| 摘要 |
A constant range ultrasonic motion detector features an ambient atmospheric condition sensor which senses the temperature, pressure, and percent relative humidity of the ambient atmosphere and produces therefrom a range compensation signal to adjust the sensitivity of the ultrasonic motion detector for stabilizing the range. The range compensation signal is applied to adapt detector amplifier gain and/or threshold level to the variation between design and ambient conditions. In one embodiment, an analog summing network at the ambient atmospheric sensor outputs provides the range compensation signal and in a second embodiment a microprocessor is operative to provide the range compensation signal. |
