Delayed-orthogonal signaling for narrow band data transmission

Abstract

Sinusoidal frequency modulation yields orthogonal spectral lines from which orthogonal spectral pairs can be formulated. The orthogonal spectral pairs can be utilized as in-phase ('I') and quadrature phase ('Q') signaling waveforms for use in data transmission. This paper describes the origins of these signaling waveforms and the delayed-orthogonal adaptation necessary to preserve phase continuity at the switching boundary. Delayed-orthogonal signaling for wireless channel transmission exhibits spectral properties nearly void of message-driven switching artifacts. This characteristic permits good spectral control regardless of the message content; which allows high-density frequency domain multiplexing utilizing low guard-band separation, with channel bandwidth on the order of the bit rate. Delayed-orthogonal signaling permits subcarrier injection that is well isolated from the message signal modulation. The subcarrier signal provides a coherent reference for demodulation, gain control, and additional signaling.