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Method for detecting underwater acoustic leading signal based on energy concentration under sparse channel

An energy-concentrated, sparse-channel technology, applied in communication channel monitoring, transmission systems, electrical components, etc., can solve problems such as unsatisfactory detection performance, mismatched templates, complex threshold values, etc., and achieve ideal detection performance and good detection performance , the effect of strong robustness

Active Publication Date: 2017-07-07
HARBIN INST OF TECH SHENZHEN GRADUATE SCHOOL
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  • Abstract
  • Description
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  • 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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  • Method for detecting underwater acoustic leading signal based on energy concentration under sparse channel
  • Method for detecting underwater acoustic leading signal based on energy concentration under sparse channel
  • Method for detecting underwater acoustic leading signal based on energy concentration under sparse channel

Examples

Experimental program
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Effect test

example 1

[0130] Simulation example 1 (additive white Gaussian noise)

[0131] 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.

[0132] 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, and the technology of the present invention, that is, the detection technology of energy concentration (EC), obviously shows better detection performance than MF. .

example 2

[0133] Simulation example 2 (narrowband interference)

[0134] 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:

[0135]

[0136] 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.

[0137] 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. Although there is no normalization process, the technology of the present invention comprehensively considers the influence of multiple main paths on the basis of effectively improving the signal-...

example 3

[0138] Simulation example 3 (short-term band-limited interference)

[0139] 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 .

[0140] 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:

[0141]

[0142] where c l As the base coefficient, the corresponding passband signal can be parameterized as

[0143] 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 freque...

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Abstract

The invention provides a method for detecting an underwater acoustic leading signal based on energy concentration (EC) under a sparse channel. The method is applied to an underwater acoustic communication system under the sparse channel. According to the method, the false drop rate of the leading signal is reduced, the detection rate is improved, the detection performance of the system is improved and the system communication efficiency is improved. Through sparse signal reconstruction and an OMP algorithm, the method estimates the energy concentration of several important elements (components) to judge whether a sparse signal is reconstructed successfully and can be applied to underwater acoustic communication, underwater acoustic location and tracking, military science, ocean navigation, radar and sonar. Compared with the existing technology, the method has the following advantages that 1.the method has strong robustness under the additive white Gaussian noise and different types of disturbances; 2.compared with a detection technology based on a matching filter, the method has better detection performance under multipath channels; and 3.compared with other existing technologies, the method has more ideal detection performance in the complicated and changeable actual underwater environment.

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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