A Low Computational Complexity Estimation Method for Doppler Factor in Underwater Acoustic Communication

Abstract

The invention provides a doppler factor estimation method with low computation complexity and relates to water sound communications. A transmission data packet structure is designed. LMP singals, protection intervals and continuous wave (CW) signals are inserted before the to-be-sent data. The doppler factor estimation method comprises two steps of: firstly, using an FFT frequency measurement method for the CW signals, and locking doppler factors in a quite small range; and precisely estimating the doppler factors for the LFM signals by use of a fuzzy function method. In the fuzzy function method, the quantity of correlators is determined by the doppler factor range required to be searched and the estimation precision of the doppler factors. According to the invention, the searching range is the doppler factor range determined in the first step, so the searching range is greatly reduced and fewer correlators are required; and by use of the characteristics of the CW signals and the LFM signals, on the premise that the absolute value of the estimation error is smaller than or equal to the estimation precision, the computation complexity is greatly reduced and doppler factor estimation method with low computation complexity can be easily achieved.

Description

【Technical field】 [0001] The invention relates to underwater acoustic communication, in particular to an estimation method of Doppler factor for underwater acoustic communication based on joint estimation of an FFT frequency measurement method and an ambiguity function method. 【Background technique】 [0002] Underwater acoustic communication not only has great application value in the military field, but its application value in civilian fields has become more and more prominent in recent years, such as marine water quality monitoring, marine disaster early warning and search and rescue, resource exploration, etc. At present, my country's underwater acoustic communication technology is still in its infancy, and it is mainly used in occasions where the transmission rate is low and the moving speed is small. This is because the development of the underwater acoustic communication system is greatly limited by the conditions of the underwater acoustic channel. Compared with other...

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Problems solved by technology

In underwater acoustic communication, the Doppler factor estimation method based on the FFT frequency measurement method is also widely used. This method has a small amount of calculation and strong real-time performance. Its detection accuracy is limited by the duration of the CW signal and the number of transformation points. Simple Relying on increasing the number of effective data points to improve the frequency detection accuracy (that is, the duration), on the one hand increases the complexity of the calculation, and more importantly, in practical applications, the number of effective data points transmitted cannot be increased arbitrarily, so this method Difficult to achieve ideal accuracy

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