Document Type and Number:
Japanese Patent JPS6367153
Kind Code:
B2
Abstract:
PURPOSE:To obtain a normal data even in case when a receiving signal is varied instantaneously, by comparing a pseudo pulse generated at the time of a peak of a normal receiving ultrasonic wave, with a zero crossing pulse generating time point of the receiving ultrasonic wave, and controlling the counting direction of a correcting counter. CONSTITUTION:When a peak of a normal ultrasonic receiving signal is detected by a comparator 2, a pseudo pulse generated circuit 4 is controlled together with an AGC 3, and a zero crossing comparator 5 generates a zero difference pulse in accordance with the ultrasonic receiving signal. Subsequently, a time difference detecting circuit 7 detects a generation time difference between a pseudo pulse from the circuit 4, based on an immediately previous normal ultrasonic receiving wave, and a zero crossing pulse of an ultrasonic receiving wave which has been varied instantaneously this time, controls a gate circuit in accordance with a time difference, and also controls the counting direction of an up-and-down counter 8 for counting a correcting value in accordance with which has been generated earlier, the pseudo pulse or the zero crossing pulse. Accordingly, even in case when the zero crossing pulse is abnormal due to an instantaneous variation of the ultrsonic receiving wave, it is possible to obtain a normal data corresponding to an arrival time of a normal ultrasonic receiving wave.
Inventors:
YOSHIDA YUKIO
SUZUKI HITOSHI
SUZUKI HITOSHI
Application Number:
JP9324881A
Publication Date:
December 23, 1988
Filing Date:
June 17, 1981
Export Citation:
Assignee:
TOKYO KEIKI KK
International Classes:
G01F1/66; G01B17/00; G01S7/52; G01S7/526; G01S7/527; G01S7/536; H04B11/00