| 摘要 |
The detector has a human body noise pick-up (M), essentially a microphone, and the electronic evaluating unit (E). The signals go through an impedance converter (2) to an amplifier (3), another amplifier (4) and then a mixer (5), for mixing with a signal from the oscillator (7). Then, there is a sensitivity regulator (8), and an IF amplifier (9), an A/D converter, a comb filter (11), an integrator (12) and then an alarm relay (14) if the threshold of a comparator (13) is exceeded. The comb filter has two filters (18, 18') forming the mirror arrangement, with the output passing to a minimum stage (19) and its output to the integrator (12). |
