The Research Of Photoelectric Conversion Circuit For Absolute Gravimeter

As one of the key technologies of the absolute gravimeter, photoelectric conversion circuit canget displacement information from the laser interferometer signal to the absolute gravimeter dataprocessing. In order to obtain the characteristic parameters of the signal conditioning circuit, thispaper studies the laser interferometer signal, by analyzing measurement principle of absolutegravimeter. The photoelectric conversion circuit is designed in case of determining photoelectricdetector and logic level standard. Furthermore, each of a different circuit structures are given.AC coupling and DC bias are discussed in the process of obtaining the AC component of theinterference signal. Both methods are discussed additional. For the purpose of obtaining the ACcomponent of the photoelectric signal by the way of DC bias. A new method which get offsetvoltage by the mean value of the signal peaks and valleys being explored. Bessel filter which hasa type of linear filter with a maximally flat group delay has been selected, after comparison ofthe frequency characteristics of the different types of filters. Two kinds of Bessel filter designedby Direct Design Method and CAD had been given by research the design method of filter. Andboth Bessel filters satisfy requirements of the frequency characteristics. Zero crossing of thesignal is the best position to get pulse signal, which proved by the theory of modern signalprocessing. Hysteresis comparator circuits have been given to get pulse signal on zero crossing.And shaping circuit which converting the pulse of signal to the appropriate logic level has beendesigned.