Selective tone event detector and method therefor
View Patent ↗In one embodiment, a tone event detector first determines whether the presence of a tone is indicated on the input signal, and then, based on this determination, selectively determines whether a tone has been detected on the input signal. For example, in one embodiment, tone detection is performed only when the presence of a tone is first indicated, such that if the presence of a tone is not indicated, tone detection need not be performed. This may help reduce complexity of a tone event detector since a simplified method may be used to indicate the presence of a tone, and the more complex algorithms for tone detection may be enabled only when needed. Also, in one embodiment, detection of a tone includes generating one or more tone characteristics corresponding to the detected tone which may then be used to determine whether the detected tone corresponds to a valid tone event.
1. In a tone event detector implemented at least partially in hardware and having a tone indicator, at least one tone detector, and a control unit, a method for performing tone event detection comprising:
receiving, at an input of said tone event detector, a sampled input signal;
determining, by said tone indicator, if at least one tone has been indicated based on said sampled input signal and providing a tone indication signal in response thereto, wherein said determining if said at least one tone has been indicated comprises detecting whether a tone of any frequency is present, and further comprises:
determining an energy estimation of said sampled input signal;
determining whether at least one segment of said energy estimation has a variance of less than a predetermined amount of variance for a predetermined duration;
when said at least one segment has said variance of less than said predetermined amount of variance for said predetermined duration, asserting said tone indication signal to indicate that said at least one tone has been indicated and providing said sampled input signal to said at least one tone detector to determine whether at least one tone has been detected;
selectively determining, by said at least one tone detector, in response to said tone indication signal, whether at least one tone has been detected, wherein selectively determining comprises:
determining whether at least one tone has been detected when said at least one tone has been indicated, wherein said determining whether at least one tone has been detected comprises identifying a frequency of said tone of any frequency; and
bypassing determining whether at least one tone has been detected when said at least one tone has not been indicated; and
when at least one tone has been detected, determining, by said control unit, whether said at least one tone corresponds to a tone event.
2. The method of claim 1 , wherein said sampled input signal has a multiple frequency tone format.
3. The method of claim 1 , further comprising pre-processing said sampled input signal.
4. The method of claim 1 , wherein said sampled input signal is sampled at 8 kHz.
5. The method of claim 1 , further comprising modulating said sampled input signal using at least one of frequency shift keying modulation, phase shift keying modulation, differential phase shift keying modulation, amplitude modulation, and multiple component frequency modulation.
6. The method of claim 1 , wherein said determining whether at least one tone has been detected comprises using said sampled input signal to generate a first tone characteristic value which provides at least one of frequency information, phase information, timing information, and magnitude information, and wherein said determining whether said at least one tone corresponds to a tone event comprises using said first tone characteristic to determine whether said at least one tone is a tone event.
7. The method of claim 6 , further comprising:
selectively adjusting said first tone characteristic value to correct at least one of a phase error, a frequency error, and a magnitude error in said first tone characteristic value.
8. The method of claim 7 , wherein said selectively adjusting said first tone characteristic value to correct at least one of a phase error, a frequency error, and a magnitude error in said first tone characteristic value comprises:
comparing said first tone characteristic value to an expected tone characteristic value, wherein said expected tone characteristic value corresponds to a previous tone characteristic value;
based on said comparing, selectively adjusting said first tone characteristic value.
9. The method of claim 1 , wherein said determining whether at least one tone has been detected comprises using said sampled input signal to generate a plurality of tone characteristics values, each of the plurality of tone characteristic values providing at least one of frequency information, phase information, timing information, and magnitude information, and wherein said determining whether said at least one tone corresponds to a tone event comprises using at least a portion of said plurality of tone characteristic values to determine whether said at least one tone is a tone event.
10. The method of claim 1 , wherein said determining whether at least one tone has been detected comprises determining at least one of a plurality of characteristics, said at least one of a plurality of characteristics comprising at least one of frequency information, phase information, and magnitude information.
11. The method of claim 1 , wherein said determining whether at least one tone has been detected comprises:
using said sampled input signal to generate a first tone characteristic value, said first tone characteristic value corresponding to at least one segment of said sampled input signal.
12. The method of claim 11 , wherein said first tone characteristic value is used to reset itself.
13. The method of claim 11 , further comprising comparing a frequency estimator value to a plurality of reference frequency estimator values and providing said first tone characteristic value based on said comparison between said frequency estimator value and said plurality of reference frequency estimator values.
14. The method of claim 11 , wherein said first tone characteristic value provides at least one of frequency information, phase information, timing information, and magnitude information.
15. The method of claim 11 , further comprising determining whether said first tone indicator remains constant over a predetermined period of time.
16. The method of claim 15 , wherein determining whether said at least one tone is a tone event comprises using said first tone characteristic value to determine whether said at least one tone is a tone event.
17. The method of claim 11 , further comprising:
selectively adjusting said first tone characteristic value to correct at least one of a phase error, a frequency error, and a magnitude error in said first tone characteristic value.
18. The method of claim 17 , wherein said selectively adjusting said first tone characteristic value to correct at least one of a phase error, a frequency error, and a magnitude error in said first tone characteristic value comprises:
comparing said first tone characteristic value to an expected tone characteristic value, wherein said expected tone characteristic value corresponds to a previous tone characteristic value;
based on said comparing, selectively adjusting said first tone characteristic value.
19. A tone event detector implemented at least partially in hardware, comprising:
a tone indicator coupled to receive a sampled input signal, said tone indicator for determining if at least one tone has been indicated based on said sampled input signal wherein said determining by the tone indicator comprises detecting whether a tone of any frequency is present, and wherein said determining by the tone indicator further comprises:
determining an energy estimation of said sampled input signal;
determining whether at least one segment of said energy estimation has a variance of less than a predetermined amount of variance for a predetermined duration;
when said at least one segment has said variance of less than said predetermined amount of variance for said predetermined duration, asserting said tone indication signal to indicate that said at least one tone has been indicated and providing said sampled input signal to said at least one tone detector to determine whether at least one tone has been detected; and
at least one tone detector coupled to said tone indicator, said at least one tone detector coupled to receive said sampled input signal, said at least one tone detector for determining whether at least one tone has been detected when said at least one tone has been indicated, wherein said determining by said at least one tone detector comprises identifying a frequency of said tone of any frequency, and wherein said at least one tone detector is bypassed when said at least one tone has not been indicated; and
control logic coupled to said tone indicator and said at least one tone detector, said control logic determining whether said at least one tone corresponds to a tone event when at least one tone has been detected.
20. The tone event detector of claim 19 , wherein said at least one tone detector comprises at least one of a single component frequency detector, a single component phase detector, or a multicomponent tone detector.
21. The tone event detector of claim 19 , wherein said control logic unit is used to control said at least one tone detector.
22. The tone event detector of claim 19 , wherein said control logic unit receives at least one tone characteristic from said at least one tone detector to determine whether said at least one tone corresponds to a tone event, wherein said at least one tone characteristic comprises at least one of frequency information, phase information, or magnitude information.
23. The tone event detector of claim 22 , wherein said tone indicator determines an energy estimation of said sampled input signal and determines whether at least one segment of said energy estimation has a variance within a predetermined range of variance for a predetermined duration in order to provide said sampled input signal to at least one said tone detector.
24. A tone event detector a method stored via a computer readable medium, wherein said computer readable medium comprises a plurality of instructions, which, when executed by a data processing system, causes the data processing system perform a method comprising:
receiving a sampled input signal;
determining if at least one tone has been indicated based on said sampled input signal, wherein said determining if said at least one tone has been indicated comprises detecting whether a tone of any frequency is present and further comprises:
determining an energy estimation of said sampled input signal;
determining whether at least one segment of said energy estimation has a variance of less than a predetermined amount of variance for a predetermined duration;
when said at least one segment has said variance of less than said predetermined amount of variance for said predetermined duration, asserting said tone indication signal to indicate that said at least one tone has been indicated and providing said sampled input signal to said at least one tone detector to determine whether at least one tone has been detected;
selectively determining whether at least one tone has been detected, wherein selectively determining comprises:
determining whether at least one tone has been detected when said at least one tone has been indicated, wherein said determining whether at least one tone has been detected comprises identifying a frequency of said tone of any frequency; and
bypassing determining whether at least one tone has been detected when said at least one tone has not been indicated; and
determining whether said at least one tone corresponds to a tone event when at least one tone has been detected.