Method and apparatus for signal detection
AssigneeFreescale Semiconductor, Inc.
InventorsJames Allen Stephens, Lam Tak Wing
Life of this patent
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Abstract
A signal detector for detecting a signal having a first nominal frequency, F1 and a second nominal frequency F2, the signal intermixed with an interfering signal to form a composite signal, the signal detector including a first and a second band pass filter centered at F1 and F2 for filtering the composite signal to provide an F1 and F2 signal; a parameter estimator for determining an F1 and F2 period for the F1 and F2 signal for a sequence of frames and an average period shift (APS) for a current frame and a plurality of earlier frames; a metric calculator for calculating a metric that corresponds to the F1 and F2 period and the APS; and a decision processor for deciding whether the signal has been detected based in part on a comparison of the metric and a threshold.
Claims28
A method of detecting a signal having a nominal frequency, the signal intermixed with an interfering signal to form a composite signal, the method including the steps of:
- filtering the composite signal with a filter centered at the nominal frequency to provide a filtered composite signal;
- estimating a filtered power for said filtered composite signal and a composite power for the composite signal;
- determining a periodicity parameter of said filtered composite signal and a variability estimate of said periodicity parameter;
- calculating a metric that corresponds to a combination of said filtered power, said composite power, said periodicity parameter, and said variability estimate;
- and
- deciding whether the signal has been detected based in part on a comparison of said metric and a threshold.
A signal detector for detecting a signal having a first nominal frequency, F1 and a second nominal frequency F2, the signal intermixed with an interfering signal to form a composite signal, the signal detector comprising in combination:
- a first and a second band pass filter centered at F1 and F2 for filtering the composite signal to provide an F1 signal and an F2 signal;
- a parameter estimator for determining an F1 period for said F1 signal and an F2 period for said F2 signal for each of a sequence of frames of said F1 signal and said F2 signal and an average period shift (APS) that is proportional to a combination of a F1 min and a F1 max period selected from said F1 period for a current frame and a plurality of earlier frames and a F2 min and a F2 max period selected from said F2 period for said current frame and said plurality of earlier frames;
- a metric calculator for calculating a metric that corresponds to said F1 period, said F2 period, and said APS;
- and
- a decision processor for deciding whether the signal has been detected based in part on a comparison of said metric and a threshold.
A software program that enables a signal detector for detecting a signal having a first nominal frequency, F1 and a second nominal frequency F2, the signal intermixed with an interfering signal to form a composite signal, the software program, when installed on and executed by a processor that is suitably interfaced to the composite signal, providing in combination:
- a first and a second bandpass filter centered at F1 and F2 for filtering the composite signal to provide an F1 signal and an F2 signal;
- a parameter estimator for determining an F1 period for said F1 signal and an F2 period for said F2 signal for each of a sequence of frames of said F1 signal and said F2 signal and an average period shift (APS) that is proportional to a combination of a F1 min and a F1 max period selected from said F1 period for a current frame and a plurality of earlier frames and a F2 min and a F2 max period selected from said F2 period for said current frame and said plurality of earlier frames;
- a metric calculator for calculating a metric that corresponds to said F1 period, said F2 period, and, said APS;
- and
- a decision processor for deciding whether the signal has been detected based in part on a comparison of said metric and a threshold.
Dependencies are inferred from the claim text.