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US 2004/0174967 A1Published application
Apparatus, method and software for call-waiting tone detection
AssigneeAltoCom, Inc.
InventorsHaixiang Liang, Zarko Draganic
Life of this patent
Estimating the term…
Abstract
Reliable detection of a call-waiting tone is provided by employing a correlation based technique. A modem or other device employing such a technique need not rely on carrier drop detection and is generally insensitive to other energy or noise on the line.
Claims30
An apparatus comprising:
- a line-input to be coupled to a telephone line;
- a first output to couple a version of a signal received at the line-input to a receive path of a modulator-demodulator (modem);
- a sampling circuit coupled to the line-input to provide a sampled version of the signal received;
- and
- a detector coupled to the sampling circuit, the processor to correlate the sampled version of the signal received with a phase-shifted version thereof to identify call-waiting tone in the sampled version of the signal and provide an indication thereof.
2 more elements
A method comprising:
- coupling a telephone line to a call-waiting detector and to a receive path of a modulator-demodulator (modem);
- sampling a signal received over the telephone line during a modem communication session;
- correlating the sampled version of the signal received with a phase-shifted version thereof to identify call-waiting tone in the sampled version of the signal;
- and
- providing an indication based on a result of the correlating.
2 more elements
A computer program product tangibly embodying a program of executable instructions, said program of instructions including:
- at least one executable instruction to determine if a sampled signal exceeds a first power threshold consistent with a notification signal;
- at least one executable instruction to perform a cross-correlation of the sampled signal with a phase-shifted version of the sampled signal;
- and
- at least one executable instruction to determine if a notification tone is present based, at least in part, on results of the determination and the cross-correlation.
1 more element
Dependencies are inferred from the claim text.