Receiver for amplitude sampled time character signals - with two input amplifiers selectively switched in to select reception frequency for optimum sensitivity

The receiver has two input amplifiers (4, 5), each with an antenna (1, 2), and a damping element (6) receiving the outputs of both input amplifiers. A variable amplifier stage (7), is coupled via a pair of filters (8) to a further amplifier (9), followed by a threshold detector (10), a peak value rectifier (14), a regulation current generator (17) and a comparator (20) which compares the demodulated time character pulses with a reference voltage. The amplification of the input amplifiers are determined by a regulating current (19) and they are switched in to select the sensitivity, or the reception frequency, the filters at the output of the variable amplifier stage comprising series resonance quartz filters for different reception frequencies with compensation of their parasitic capacitances. The regulation time constant can be switched to match codes with differing pulse lengths. ADVANTAGE - Reliable reception over inside field strength range and matching to different time character codes.