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Underwater acoustic leading signal detection method based on accumulative correlation coefficient (ACC) under sparse channel

A technology of correlation coefficient and preamble signal, applied in transmission systems, transmission channel monitoring, electrical components, etc., can solve problems such as template mismatch, performance deterioration, and unsatisfactory detection performance, and achieve strong robustness, good detection performance, The effect of ideal detection performance

Active Publication Date: 2017-07-21
HARBIN INST OF TECH SHENZHEN GRADUATE SCHOOL
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  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

Among them, the MF algorithm, the underwater multipath channel will cause template mismatch, in addition to the underwater environment noise is unstable and there are various external noises
This makes it more complicated for the receiver to choose an appropriate threshold value; the Page test algorithm is severely affected when the interference duration is short and the frequency band overlaps with Hyperbolic FM (HFM) / Linear FM (LFM) , the detection performance is not ideal; the NMF algorithm does not take multipath into account, and its performance will deteriorate significantly in dense multipath channels

Method used

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  • Underwater acoustic leading signal detection method based on accumulative correlation coefficient (ACC) under sparse channel
  • Underwater acoustic leading signal detection method based on accumulative correlation coefficient (ACC) under sparse channel
  • Underwater acoustic leading signal detection method based on accumulative correlation coefficient (ACC) under sparse channel

Examples

Experimental program
Comparison scheme
Effect test

example 1

[0129] Simulation example 1 (additive white Gaussian noise)

[0130] Gaussian noise with time-varying variance can be expressed as where N(0,σ 2 ) means the mean is 0 and the variance is σ 2 The normal distribution of . Underwater environmental noise is non-stationary, and the non-stationarity of environmental noise poses a challenge for the detector to choose an appropriate threshold.

[0131] This example compares the performance of different detectors with additive white Gaussian noise. attached figure 2 Shown is the simulated ROC curve at SNR=-13dB, and the expansion gain of the HFM waveform is set to 27dB. Under the simulation conditions, the detection performance of MF is better than that of NMF and MF-PT. Obviously, because of the accumulation of multiple main paths, the technology of the present invention, that is, the cumulative correlation coefficient (ACC) detection method has better detection performance than MF.

example 2

[0132] Simulation example 2 (narrowband interference)

[0133] Narrowband interference is usually of long duration and band limited, in special cases it has only one tone, in common cases it has multiple tones and is expressed as:

[0134]

[0135] where f nb [i],A nb [i], φ nb [i] represent the frequency, amplitude, and phase offset of the i-th tone, respectively. Typically, narrowband interference has a longer duration than the pilot signal.

[0136] In this example, the narrowband interferer is a 13.5KHz single tone signal that covers the entire block duration and has three times the power of the preamble. From attached image 3 It can be seen that under narrow-band interference, PT exhibits better detection performance than MF, NMF given its effective normalization step. The accumulative correlation coefficient (ACC) detection technique of the present invention is obviously superior to the above matched filter-based detectors because of the integration of energy n...

example 3

[0137] Simulation example 3 (short-term band-limited interference)

[0138] Short-term band-limited interference, band-limited interference frequency band range [f L , f H ] limited and within the signal frequency band, short-term means that the duration of the interference is shorter than that of the preamble signal. The interference may also be waveforms transmitted by nearby systems for other purposes. Define the interference bandwidth as B 1 = f H -f L , the interference duration is T 1 .

[0139] Without loss of generality, suppose N 1 = [B 1 T 1 ] is an even number. Transfer the interference to the baseband [-B / 2,B / 2), and the baseband signal is expressed as:

[0140]

[0141] where c l As the base coefficient, the corresponding passband signal can be parameterized as

[0142] The short-term band-limited interference in this example is obtained by passing Gaussian white noise with a fixed duration of 33.3ms through a band-pass filter with a center frequ...

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Abstract

The invention provides an underwater acoustic leading signal detection method based on an accumulative correlation coefficient (ACC) under a sparse channel, which is applied to an underwater acoustic communication system under the sparse channel and can be used for reducing the false detection rate of leading signals, increasing the detection rate, improving the detection performance of the system, and increasing the communication efficiency of the system. The method comprises the following steps: performing sparse signal reconstruction and OMP algorithms, achieving the separation of main paths of the sparse channel by using a reconstruction process of the signals, calculating the relevancy between the signals of each path and the transmitted signals, accumulating to obtain a correlation coefficient, and performing leading signal detection based on the correlation coefficient. Compared with the prior art, the underwater acoustic leading signal detection method provided by the invention has the advantages as follows: 1, the method has strong robustness under additive white Gaussian noises and different types of interference; 2, compared with a detection technique based on a matching filter, the method has better detection performance under multi-path channels; and 3, compared with other prior arts, the method has more ideal detection performance under complicated and changeable actual underwater environments.

Description

technical field [0001] The invention relates to the technical field of underwater acoustic communication systems, in particular to an underwater acoustic leading signal detection method under sparse channels. Background technique [0002] Before transmitting a large data stream, a preamble signal is usually sent to assist the receiver in detecting the transmitted data. This preamble signal will cause the receiver to transition from a potentially low-power mode to a high-power data processing mode. . False detection of preambles can reduce receiver battery life. At the same time, with the continuous development of the underwater network, its application scope is becoming wider and wider, and the coexistence of different systems has become increasingly prominent. The coexistence of different underwater systems requires the receiver not to be triggered by signals from other systems. [0003] However, leading signal detection in underwater acoustic systems is challenging in t...

Claims

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Application Information

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IPC IPC(8): H04B13/02H04B17/30
CPCH04B13/02H04B17/30
Inventor 李维辛梦颖刘永芳刘旸旭陈希
Owner HARBIN INST OF TECH SHENZHEN GRADUATE SCHOOL
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