Time compression scanner

Details Time compression scanner Time compression scanner

1974-09-04

1976-02-03

Brown, Thomas W.

179 18FG, 179 84VF, H04B 166

Patent

active

039366111

ABSTRACT:
Time compression scanner for monitoring telephone lines to detect supervisory tones. Eighty-eight lines are organized into eight groups of 11 lines each. The corresponding lines of each group are sampled simultaneously by a first arrangement of eight multiplexers. A second multiplexer repeatedly samples the eight samples from the first multiplexers. These analog samples are converted to digital samples and stored in a digital memory. The memory stores a set of samples pertaining to the incoming signals present on one line of each of the groups. When the first multiplexers each switch to the next line of each of the groups, the stored digital samples are read out of the memory. The samples are read out of the memory for each group in order, converted to analog signals, and passed through a low pass filter. The frequencies present in the resulting signal are speeded up by a factor of eight over the frequencies of any supervisory tones present in the incoming signal from which it was derived. These signal frequencies are passed through reject filters, comparator and limiter circuits, a bank of tone filters, and level detectors to check for each possible resultant frequency and to produce an indication of the presence or absence of each.

REFERENCES:
patent: 3223783 (1965-12-01), Yamamoto
patent: 3337800 (1967-08-01), Halley
patent: 3581017 (1971-05-01), Stevens
patent: 3715509 (1973-02-01), Dawson
patent: 3860760 (1975-01-01), Rittenbach

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