High-dynamic weak-signal rapid capture method for direct sequence spread spectrum system

Abstract

The invention discloses a high-dynamic weak-signal rapid capture method for a direct sequence spread spectrum system, belonging to the field of radio communication. Because a spread spectrum carrier has a chirp signal characteristic under the condition of high-dynamic motion (high-speed and high-acceleration), the high-dynamic weak-signal rapid capture method comprises the steps of: firstly, carrying out carrier Doppler frequency compensation by using a time frequency focusing characteristic of fractional order Fourier transform; secondly, carrying out incoherent accumulation on a spread frequency signal by using an order resolving capacity of the fractional order Fourier transform; and finally, carrying out capture judgment on the signal in an order Fourier domain by using a constant false alarm rate detection technology. According to the invention, the difficulty of incapability of long-time coherent accumulation under the high-dynamic condition in the traditional Fourier transform based rapid capture method is solved; and under the condition of high dynamicity and low signal to noise ratio, the signal to noise ratio is effectively increased and the signal capture time is shortened. In addition, a rapid algorithm exists in the invention and is easy to realize on the engineering in real time.

Description

A Fast High Dynamic Acquisition Method for Weak Signals in Direct Sequence Spread Spectrum Systems technical field The invention belongs to the field of wireless communication, and in particular relates to a synchronization method of a spread spectrum communication system, which realizes fast capture of spread spectrum signals under high dynamic and low signal-to-noise ratio conditions. Background technique Direct Sequence Spread Spectrum (DSSS) has the advantages of anti-interception, anti-jamming, anti-multipath fading, and easy realization of multiple access communication and high-precision measurement. It is widely used in broadband wireless communication, navigation and positioning, etc., such as CDMA ( CodeDivisionMultipleAccess) communication system, GPS (GlobalPositioningSystem) navigation and positioning, etc. In the direct spread system, the pseudo-code synchronization is the premise of the normal despreading and demodulation of the receiver, and the synchronizat...

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Problems solved by technology

In the direct spread system, in order to solve the problem that the traditional method is difficult to quickly capture the spread spectrum signal under the condition of high dynamic (high speed, high acceleration) and low signal-to-noise ratio, the present invention proposes a method based on fractional Fourier transform quick capture method

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