Decoding an alternator output signal
AssigneeSnap-on Incorporated
InventorsRobert D. DeCarlo, Dennis M. Mutzabaugh, Nicolaas M. J. Stoffels
Life of this patent
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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.
Claims19
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.
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 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.
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;
- and
- a slope rate limiter configured to receive the phase demodulated signal and to identify a discontinuity in the phase demodulated signal.
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;
- and
- an indexer configured to sample the phase demodulated signal to produce indexed engine data.
A method for angle demodulating a ripple signal obtained from an alternator output signal, the method comprising:
- 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.
A method for angle demodulating a ripple signal obtained from an alternator output signal, the method comprising:
- 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.
A method for angle demodulating a ripple signal obtained from an alternator output signal, the method comprising:
- 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.
A method for angle demodulating a ripple signal obtained from an alternator output signal, the method comprising:
- 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.
Dependencies are inferred from the claim text.