The improved method of instrument design for ocean data measurement

The instruments used for the oceanographic measurement should be designed in consideration of the stability for the change of the parameters such as ambient temperature, pressure and any other environmental conditions. Furthermore, it is difficult to keep the voltage of power source and the characteristics of the components on circuit boards stable during the long time in marine environment. Then, the stable method is necessary. "Dual slope integration analog to digital converter" has a function of division, so that the fluctuation occurring in two integrands in the same ratio by the above causes can not appear in final result. Therefore, to take advantage of the effect, we set the reference output in each sensor circuit which has the fluctuation in the same ratio as the measurement output. If these two outputs of sensors are treated as the inputs of the "Dual slope integration analog to digital converter", it is possible to improve the accuracy of the measurement system. Regarding the sensors designed and fabricated on the basis of that principle, the experiment proved that the principle is available to improve the accuracy of measurement for many kinds of fluctuation. Further, we confirmed that these sensors functioned continuously with good stability in marine environment.