Design And Realization Of Underwater Acoustic Communication Modulator System Based On μCos-II

Underwater acoustic communication technology is the key for solving the transmission and processing of underwater information and is widely used in the fields of AUV, underwater communication network, telemetry, and target detection. So a flexible, reliable and high-performance underwater acoustic communication modulator is indispensable in the study of this area.Direct Digital Synthesize technology is new generation of frequency synthesize technology. It controls phase increment of the signal with digital. And it is widely adopted for its advantages, such as high resolution of frequency, rapid switching of frequency, continuous phase while switching, low phase noise, full digitized, and easy to integrate.This underwater acoustic communication modulation system is composed of PC and a modulation circuit, and they are connected through the RS232 interface. The hardware circuit of the modulation system is designed by STC89LE58RD+ of STC, Inc. as its MCU, and DDS chip AD9852 of Analog Devices, Inc.Software design of the modulation system includes design of the PC and the modulation circuit. PC software is designed in Visual Basic integrated develop environment, in which User-defined serial communication protocol and the MSComm control have been applied to realize the communication between PC and the modulation circuit. By using the real-time operating systemμCos-II in software design of the modulation circuit, the application program is divided into several tasks by function, and scheduled by the real-time kernel, so the efficiency and reliability are greatly improved.This underwater acoustic communication modulation system can realize not only FSK, MSK, LFM modulation, wireless and local input of the information, but also multi-bit coding of the modulating data and the flexible set of the modulating parameters. It has been proved that the modulation system can work reliably, has high output frequency resolutions, and can satisfy the modulating requirements of underwater acoustic communication system.