Chip implementing fast high-efficient non-cooperative signal-noise ratio direct spreading signal detection method

Abstract

The invention relates to a method for detecting direct sequence signals, which can be realized by a chip and has rapid speed, high efficiency, none cooperation, low signal-to-noise ratio. The method comprises the following steps: pre-collating received data, pre-calculating FFT, estimating consolidation biased autocorrelation functions, synthesizing consolidation unbiased autocorrelation functions, calculating four-level cross-correlation statistics quantity, and supposing examination. The method uses a covering principle (MCT) with FFT as a core and uses maximum cost to calculate main elements in a detector with optimum principles, and then an optimum detector can be rapidly and approximately realized through detecting symbolic code period parameters. The saved calculation amount and the size of a memory of the method are two magnitude orders more than that of the optimum detector. The mode of modulating signals has wide application range, wide Doppler frequency shift is tolerated, the constant false alarm rate and the detecting precession of the parameter are high, the detecting performance is much better than an existing symbolic code period detector, and the problem that OPSK or higher digital phase modulation DSSS signals can not be detected by a carrier frequency detector under low signal-to-noise ratio is solved.

Description

technical field [0001] The method belongs to the field of communication technology, and is specifically applied to frequency band management, signal interception and distress information analysis, and can also be used in a self-organized sensor network or as a realization of a new generation of spread spectrum communication network. It is a fast realization method of directly approximating the optimal detector of direct sequence spread spectrum signal with all parameters unknown under very low signal to noise ratio. [0002] DSSS (Direct Sequence Spread Spectrum, referred to as DSSS) signal is a typical signal with confidentiality characteristics. In many non-cooperative applications, if the parameters of the DSSS signal such as the carrier frequency f are not available to the cooperative receiver in advance c , symbol rate R, pseudo code period T p Like the pseudo code sequence, the signal is difficult to be detected at a low signal-to-noise ratio. The detection method that...

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Problems solved by technology

The disadvantage of the above algorithm is mainly that the performance is not good when the signal-to-noise ratio is low, and it can only achieve above -15dB (in the case of code length L≤1023) (see Table 1)

These methods are difficult to use as the main detection method for low signal-to-noise ratio DSSS signals

In addition, if it is considered that the sampling rate and the symbol rate in practical applications are often not in integer multiples, the pseudo-code period estimated by the above algorithm is only an integer approximation of the real pseudo-code period

Due to the large error, these algorithms are also difficult to perform the task of accurately estimating the period of the pseudo code

[0018] In short, there are many weaknesses in the existing DSSS signal detection methods, especially in low signal-to-noise ratio and high-order digital modulation, there is still a considerable distance from practicality

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