Research Of Underwater Acoustic Power Amplifier And Broadband Matching Technique

Underwater acoustic transmitter is very important component for an active sonar equipment. It consists of four parts, which are the signal generator, the power amplifier the matching network section and the transverter. As the development of modern electronic technology, the high efficiency and broad band acoustic transmitter for the battery using equipments, such as acoustic buoyage, portable underwater acoustic communication equipment and small scale underwater detector is demanded. In order to meet the need, the principle of the transmitter circuit is analyzed and the structure of circuit was improved; the methods of extending the bandwidth, increasing the output power, and improving the efficiency of the transmitter system were provided. The effectiveness of these methods were proved on the designed power amplifiers.These methods are: i. Reducing the high-frequency signal feedback in the amplification part of the power transistor to extend the superior frequency of the power amplifier, meanwhile reducing the amplification in the mail loop to prevent the self-excitation of the circuit, ii. A structure of digital equalizer plus class-D power amplifier is used. The low power DSP and the high speed MOSFET working as a switch were utilized in the structure, iii. Optimizing the matching net and reducing the phase angle between the output voltage and current to reduce the reflection power of the loads, iv. Using the coil with low resistance and magnetic-core with high magnetic conductivity in the transformer and inductor to reduce the power loss and increase the efficiency.The elements and structures of some functional unit of power amplifier are analyzed. In order to increase the efficiency of the power amplifier, class D power amplifier is used. Digital equalizer in the system makes the output voltage even in the passed band. Then from the double port network scattering matrix and the transducer power gain function, the commonly used single or double resonance point matching and real frequency solution were discussed, and the computer computation and design problems of the real frequency were proposed.Some transmitters are designed and debugged for several types of sonar equipments and have passed the test and the field trials in the lake and sea. These transmitters include ultrahigh frequency high power pulse amplifiers, broadband...