Rotational Sensor R1 - A Performance Test

Felix Bernauer, Joachim Wassermann and Heiner Igel

Object of our test was the rotational seismometer R1 manufactured by Eentec. The basic operating principle of the R1 is that incoming ground movement is transduced into an electrical voltage output by an electrochemical sensor. This sensor contains an electrolytic fluid as transducing medium. As the properties of fluids (diffusivity, viscosity, etc.) vary strongly with temperature we where suspicous of the nominal operating temperature, that ranges from -15 up to 55 degrees of Celsius. For the test we used the steptable CT-EW01 with an attached bridge that gives a constant input rotational motion signal. Comparing this input signal to the output of the R1 at four different temperatures (20, 30, 40 and 50 degrees of Celsius) we found that the generator constant deviates up to 30% from the nominal value of 50V*s/rad . Two more tests on stability of the generator constant with respect to time and high gain input and one simple noise test were carried out.