High-dynamic fast acquisition implementation method in spread spectrum measurement and control communication

Abstract

The invention provides a high-dynamic fast acquisition implementation method in spread spectrum measurement and control communication. The method includes the steps of multi-phase rotation, down-sampling data storage, dispreading conducted in segments, HDFT operation conducted in segments, iterative self-adaption threshold calculation, frequency acquisition conducted through threshold judgment, and Doppler frequency offset correction conducted according to the acquired frequency. According to the method, through multi-phase rotation, data pre-storage and offline fast related operation, acquisition time is shortened to a great extent; through HDFT operation and iterative self-adaption threshold calculation, Doppler frequency offset is obtained rapidly and corrected; under the condition that the frequency offset is as high as + / -180kHz and the Doppler frequency change rate reaches 10 kHz / s, acquisition, chip synchronization and Doppler frequency offset correction are conducted on signals by a measurement and control communication receiver within 50 ms, complexity is low, stability and reliability are achieved, and resource consumption is low.

Description

technical field [0001] The invention relates to a method for realizing high dynamic fast capture in spread spectrum measurement and control communication. Background technique [0002] There are three common fast capture methods of pseudocode in high dynamic environment: two-dimensional search, FFT circular correlation, FFT partial matching, etc. [0003] Pseudo-code-Doppler two-dimensional search is to divide the Doppler interval into several segments, and perform pseudo-code acquisition on each small interval. Acquisition time depends on Doppler frequency offset range, frequency search step, chip length, etc. Taking spread spectrum measurement and control communication as an example, the chip length is 1023, the code rate is 10.23MHz, the data rate is 1kps, the maximum Doppler range is ±180kHz, and the frequency search step is selected as 2.5kHz, sliding one chip at a time For real-time sampling and capture, the maximum capture time is 1023×(180×2÷2.5)×1023÷(10.23×10^6)=...

AI Technical Summary

Problems solved by technology

This method searches all code phase units simultaneously within a pseudo-code period, and changes the two-dimensional search into a one-dimensional search in the frequency domain, which greatly reduces the acquisition time, but this method requires multiple FFT operations with large points, among which The single-channel 1024-point FFT operation accounts for 30% of the resources of the V5-SX50T, which consumes a lot of resources

[0005] The FFT-based partial matching correlation acquisition method is to perform a partial correlation operation on the input sequence and the local sequence, perform FFT analysis on the correlation result, and obtain the estimated value of Doppler according to the position of the FFT maximum value. The estimated value of Doppler frequency shift is obtained, thereby changing the two-dimensional search into a one-dimensional search of the pseudo-code phase, reducing the acquisition time. This method requires a small number of points for FFT operations, but the chip search time is still more than 100ms, and it needs to be accelerated To capture, you need to increase the number of FFT points, and the maximum consumption of V5-SX50T exceeds 70% of resources

[0006] The currently used high dynamic capture methods either take a long time to capture or consume a lot of resources, and cannot achieve a balance between resources and capture time

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