Abstract: A system for generating angular modulation comprising a balanced modulator and an adding circuit to which a surface wave device quadrature oscillator applies two signals at the carrier frequency differing 90.degree. in phase, such phase difference being accurately maintained independent of aging and variations in operating temperatures. More particularly, an information signal is applied to one input of the balanced modulator, the output of which is applied to the adding circuit. The surface wave device oscillator completes the system by applying an in-phase carrier frequency to a second input of the balanced modulator and a carrier frequency shifted 90.degree. in phase to a second input of the adding circuit. Angular modulation is thus produced at the output of the adding circuit.

Abstract: An SWD structure is employed in an FM receiver for signal demodulation and band limiting. An FM signal is applied to the input of an SWD patterned for bandwidth limitation. Two SWD output channels characterized by predetermined differential delays of the modulated input signal are amplitude limited and mixed to produce an audio modulation component.