Method of differential-phase/absolute-amplitude QAM
AssigneeHoneywell Federal Manufacturing & Technologies, LLC
InventorJeffrey William Dimsdle
Life of this patent
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Abstract
A method of quadrature amplitude modulation involving encoding phase differentially and amplitude absolutely, allowing for a high data rate and spectral efficiency in data transmission and other communication applications, and allowing for amplitude scaling to facilitate data recovery; amplitude scale tracking to track-out rapid and severe scale variations and facilitate successful demodulation and data retrieval; 2N power carrier recovery; incoherent demodulation where coherent carrier recovery is not possible or practical due to signal degradation; coherent demodulation; multipath equalization to equalize frequency dependent multipath; and demodulation filtering.
Claims7
A method of amplitude scaling to facilitate data recovery, the method comprising the steps of:
- (a) identifying an actual constellation amplitude level by examining an amplitude transition;
- (b) calculating a scale factor by dividing a normalized ideal amplitude level by the actual constellation amplitude level;
- (c) performing multiple iterations of steps (a) and (b) to result in a plurality of scale factors;
- (d) calculating an average scale factor by averaging at least two of the plurality of scale factors;
- and
- (e) recovering data from a signal, comprising applying the average scale factor to at least one sampled amplitude value of the signal.
Dependencies are inferred from the claim text.