Multi-band Sonar Transducer Matching Network And Linear Power Amplifier

The underwater sonar transmitter can be classified into active sonar and passive sonar. The active sonar takes advantage of sonar system to transmit sonar signal in the ocean to detect some targets. After the sonar signal transmitted by the sonar system, it will be reflected back to the receiver when it encounters the target. The reflected sonar signal can be received by the receiver in the sonar system and then processed by the circuits such as amplifier and filter. Those signals can be used to detect the target and to locate the target’s distance and speed. However, the passive sonar can not transmit any sonar signals actively. It can only receive signals reflected by the aim stuff in the ocean. Also, these reflected signals received by the passive system can be processed which is similar with the active sonar system. These two sonar systems have their own faults and according to their faults, they are different in the applications. Generally, the active sonar system is not used so often as the passive system since the active system has to transmit signals which can expose its own position to the target. But no matter it is active system or passive sonar system, they have similar system design outline and structure. For both of them are combined with the transducer, the matching network and the power amplifier. The only different is there is signal generator for the active sonar system to give signal actively. While in this paper, the active sonar system is the research aim which includes signal generator, the linear power amplifier, the matching network and the transducer. The power amplifier and the matching network are the two parts studied in this project.As the modern technology developed faster and faster, the performance of underwater acoustics and sonar system is required much more higher and higher such as the efficiency, the accuracy and the bandwidth. In order to raise the efficiency of receiving signals, in another words to acquire the multi-bands in the same time in the ocean, the multi-design idea is generated in this paper. This is also achieving the wide bandwidth requirement in the modern ocean application. Meanwhile, in order to increase the power efficiency, get the good linear performance, few measurements should be taken. One way is to improve the matching network which is between the power amplifier and the transformer. The improvements include decreasing the phase angles of the load current and voltage which can decrease the power reflected by the transformer caused by the non-matching. This way can help the system to acquire much better efficiency. During making components such as inductor during the hardware system testing, take attention on selecting core and copper. The copper should choose the low resistivity and the iron core should be with high permeability to increase the converting efficiency. At the last part, the power amplifier should be chosen as the Class AB amplifier to get better linear consequent.The traditional methods to study the sonar transducer are mainly limited to the single bandwidth signals while these methods are consuming time and with low efficiency because each time they can only detect one bandwidth range signals. Often, in the ocean detecting, there are many unknown useful signals at the same time. If using the single bandwidth system in the underwater, when we want to get the second frequency range signals, the system has to be changed to get the corresponding matching network and some switching circuit networks. However, the way referred in this paper is different with the traditional ones since it is based on them which can be worked synchronously when there are few frequency bandwidth signals. This paper explained the single frequency bandwidth system in detail and then proposed the multi-band frequency sonar transducer matching network system including the circuit structure, the algorithm and the simulation results. Matlab tool is taken as the analysis tool to coding the matching network. Meanwhile, the hardware system is designed and this is put into underwater to test its performance. At last, the simulation results are compared with the test data. Through the comparison, we can make analysis and improvements. Finally, the linear power amplifier is initially designed with the tool called LTSpice.