Low-orbit satellite spread spectrum communication system signal capturing and tracking system

Abstract

The invention relates to a low-orbit satellite spread spectrum communication system signal capturing and tracking system. The system disclosed by the invention has the advantages of interference resistance, high capturing speed and high tracking efficiency. The system is implemented through the following technical schemes, a receiver obtains a digital low-intermediate frequency signal after frequency mixing and filtering through a frequency mixing and filtering module and analog-to-digital AD conversion through an ADC module; a digital baseband signal is obtained through digital down-conversion of an orthogonal down-conversion module and low-pass filtering of a low-pass filtering module, the digital baseband signal is divided into two paths to be sent to a correlation capturing module and a tracking module respectively, the correlation capturing module carries out correlation processing on the digital baseband signal through a parallel capturing algorithm based on FFT, obtains a code phase and a Doppler frequency offset rough estimation value, and captures a carrier frequency and a code starting point of a spread spectrum signal; the tracking module accurately estimates the digital baseband signal; and the correlation capturing module and the tracking module continuously correct the frequency and the phase through carriers NCO and codes NCO to realize synchronization and rapid capturing of the long address codes, and finally the communication information of a satellite signal is obtained through analysis of an information analysis module.

Description

technical field [0001] The invention relates to a low-orbit (LEO) satellite communication signal capture and tracking system, more specifically, a low-orbit satellite spread-spectrum communication system signal capture and tracking system used in a spread-spectrum system. Background technique [0002] With the development of satellite mobile communication technology, in addition to geostationary orbit (GEO) satellite communication systems, modern satellite communication systems also have medium and low orbit satellite communication systems, which have communication advantages such as small transmission loss and low delay, and cellular communication The development of technologies such as , multiple access, and frequency reuse also provides technical support for low-orbit satellite mobile communications, so the low-orbit satellite communication system is considered to be the latest and most promising satellite mobile communication system. With the rapid growth of mobile commu...

AI Technical Summary

Problems solved by technology

However, when the clock frequencies of the PN codes at both ends are similar, the relative sliding speed of the sliding correlation method is very slow, resulting in too long search time

The hardware complexity of the matched filter method is high, and the calculation of the correlation value directly in the time domain is very computationally intensive

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