Receiver for high spectral efficiency data communications system using encoded sinusoidal waveforms

A system for recovering information encoded by a modulated sinusoidal waveform having first, second, third and fourth amplitude perturbations at respective phase angles Θ1, Θ2, Θ3, Θ4 wherein a power of the modulated sinusoidal waveform is reduced relative to a power of an unmodulated sinusoidal waveform within selected ones of the first, second, third and fourth amplitude perturbations so as to encode input digital data, the system comprising:

• one or more analog-to-digital converters for generating digital values representing the modulated sinusoidal waveform;
• an input buffer for storing the digital values;
• a sine wave subtraction apparatus for subtracting a digital representation of the unmodulated sinusoidal waveform from the digital values in order to generate a received digital data sequence including digital amplitude perturbation values representative of the amplitude of the modulated sinusoidal waveform within the first, second, third and fourth amplitude perturbations;
• and
• a sub-periodic time domain demodulator for estimating the input digital data based upon the digital amplitude perturbation values.

A method of recovering input data represented by amplitude perturbations at a plurality of phase angles of a modulated sinusoidal waveform wherein at least two of the plurality of phase angles are separated by approximately 180 degrees, the method comprising:

• receiving the modulated sinusoidal waveform;
• generating data values representing the modulated sinusoidal waveform;
• generating a received data sequence including perturbation data values representative of the amplitude of the modulated sinusoidal waveform within the plurality of amplitude perturbations;
• and
• estimating the input data based upon the perturbation data values.