Adaptive Spectral Enhancement and Harmonic Separation
First Claim
1. An apparatus to perform adaptive spectral enhancement and harmonic separation, the apparatus comprising:
- a spectral enhancement and harmonic notching circuit comprising a coefficient input line, a signal input line, a first output port and a second output port;
wherein the spectral enhancement and harmonic notching circuit receives on the signal input line, an input signal comprising electromagnetic interference (EMI) at an unknown frequency;
wherein the spectral enhancement and harmonic notching circuit comprises a spectral enhancement circuit to supply on the first output port, a fundamental-enhanced signal or complement thereof generated by enhancing the input signal at least at a current estimate of the unknown frequency, the current estimate being identified from a coefficient signal on the coefficient input line;
wherein the spectral enhancement and harmonic notching circuit further comprises a cascade of notching circuits to supply on the second output port, a cascaded-harmonic-notched signal generated by notching the input signal at the current estimate followed by notching at a harmonic of the current estimate;
an adaptation circuit comprising an initialization line, an input line, an error line, and a coefficient output port;
wherein the input line of the adaptation circuit is coupled to the first output port, of the spectral enhancing and harmonic notching circuit;
wherein the error line of the adaptation circuit is coupled to the second output port, of the spectral enhancing and harmonic notching circuit;
wherein the adaptation circuit generates the coefficient signal on the coefficient output port, using at least;
(i) the fundamental-enhanced signal or complement thereof received on the input line of the adaptation circuit, (ii) the cascaded-harmonic-notched signal received on the error line, and (iii) an initial estimate of the unknown frequency received on the initialization line;
wherein the coefficient output port of the adaptation circuit is coupled to the coefficient input line of the spectral enhancement and notching circuit, to adaptively change the current estimate over time.
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Abstract
A circuit and method perform adaptive spectral enhancement at a frequency ω1 (also called “fundamental” frequency) on an input signal y which includes electromagnetic interference (EMI) at an unknown frequency, to generate a fundamental-enhanced signal φ1 (or its complement). The fundamental-enhanced signal φ1 (or complement) is thereafter used in a notching circuit (also called “fundamental notching” circuit) to generate a fundamental-notched signal y−φ1. The fundamental-notched signal y−φ1 is itself enhanced to generate a harmonic-enhanced signal φ2 that is used to notch the fundamental-notched signal y−φ1 again, in one or more additional notching circuits that are connected in series with the fundamental notching circuit. The result (“cascaded-harmonic-notched” signal) is relatively free of EMI noise (fundamental and harmonics), and is used as an error signal for an adaptation circuit that in turn identifies the fundamental frequency ω1. Use of a cascaded-harmonic-notched signal as the error signal improves speed of convergence of adaptation.
15 Citations
20 Claims
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1. An apparatus to perform adaptive spectral enhancement and harmonic separation, the apparatus comprising:
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a spectral enhancement and harmonic notching circuit comprising a coefficient input line, a signal input line, a first output port and a second output port; wherein the spectral enhancement and harmonic notching circuit receives on the signal input line, an input signal comprising electromagnetic interference (EMI) at an unknown frequency; wherein the spectral enhancement and harmonic notching circuit comprises a spectral enhancement circuit to supply on the first output port, a fundamental-enhanced signal or complement thereof generated by enhancing the input signal at least at a current estimate of the unknown frequency, the current estimate being identified from a coefficient signal on the coefficient input line; wherein the spectral enhancement and harmonic notching circuit further comprises a cascade of notching circuits to supply on the second output port, a cascaded-harmonic-notched signal generated by notching the input signal at the current estimate followed by notching at a harmonic of the current estimate; an adaptation circuit comprising an initialization line, an input line, an error line, and a coefficient output port; wherein the input line of the adaptation circuit is coupled to the first output port, of the spectral enhancing and harmonic notching circuit; wherein the error line of the adaptation circuit is coupled to the second output port, of the spectral enhancing and harmonic notching circuit; wherein the adaptation circuit generates the coefficient signal on the coefficient output port, using at least;
(i) the fundamental-enhanced signal or complement thereof received on the input line of the adaptation circuit, (ii) the cascaded-harmonic-notched signal received on the error line, and (iii) an initial estimate of the unknown frequency received on the initialization line;wherein the coefficient output port of the adaptation circuit is coupled to the coefficient input line of the spectral enhancement and notching circuit, to adaptively change the current estimate over time. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
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12. A method for adaptive spectral enhancement and harmonic separation, the method comprising:
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enhancing an input signal that comprises electromagnetic interference (EMI) at an unknown frequency, at least at a current estimate of the unknown frequency, the current estimate being identified from a coefficient signal, thereby to generate a fundamental-enhanced signal or complement thereof; using the fundamental-enhanced signal to notch the input signal at the fundamental frequency, thereby to generate a fundamental-notched signal; enhancing the fundamental-notched signal at a second harmonic of the current estimate thereby to generate a second harmonic-enhanced signal; notching the fundamental-notched signal at least at the second harmonic by using at least the second harmonic-enhanced signal thereby to generate a cascaded harmonic-notched signal; and performing adaptation to generate the coefficient signal, by using at least;
the fundamental-enhanced signal or complement thereof, the cascaded-harmonic-notched signal, and (iii) an initial estimate of the unknown frequency, wherein the current estimate is changed adaptively over time. - View Dependent Claims (13, 14, 15, 16, 17, 18)
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19. A system for adaptive spectral enhancement and harmonic separation, the system comprising:
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means for enhancing an input signal that comprises electromagnetic interference (EMI) at an unknown frequency, at least at a current estimate of the unknown frequency, the current estimate being identified from a coefficient signal, thereby to generate a fundamental-enhanced signal or complement thereof; means for using the fundamental-enhanced signal to notch the input signal at the fundamental frequency, thereby to generate a fundamental-notched signal; means for enhancing the fundamental-notched signal at a second harmonic of the current estimate thereby to generate a second harmonic-enhanced signal; means for notching the fundamental-notched signal at least at the second harmonic by using at least the second harmonic-enhanced signal thereby to generate a cascaded harmonic-notched signal; and means for performing adaptation to generate the coefficient signal, by using at least;
the fundamental-enhanced signal or complement thereof, the cascaded-harmonic-notched signal, and (iii) an initial estimate of the unknown frequency,wherein the current estimate is changed adaptively over time. - View Dependent Claims (20)
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Specification