High performance multifrequency signal detection

A method for detecting multifrequency signals, comprising:

• calculating a plurality of estimated frequencies for an input signal and quality information corresponding to the estimated frequencies, the input signal being based on a frame of a signal;
• performing digit detection based on the quality information and a frame decision result for the frame;
• and
• incrementing a counter value when a first predetermined condition is satisfied and resetting the counter value when a second predetermined condition is satisfied, determinations of whether the first and second predetermined conditions are satisfied being based on the quality information, wherein
• the digit detection operation is performed based on whether the counter value satisfies a third determined condition.

A computer readable medium encoded with program instructions for detecting multifrequency signals, said program instructions comprising:

• calculating a plurality of estimated frequencies for an input signal and quality information corresponding to the estimated frequencies, the input signal being based on a frame of a signal;
• and
• performing digit detection based on the quality information and a frame decision result for the frame, wherein:
• said program instructions further comprise instructions for incrementing a counter value when a first predetermined condition is satisfied and resetting the counter value when a second predetermined condition is satisfied, determinations of whether the first and second predetermined conditions are satisfied being based on the quality information;
• and
• said instructions for digit detection include instructions for basing the digit detection on whether the counter value satisfies a third predetermined condition.

A multifrequency detector, comprising:

• an energy analysis module generating a plurality of indices based on a plurality of spectral coefficients for a frame of a signal;
• and
• a decision unit generating a decision level based on a combination of at least two of the indices and outputting the decision level for comparison with a predetermined threshold value, wherein:
• the combination of the indices is a linear combination;
• and
• said decision unit scales the indices by respective predetermined first weights, generates a plurality of first sums each including a linear combination of the scaled indices, and generates the decision level based on the plurality of first sums.

A method for detecting multifrequency signals, comprising:

• generating a plurality of indices based on a plurality of spectral coefficients for a frame of a signal;
• and
• generating a decision level based on a combination of at least two of the indices and outputting the decision level for comparison with a predetermined threshold value, wherein:
• the combination of the indices is a linear combination;
• and
• the decision level generating operation includes scaling the indices by respective predetermined first weights, generating a plurality of first sums each including a linear combination of the scaled indices, and generating the decision level based on the plurality of first sums.

A computer readable medium encoded with program instructions for detecting multifrequency signals, said program instructions comprising:

• generating a plurality of indices based on a plurality of spectral coefficients for a frame of a signal;
• and
• generating a decision level based on a combination of at least two of the indices and outputting the decision level for comparison with a predetermined threshold value, wherein:
• the combination of the indices is a linear combination;
• and
• said instructions for generating the decision level comprise instructions for scaling the indices by respective predetermined first weights, generating a plurality of first sums each including a linear combination of the scaled indices, and generating the decision level based on the plurality of first sums.