A Synchronous Decision Demodulation Method Based on Short-time Discrete Fourier Transform

Abstract

The invention provides a multipath delay synchronous decision demodulation method based on short-time discrete Fourier transform. The method comprises the following steps: firstly receiving a carrier signal on a power line by a receiving end, and then filtering out of band noise through a band-pass filter; then performing sampling and quantization on the carrier signal after the band-pass filtering, and performing discretization on the signal; performing short-time discrete Fourier transform on a discrete sequence obtained by the discretization; performing approximating to obtain amplitudes at two carrier frequency; selecting the optimal branch; and performing demodulation decision by using the optimal branch information to accomplish the signal demodulation. The multipath delay synchronous decision demodulation method has the technical effects that the symbol synchronization can be quickly achieved, accurate signal demodulation is also achieved, the system is not affected by the initial phase of the carrier or the carrier frequency estimation error, robustness is high, and the implementation is easy. A simulation result shows that the performance of the method is close to the performance of coherent demodulation. A field operation result shows that the method has a high rate of communication results and is of a practical application value.

Description

technical field [0001] The present invention relates to a non-coherent 2FSK demodulation method, in particular to a multi-channel delay synchronous decision demodulation method based on short-time discrete Fourier transform (Discrete Short-time Fourier Transform, DSTFT), which belongs to the field of communication . Background technique [0002] In recent years, the power line carrier communication technology has gradually been widely used in the power information collection system. Since the power line is a non-uniform distribution transmission line, the channel characteristics of the power network are very bad, which has caused great damage to the power line carrier communication transmission. Therefore, how to improve the accuracy of signal demodulation is crucial to improving the user experience of the power line carrier communication system. [0003] 2FSK modulation is mostly used in current narrowband power line carrier communication systems, and the demodulation of 2...

AI Technical Summary

Problems solved by technology

Coherent demodulation uses carrier frequency and phase information for demodulation, which has good anti-noise performance, but there is an "inverted π" phenomenon, and two synchronous carriers need to be extracted at the same time, which is extremely complex and difficult to achieve in a short time. Therefore, the bit error rate is high in practical applications; non-coherent demodulation schemes are widely used because they do not require carrier extraction. Common non-coherent demodulation methods include frequency discrimination method, zero-crossing detection method, Hilbert method, differential detection method, etc.

However, the performance of some methods is not ideal, and the description of some methods is more complicated, and it is carried out under the assumption that various information is known, which is not easy to achieve

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