Long-code spread spectrum signal rapid capturing method adaptive to high dynamic environment

Abstract

The invention discloses a long-code spread spectrum signal rapid capturing method adaptive to a high dynamic environment. The method comprises the following steps: sampling spread spectrum signals by use of an analog-to-digital converter, and then obtaining complex baseband signals through a digital down converter; then in a first residence phase, realizing time frequency two-dimensional search by use of code phase compression and fast Fourier transform, and determining a substantial pseudo code phase compression interval and a frequency offset estimated value; and in a second residence phase, searching each code phase in a code phase compression phase interval one by one by use of a conventional coherent accumulation algorithm. According to the invention, the method has the following advantages: large-interval search is performed on a time domain by use of a code phase compression correlator and parallel search is carried out on a frequency domain by use of the fast Fourier transform so that large dynamic spread spectrum signals can be rapidly captured; and at the same time, the method is quite low in complexity and can save enormous hardware resources.

Description

technical field [0001] The invention relates to a method for quickly capturing long code spread spectrum signals adapted to high dynamic environments in a radio communication and navigation system. Background technique [0002] In direct sequence spread spectrum systems, pseudo code acquisition plays a very important role in establishing a good communication link. In a high dynamic environment, the spread spectrum receiver and the transmitter have a relatively large speed of motion, and considering factors such as anti-interference and anti-interception, a longer spread spectrum code is often used, so for the receiver, the acquisition phase requires The searched code phase and Doppler frequency offset range is very large, and the acquisition time required by the traditional serial acquisition method is very long, which cannot meet the requirements of fast acquisition in a high dynamic environment. [0003] At present, there are three main types of fast acquisition methods f...

AI Technical Summary

Problems solved by technology

In a high dynamic environment, the spread spectrum receiver and the transmitter have a relatively large speed of motion, and considering factors such as anti-interference and anti-interception, a longer spread spectrum code is often used, so for the receiver, the acquisition phase requires The search code phase and Doppler frequency offset range is very large, and the acquisition time required for acquisition according to the traditional serial acquisition method is very long, which cannot meet the requirements of fast acquisition in a high dynamic environment

[0003] At present, there are three main types of fast acquisition methods for spread spectrum signals under high dynamic conditions: (1) using fast Fourier transform / inverse fast Fourier transform to realize pseudo-code phase capture, changing the serial search of code phase into parallel search, However, Doppler frequency shift and symbol flip have a great impact on its acquisition performance, and the acquisition algorithm requires a long Fourier transform resource when capturing long codes

(2) Use fast Fourier transform to capture Doppler frequency offset, combining multiple partial matched filters and fast Fourier transform, the capture speed is very fast, but as the period of the pseudo code becomes longer and the signal Oversampling will consume a lot of hardware resources

However, this capture algorithm increases the demand for hardware resources in the process of frequency compression, and the capture bandwidth of a single dwell is limited by the number of frequency compression channels

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