Abstract: A circuit adapted to detect an angle-modulated signal including a pair of terminals to which the angle-modulated signal is supplied in push-pull relation and a high-pass filter circuit coupled to the pair of terminals for transmitting those frequencies of the angle-modulated signal which exceed a cut-off frequency. A differential amplifier has a pair of inputs coupled to the high-pass filter circuit to receive the filtered angle-modulated signal as a reference signal and a quadrature generator is coupled to the high-pass filter circuit and is responsive to the filtered reference signal for generating a quadrature signal whose phase varies with respect to the reference signal as a function of the change in frequency of the reference signal.

Abstract: A receiver has a first input circuit and a first amplifier connected to a first rectifier circuit and has a second input circuit and a second amplifier connected to a second rectifier circuit. The first and second rectifier circuits produce first and second direct current signals, and the first and second rectifier circuits are connected to a meter drive circuit which produces a direct current signal in response to the first or second direct current signal so that the direct current signal from the meter drive circuit actuates a meter to indicate the input level of either the first input circuit or second input circuit.