Telephonic communications – Supervisory or control line signaling – Signal receiver
Reexamination Certificate
2005-02-01
2005-02-01
Barnie, Rexford (Department: 2644)
Telephonic communications
Supervisory or control line signaling
Signal receiver
C379S282000, C379S283000
Reexamination Certificate
active
06850616
ABSTRACT:
A method of detecting frequency errors exceeding a predetermined limit in a sampled signal includes the step of determining a peak amplitude of the signal at a tone frequency for a first frame of samples of the sampled signals using a filter having a first amplitude versus frequency response. A peak amplitude of signal at the tone frequency is determined for a second frame of samples of the sampled signal using a filter having a second amplitude versus frequency response. A ratio between the peak amplitude of the first frame and the peak amplitude of the second frame is calculated and compared against a threshold to detect frequency errors exceeding the predetermined limit. Among other things, this method decouples the frequency error detection problem from the twist factor estimation problem.
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Datar Rajendra
Ghanekar Sachin
Soman Manoj
Barnie Rexford
Cirrus Logic Inc.
Murphy James J.
Thompson & Knight LLP
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