System and method for matched filtering of spread spectrum signal based on frequency domain processing

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

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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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