Underwater Acoustic Frequency Hopping Communication Method Based on LFM Signal Modulation and Demodulation

A linear frequency modulation signal, modulation and demodulation technology, applied in electrical components, transmission systems, etc., can solve the problem of reducing the sampling value of fractional Fourier spectrum, improve frequency band utilization, increase information transmission rate, and ensure anti-multiple problems. The effect of path ability

Inactive Publication Date: 2016-08-17
XIAMEN UNIV
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Problems solved by technology

[0025] When there is a Doppler shift f d When , the peak position moves, causing the sampling value of the fractional Fourier spectrum at the sampling position to decrease

Method used

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  • Underwater Acoustic Frequency Hopping Communication Method Based on LFM Signal Modulation and Demodulation
  • Underwater Acoustic Frequency Hopping Communication Method Based on LFM Signal Modulation and Demodulation
  • Underwater Acoustic Frequency Hopping Communication Method Based on LFM Signal Modulation and Demodulation

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Embodiment Construction

[0051] The invention will be further described in detail below in conjunction with the drawings.

[0052] figure 1 Shows a functional block diagram of an embodiment of the present invention. The communication transmitter first encodes the original signal source to obtain a compressed digital signal, and then performs channel encoding on the compressed digital signal. The encoding can use convolutional codes, turbo codes, etc. for encoding.

[0053] The digital signal after channel coding is modulated by the 4FH-LFM modulation method. The modulation pattern of the chirp signal of each frequency hopping group is shown in figure 2 , image 3 , The decimal information represented by each chirp signal is correspondingly marked below the pattern. The system sampling rate fs is set to 96kHz, the frequency range is 10-20kHz, the frequency hopping number is 4, the frequency hopping pattern is sequentially increasing, the symbol width is 10ms, and the communication rate is 600bps. Binary d...

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Abstract

The invention provides a water sound frequency hopping communication method for linear modulation signal modulation and demodulation, and relates to a water sound frequency hopping communication. The water sound frequency hopping communication method comprises the following steps: carrying out source encoding on original information so as to obtain compressed digital signals; carrying out channel coding; using data obtained by the channel coding as a linear modulation signal control code; controlling to generate a linear modulation signal according to a frequency hopping sequence as a carrier for modulation, so as to obtain modulation signals; carrying out D / A (Digital / Analogue) conversion and power amplification on the modulation signals; converting the modulated signals into sound waves to spread in an ocean underwater acoustic channel through a transmission energy converter; receiving and converting acoustic signals spreading in the ocean underwater acoustic channel into electric signals through the receiving energy converter; obtaining stimulation signals through front amplification and band-pass filtering; carrying out A / D (Analogue / Digital) conversion on the received stimulation signals; after detecting that the digital signals after the A / D conversion are synchronous, carrying out linear modulation signal demodulation center frequency and demodulation frequency to obtain demodulation data; and carrying out channel decoding on the demodulation data; and carrying out source decoding on the digital signals to obtain information.

Description

Technical field [0001] The present invention relates to underwater acoustic frequency hopping communication, in particular to a chirp that uses inversion multiplication to resolve chirp signal center frequency method, refined discrete fractional Fourier transform (Zoom-DFRFT) chirp signal frequency modulation Signal modulation and demodulation underwater acoustic frequency hopping communication method. Background technique [0002] In traditional underwater acoustic frequency hopping communication, the frequency of the carrier is often used to carry information. Compared with other modulation methods such as MPSK, the MFSK modulation frequency band utilization rate is relatively low, and its information transmission rate is relatively backward under the same bandwidth, but its robust and reliable performance makes it occupy an important place in underwater acoustic communication. Therefore, improving the frequency band utilization of the underwater acoustic frequency hopping com...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): H04B1/713
Inventor 涂星滨许肖梅邵志文陶毅张小康
Owner XIAMEN UNIV
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