Evaluation circuit for signals from protection system - has circuit monitoring adaptors of ultrasonic movement detector based on Doppler principle

摘要

Signals come from adaptors of an ultrasonic movement detector based on the Doppler principle, with the adaptor provided with at least one transducer operating as a sender and receiver, and excited by an oscillator. Signals reflected from a moving object and shifted in frequency are received, amplified limited and evaluated. A circuit monitoring each adaptor for sabotage or technical defects is connected in parallel with the inputs of individual adaptors, whose signal outputs are connected through an amplifier, two limiting diodes, a further amplifier with an evaluation filter and alarm threshold switch to a timer.