Amplitude equalization circuit for mobile underwater sound frequency-hopping communication receiving system

Abstract

The invention discloses an amplitude equalization circuit for a mobile underwater sound frequency-hopping communication receiving system, and relates to a frequency-hopping communication system. The circuit is provided with an impedance transformation circuit, an automatic gain control circuit, and a bandpass filter. The input end of the impedance transformation circuit is externally connected with an energy converter, and the automatic gain control circuit is provided with a primary amplification circuit, a secondary amplification circuit, and a feedback control circuit. The input end of the primary amplification circuit is connected with the output end of the impedance transformation circuit, and the output end of the secondary amplification circuit is connected with the input end of the bandpass filter. The output end of the bandpass filter is connected with the input end of the secondary amplification circuit, and the output end of the secondary amplification circuit is connected with the input end of the feedback control circuit. A control signal output end of the feedback control circuit is connected with the primary amplification circuit, and the output end of the secondary amplification circuit is externally connected with a subsequent circuit. The circuit can effectively reduce the size of the range of an amplitude change, caused by frequency change, of an echo signal of a receiving end, reduces the operation amount of a system, and improves the detection accuracy.

Description

technical field [0001] The invention relates to a frequency hopping communication system, in particular to an amplitude equalization circuit of a mobile underwater acoustic frequency hopping communication receiving system. Background technique [0002] The underwater acoustic channel has the characteristics of time-space-frequency variation, narrow band, high noise, strong multi-path interference, long transmission delay, and large random fluctuation. It is one of the most complex wireless communication channels so far. Because of its strong anti-jamming, anti-noise, anti-multi-path capabilities, good confidentiality and easy implementation of code division multiple access, the frequency hopping communication system is the most robust, Reliable communication system. Frequency hopping communication is a spread spectrum communication method, which occupies a relatively wide frequency band, and is subject to sound propagation attenuation, channel frequency selective fading, re...

AI Technical Summary

Problems solved by technology

Frequency hopping communication is a spread spectrum communication method, which occupies a relatively wide frequency band, and is subject to sound propagation attenuation, channel frequency selective fading, relative distance changes between the transmitter and receiver, and frequency response of the transmitter power amplifier and receiver signal conditioning circuit. Affected by factors such as uniformity, the amplitude of the acoustic signal at the receiving end will fluctuate with the frequency in a large dynamic range, which will have a great impact on the computational complexity and detection performance of the receiving system using the non-coherent energy detection method.

[0003] The inventor of this application, Xu Xiaomei (Xu Xiaomei, Chen Dongsheng, Tong Feng. Amplitude equalization design in MFSK underwater acoustic communication receiving system [J]. Ocean Science, 2001, 25 (06): 44-47) introduced that the amplitude equalization method is to adopt Amplification - the mechanism of filtering, but the signal and noise are amplified synchronously. After filtering, the fluctuation of the signal amplitude is still relatively large, and the improvement of the processing gain is not obvious.

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