Research On Multi-Channel Image Sonar Analog Electronic System

The unfathomable form of marine security is gradually becoming more and more severe.Shore-based,important activities on the water,and underwater detection equipment all need to make predictions about the safety of the ocean beyond the horizon ahead of sailing.When the underwater optical equipment cannot be used normally,the imaging sonar can be widely used to detect the motion trajectory of the measured target that cannot install the test equipment ahead of the sailing through the intuitive and rich images.Aiming at the limited installation space of the actual underwater equipment and the stability of the system,this paper studies the improvement of the key technologies of the imaging sonar analog electronic system,including the stability and the high-efficiency design method of the sonar transmitter,and the miniaturization,low noise,low power consumption and low cost design method of the sonar receiver.The design improves the flexibility of the use of imaging sonar.According to the requirements of system technical indicators,the thesis completes the design,debugging and verification of the analog electronic system of the imaging sonar transmitter and receiver from theoretical simulation to design implementation.The main contents and conclusions of this paper are as follows:(1)This paper starts the design research of the transmitter from the realization of high efficiency.By comparing the applicable occasions and implementation methods of different types of power amplifier circuits,the power amplifier circuit is constructed by selecting the working mode of the class D half-bridge push-pull differential output.According to the electrical parameters of the load sensor,based on the difference between parallel matching and series matching,it is concluded from theoretical calculation that the working mode of series matching is easy to take into account high efficiency and system miniaturization design.And considering that the actual transformer leakage inductance accounts for a large proportion of the matching.After the influence,the best matching parameters are obtained.(2)In view of the problem that the switch MOSFET is prone to breakdown damage under high frequency working conditions,the paper starts from the structure of the power amplifier circuit,and designs the input drive protection,output RDC absorption circuit protection and heat dissipation for the MOSFET through simulation analysis and theoretical calculation.According to the image data collected by the module experiment,the protection system designed in this paper can effectively improve the problems of excessive input and output waveform overshoot and high temperature rise during operation of the switch tube.This method effectively protects the MOSFET from breakdown damage under high frequency working state,and improves the working stability of the transmitter.(3)Aiming at the problem that the analog electronic system of the imaging sonar receiver is bulky,with high noise,and is easy to ignore small signals,this paper selects a low-power amplifier to achieve multi-stage gain adjustable amplifier circuit through the analysis of the circuit noise figure and the calculation of the noise introduced by the chip.Combined with power supply system and PCB design for noise reduction methods,the equivalent input noise of a single channel of the receiving analog electronic system is effectively reduced to less than5μV,the power consumption is reduced to less than 5W,and the size of the equipment is reduced to 550mm×300mm×300mm.The adaptability of the equipment has been improved in terms of device size,power consumption,and noise.(4)In this paper,the cascade filtering system is used to realize the high-frequency and high-Q filtering function.In view of the large number of components used in the 160-channel receiving channels and the large debugging workload,the component sensitivity of the filtering circuit is simulated and analyzed.The allowable variation range of each element value of the filter module is obtained so that the multi-channel filter parameters are within the specified accuracy range.In terms of engineering implementation,this method effectively reduces the cost of manual debugging to within 20% of the total components.Due to the existence of the error of the actual component value of the filtering module,there will be a significant difference in phase between the receiving channels.Aiming at the problem that the center frequency,bandwidth and phase parameters of the filter system must be considered at the same time in the traditional phase adjustment method,which makes it difficult to adjust the parameters of each element of the filter system,this paper designs an RC phase adjustment circuit,which is easy to realize multi-channel without changing the main parameters of the filter.The phase consistency of the receiving conditioning circuit significantly reduces the difficulty of phase adjustment between channels.The debugging and testing of the imaging sonar analog electronic system unit has been finished,and the index requirements are met.It verifies the feasibility of the improved design method proposed in the paper,which can effectively improve the stability of the transmitter,reduce the noise of the receiver electronic system,and achieve small size,low power design.Through the water acoustic pool test of the whole machine,the position of the stationary target and the trajectory of the moving target in front of the equipment are successfully measured and imaged,which meets the requirements of the equipment and verifies that the research and design method in this paper has practical application value.