| 摘要 |
<p>The speed measuring arrangement is esp. for experimental arrangements and school experiments. A receiver with a frequency discriminator compres the frequencies of a transmitted and receives ultrasonic signal and produces a voltage proportional to their difference. The arrangement is sufficiently accurate in the range 0 to +15 m/s to permit integration and differentiation of the voltage for distance and acceleration measurement of moving pendulums, model vehicles etc. The discriminator contains a phase detector (8) and a voltage controlled oscillator (10) producing the transmitter frequency for zero input voltage. The phase detector receives the oscillator signal and the signal from the ultrasonic receiver. Its output is integrated (11) and used to synchronise the oscillator to the received signal so that the control voltage is practically proportional to the body velocity.</p> |
