Signal analyzing system

Mechanism for analyzing an analog signal represented by digital samples to determine whether the signal has components of uniform frequency comprising means for selecting a first set of the digital samples representing a first segment of the signal beginning at a predetermined point in time, means for selecting several other second sets of the digital samples each of which second sets represents a segment of the signal beginning later than the first segment by a delay interval different from the delay interval of any of the other second sets, each sample of each of the second sets corresponding to one sample of the first set taken earlier by the delay interval of such second set, and means for characterizing the degree of correspondence between the samples of the first set and the samples of each of the other second sets, respectively, indicative of a signal having uniform frequency components.

Mechanism for analyzing signals on a telephone line to detect the presence of call progress signals comprising means for converting the signal on the telephone line to digital samples representing the signal, and means for analyzing the digital samples so as to detect presence of a signal of uniform frequency content over a substantial period indicative of a call progress signal.

The method of determining whether an analog signal has uniform frequency components which comprises converting the analog signal to digital form, selecting a first set of digital samples representing a first segment of the signal beginning at a predetermined point in time, selecting a second set of digital samples representing a second segment of the signal which segment begins later than the first segment by a preselected delay interval, and detecting whether there is correspondence between the samples of the first set and the samples of the second set, respectively, indicative of a signal having uniform frequency components.

The method of detecting whether an analog signal has components of uniform frequency which comprises converting the analog signal to digital form, selecting a first set of digital samples representing a first segment of the signal beginning at a predetermined point in time, selecting several other second sets of digital samples each of which second sets represents a segment of the analog signal beginning later than the first segment by a delay interval different from the delay interval of any of the other second sets, and comparing the samples of the first set and the samples of each of the other second sets, respectively, to detect correspondence indicative of a signal having uniform frequency components.

The method of analyzing signals on a telephone line to detect the presence of call progress signals which comprises converting the signal on the telephone line to digital samples representing the signal, storing the digital samples in the memory of a computer, selecting a first set of the digital samples representing a first segment of the signal beginning at a predetermined point in time, selecting a second set of the digital samples representing a segment of the signal beginning later than the first segment, and comparing the two sets of samples to detect whether or not the signal has uniform frequency content over a substantial period of time.

The method of detecting the presence of call progress signals on a telephone line which comprises converting the signal to digital samples representing the signal, and analyzing the samples so as to detect presence of a signal of uniform frequency content over a substantial period indicative of a call progress signal.

The method of eliminating digital call progress signals from a computer memory bank containing digital voice signals which comprises examining the computer memory bank to detect signal segments having uniform frequency content, and deleting such signal segments from the computer memory bank.