Design And Implementation Of Low Frequency And High Power Class D Underwater Acoustical Transmitter

With the emergence of underwater low-noise targets attached with sound-absorbing materials,it has brought many challenges to modern active sonars.The current sound-absorbing materials have obvious sound absorption effects on medium and high frequency sound waves,which significantly reduces the target reflection in this frequency band.The detection performance of medium and high frequency active sonar significantly deteriorated.Sound-absorbing materials have poor noise reduction capabilities for low-frequency signals.In order to meet the performance requirements of long-distance sonar detection,low-frequency and high-power have become an important development trend of active sonar for underwater acoustic detection in recent years.The low-frequency and high-power underwater acoustic transmitter has thus become an important part of the development of active sonar.The thesis has carried out research work on the design and realization of the low-frequency and high-power Class D underwater acoustic transmitter.The types of sonar transmitter power amplifiers mainly include several typical categories: Class A,Class B,Class AB and Class D.Among them,class A,class B,and class AB power amplifiers have high static power consumption and low efficiency,making it difficult to achieve low-frequency and high-power designs.The class D transmitter has some typical advantages of small size,high power utilization,high power density,etc.,which makes the class D power amplifier underwater acoustic transmitter more suitable for the development needs of low-frequency and high-power active sonar equipment,thus becoming the preferred scheme for the design of active sonar equipment.The thesis focuses on the design and implementation of low-frequency and high-power Class D underwater acoustic transmitters.Firstly,the design principles of Class D underwater acoustic transmitters are introduced,including waveform generator design principles,power amplifier design principles,and matching network design principles.On this basis,according to the requirements of the design index,the design scheme of the low-frequency high-power class D underwater acoustic transmitter is given,including the hardware schematic design of each part,the circuit board design,etc.A low-frequency high-power class D underwater acoustic transmitter is developed and was realized according to the design scheme.The equipment has been tested in the laboratory and lake experiment.The results show that the performance of the low-frequency and high-power Class D underwater acoustic transmitter is stable and meets the design index requirements.