Reducing harmonic distortion by dithering
AssigneeUltraleap Limited
InventorsBenjamin John Oliver Long, Brian Kappus
Life of this patent
Estimating the term…
Abstract
A digital signal generation assumes that a base frequency (the frequency with which the primitive phase angles are specified relative to) is equal to the carrier frequency for all relevant times. But this causes errors in the digital signals output to each array element transducer. Thus, it is necessary for the development of a signal generation system that is capable of producing a digital signal using the free selection of amplitude and phase. This is used to produce a substantially error-free signal that preserves the amplitude and phase relative to a constant base frequency while allowing the carrier frequency to vary.
Claims19
A system comprising:
- an electrical signal wherein the electrical signal is driven by a real-time progressive polynomial spline evaluation of interpolated phase angle samples that achieves an up-sampling by a power-of-two factor using a linear combination;
- wherein a result of at least one of the spline evaluation is used to control an aspect of an output electrical signal;
- wherein a resulting value of the spline evaluation when added to a base frequency phase counter is used to determine a location of an output signal edge of the output digital signal;
- wherein the location is perturbed by a random dither on the phase angle drawn from a uniform distribution;
- wherein action of the phase dither is variable in a time domain as a conversion from phase to an output time series is naturally dependent on instantaneous frequency of the location.
A system comprising:
- an electrical signal wherein an instantaneous phase angle of the electrical signal is substantially calculated by a real-time progressive polynomial spline evaluation that achieves an up-sampling by a power-of-two factor using a linear combination of counters;
- wherein a result of at least one of the spline evaluation is used to control an aspect of an output electrical signal;
- wherein an interpolated phase angle added to a base frequency phase counter used to determine the location of an output signal edge of the output electrical signal,
- has a further test applied to determine an update time free of possible race conditions to reinitialize random dither for its corresponding signal edge of the output digital signal.
Dependencies are inferred from the claim text.