| 摘要 |
The instant invention relates to a device which automatically adjusts the sensitivity level of a system which can be used to control power circuits. In particular, the device has particular value in connection with devices which detect motion in a confined space through the use of a Doppler shift of ultrasonic or electromagnetic waves and turn lights on and off depending upon whether or not there is human movement in the confined space. The device adjusts the gain of an AGC such that the gain varies inversely with the amplitude after a predetermined time delay. The time delay permits short term amplitude gain but suppresses the gain of constant amplitude signals thereby suppressing or filtering out long term constant noise. The gain in a "noisy" environment would be suppressed thus causing the sensitivity of the system to be lowered when ambient noise is at an appreciable level and conversely, would increase the gain and correspondingly the gain when there is a low noise environment.
|
