Analog System Realization And Digital Logic Design Of Multi-beam Fish-finder

Fish-finder is an equipment helping to fish, which can detect and locate the position of underwater fish school quickly. Besides, it can reduce the catching blindness and improve the fishing efficiency. This paper does many researches on and complete the design of multi-channel sonar transmitter and receiver, the system power board and the logic of signal processing platform by taking the project of multi-beam fish-finder as background.During the design of multi-channel transmitter, many kinds of amplifiers are first compared carefully, and the D class power amplifier is chosen. Then the key researches points are focused on the choices of amplifier tube, transformer design, technique of matching network, the driver circuit of D class power amplifier and reserved capacitance calculation.The power system board is designed with the DC/DC module to provide many kinds of power supplies. In order to make the noise and ripple of output power to meet the requirement, the peripheral filter circuits of power module are designed and debug. Meanwhile, the circuit that can control the sequence of the power modules is added to the power system board.Multi-channel sonar receiver designed in this paper is mainly composed of Automatic Gain Control circuit, band-pass filter circuit and fixed-plus amplifier circuit. Among the design of multi-channel receiver, the design of low noise and phase coherence are the key points and difficulties. The study of noise source, amplifier and PCB layout wiring in this paper effectively eliminates the noise of the receiver. In order to guarantee the phase coherence of the multi-channel receiver, a GIC band-pass filter is used as receiver filter circuit, and the filter parameters are determined by theoretical analysis and calculation.DSP and FPGA are the core processors on the digital signal processing platform of the multi-beam fish-finder. DSP is the core of calculation and control, and with its assistance FPGA can finish the corresponding function. This paper completes the logic design and its debugging based on FPGA, which mainly includes signal source of transmitter, 32-channel data acquisition, keyboard control, LCD control, D/A control and so on. During the design of signal source module and data acquisition module, the principle of the multi-channel phase control transmitter and band-pass sampling theory are studied.