Abstract :
A form of modulation is described which may be used in amplitude nonlinear systems. The signal is a form of phase modulation, but the use of synchronous detection means that it is threshold-free, and certain forms of distortion associated with angle modulation are not present. There is a gain of 6 dB over peak-power-limited a.m. For low-index p.m. systems which are distortion-limited, it may be possible to obtain substantial improvements in signal/noise ratio.
