Design And Implementation Of Underwater Acoustic Transmitter Based On PWM And Digital Power

Underwater acoustic transmitter has been widely applied on oceanic resources development and oceanic construction rig,the signal modulation and power amplifier selection have great influence on the efficiency,volume and weight of underwater acoustic transmitter. Further, it has influence on the index of positioning accuracy and action range in the position fixing, navigation and detection of underwater.So in recent years people have been trying to develop an underwater acoustic transmitter for superior performance with digital power amplifier type at home and abroad.PWM technology is a kind of pulse modulation mode, can uses the digital signal to control the analog circuit, Widely used in the measurement and communication fields, etc.The underwater acoustic transmitter’s power amplifier type is from the class AB amplifier to digital power amplifier,this paper designs the underwater acoustic transmitter based on PWM technology and digital power amplifier.In the paper,the background and application value of underwater acoustic transmitter are described, the characteristics, composition and main technical index are expounded,the structure,principle and application of digital power amplifier are introduced, the basic principle and practical and effective method for signal of PWM, and hardware circuit design of underwater acoustic transmitter based on PWM technology and digital power amplifier are discussed, the software design of SCM and programmable logic device on the underwater acoustic transmitter are introduced, in order to constitute a complete equipment of underwater acoustic transmitter.Digital power amplifier is the core technology of the underwater acoustic transmitter, also is a difficult point for research, is divided into half bridge and the whole bridge according to the topological structure. At present most of the digital power amplifiers are used in medium and small power of digital products, rarely used in the underwater acoustic power. Should choose small size, high efficiency and low total harmonic distortion of digital power amplifier. In the paper, the circuit design of digital power amplifier using TI’s integrated chip, has the advantages of good flexibility, strong adaptability, high integration, high reliability and scalability. The signal modulation processing platform uses MCU and CPLD combined circuit,which has the characteristics of strong processing ability, high real-time, good versatility, and makes the system processing performance greatly improved.In general, the transmitting transducer’s impedance is resistance capacity used in underwater acoustic engineering, according to the principle of transducer matching design, to realize impedance matching transformer, the matching capacitive reactance inductance transducer is used to implement tuning matching.In the case of output power must be, uses series matching to reduce the volume and weight of the transformer.In the paper,the debug process of underwater acoustic transmitter in the laboratory is introduced.The transmitter is finally tested the sound source level in anechoic pool of the laboratory, it is meeted the technical requirements which can reach to 187.99 dB. The tests validate correctness of the design and the expected research target is realized.