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Multi-band hyperbolic frequency modulation spread spectrum communication method based on crossed sub-band division

A hyperbolic frequency modulation and spread spectrum communication technology, applied in the field of spread spectrum communication, can solve the problem of low frequency band utilization and achieve the effect of improving tolerance, frequency band utilization and transmission rate

Active Publication Date: 2020-07-31
SOUTH CHINA UNIV OF TECH
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Problems solved by technology

[0019] Although the use of HFM for spread spectrum communication can enhance the anti-interference ability and anti-Doppler effect, but a more serious problem is that the frequency band utilization is relatively low

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  • Multi-band hyperbolic frequency modulation spread spectrum communication method based on crossed sub-band division
  • Multi-band hyperbolic frequency modulation spread spectrum communication method based on crossed sub-band division
  • Multi-band hyperbolic frequency modulation spread spectrum communication method based on crossed sub-band division

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Embodiment Construction

[0059] In order to make the object, technical solution and advantages of the present invention more clear and definite, the present invention will be further described in detail below with reference to the accompanying drawings and examples. The meaning of each label is as follows:

[0060] f 0 : The starting frequency of the communication frequency band, this example takes f 0 = 9KHz.

[0061] f 1 : The cut-off frequency of the communication frequency band, this example takes f 1 = 15KHz.

[0062] B: Bandwidth, in this example, B=6KHz.

[0063] T H : Period of the hyperbolic FM signal, T is taken in this example H = 20.48ms.

[0064] T G : symbol guard interval period.

[0065] T L : Frame header duration.

[0066] f s : hyperbolic FM signal sampling rate, this example takes f s = 100KHz.

[0067] N: The number of sampling points of a spread spectrum cycle of the hyperbolic FM signal, N=T H *f s , N=2048 in this example.

[0068] K 1 : The number of subband...

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Abstract

The invention discloses a multi-band hyperbolic frequency modulation spread spectrum communication method based on crossed sub-band division. According to the scheme, multi-band division of differentsub-band numbers is carried out on the available bandwidth of an underwater acoustic system according to the parity of a current spread spectrum period sequence number, so that the purpose of cross sub-band division is achieved. Therefore, the divided sub-bands are grouped in pairs, and each group selects the sub-bands according to different transmission data by adopting a sub-band selection activation mode, so that multi-band parallel transmission is realized. And meanwhile, in each spread spectrum period, the activated sub-band performs frequency modulation on the modulated signal by adopting the ascending and descending hyperbolic frequency modulation signals respectively. Compared with other underwater acoustic hyperbolic spread spectrum frequency modulation schemes, the scheme of cross sub-band division is adopted, so that the tolerance to the maximum time delay of the channel is improved; different information is carried and transmitted by utilizing the weak correlation of the ascending and descending hyperbolic frequency modulation signals; and a multi-band parallel transmission scheme based on QPSK modulation is adopted, so that the frequency band utilization rate and the transmission rate of the system are further improved.

Description

technical field [0001] The invention relates to the field of underwater acoustic communication, in particular to a hyperbolic FM signal and a spread spectrum communication method combining cross subbands and up-and-down HFM signals. Background technique [0002] Due to the complexity of the ocean environment, the underwater acoustic channel has serious multipath effects and time-varying characteristics. However, the seawater medium has a very serious attenuation of high frequencies, resulting in a very small available bandwidth for underwater acoustic communication. Underwater acoustic communication has experienced the development from non-coherent technology to coherent technology. Compared with non-coherent technology, coherent technology has high spectrum utilization rate and can greatly improve the efficiency of communication system. However, severe multipath effects and time-varying characteristics are the main constraints for underwater acoustic coherent communication...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H04B1/69H04B13/02H04L27/20
CPCH04B1/69H04B13/02H04L27/20H04B1/707
Inventor 余华张雅琦季飞陈芳炯
Owner SOUTH CHINA UNIV OF TECH
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