Pulse signal waveform asymmetry identification utilizing symbolic dynamics
View Patent ↗A method for identifying asymmetry in a pulse signal is disclosed. An asymmetrical condition is when the time interval of a first input pulse signal having a first value is longer than the time of a second input pulse signal having a second value. Identifying asymmetry includes receiving and detecting the instantaneous signal values of first and second input pulse signals, and associating a unique state symbol with each distinct pair of instantaneous signal values thereby producing a sequence of state symbols. A sequence of state symbols of a first type, a second type, and a third type is identified and associated with a distinct enveloping event pattern. A macroscopic behavioral signature pattern indicating an asymmetrical condition is identified when a first symmetry event symbol of a first kind is followed by a first interval having no identified symmetry event symbol, a second symmetry event symbol of a second kind, and a second interval having no identified symmetry event symbol.
1. A method, comprising:
detecting samples of a first signal and samples of a second signal;
identifying, from the detected samples of the first and second signals, an event in which at least two transitions of the first signal have occurred between two transitions of the second signal; and
in response to identifying the event, providing an output indicative of the first signal having a different frequency than the second signal.
2. The method of claim 1 , wherein the output specifies that the first signal has a higher frequency than the second signal.
3. The method of claim 1 , wherein the identifying includes:
determining a sequence of symbols from the detected samples of the first and second signals; and
identifying a pattern in the sequence of symbols, wherein the pattern is indicative of the event.
4. The method of claim 3 , wherein a given one of the symbols is indicative of a sample of the first signal and a sample of the second signal.
5. The method of claim 3 , wherein the pattern indicates that values of the first signal have changed within an interval while values of the second signal have not changed within the interval.
6. The method of claim 1 , wherein the detecting the samples of the first signal includes capturing the samples of the first signal in response to one or more transitions of the second signal, and wherein detecting the samples of the second signal includes capturing the samples of the second signal in response to one or more transitions of the first signal.
7. An apparatus, comprising:
a comparison circuit, wherein the comparison circuit is configured to make a determination of whether a pulse of a first signal is enveloped within a pulse of a second signal, and wherein the comparison circuit is further configured to indicate, based on the determination, whether the first signal has a different frequency than the second signal.
8. The apparatus of claim 7 wherein the comparison circuit is configured to:
determine a sequence of symbols based on instantaneous values of the first and second signals; and
identify one of a set of patterns in the sequence of symbols, wherein the patterns indicate 1) whether a pulse of the first signal is enveloped within a pulse of the second signal or 2) whether a pulse of the second signal is enveloped within a pulse of the first signal.
9. The apparatus of claim 8 , wherein the comparison circuit is configured to:
generate a clock pulse signal from the first and second signals; and
based on the clock pulse signal, capture instantaneous values of the first and second signals into a shift register, wherein the comparison circuit is configured to use the captured instantaneous values to identify one of the set of patterns in the sequence of symbols.
10. The apparatus of claim 7 , wherein the comparison unit includes:
a first set of latches, wherein each of the first set of latches is configured to capture instantaneous values of the first signal in response to a respective clock signal, wherein one of the respective clock signals is the second signal, and wherein one of the respective clock signals is an inverted form of the second signal; and
a second set of latches, wherein each of the second set of latches is configured to capture instantaneous values of the second signal;
wherein the determination is based on the captured values of the first and second signals.
11. The apparatus of claim 7 , wherein the comparison unit includes:
a plurality of set-reset latches, wherein each set-reset latch is configured to:
receive a respective set signal that is either the first signal or an inverted form of the first signal;
receive a respective reset signal that is either the second signal or an inverted form of the second signal; and
output a respective value usable in making the determination.
12. The apparatus of claim 7 , further comprising:
another comparison circuit configured to receive a third signal, wherein the apparatus is configured to indicate whether the third signal has a different frequency relative to the first signal or relative to the second signal.
13. The apparatus of claim 7 , wherein the comparison circuit is configured to: identify a signal as having an asymmetric waveform; and
generate a corresponding output indicative of the asymmetric waveform.
14. A non-transitory computer readable medium having program instructions stored thereon that are executable to cause a computing device to perform:
comparing a first signal and a second signal by determining whether at least two transitions of the first signal have occurred within two transitions of the second signal; and
based on the comparing, providing an output indicative of whether the first signal has a different frequency than the second signal.
15. The computer readable medium of claim 14 , wherein the output identifies one of the first and second signals as having a higher frequency than the other signal.
16. The computer readable medium of claim 14 , wherein the determining includes:
determining a set of symbols from the first and second signals; and
identifying a pattern in the set of symbols.
17. The computer readable medium of claim 16 , wherein the set of symbols includes at least three symbols, and wherein each of the at least three symbols is determined based on a respective instantaneous value of the first signal and a respective instantaneous value of the second signal.
18. The computer readable medium of claim 14 , wherein the determining includes:
capturing an instantaneous value of the first signal in response to a transition of the second signal; and
capturing an instantaneous value of the second signal in response to a transition of the first signal.
19. The computer readable medium of claim 14 , wherein the program instructions are further executable to perform:
comparing a third signal with the first signal and the second signal; and
provide an output indicative of whether the third signal has a higher frequency than the first signal and the second signal.
20. The computer readable medium of claim 14 , wherein the program instructions are further executable to perform:
detecting that the first signal or the second signal has an asymmetric waveform.