| 摘要 |
PCT No. PCT/GB81/00025 Sec. 371 Date Oct. 20, 1981 Sec. 102(e) Date Oct. 20, 1981 PCT Filed Feb. 23, 1981 PCT Pub. No. WO81/02472 PCT Pub. Date Sep. 3, 1981.A distance sensing apparatus is provided in the form of a case housing electronic equipment including a piezoelectric transducer for radiating pulsed sonic or ultrasonic signals along a measurement path through a sound horn (3) which creates a narrow beam. Reflected signals received back through the horn are received by the transducer and converted into electric measurement signals. A time measurement device is providing for determining the time lapse between radiation of a pulse and receipt of a reflected signal so as to provide a distance signal which will be representative of the path distance between the apparatus and the surface which will trigger a display (7) to give a distance reading. An important feature of the apparatus is that the electronic circuitry will include an amplifier which will increase the amplification of the electrical signals carried by a reflected pulse at a function of time lapsed from the radiation of a measurement signal pulse so as to compensate for the attenuation of the received signal. |
