| 摘要 |
PROBLEM TO BE SOLVED: To shorten a clamp level switching time at continuous finding of a range by adding a required value to a previously set level by a clamp level switching means and setting a new level. SOLUTION: A far side signal I2 outputted from a 2nd signal processing circuit 12 is inputted to a clamp circuit 13, then among a clamp signal Ic and the far side signal I2, a signal I2c having a larger value is outputted by the circuit 13. A close side signal I1 outputted by a 1st signal processing circuit 11 and a signal I2c outputted by the clamp circuit 13 are inputted to a calculating circuit 14, then an output ratio (I1/(I1+I2c)) is calculated, and an output ratio signal showing the result is outputted by the circuit 14. The output ratio signal is inputted to an integration circuit 15, and the output ratio is integrated by the circuit 15, together with an integration capacitor 6 many times. When switching the level of the clamp signal Ic before the 2nd and subsequent range finding times of the continuous range finding, the required value is added to a previously set level of the clamp level switching circuit 16 for setting the new level. |
