Selective monitoring unit with object to be monitored carrying transmitter

摘要

The transmitter has a modulator which modulates the pulse sequence to a HF transmission signal, and the receiver input stage is tuned to the reception of the signals radiated from the transmitter. Also included is a demodulator (24), a decoder and an evaluation unit for evaluating these sequences. A regulating amplifier (17) is preconnected to the demodulator (24) in the receiver (5), for the evaluation of the pulse sequence (30) identified as correct. A computer (27) is provided for making a decision to give an alarm. A correlation measuring system (25) is interposed between the amplifier (23), the demodulator, the decoder (26) and the computer (27).