| 摘要 |
<p>PURPOSE:To obtain information on a frequency component corresponding to a transmitted electromagnetic wave with high precision by having circuits which execute analog sine conversion and analog cosine conversion in accordance with the frequency of the transmitted electromagnetic wave on a real time basis respectively. CONSTITUTION:Information on a frequency (f) specified by an operation panel 9 is given to a clock generating circuit 107, the circuit 107 outputs a clock signal CLK of (f)Hz to a sine and cosine conversion circuits 103 and 104, and thereby the conversion characteristics of these circuits are controlled. Analog signals HS and HC after conversion are digitized by an A/D converter 105. On the electric field side, likewise, an electric field signal E(t) amplified by an amplifier 108 is subjected to conversion is parallel by a sine conversion circuit 110 and a cosine conversion circuit 111 in an electric field signal conversion circuit 10, so as to be turned into signals ES and EC after conversion, which are digitized by an A/D converter 112. Each of these signals is taken in a microcomputer 10 through an input interface circuit 106. Using the value of a frequency component drawn out by the sine conversion and the cosine conversion, the microcomputer 10 calculates the specific resistance of a part of an earth crust to be investigated, for each depth.</p> |
