Method and system for indicating zero-crossings of a signal in the presence of noise
View Patent ↗A device, method, and computer readable medium are used in connection with providing an indication of zero crossings corresponding to a signal. The signal ( 113 ) is received. Noise is removed from the signal ( 103 ). In response to the signal with noise removed ( 115 ), pairs of points and a time value corresponding to each point are determined ( 105 ), wherein the points of each pair are proximate to a predetermined change in an amplitude of the signal. In response to the pairs and the corresponding time values ( 117 ), a zero crossing time is determined for each pair ( 107 ). A variation in the plurality of zero crossing times ( 119 ) is corrected ( 109 ). A signal ( 123 ) or indication representative of the corrected zero crossing times is output.
1. A method of providing an indication of zero crossings corresponding to a signal, comprising:
receiving the signal;
removing noise from the signal;
responsive to the signal with noise removed, first determining a plurality of pairs of points and a time value corresponding to each point, wherein the points of each pair are proximate to a predetermined change in an amplitude of the signal;
responsive to the plurality of pairs and the corresponding time values, second determining a zero crossing time for each pair;
correcting a variation in the plurality of zero crossing times; and
outputting an output signal representative of the corrected zero crossing times.
2. The method of claim 1 , further comprising providing the output signal to a controller.
3. The method of claim 1 , wherein the second determining assumes a linear relationship between the points of each pair and calculates the zero crossing times.
4. The method of claim 1 , wherein the correcting further comprises averaging a periodicity of a waveform corresponding to the signal responsive to the zero crossing times.
5. The method of claim 1 , wherein the signal is received as analog, the method further comprising converting the received signal to digital.
6. The method of claim 1 , wherein the correcting is performed in a third order filter.
7. The method of claim 1 , wherein the removing is performed in a bandpass finite impulse response (FIR) filter.
8. The method of claim 1 , wherein the removing introduces a time delay to the signal, the method further comprising adjusting the plurality of zero crossing times to accommodate the time delay.
9. The method of claim 1 , wherein the predetermined change is a polarity change.
10. The method of claim 1 , wherein the first determining includes detecting the predetermined change.
11. A computer-readable medium comprising instructions executable by a processor, the instructions including a computer-implemented method for indicating zero crossings in a signal, the instructions for implementing the steps of:
responsive to the signal, wherein the signal has noise removed, determining a plurality of pairs of points and a time value corresponding to each point, wherein the points of each pair are proximate to a change in polarity of an amplitude of the signal;
responsive to the plurality of pairs and the corresponding time values, performing a calculation of a zero crossing time for each pair;
correcting a variation in the plurality of zero crossing times; and
outputting a data stream indicative of the corrected zero crossing times.
12. The medium of claim 11 , wherein the correcting further comprises instructions for averaging a periodicity of a waveform corresponding to the signal responsive to the zero crossing times.
13. The medium of claim 11 , wherein the noise removal introduces a time delay to the signal, further comprising instructions for adjusting the plurality of zero crossing times to accommodate the time delay.
14. The medium of claim 11 , further comprising instructions for saving an amplitude value corresponding to each point and the time value corresponding thereto to memory.
15. The medium of claim 11 , wherein the correcting further includes instructions for providing phase correction, frequency correction and acceleration correction.
16. A device for providing an indication of zero crossings corresponding to a signal, comprising:
a receiver, responsive to receiving the signal;
an analog/digital converter, responsive to the received signal, to digitize the received signal;
a bandpass finite impulse response (FIR) filter, responsive to the digitized signal, to remove noise from the digitized signal; and
a processor, the processor being configured to facilitate, responsive to the signal with noise removed, determining a plurality of pairs of points and a time value corresponding to each point, wherein the points of each pair are proximate to a change in polarity of an amplitude of the signal; responsive to the plurality of pairs and the corresponding time values, performing a calculation of a zero crossing time for each pair; and responsive to the zero crossing time for each pair, correcting a variation in the plurality of zero crossing times and outputting a data stream indicative of the corrected zero crossing times.
17. The device of claim 16 , wherein the correcting further comprises averaging a periodicity of a waveform corresponding to the signal responsive to the zero crossing times.
18. The device of claim 16 , wherein the bandpass FIR filter introduces a time delay to the signal, wherein the processor is further configured to facilitate adjusting the plurality of zero crossing times to accommodate the time delay.
19. The device of claim 16 , wherein the determining includes detecting the change in polarity.
20. The device of claim 16 , wherein the processor is further configured to facilitate saving an amplitude value corresponding to each point and the time value corresponding thereto to memory.