Signal Acquisition And Processing Board Design And Implementation Of Multi-beam Fishfinder

As a fishing aid equipment, the fishfinder can acquire the information about the position, amount and species of the underwater fish stock. Therefore, fishfinder can search, track, identify, locate and measure the fish stock, which improves the efficiency of fishing production.Because the detection precision of single beam fishfinder is low, the thesis describes a multi-beam fishfinder system which can improve the detection precision. The system uses a kind of new architecture, which detects and locates the fish stock through recording and processing the time intensity sequence of many echoes from different directions at first and acquiring the image of fish stock and seafloor accordingly. Because of the using of these technologies, the system has many characteristics such as high detection precision, long detection distance and wide coverage. Signal acquisition and processing with high efficiency and rotational directional signal source with high performance are the key technologies of hardware design. Based on these technologies, the content discussed in this thesis can be concluded as follows:First, the architecture of multi-beam fishfinder system is discussed. The features of the architecture are analyzed such as flexibility, convenient debugging, strong extension ability and etc.Second, the hardware design of the hardware platform of signal acquisition and processing board is accomplished, which is based on the DSP and FPGA. This part includes 32 channels A/D signal acquisition, the communication interface which connnects DSP and FPGA, and the communication interface which connnects DSP and PC/104 board.Third, the software design of the signal acquisition and processing board is accomplished, which is based on the DSP and FPGA. This part includes a software signal acquisition mechanism with programmable parameters, the interface software of communication between DSP and FPGA and the interface software of communication between DSP and PC/104 board. A new bootloader method of DSP is also described.Fourth, a signal source with high performance is finished. The signal source is based on the DSP and FPGA, which has two transmission pattern: rotational transmission pattern and directional transmission pattern. DSP mainly takes responsibility of parameters operation of signal source. These parameters are transferred to the the FPGA through the hardware interface and software handshake protocol. On the basis of these parameters, FPGA produces related waveforms using beam forming technology.After debugging, the results suggest that the signal acquisition and processing board meets the design requirements.