsk Signal Based on Complex Domain Filter

Abstract

The invention belongs to the field of signal processing, and discloses a baseband 2FSK signal non-coherent demodulation method based on a complex domain filter, comprising the following steps: Step (1): performing complex numbering on the positive frequency domain of the baseband 2FSK signal in the first branch Domain band-pass filtering or Hilbert transform, carry out complex number domain band-pass filtering or Hilbert transform to the negative frequency domain of baseband 2FSK signal in the second branch to realize carrier frequency separation; Step (2): separately to the first Carry out full-wave rectification to the result of carrier frequency separation of the first branch and the second branch; Step (3): carry out low-pass filtering to the result of full-wave rectification of the first branch and the second branch respectively to obtain envelope; Step (4 ): subtracting the results of the low-pass filtering of the first branch and the second branch to obtain the baseband data waveform; step (5): according to the bit timing pulse, the baseband data waveform is judged and output to obtain the final demodulation data. In the invention, the positive and negative frequency domains are filtered out respectively, and then the non-coherent demodulation is performed, and the anti-noise performance is stronger.

Description

technical field [0001] The invention belongs to the field of signal processing, in particular to a baseband 2FSK signal non-coherent demodulation method based on a complex domain filter. Background technique [0002] 2FSK is binary digital frequency modulation, that is, binary frequency shift keying, which uses the frequency of the carrier to transmit digital information, that is, uses the transmitted digital information to control the frequency of the carrier. The 2FSK signal is that the symbol "0" corresponds to the carrier frequency f1, and the symbol "1" corresponds to the modulated waveform of the carrier frequency f2, and the change between f1 and f2 is instantaneous. When a "0" signal is transmitted, a carrier frequency of f1 is sent; when a "1" signal is transmitted, a carrier frequency of f2 is sent. It can be seen that FSK uses carriers of different frequencies to transmit digital messages. [0003] Generally speaking, there are two methods for 2FSK signal genera...

AI Technical Summary

Problems solved by technology

But for the baseband 2FSK signal, because the carrier frequency in the positive and negative frequency domains is symmetrical about the zero frequency, the traditional envelope detection method needs two branch bandpass filters to filter out the corresponding carrier frequency, and its frequency response is also symmetrical about the zero frequency. , so it is not suitable for baseband 2FSK signal demodulation

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