Decoding an alternator output signal
First Claim
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1. A signal processing system for angle demodulating a ripple signal obtained from an alternator output signal, the system comprising:
- an analog-to-digital converter configured to sample the ripple signal to generate a diode ripple data stream;
a bandpass filter configured to receive the diode ripple data stream and further configured to filter the diode ripple data stream to generate a complex diode tone;
an angle demodulator configured to generate a phase demodulated signal by receiving the complex diode tone and demodulating the complex diode tone;
a slew rate limiter configured to receive the diode ripple data stream and to apply a slew rate limit to identify an impulse in the diode ripple data stream, the slew rate limiter further configured to reduce the impulse magnitude before the bandpass filter processes the diode ripple data stream; and
a spectrum analyzer operatively coupled to the band pass filter and configured to determine a center frequency for the band pass filter.
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Abstract
An engine diagnostic system is provided that enables a service technician to evaluate engine cylinder contribution to output power. The service technician couples one or more signal leads to the vehicle'"'"'s battery, alternator, or accessory receptacle (e.g., cigarette lighter receptacle) to provide an alternator output signal to a signal analyzer. The signal analyzer processes the alternator output signal to generate an engine signature, which represents engine cylinder contribution to engine output power.
31 Citations
19 Claims
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1. A signal processing system for angle demodulating a ripple signal obtained from an alternator output signal, the system comprising:
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an analog-to-digital converter configured to sample the ripple signal to generate a diode ripple data stream; a bandpass filter configured to receive the diode ripple data stream and further configured to filter the diode ripple data stream to generate a complex diode tone; an angle demodulator configured to generate a phase demodulated signal by receiving the complex diode tone and demodulating the complex diode tone; a slew rate limiter configured to receive the diode ripple data stream and to apply a slew rate limit to identify an impulse in the diode ripple data stream, the slew rate limiter further configured to reduce the impulse magnitude before the bandpass filter processes the diode ripple data stream; and a spectrum analyzer operatively coupled to the band pass filter and configured to determine a center frequency for the band pass filter. - View Dependent Claims (2)
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3. A signal processing system for angle demodulating a ripple signal obtained from an alternator output signal, the system comprising:
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an analog-to-digital converter configured to sample the ripple signal to generate a diode ripple data stream; a bandpass filter configured to receive the diode ripple data stream and further configured to filter the diode ripple data stream to generate a complex diode tone; an angle demodulator configured to generate a phase demodulated signal by receiving the complex diode tone and demodulating the complex diode tone; a Fourier transform module configured to receive the diode ripple data stream and to convert the diode ripple data stream from a time domain signal to a frequency domain signal; a bandpass filter operatively coupled to the Fourier transform module and configured to filter the frequency domain signal; and an inverse Fourier transform module operatively coupled to the bandpass filter and configured to transform the filtered frequency domain signal into the diode tone, the diode tone comprising a complex time domain signal.
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4. A signal processing system for angle demodulating a ripple signal obtained from an alternator output signal, the system comprising:
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an analog-to-digital converter configured to sample the ripple signal to generate a diode ripple data stream; a bandpass filter configured to receive the diode ripple data stream and further configured to filter the diode ripple data stream to generate a complex diode tone; an angle demodulator configured to generate a phase demodulated signal by receiving the complex diode tone and demodulating the complex diode tone; and a slope rate limiter configured to receive the phase demodulated signal and to identify a discontinuity in the phase demodulated signal. - View Dependent Claims (5)
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6. A signal processing system for angle demodulating a ripple signal obtained from an alternator output signal, the system comprising:
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an analog-to-digital converter configured to sample the ripple signal to generate a diode ripple data stream; a bandpass filter configured to receive the diode ripple data stream and further configured to filter the diode ripple data stream to generate a complex diode tone; an angle demodulator configured to generate a phase demodulated signal by receiving the complex diode tone and demodulating the complex diode tone; and an indexer configured to sample the phase demodulated signal to produce indexed engine data. - View Dependent Claims (7, 8)
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9. A method for angle demodulating a ripple signal obtained from an alternator output signal, the method comprising:
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sampling the ripple signal to generate a diode ripple data stream; filtering the diode ripple data stream to generate a diode tone; performing an angle demodulation on the diode tone to obtain a phase demodulated signal; and applying a slew rate limit to the diode ripple data stream to identify an impulse and to reduce the impulse magnitude before filtering the diode ripple data stream to generate a diode tone. - View Dependent Claims (10, 11)
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12. A method for angle demodulating a ripple signal obtained from an alternator output signal, the method comprising:
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sampling the ripple signal to generate a diode ripple data stream; filtering the diode ripple data stream to generate a diode tone; and performing an angle demodulation on the diode tone to obtain a phase demodulated signal; wherein filtering the diode ripple data stream to generate a diode tone further comprises transforming a filtered frequency domain signal into the diode tone, the diode tone comprising a time domain signal.
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13. A method for angle demodulating a ripple signal obtained from an alternator output signal, the method comprising:
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sampling the ripple signal to generate a diode ripple data stream; filtering the diode ripple data stream to generate a diode tone; performing an angle demodulation on the diode tone to obtain a phase demodulated signal; and applying a slope rate limit to the phase demodulated signal to identify a discontinuity in the phase demodulated signal. - View Dependent Claims (14, 15)
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16. A method for angle demodulating a ripple signal obtained from an alternator output signal, the method comprising:
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sampling the ripple signal to generate a diode ripple data stream; filtering the diode ripple data stream to generate a diode tone; performing an angle demodulation on the diode tone to obtain a phase demodulated signal, and sampling the phase demodulated signal by the diode tone to produce indexed engine data. - View Dependent Claims (17, 18, 19)
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Specification