A frequency domain processing based spread spectrum signal matched filtering system and method

Abstract

The invention discloses a system and a method for matched filtering of a spread spectrum signal based on frequency domain processing. In the invention, the spread spectrum signal is sent to a data caching module through an odd-even sequence gating module, data output by the data caching module is sent to a fast Fourier transform module to figure out a frequency spectrum and the frequency spectrum is sent to an odd-even sequence spectrum separation module, and a frequency spectrum of an input digital signal is obtained by an output result through a spectrum synthesis module. The frequency spectrum of the input digital signal is input into a coefficient matching module, and a digital spread spectrum signal autocorrelation result is obtained through multiplication, addition and shift operations with matching coefficients. According to the system and the method, frequency mixing and filtering are realized in a time domain, a quantization error introduced by frequency mixing and filtering during time domain multiplication can be avoided and hardware resources occupied by processing of a high-order filter are reduced.

Description

technical field [0001] The invention relates to the technical field of digital filtering, in particular to a frequency-domain processing-based spread-spectrum signal matching filtering system and method. Background technique [0002] In the process of digital signal processing in satellite navigation and communication systems, digital spread spectrum signal autocorrelation is used to realize matched filtering of digital received signals. In practical applications, matched filtering can realize functions such as correlation detection of spreading codes and optimal receiver processing. [0003] At present, the matching filtering of intermediate frequency digital spread spectrum signals is basically realized by the method of processing baseband signals after digital down-conversion, mainly including digital mixing, low-pass filtering, data extraction, Fourier transform, frequency domain multiplication of matching coefficients and inverse Fourier transform steps. [0004] Beiha...

AI Technical Summary

Problems solved by technology

[0006] (1) Quantization error is introduced in the process of digital mixing: digital mixing is calculated by multiplying the sampling information and the local oscillator signal of the numerical control oscillator. If the multiplication calculation result is completely preserved, it will take up a lot of storage in subsequent processing space, if the multiplication result is truncated, quantization error will be introduced

[0007] (2), the low-pass filtering process will introduce quantization errors, and the calculation process requires a large number of multipliers

When the order of digital filtering is high, the calculation result must be truncated, which will introduce quantization error and reduce the signal-to-noise ratio of the signal; at the same time, in order to ensure the calculation speed, a large number of multipliers must be used for parallel operation

[0008] (3) The order of the filter will increase greatly with the increase of passband ripple and stopband suppression requirements

This leads to the inability to meet the requirements of the system in the case of limited hardware resources

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