The peak time detecting circuit which is composed of full-wave rectification circuit and differential circuit can detect the reach time of echo signal accurately.

采用时间增益补偿技术，补偿超声波在空气中的衰减，减少回波信号的起伏；由有源全波整流电路和微分电路等组成峰值时间检测电路，可正确检测回波的峰值到达时间。

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Black churchgoers, of course, often do the same thing at Sunday-morning services, and I suspect that the amenlike responses of black theatergoers are a not-so-distant echo of that old-time religion.

WSJ: Theatergoers: Can I Get an Amen? | Sightings by Terry Teachout

Across the uncertain ways of space and time our hearts echo those words.

WSJ: Thomas Fleming: An English Thanksgiving, 1942

First-time buyers are circling east LA neighbourhoods like Boyle Heights, Echo Park and the unincorporated parts of East Los Angeles, according to Smith.

BBC: Living in: Los Angeles