A Pseudocode Delay Measurement Method for High Dynamic and Low SNR Spread Spectrum Signals

Abstract

The invention discloses a measuring method for pseudo code delay of a spread spectrum signal with high dynamic range and low signal-to-noise ratio. A spread spectrum receiver is used for performing ADC (Analog to Digital Converter) sampling on an intermediate frequency analog signal; the intermediate frequency analog signal is subjected to digital downconversion to obtain a baseband complex signal r(k)=I(k)+jQ(k); the baseband complex signal is simultaneously outputted to a pseudo code capturing unit, a carrier and pseudo code closed-loop tracking unit and a pseudo code time delay open-loop estimation unit; the carrier and pseudo code closed-loop tracking unit is used for tracking carrier frequency and pseudo code phase according to the captured doppler frequency and pseudo code phase information; a pseudo code time delay measuring pulse is used for outputting the doppler frequency and the pseudo code phase information to the pseudo code time delay open-loop estimation unit and outputting the pseudo code phase information to a pseudo code time delay calculation unit; the pseudo code time delay calculation unit is used for correcting closed-loop tracking measurement data of the pseudo time delay by using the open-loop estimation result and realizing quick high-precision measurement of the pseudo time delay. By the adoption of the method, the quick high-precision measurement of the pseudo time delay in the complex environment can be realized.

Description

technical field [0001] The invention relates to the technical field of time difference positioning of a spread spectrum system, in particular to a method for measuring time delay of a pseudo-code spread spectrum signal with high dynamic and low signal-to-noise ratio. Background technique [0002] Time difference positioning, also known as hyperbolic positioning, is a passive positioning technology. It uses the time difference of the target signal to reach multiple receiving stations, and determines the position of the target according to the principle of hyperboloid intersection. The time-difference positioning system based on the spread spectrum system has the characteristics of good concealment and high positioning accuracy, and has been rapidly developed and widely used. The key is to quickly and accurately measure the pseudo-code delay. [0003] The author, Yang Jingchao, published a journal document titled "Research on High-precision Time Delay Measurement Technology ...

AI Technical Summary

Problems solved by technology

On the one hand, high dynamics and low signal-to-noise ratio bring great challenges to the carrier tracking of spread spectrum signals

On the other hand, the measurement accuracy and speed of pseudo-code delay are a pair of mutually restrictive factors. The smaller the bandwidth of the DLL loop, the higher the measurement accuracy of pseudo-code delay, and the longer it takes for the DLL loop to stabilize.

In some complex environments, the frequent interruption of the spread spectrum signal makes the pseudo-code loop unable to achieve a stable tracking state, which brings difficulties to the rapid and high-precision measurement of the pseudo-code delay

In this case, there is no way to quickly obtain high-precision pseudo-code delay

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