Method and apparatus for detecting a waveform

A method for detecting a predetermined waveform in a signal, the method comprising:

• providing at least one reference set of encoded values, the at least one reference set representing an encoded version of the predetermined waveform;
• encoding the signal to thereby obtain at least one signal set of encoded values;
• and
• calculating at least one statistical correlation coefficient of the at least one reference set and the at least one signal set, whereby the predetermined waveform is detected in the signal if the at least one statistical correlation coefficient is greater than a predetermined threshold value.

A device for detecting a predetermined waveform in a signal transmitted by a telecommunications system in a network, the device comprising:

• an interface unit coupled to the network, the interface unit being operative to automatically establish a telephonic connection between the device and the telecommunications system and capture the signal transmitted by the telecommunications system;
• an encoder coupled to the interface unit, the encoder being operative to encode the signal to thereby obtain at least one signal set of encoded values;
• and
• a processor coupled to the encoder, the processor being operative to calculate at least one statistical correlation coefficient of at least one reference set and the at least one signal set, whereby the predetermined waveform is detected in the signal if the at least one statistical correlation coefficient is greater than a predetermined threshold value.

A computer readable medium having computer executable instructions for performing a method, the method comprising:

• obtaining a reference set of encoded values, the reference set representing an encoded version of a predetermined waveform;
• encoding a signal to thereby obtain at least one signal set of encoded values;
• calculating at least one statistical correlation coefficient of the reference set and the at least one signal set;
• and
• comparing the at least one statistical correlation coefficient with a predetermined threshold value, whereby it is determined that the signal includes the predetermined waveform if the at least one statistical correlation coefficient is greater than a predetermined threshold value.

A device for determining whether a signal is a pure tone, the device comprising:

• an encoder operative to encode a portion of the signal to thereby obtain a reference set of PCM encoded values;
• and
• a processor coupled to the encoder, the processor being programmed to, calculate a second-differences of the signal to thereby obtain a second-differences set of encoded values,
• calculate a statistical correlation coefficient of the reference set and the second-differences set, and
• compare the statistical correlation coefficient to a predetermined threshold, whereby the signal is determined to be a pure tone if the statistical correlation coefficient is greater than the predetermined threshold value.

A method for determining whether a signal is a pure tone, the method comprising:

• encoding at least a portion of the signal to thereby obtain a reference set of encoded values;
• calculating the second-differences of the signal to thereby obtain a second-differences set of encoded values;
• calculating a statistical correlation coefficient of the reference set and the second-differences set;
• and
• comparing the statistical correlation coefficient to a predetermined threshold, whereby the signal is determined to be a pure tone if the statistical correlation coefficient is greater than the predetermined threshold value.

A device for detecting a predetermined waveform in a signal, the device comprising:

• a memory element for storing at least one reference set of encoded values, the at least one reference set representing an encoded version of the predetermined waveform;
• an encoder adapted to encode the signal to thereby obtain at least one signal set of encoded values;
• and
• a processor programmed to encode at least a portion of the signal to thereby obtain a reference set of encoded values,
• calculate the second-differences of the signal to thereby obtain a second-differences set of encoded values,
• calculate a statistical correlation coefficient of the reference set and the second-differences set, and
• compare the statistical correlation coefficient to a predetermined threshold, whereby the signal is determined to be a pure tone if the statistical correlation coefficient is greater than the predetermined threshold value.

A method for synchronizing a received signal with a predetermined waveform, the method comprising:

• providing a reference set of encoded values, the reference set representing an encoded version of the predetermined waveform;
• encoding the signal to thereby obtain a plurality of encoded values;
• calculating a plurality of correlation coefficients for the reference set and each of a plurality of signal sets;
• determining a maximum value correlation coefficient of the plurality of correlation coefficients;
• and
• aligning the reference set with a signal set corresponding to the maximum value correlation coefficient.

A device for detecting a predetermined waveform in a signal, the device comprising:

• a memory element for storing at least one reference set of encoded values, the at least one reference set representing an encoded version of the predetermined waveform;
• an encoder adapted to encode the signal to thereby obtain at least one signal set of encoded values;
• and
• a processor programmed to provide a reference set of encoded values, the reference set representing an encoded version of the predetermined waveform,
• encode the signal to thereby obtain a plurality of encoded values, calculate a plurality of correlation coefficients for the reference set and each of a plurality of signal sets,
• determine a maximum value correlation coefficient of the plurality of correlation coefficients, and
• align the reference set with a signal set corresponding to the maximum value correlation coefficient.