A Fast Adaptive Doppler Estimation Method Based on Pseudorandom Sequence Synchronization

Abstract

The invention discloses a fast adaptive Doppler estimation method based on pseudorandom sequence synchronization. The method comprises the steps that 1, a signal sequence received by a receiver is input to a band-pass filter, and out-band noise is filtered out; 2, a signal sequence output by the band-pass filter is subjected to copy correlation by adopting a matched filter, and Doppler coarse estimation is achieved to obtain a Doppler coarse estimation result; 3, in the i estimation, the received signal sequence is correlated with local signal sequences of which the Doppler estimation results are shown in the specification to obtain the i Doppler estimation result (please see the result in the specification), wherein delta i is the i stepping, i is progressively increased to Nfrom 1, and N is the maximum iteration number; and 4, the received signal sequence is subjected to variable sampling by taking the N Doppler estimation result (please see the result in the specification) as the final Doppler estimation result, and then Doppler compensation is achieved. According to the method, the estimation time is greatly shortened, the computing complexity is greatly reduced, and the good adaptive characteristic is achieved.

Description

technical field [0001] The present invention relates to, in particular to a fast adaptive Doppler estimation method based on pseudo-random sequence synchronization. Background technique [0002] In recent years, all countries are stepping up ocean development, exploration and construction of submarine information network. Among them, Unmanned Underwater Vehicle (UUV) has played an extremely important role in the field of marine engineering due to its advantages in intelligence, concealment, mobility, and portability. Therefore, the mobile underwater acoustic communication system designed and applied to UUV high-speed movement is one of the high-tech countries in the world that covers marine technology and information technology. [0003] Wireless communication in the air uses electromagnetic waves to propagate information, and the propagation speed of electromagnetic waves is approximately the speed of light, which can reach 3×10 8 m / s, so in wireless communication, the im...

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Problems solved by technology

[0007] 1) It is necessary to correlate the first and last sequences to obtain the time difference, so it is necessary to save a complete frame signal first, which takes up a lot of memory, does not use real-time implementation, and reduces the effectiveness of high-speed underwater acoustic communication;

[0008] 2) This method is only suitable for Doppler estimation when the channel environment is stable

When the channel is found to change drastically or the channel environment changes due to UUV high-speed movement, the channel impulse response of the first and last sequences is different, and the time difference between correlation peaks is no longer determined by Doppler alone. At this time, the accuracy of Doppler estimation will be significantly reduced or even appear. miscalculation;

[0009] 3) In the actual underwater acoustic channel environment, more time-varying Doppler is used instead of fixed Doppler. The head-to-tail sequence correlation can only obtain the approximate average of Doppler during this period, and the stability is poor.

However, there are two big problems with this technology. One is that the improvement of estimated performance must be at the cost of a sharp increase in calculation and resources, which greatly limits the application of this method in practical systems, especially for A system that requires high Doppler estimation accuracy; second, the estimation performance is determined by the sequence length and the design of the matched filter. Once the design is completed, it is difficult to flexibly adjust the estimation performance according to the actual scene, and the adaptability is poor

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