Method and apparatus for frequency analysis of telephone signals
First Claim
1. A method for identifying an analog or digital signal on a telecommunications line which was produced by a predetermined human voice response, which method comprises the steps of:
- (a) storing Ck (xk,n) and Sk (xk,n) where;
space="preserve" listing-type="equation">C.sub.k (x.sub.k,n)=x.sub.k *cos (2π
kn/N) and S.sub.k (x.sub.k,n)=x.sub.k *sin (2π
kn/N)for;
k=0, . . . , (N-1);
n=0, . . . , (N-1); and
xk ranging over all the values of a set of M predetermined digital levels into which the amplitude of the signal is mapped, if the signal is a digital signal, or into which samples of the amplitude of the signal is mapped, if the signal is an analog signalwhere;
N is a predetermined number of values of the signal, if the signal is a digital signal, or N is the predetermined number of samples of the signal, if the signal is an analog signal, which values or samples are used in determining at least a portion of the frequency spectrum; and
n is an index of frequency bins of the frequency spectrum;
(b) determining the sound level of the signal and, when the sound level of the signal exceeds a first predetermined sound level, setting a timer and a frame counter;
(c) obtaining a digital value from the signal, the digital value comprising an amplitude value of the signal if the signal is a digital signal and the digital value comprising a sample of the amplitude of the signal if the signal is an analog signal;
(d) matching the digital value with one of the predetermined set of M predetermined digital levels into which the signal is mapped to provide a value xj ;
(e) retrieving Cj (xj,f) and Sj (xj from storage for each of predetermined frequency bins f for the value xj ;
(f) accumulating the sum of Cj (xj,f) and Sj (xj,f) for N digital values xj, by repeating steps (c) through step (f) a sufficient number of times, to provide the real and imaginary part of the content for each of the predetermined frequency bins f;
(g) determining the sound level of the signal and, when the sound level of the signal falls below a second predetermined sound level, proceeding to step (i), otherwise proceeding to step (h);
(h) determining a measure of energy for each of the predetermined frequency bins f from the real and imaginary part of the content thereof, incrementing the frame counter and the timer and, if the frame counter is less than a predetermined frame count, proceeding to step (c), otherwise, storing the measure of energy in the predetermined frequency bins f for predetermined frames, resetting the frame counter and proceeding to step (c);
(i) determining if the timer is outside of a predetermined time range and, if so, transmitting a message that the signal corresponds to an unrecognized response;
(j) comparing variations of functions of the measure of energy for the predetermined frequency bins f in predetermined frames with predetermined variations of the measure of energy for the predetermined frequency bins f for the predetermined human voice response and, if they compare within predetermined limits, transmitting a message that the predetermined human voice response has been detected.
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Accused Products
Abstract
For faster realtime analysis related to Discrete Fourier Transform (DFT), prestored pre-multiplied values of amplitude times cosine and sine functions are used. Method and apparatus for determining the content of a predetermined frequency bin f in the frequency spectrum of a signal and, in particular, a signal which occurs in a telephone network, includes the step of storing on a storage means:
C.sub.k (x.sub.k,n)=x.sub.k *cos(2πkn/N) and S.sub.k (x.sub.k,n)=x.sub.k
*sin(2πkn/N)
for: k=0, . . . , (N-1); n=0, . . . , (n-1); and xk ranging over all the values of the set of M predetermined digital levels into which the amplitude of the signal is mapped, if the signal is a digital signal, or into which a sample of the amplitude of the signal is mapped, if the signal is an analog signal. N is a predetermined number of amplitudes or samples of the amplitude of the signal which are used in analyzing the frequency spectrum and n is a frequency index.
53 Citations
20 Claims
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1. A method for identifying an analog or digital signal on a telecommunications line which was produced by a predetermined human voice response, which method comprises the steps of:
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(a) storing Ck (xk,n) and Sk (xk,n) where;
space="preserve" listing-type="equation">C.sub.k (x.sub.k,n)=x.sub.k *cos (2π
kn/N) and S.sub.k (x.sub.k,n)=x.sub.k *sin (2π
kn/N)for;
k=0, . . . , (N-1);
n=0, . . . , (N-1); and
xk ranging over all the values of a set of M predetermined digital levels into which the amplitude of the signal is mapped, if the signal is a digital signal, or into which samples of the amplitude of the signal is mapped, if the signal is an analog signalwhere;
N is a predetermined number of values of the signal, if the signal is a digital signal, or N is the predetermined number of samples of the signal, if the signal is an analog signal, which values or samples are used in determining at least a portion of the frequency spectrum; and
n is an index of frequency bins of the frequency spectrum;(b) determining the sound level of the signal and, when the sound level of the signal exceeds a first predetermined sound level, setting a timer and a frame counter; (c) obtaining a digital value from the signal, the digital value comprising an amplitude value of the signal if the signal is a digital signal and the digital value comprising a sample of the amplitude of the signal if the signal is an analog signal; (d) matching the digital value with one of the predetermined set of M predetermined digital levels into which the signal is mapped to provide a value xj ; (e) retrieving Cj (xj,f) and Sj (xj from storage for each of predetermined frequency bins f for the value xj ; (f) accumulating the sum of Cj (xj,f) and Sj (xj,f) for N digital values xj, by repeating steps (c) through step (f) a sufficient number of times, to provide the real and imaginary part of the content for each of the predetermined frequency bins f; (g) determining the sound level of the signal and, when the sound level of the signal falls below a second predetermined sound level, proceeding to step (i), otherwise proceeding to step (h); (h) determining a measure of energy for each of the predetermined frequency bins f from the real and imaginary part of the content thereof, incrementing the frame counter and the timer and, if the frame counter is less than a predetermined frame count, proceeding to step (c), otherwise, storing the measure of energy in the predetermined frequency bins f for predetermined frames, resetting the frame counter and proceeding to step (c); (i) determining if the timer is outside of a predetermined time range and, if so, transmitting a message that the signal corresponds to an unrecognized response; (j) comparing variations of functions of the measure of energy for the predetermined frequency bins f in predetermined frames with predetermined variations of the measure of energy for the predetermined frequency bins f for the predetermined human voice response and, if they compare within predetermined limits, transmitting a message that the predetermined human voice response has been detected. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. A method for identifying an analog or digital signal on a telecommunications line which was produced by a predetermined human voice response, which method comprises the steps of:
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(a) storing Ck (xk,n) and Sk (xk,n) where;
space="preserve" listing-type="equation">C.sub.k (x.sub.k,n)=x.sub.k *cos (2π
kn/N) and S.sub.k (x.sub.k,n)=x.sub.k *sin (2π
kn/N)for;
k=0, . . . , (N-1);
n=0 , . . . , (N-1); and
xk ranging over all the values of a set of M predetermined digital levels into which the amplitude of the signal is mapped, if the signal is a digital signal, or into which a sample of the amplitude of the signal is mapped, if the signal is an analog signalwhere;
N is a predetermined number of values of the signal, if the signal is a digital signal, or N is a predetermined number of samples of the signal, if the signal is an analog signal, which values or samples are used in determining at least a portion of the frequency spectrum; andn is an index of frequency bins of the frequency spectrum; (b) determining the sound level of the signal and, when the sound level of the signal exceeds a first predetermined sound level, setting a timer and a frame counter; (c) obtaining digital values from the signal, the digital values comprising N amplitude values of the signal if the signal is a digital signal and the digital values comprising N samples of the amplitude of the signal if the signal is an analog signal; (d) matching each of the digital values with one of the predetermined set of M predetermined digital levels into which the signal is mapped to provide N values xj for j=0, . . . , N-1; (e) retrieving Cj (xj,f) and Sj (xj,f) from storage for each of predetermined frequency bins f and each of the N values xj ; (f) accumulating the sum of Cj (xj,f) and Sj (xj,f) for the N values xj to provide the real and imaginary part of the content for each of the predetermined frequency bins f; (g) determining the sound level of the signal and, when the sound level of the signal falls below a second predetermined sound level, proceeding to step (i), otherwise proceeding to step (h); (h) determining a measure of energy for each of the predetermined frequency bins f from the real and imaginary part of the content thereof, incrementing the frame counter and the timer and, if the frame counter is less than a predetermined frame count, proceeding to step (c), otherwise, storing the measure of energy in the predetermined frequency bins f for predetermined frames, resetting the frame counter and proceeding to step (c); (i) determining if the timer is outside of a predetermined timer range and, if so transmitting a message that the signal corresponds to an unrecognized response; (j) comparing variations of functions of the measure of energy for the predetermined frequency bins f in predetermined frames with predetermined variations of the measure of energy for the predetermined frequency bins f for the predetermined human voice response and, if they compare within predetermined limits, transmitting a message that the predetermined human voice response has been detected.
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11. Apparatus for identifying an analog or digital signal on a telecommunications line which was produced by a predetermined human voice response, which apparatus comprises:
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storage means for storing Ck (xk,n) and Sk (xk,n) where;
space="preserve" listing-type="equation">C.sub.k (x.sub.k,n)=x.sub.k *cos (2π
kn/N) and S.sub.k (x.sub.k,n)=x.sub.k *sin (2π
kn/N)for;
k=0, . . . , (N-1);
n=0, . . . , (N-1); and
xk ranging over all the values of a set of M predetermined digital levels into which the amplitude of the signal is mapped, if the signal is a digital signal, or into which a sample of the amplitude of the signal is mapped, if the signal is an analog signalwhere;
N is a predetermined number of values of the signal, if the signal is a digital signal, or N is a predetermined number of samples of the signal, if the signal is an analog signal, which are used in determining at least a portion of the frequency spectrum; andn is an index of frequency bins of the frequency spectrum; sound level for determining the sound level of the signal and for transmitting a sound level indicator signal; first initial means, responsive to the sound level indicator signal, for setting a timer and a frame counter when the sound level of the signal exceeds a first predetermined sound level and for sending a signal to a second initial means; second initial means, responsive to a signal from a measure means or the first initial means, for initializing a sum of Cj (xj,f) and Sj (xj,f) for N amplitude values of the signal, if the signal is a digital signal, or for N samples of the amplitude of the signal, if the signal is an analog signal, and for sending a signal to a value means; value means, responsive to a signal from the first initial means or the accumulating means, for obtaining a digital value from the signal, the digital value comprising an amplitude value of the signal if the signal is a digital signal and the digital value comprising a sample of the amplitude of the signal if the signal is an analog signal; matching means, responsive to a signal from the value means, for matching the digital value with one of the predetermined set of M predetermined digital levels into which the signal is mapped to provide a value xj ; retrieving means, responsive to a signal from the matching means, for retrieving Cj (xj,f) and Sj (xj,f) from the storage means for each of predetermined frequency bins f for the value xj ; accumulating means, responsive to a signal from the retrieving means, for accumulating the sum of Cj (xj,f) and Sj (xj,f) for the value of xj to provide the real and imaginary part of the content for each of the predetermined frequency bins f and for determining if this is the Nth value of xj and, if so, for transmitting a signal to a level means, otherwise, transmitting a signal to the value means; level means, responsive to a signal from the accumulating means and the sound level indicator signal, for determining the sound level of the signal and, when the sound level of the signal falls below a second predetermined sound level, for sending a signal to a time check means, otherwise, for sending a signal to the measure means; measure means, responsive to a signal from the level means, for determining a measure of energy for each of the predetermined frequency bins f from the real and imaginary part of the content thereof, for incrementing the frame counter and the timer and, if the frame counter is less than a predetermined frame count, for sending a signal to the second initial means, otherwise, for storing the measure of energy in the predetermined frequency bins f for predetermined frames, for resetting the frame counter, and for sending a signal to the second initial means; time check means, responsive to a signal from the level means, for determining if the timer is outside of a predetermined time range and, if so, for transmitting a message signal denoting that the signal corresponds to an unrecognized response; and
, otherwise, for transmitting a signal to a comparison means;comparison means, responsive to a signal from the time check means, for comparing variations of functions of the measure of energy for the predetermined frequency bins f in predetermined frames with predetermined variations of functions of the measure of energy for the predetermined frequency bins f for the predetermined human voice response and, if they compare within predetermined limits, for transmitting a message signal denoting that the predetermined human voice response has been detected. - View Dependent Claims (12, 13, 14, 15, 16, 17, 18, 19)
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20. Apparatus for identifying an analog or digital signal on a telecommunications line which was produced by a predetermined human voice response, which apparatus comprises:
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means for storing Ck (xk,n) and Sk (xk,n) where;
space="preserve" listing-type="equation">C.sub.k (x.sub.k,n)=x.sub.k *cos (2π
kn/N) and S.sub.k (x.sub.k,n)=x.sub.k *sin (2π
kn/N)for;
k=0, . . . , (N-1);
n=0, . . . , (N-1); and
xk ranging over all the values of a set of M predetermined digital levels into which the amplitude of the signal is mapped, if the signal is a digital signal, or into which a sample of the amplitude of the signal is mapped, if the signal is an analog signalwhere;
N is a predetermined number of values of the signal, if the signal is a digital signal, or N is a predetermined number of samples of the signal, if the signal is an analog signal, which are used in determining at least a portion of the frequency spectrum; andn is an index of frequency bins of the frequency spectrum; sound level means for determining the sound level of the signal and for transmitting a sound level indicator signal; initial means, responsive to the sound level indicator signal, for setting a timer and a frame counter when the sound level of the signal exceeds a first predetermined sound level and for sending a signal to a value means; value means, responsive to a signal from the initial means or a measure means, for obtaining digital values from the signal, the digital values comprising N amplitude values of the signal if the signal is a digital signal and the digital values comprising N samples of the amplitude of the signal if the signal is an analog signal; matching means, responsive to a signal from the value means, for matching each of the digital values with one of the predetermined set of M predetermined digital levels into which the signal is mapped to provide N values xj for j=0, . . . , N-1; retrieving means, responsive to a signal from the matching means, for retrieving Cj (xj,f) and Sj (xj,f) from the storage means for each of predetermined frequency bins f and each of the values xj ; accumulating means, responsive to a signal from the retrieving means, for accumulating the sum of Cj (xj,f) and Sj (xj,f) for the N values xj to provide the real and imaginary part of the content for each of the predetermined frequency bins f, and for sending a signal to a level means; level means, responsive to a signal from the accumulating means and the sound level indicator signal, for determining the sound level of the signal and, when the sound level of the signal falls below a second predetermined sound level, for sending a signal to a time check means, otherwise, for sending a signal to the measure means; measure means, responsive to a signal from the level means, for determining a measure of energy for each of the predetermined frequency bins f from the real and imaginary part of the content thereof, for incrementing the frame counter and the timer and, if the frame counter is less than a predetermined frame count, for sending a signal to the value means, otherwise;
for storing the measure of energy in the predetermined frequency bins f for predetermined frames, for resetting the frame counter, and for sending a signal to the value means;time check means, responsive to a signal from the level means, for determining if the timer is outside of a predetermined time range and, if so, for transmitting a message signal denoting that the signal corresponds to an unrecognized response; and
, otherwise, for transmitting a signal to a comparison means;comparison means, responsive to a signal from the time check means, for comparing variations of functions of the measure of energy for the predetermined frequency bins f in predetermined frames with predetermined variations of functions of the measure of energy for the predetermined frequency bins f for the predetermined human voice response and, if they compare within predetermined limits, for transmitting a message signal denoting that the predetermined human voice response has been detected.
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Specification