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US 9,055,145 B1Granted
Recovery of DTMF tones in the presence of periodic interference and obstruction
AssigneeThe United States of America as represented by the Secretary of the Army
InventorsWei Su, Muhammed Karim
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Abstract
While a dual tone multi-frequency (DTMF) signal can be easily processed if cleanly obtained, difficulties can arise if the DTMF signal is not cleanly obtained. In one example, part of the signal can be cleanly obtained, but part of the signal can be obstructed. In order to determine the content of the DTMF signal the parts that are cleanly obtained can be compared with known DTMF signals, such as DTMF signals that correspond with buttons on a telephone keypad. A classification of a closest matching known DTMF signal can be identified and that classification can be assigned to the partially obtained DTMF signal. Thus, without clearly obtaining the whole DTMF signal a content of the DTMF signal can be ascertained.
Claims20
A system, comprising:
- a comparison component configured to compare a signal part group of a dual tone signal against a known signal set to produce a comparison result, where the signal part group is less than the signal;
- an identification component configured to perform an identification of a known signal that matches the dual tone through use of the comparison result, where the known signal is part of the known signal set;
- a construction component configured to construct a first error check window through use of the signal part group;
- an error component configured to make a determination when an error associated with the first error check window is not at a minimum, where the construction component is configured to construct a subsequent error check window after the determination is that the error associated with the first error check window is not at a minimum;
- an output component configured to cause an output that indicates the known signal that matches the dual tone signal when the error associated with the first error check window is at the minimum and configured to cause the output that indicates the known signal that matches the dual tone signal when the error associated with the subsequent error check window is at the minimum;
- and
- a processor configured to execute an instruction that relates to the comparison component, the identification component, the construction component, the error component, the output component, or a combination thereof.
4 more elements
A system, comprising:
- a comparison component configured to compare a signal part group of a dual tone signal against a known signal set to produce a comparison result, where the signal part group is less than the signal;
- an identification component configured to perform an identification of a known signal that matches the dual tone signal through use of the comparison result, where the known signal is part of the known signal set;
- a reference component configured to choose a reference signal part of the dual tone signal;
- a choice component configured to choose the signal part group based, at least in part, on the reference signal, where the signal part group comprises the reference signal part and at least one non-reference signal part;
- a check component configured to perform a check of an iteration of times the identification component is unable to perform the identification;
- and
- an evaluation component configured to determine if the iteration meets a threshold, where the reference component is configured to choose a different reference signal part of the dual tone signal in response to the iteration not meeting the threshold and where the choice component is configured to choose the signal part group based, at least in part, on the different reference signal;
- and
- a processor configured to execute an instruction that relates to the comparison component, the identification component, the reference component, the choice component, the check component, the evaluation component, or a combination thereof.
6 more elements
A method, comprising:
- executing, instructions from a non-transitory computer-readable medium, the instructions comprising:
- sampling segments of a signal that is multi-tone and periodic, where the segments are outside of obstructions;
- selecting a first segment from the sampled segments as a reference segment;
- combining the reference segment with at least one other sampled segment to form a combined segment;
- performing a Fast Fourier transform upon the combined segment that produces a transform result;
- making an attempt to locate a match signal for the signal through use of the transform result;
- causing a dataset that pertains to the match signal to be outputted in response to the match signal being located;
- checking if a threshold level is reached in response to the attempt being a failure;
- and
- selecting a different segment from the first segment as the reference segment and repeating the combining, performing, and making with the different segment when the attempt is unsuccessful, where the different segment is selected in response to the threshold level not being reached.
7 more elements
Dependencies are inferred from the claim text.