Description of a differential pulse-frequency modulator

The operation of a novel differential pulse-frequency modulator based on th e Asynchronous Delta Modulation principle is described in this paper. The c omplete modulator consists of a Voltage Controlled Oscillator (VCO) in a fe edback configuration and generates an output pulse train whose frequency is proportional to the slope of the input signal. It is shown that the propos ed system allows substantially larger input signal amplitudes for linear op eration than those permitted by open loop VCO schemes or other voltage-to-f requency converters. In addition, the feedback path provides "locally" a si gnal that tracks the input, so that the feedback arrangement can be readily used as a demodulator at the receiver end.