The Design Of Multi-Channel Parametric Array Signal Generator And Power Amplifier Circuit

Parametric array sonar has been widely used in the marine sediment classification and exploration due to its advantages of sharp directivity, low-frequency sound waves in a narrow-beam broadband launch, directional map without side lobe, etc. According to the theory and principles of sonar's design, this essay discusses the relevant issues about parameter array sonar signal generator and power amplifier circuit design.First of all, this article introduces the relevant content of non-linear acoustics, describes the principles theoretically on how the difference frequency signal forms and highlights the Vestervelt wide-band parametric array theory. The theory proves that, for amplitude modulation of wide-band signals, the difference frequency signal is only related to the signal envelope's square of secondary derivative.Secondly, it also talks about the signal generator design technology. Based on the analysis of the parametric array signal generator's requirements, we put forward an idea to adopt the DSP + FPGA + D / A structure and give more details on the circuit design. It may lead to bad effects on transmitter if the improper sequence of signal generator power-on and power-off gives. The root cause of the problem is stated and its solution is to make IO and core voltage track output voltage. In addition, it discusses the principle of the DDS, designs a variety of modulation wave's logic and provides design flow diagram on DSP's software.Thirdly, it mentions the power amplifier design. The power amplifier adopts three stage amplifier cascade structure by putting the integrated operational amplifier OPA541 as the first-class amplification and the second and third stage amplifier circuit consisting of NPN-type and PNP-type transistor, which is used the class AB amplifier circuit, so that the class B amplifier's crossover distortion will be eliminate by the method of the resistor divider or a diode-clamped. The signal passes through the step-up transformer load to the transducer. The circuit design process, methods and the way of calculating relevant parameters are described in this paper as well.In order to meet the sonar system's requirements, it is fully considered the convenience and accuracy on debugging and application process. On the process of signal generator design, we take full advantage of the characteristic of FPGA to reduce the circuit scale; proposing phase pre-compensation in order to meet the phase consistency requirement; The transmitter's debugging and rapid diagnosing benefit from the modularization of the power amplifier circuit; simultaneously adjustment-friendly of the power amplifier's output power meets the consistency requirement of the transmitter power. This paper plays an important role and can be referred during the research of parameter array sonar.