Underwater acoustic communication modulation and demodulation module for frequency-combined signal

Abstract

The invention discloses an underwater acoustic communication modulation and demodulation module of a frequency combination signal, and belongs to the technical field of underwater communication and electronics. An embedded processor is used for controlling a frequency combination signal and single-frequency signal encoding and decoding chip CMX865A special for wired communication, and the chip CMX865A serves as a hardware modem of underwater acoustic signals. And the signal sending part adopts a combined frequency or single frequency baseband signal generated by CMX865A to be mixed and modulated with a local oscillator carrier of a processor, and drives a transducer after frequency selection and power amplification of a switched capacitor filter to realize modulation and emission of a coded signal. Underwater acoustic signals input by the receiving circuit are pre-amplified by the gain control chip, subjected to frequency selection by the switched capacitor filter, subjected to frequency mixing by the switch and subjected to low-pass filtering, and then recovered baseband signals are demodulated by the CMX865A hardware and sent to the processor. The modulation and demodulation process is completed by adopting a special chip, so that the whole circuit is low in power consumption, high in speed, simple in structure and high in anti-interference capability.

Description

technical field [0001] The invention belongs to the technical field of underwater acoustic communication and underwater acoustic electronics, and relates to an underwater acoustic communication modulation and demodulation module for combined frequency signals. Background technique [0002] Underwater acoustic communication technology was originally used for military and national defense. As people pay more attention to the development of underwater resources such as oceans and lakes, the demand for information transmission technology related to various civilian underwater farming, underwater detection and underwater robots has soared. . Underwater communication mainly uses underwater sound as the information carrier, and the technical threshold is relatively high. In order to reduce the application cost and be accepted by the civilian market, it is necessary to continuously develop new underwater communication technology products. [0003] At present, the main methods of un...

AI Technical Summary

Problems solved by technology

This method uses single-frequency transmission, which has a low utilization rate for the channel. At the same time, the demodulation device needs to perform frequency discrimination and judgment on the transmitted signal, so the transmission speed is slow and the interference is large.

[0005] 2. Amplitude keying (ASK): ASK is the opposite of FSK. It multiplies the binary code with a single frequency signal and transmits information through the change of signal amplitude. This method requires high signal quality and is resistant to intersymbol interference and multiple It is suitable for fixed-point and fixed-distance communication, and the transmission rate is roughly the same as that of FSK, and the transmission rate has not been improved.

[0006] To sum up, at present, single-frequency mode is mostly used for underwater data transmission, and software demodulation is often used, which requires strong computing power and high power consumption.

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