Design And Realization Of Sixteen Channels Signal Conditioner

Before the collection of underwater acoustic signals, the signals of underwater acoustictransducer are very weak and not suitable for the A/D converter. Therefore, these weaksignals need amplification, filtering and other processing. However, different applicationsfor signal amplification and filtering bandwidth requirements are not the same, for the sakeof satisfy most applications, we need to develop a gain and bandwidth can be adjustedflexibly universal acoustic signal conditioning equipment.This article takes underwater acoustic signal processing as the research object, designand implementation a underwater acoustic signal conditioner which gain and bandwidth canbe adjusted flexibly, and has ability of self-check.The conditioner includes two elements:one is programmable signal conditioning unit, the other is a conditioner self-check unit.Programmable signal conditioning unit composed of a pre-amplifier, voltage controlled gainamplifier, a Band-Pass filter, active low pass filter, parameter control module.Signalscoming from underwater acoustic transducer get fixed multiple amplification by thepreamplifier, then the voltage controlled gain amplifier achieve the small range of signalrequired for measurement of Band-Pass filter. In order to meet the acquisition device on theoutput signal amplitude of the requirement, the signal come out from band-pass filter needto be amplified by the voltage controlled gain amplifier. At last the signals come out fromthe active lowpass filter. Bandpass filter comprising two switched capacitor filter, the formeris8th order highpass filter, after the class of10th order lowpass filter, and the cutofffrequency can be set with an external clock. Parameter control module receives variouscontrol orders from the communication interface and controls the collaborative work ofvoltage controlled gain amplifier, a Band-Pass filter. Conditioner self-check unit is mainlycomposed of DDS, ADC, and control operation module（DSP）. Control operation modulehas function of control DDS generate signal to the16input ends of signal conditioner, andthen synchronous sampling each signal which come out from the signal conditioner. Finallywe can obtain the coherence of each channel from analysis the results of sampling data.This paper focuses on the design and realization of the hardware platform and self-testprogram. Throught joint adjusting of the whole system, all units in the module has attainedthe design requirements. The programmable signal conditioning unit and the self-check unithave operated stably and reliably as a whole.