| 摘要 |
The invention relates to a device for adjusting the trigger timing of distance measuring equipment based on measuring the delay time for reflection of transmitted pulses of energy, e.g. echo-sounding equipment. The device comprises a detector designed to indicate whether an echo of prescribed characteristics is received within a prescribed period of time, or whether the echo fails to arrive. A phase comparator determines whether an echo of prescribed characteristics is received before or after the prescribed period of time. A variable-delay circuit is controlled by the detector and the phase comparator in order to delay the triggering of the transmitter of energy pulses, in such a way that echoes of prescribed characteristics will be received within the prescribed region of time, by maintaining the delay constant when the detector indicates echoes within the prescribed period of time, and by increasing or reducing the delay according to command from the phase comparator when the echo is received before or after the prescribed period of time, respectively.
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