Boots – shoes – and leggings
Patent
1978-05-17
1980-01-22
Konick, Bernard
Boots, shoes, and leggings
179 84VF, 364728, H04Q 1100
Patent
active
041851722
ABSTRACT:
Digitized samples of switching or supervisory signals in the form of specific frequency pairs, selected from n predetermined signaling frequencies, are received at a PCM terminal of a telephone exchange and fed to n frequency correlators, one for each signaling frequency used in the system, where the samples are multiplied by a sine function and a cosine function of the respective signaling frequency and the two products are integrated and vectorially added to form a resulting binary signal. The absolute value of the incoming-signal sample in each PCM time slot is multiplied in a pair of pseudo-correlators with two fixed values of approximately equal magnitude but opposite sign. A microcomputer compares the output signals of the several frequency correlators with a fixed threshold, or with an adaptive threshold derived from the output of one of the pseudo-correlaors if that threshold surpasses the fixed one. If the threshold used as a reference is exceeded for a predetermined length of time, the output signal is recognized as being a true signaling pulse. A significant discrepancy between the absolute magnitudes of the two pseudo-correlator outputs, detected by the microcomputer, gives rise to an alarm signal indicative of a malfunction. The several frequency correlators and pseudo-correlators can all be constituted by a single circuit component to which the various signaling frequencies are successively applied in any time slot assigned to an incoming signaling channel.
REFERENCES:
patent: 3976843 (1976-08-01), Buchner et al.
patent: 4001521 (1977-01-01), Fukata et al.
patent: 4025730 (1977-05-01), Sawai
Claasen et al., "A Digital Receiver for Tone Detection Applications", IEEE Transactions on Communications, vol. Com-24, No. 12, Dec. 1976, pp. 1291-1300.
C. R. Baugh, "Design and Performance of a Digital Multifrequency Receiver", IEEE Transactions on Communications, Jun. 1977, pp. 608-615.
Melindo Flavio
Rocci Renato
CSELT - Centro Studi e Laboratori Telecomunicazioni S.P.A.
Konick Bernard
Popek Joseph A.
Ross Karl F.
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