Time sharing of a supervisory receiver unit

Claim 2

In an automatic telephone switching system having at least a transmit highway and a receive highway, a plurality of lines over which analog signals including speech and supervisory signals are transmitted, at least certain of said lines having means for providing a first set of voice frequency signals for supervisory purposes including off hook indication signals, and a second set of voice frequency signals for address signalling purposes, a plurality of line coupling circuits, each of which line coupling circuits is connected to a different one of said lines, and each of which has a plurality of switching means associated therewith selectively operative to connect the line coupling circuit for its associated line to said transmit and receive highways, first means in each line coupling means connected between its associated line and at least one of said switching means associated with said line to derive a constant level signal independent of the changing terminal impedances which occur on its associated line with operation of its associated switching means to different conditions, a plurality of supervisory signal receiver means, each of which includes a plurality of analog switching means, an output circuit connected to said analog switching means, second means in each line coupling means for connecting the constant level signal provided by the first means in its line coupling means and the voice frequency signals on its line to an associated one of said analog switching means, means for providing strobe signals in sequence to each one of said analog switching means to control each of said analog switching means to gate the voice frequency signals on its associated line to said output circuit, first means connected to said output circuit for detecting the frequency of only the voice frequency signals of said first set of signals which are gated over said output circuit including said off hook indication signals, and further means controlled by said first means to provide signals which indicate the supervisory signals which were detected in said first set of signals.

Claim 3

A system as set forth in claim 1 in which each line comprises a transmit and a receive path, and in which said line coupling circuit comprises a hybrid transformer having a first and second port connected to said receive path, and a third port connected to a circuit which provides said constant level signal to the analog switching means for said line.

Claim 4

An automatic telephone switching system as set forth in claim 1 in which others of said lines provide DC supervisory signals, and which includes means for detecting said DC supervisory signals on said other lines, and means for providing an indication of the line and type of supervisory signal detected to said associated equipment.

Claim 5

In a time division multiplex automatic telephone switching system having a plurality of lines over which speech and supervisory analog signals are transmitted, and a time division multiplex highway, at least certain of said lines having means for providing a first set of voice frequency signals for line supervision purposes and a second set of voice frequency signals for address signalling purposes, supervisory receiver means for a group of said certain lines including a plurality of analog switching circuits, each of said certain lines having gating means for selectively connecting its line to said highway on a time division basis, filter means connected to said gating means and hybrid transformer means for coupling said gating means and said filter means to its associated line, circuit means connected to said hybrid transformer means to provide a constant voltage over an input path to said analog switching means independent of the changing impedance which occurs on said line with changes in the state of said gating means, common control means for processing detected supervisory signals including means for providing enabling signals to the control circuits of said analog switching circuits in a predetermined pattern, said analog switching means being operative as enabled by said signal to connect the voice frequency signal which appears on its associated line and input path to an output circuit, circuit means connected to said output circuit responsive to only said voice frequency signals of said first set as gated thereto by one of said analog switching circuits to provide logic signals which present the detected ones of the supervisory signals, and output means connected to said circuit means for providing the output logic signals to said common control means.

Claim 6

In a time division multiplex automatic telephone switching system having a plurality of lines over which speech and supervisory analog signals are transmitted, and a time division multiplex highway, at least certain of said lines having means for providing a first set of voice frequency signals for line supervision purposes and a second set of voice frequency signals for address signalling purposes, supervisory receiver means for a group of said certain lines including a plurality of analog switching circuits, each of said certain lines having gating means for selectively connecting its line to said highway on a time division basis, filter means connected to said gating means and hybrid transformer means for coupling said gating means and said filter means to its associated line, circuit means connected to said hybrid transformer means to provide a constant voltage over an input path to said analog switching means independent of the changing impedance which occurs on said line with changes in the state of said gating means, common control means for processing detected supervisory signals including means for providing enabling signals to the control circuits of said analog switching circuits in a predetermined pattern, said analog switching means being operative as enabled by said signal to connect the voice frequency signal which appears on its associated line and input path to an output circuit, circuit means connected to said output circuit responsive to only said voice frequency signals of said first set as gated thereto by one of said analog switching circuits to provide logic signals which present the detected ones of the supervisory signals, and output means connected to said circuit means for providing the output logic signals to said common control means.

Claim 7

An automatic telephone switching system as claimed in claim 4 in which cerTain of said voice frequency signals of said first set are assigned to represent predetermined conditions of said lines, and in which said circuit means includes filter network means for detecting said conditions represented by said voice frequency signals of said first set, and means connecting said filter network means to said output circuit for said analog switching circuits, and a threshold detector control circuit connected to said output circuit having means connected to enable said filter network means only in response to occurrence of a minimum signal level of a predetermind minimum value on one of said lines.

Claim 8

An automatic telephone switching system as claimed in claim 5 in which each of said filter network means has a turn on delay time and a turn off delay time, and wherein said logic signal provided to said common control means by said output means has a time period determined by the duration of the strobe signal of said analog switching circuit minus said turn on delay time plus said turn off delay time.

Claim 9

An automatic telephone switching system as set forth in claim 4 wherein said circuit means includes a plurality of network means for detecting only said voice frequency signals of said first set, and first means for connecting the input of said network means to said output circuit for analog switching circuits, and each of said network means includes a different filter means, each of which is connected to its input means to pass only predetermined ones of said plurality of voice frequency signals, limiter clipper means connected to the output of said filter means, tuned circuit means connected to the output of said limiter clipper means, detector circuit means connected to the output of said tuned circuit means, switch means connected to the output of said detector circuit means, comparator circuit means connected to the output of said switch means, and output means for connecting the output of said comparator circuit means to said common control means.

Claim 10

An automatic telephone switching system as set forth in claim 7 wherein said circuit means also includes a threshold control circuit connected to said output circuit having means operative only upon receipt of a set minimum voltage level to enable each of said tuned circuit means.

Claim 11

An automatic telephone switching system as set forth in claim 4 in which said circuit means includes a plurality of network means having means connected to said output circuit to detect the frequency signals of said first set gated by said switching circuits to said circuit means, and tuned circuit means connected to said means for detecting the frequency signals to provide a given signal output responsive to receipt of a predetermined one of said voice frequency signals of said first set, and logic circuit means connected to the output of said tuned circuit means for providing a first logic signal output in the absence of a signal from its associated tuned circuit means and enabled by an output signal from its associated tuned circuit means to provide a second logic signal output.

Claim 12

An automatic telephone switching system as set forth in claim 9 in which said logic circuit means includes common logic means for providing output logic signals representative of the detected voice frequency signals, input means for connecting the signal output of only a certain group of said network means to the input for said common logic means, and means in said common logic means connected to said input means for providing a predetermined output logic signal only when an input signal is simultaneously provided to the tuned circuit means for each of said network means in said certain group.

Claim 13

An automatic telephone switching system as set forth in claim 9 in which each of said certain lines includes means for providing a first voice frequency signal and a second voice frequency signal for operator recall, and in which said plurality of network means includes a first network connected to said output circuit for deteCting said first voice frequency signals and a second network for detecting said second voice frequencysignals.

Claim 14

In an automatic telephone system as set forth in claim 9 in which said logic circuit means includes further means for providing said second output logic signal only when the frequency signal provided to its associated tuned circuit is of a predetermined duration.

Claim 15

In an automatic telephone system having at least a transmit highway and a receive highway and a plurality of transmission lines, each of which lines has a receive and a transmit path, pulse amplitude modulator means associated with said receive path and switching means associated with said receive and transmit paths for selectively connecting its associated line to respective receive and transmit highways, certain of which lines have means for providing a first set of voice frequency signals to indicate different conditions of the line for supervision purposes, and a second set of voice frequency signals of correspondingly different frequencies for address signalling purposes, a hybrid transformer means for each line including a first winding and a second winding connected in said receive path between the line and said pulse amplitude modulator means, and a constant signal circuit connected to said second winding for providing a constant level signal independent of changing impedance on said receive path, supervisory receiver unit means including a plurality of analog switch means, means connecting the input of each of said analog switch means to said constant signal circuit for an associated one of said hybrid transformer means, an output circuit for said analog signal means, circuit means in said supervisory receiver unit means connected to said output circuit, common control means including means for strobing each of said analog switch means in sequence to gate the voice frequency signals on the corresponding transmission lines to pass through said analog switching means and over said output circuit to said circuit means, means in said circuit means connected to said output circuit for converting only said voice frequency signals of said first set of the signals gated thereto by said analog switch means which is of a predetermined amplitude to logic signals which represent said voice frequency signals of said first set, output means for transmitting said logic signals output from said circuit means to said common control means, and means in said common control means connected to enable said analog switch means in a predetermined sequence to provide said logic signals on a time sharing basis.

Claim 16

In an automatic telephone system having at least a transmit highway and a receive highway and a plurality of transmission lines, each of which lines has a receive and a transmit path, pulse amplitude modulator means associated with said receive path and switching means associated with said receive and transmit paths for selectively connecting its associated line to respective receive and transmit highways, certain of which lines have means for providing a first set of voice frequency signals to indicate different conditions of the line for supervision purposes, and a second set of voice frequency signals of correspondingly different frequencies for address signalling purposes, a hybrid transformer means for each line including a first winding and a second winding connected in said receive path between the line and said pulse amplitude modulator means, and a constant signal circuit connected to said second winding for providing a constant level signal independent of changing impedance on said receive path, supervisory receiver unit means including a plurality of analog switch means, means connecting the input of each of said analog switch means to said constant signal circuit for an associated one of said hybrid transformer means, an output circuit for said analog signal means, circuit means in said supervisory receiver unit means connected to said output circuit, common control means including means for strobing each of said analog switch means in sequence to gate the voice frequency signals on the corresponding transmission lines to pass through said analog switching means and over said output circuit to said circuit means, means in said circuit means connected to said output circuit for converting only said voice frequency signals of said first set of the signals gated thereto by said analog switch means which is of a predetermined amplitude to logic signals which represent said voice frequency signals of said first set, output means for transmitting said logic signals output from said circuit means to said common control means, and means in said common control means connected to enable said analog switch means in a predetermined sequence to provide said logic signals on a time sharing basis.

Claim 17

An automatic telephone system as set forth in claim 13 in which at least certain of said transmission lines include a transformer connected in said transmit path and DC supervisory signal detector means capable of detecting a plurality of DC supervisory signals having an input circuit connected to taps on said hybrid transformer and said transformer in said transmit path, said DC supervisory signal detector means comprising at least one switch means connected to said input circuit, logic gating means, and means enabled by said switch means in response to DC supervisory signals on said line to indicate the presence of such signal to said logic gate means.

Claim 18

An automatic telephone switching system as set forth in claim 14 in which said logic gating means for said one line includes first logic gate means and second logic gate means, said first logic gate means having a first input terminal connected to the output of said switch means for said line, and a second input terminal connected to the output of the one of said analog switch means which is connected to said line, means connecting the output of said first logic gate means to an input of said second logic gate means, and means connecting the output of said second logic gate means to said common control means to indicate the presence of said one supervisory signal.

Claim 19

An automatic telephone switching system as set forth in claim 15 in which said common control means includes means for cyclically strobing said first logic gate means and its associated analog switch means for the different lines in a predetermined sequence, whereby said DC supervisory signal detector means are enabled to indicate to said common control means in sequence the lines which have DC supervisory signals thereon and the identity of said line.