Circuit arrangement for eliminating waveform distortion of an angle-modulated signal transmitted over multipaths

DETAILED DESCRIPTION The present invention has been developed in order to overcome the above mentioned drawbacks of the conventional type of multipath distortion compensation circuit.
It is therefore an object of the present invention to provide an improved compensation circuit for eliminating waveform distortion of an angle modulated, e.
g.
, an FM, signal in which no delay element or circuit is required.
Another object of the present invention is to provide such a compensation circuit which can be utilized without any adjustment.
According to the present invention there is provided a circuit arrangement for eliminating waveform distortion of an angle modulated, e.
g.
frequency-modulated, signal subject to multipath distortion, comprising: (a) an automatic gain controlled amplifier responsive to the angle modulated signal for producing a gain controlled angle signal, said gain controlled FM signal being supplied to a first angle demodulator; (b) an envelope signal generator responsive to the automatic gain controlled amplifier for producing a first signal in accordance with the envelope level of the gain controlled angle signal derived from the automatic gain controlled amplifier; (c) DC component blocking means connected to the output of the envelope signal generator for permitting transmission of only the AC component of the first signal; (d) a function generator operatively connected to the DC component blocking means for producing a second signal Y expressed by Y=X/(1+2X) wherein X is the input signal thereof; (e) occupied-frequency shifting means connected to the DC component blocking means for shifting the occupied-frequency of the AC component of the first signal to a predetermined extent; (f) second angle demodulator connected to the occupied-frequency shifting means for producing a third signal; (g) an analog multiplier having first and second inputs respectively connected to the output of the function generator and to the second angle demodulator, the analog multiplier producing a signal representing the product of the second and third signals; (h) an adder having first and second inputs respectively connected to the output of the first angle demodulator and to the output of the analog multiplier, for adding the product signal obtained by the analog multiplier to a demodulated signal derived from the first angle demodulator