The receiver and transmitter has always been the impotant part of sonar system, and with the development of microelectronic chips, the hardware realization of receiver and transmitter has become more and more flexible .The receiver designed in this paper is composed of preamplifier, signal conditioning and analog-to-digital conversion components. Among them signal conditioning circuit is the most important part of the receiver, it can pre-process the input signal such as amplifing, filtering, conditioning and isolating. All chips in this system are selected in accordance with low noise and low power. By using DSP auto-gain algorithms, the system can change the receiver's magnification in real time to avoid large-signal obstruction, distortion and small signal lossing .The transmitter designed in this system is mainly composed of signal generator, power amplifier and matching networks. In this paper we bring the integrated digital audio power amplifier technology to the acoustic transmitter. In the design process based on the basic theory, combined with modern audio amplifier design methods and the experience of using TI's integrated chip, the paper bring forward a new scheme to design portable acoustic signal transmitter. The signal source and control part use DSP and CPLD, as key chips which makes the system more stable and convenient for future upgrade. As the load impedance fluctuates with the frequency, the difficulty of matching technology is broadband matching, we only make some tries here.Lake and ocean experiments prove that the portable transmitter has on which achived the pre-determined targets and the receiver has realized the characteristic of low noise, low power and large dynamic range. |