US2424579A - Electric signaling system - Google Patents

Description

July 29,- 1947.

G. J. M. PENET ELEcTRlC sIGNALNG 'SYSTEM Filed March lO, 1945 .Alu IIR@ TM/Mfr Patented July 29, 1947 UNITED STATES PATENT OFFICE ELECTRIC SIGNALING SYSTEM Gabriel J. Penet, Paris, France, assignor to International Standard Electric Corporation, New York, N. Y., a corporation of Delaware Application March 10, 1943, Serial No. 478,701

In France July 1I), 1939 i vs claims. (cryin- 353) One of the characteristics of the invention rei sides in the fact that, when a connection has been set up between two exchanges and while thisconnection endures, a current impulse of the same nature as the signaling or control current is inopportunely transmitted to one of the exchanges, the arrival of the saidimpulse is registered on the impulse receiving device of each of the exchanges but the operation of the receiver device of the exchange in which the impulse was transmitted causes the junction line between exchanges to be cut off before the device at the exchange receiver has been able to send out an instruction or signal. l

A further characteristic of the invention resides in the fact that in the impulse receiver device, means are provided so that the said `device does not cause instructions or signals to be sent out except when the impulse is of duration greater than a predetermined value. Infthis case the impulse receiver device only causes the junction line between the exchanges to be cut off if the duration of the impulse exceeds the predetermined value, the said value being nevertheless less lthan the value of the duration of the normal signaling impulse. i

The subject matter of this invention and its various characteristics will appear from the following description of one embodiment thereof which has been given as a non-limiting example.

The improvements of the invention are particularly adapted for use' in connection with remote control circuits employing code responsive control equipments such as switch equipment of sub-stations controlled from` a `central control station with associated condition signalling equipy ment reporting by code signals to the" central station and wherein as is common practice the lines are. likewise employed for telephone communication.

Other and more detailed objects of the invention will be apparent from the following disclosure of the embodiment illustrated in the drawings. y

.rIn the accompanying drawings the single figure Ais a schematic and diagrammatic illustration of the embodiment selected for purposes of disclosure herein. s `T'Wo connected exchanges have been generally indicated by the reference characters A and B connected together by the line Ll-LZ. This is a two-Wire interexchange trunk to which talking line 'conductors lI-ZZ at exchange A may be ex- .tendedto the'exchange B and there connected to thetwo conductors of line l -ZZ. The receiver equipment is shown at RE and RE' at the respective exchanges A and B. `The exchanges A and 2'5 ilyp'understood, the exchanges A and B may consist of sub-station control equipments or circuits connected in tandem relation to the lines leading to acentral control station. These receivers are normally connected across the ends of the trunk` line between the exchanges at the` switches 45-4'4 and l2- 4I and tif-4 and il24l. In they present embodiment, these switches are armatures and basic contacts of relays l and il', respectively. At exchange A are the relay magnets I, 2 and 4 and at exchange B are the corre- .sponding relay magnets I', 2 and t. Relays Il and 4 have two energizing windings. Relays I and I have retarding windings short circuited over V'their back contacts I5 and I5 respectively. RelayA, which is shown` de-energized, controls the switches 46, 44, `t5, 42, 4I and t3. Relay 2 controls the switch 2I and relay I the switches I3, I5; I4, |E,yl2 and II. Relays I', 2' and 4 correspondingly control switches of the same reference, characters primed, The wires extending frornthe magnets I, 4', I and 4 and terminating :arrowheads` are connected to the positive side of a `suitable grounded current source, not shown for the sake of simplicity. This statement, of course, does not apply to the various arrowheads which 3 obviously indicate the switch contacts. The circuits SW and SW' are connected to any suitable source of signaling current or signal impulse generating device.

In describing the operation of this system, it will be assumed that the signaling impulses are to be transmitted from exchange A to exchange B although obviously they may be transmitted in the reverse direction. In order to send an impulse, the circuit wire FD is grounded which connection is continued for the duration of the impulse. This energizes magnet 4 which opens switches 44, 45, 42 and 4I and closes switches 46 and 43. Thus, at this time, the receiver equipment RE is disconnected from the trunk line and the signaling circuit SW is connected to the trunk line. seen that the signal current or signaling impulses will be sent to exchange B by way of line LI-VL2 as long as wire FD is grounded.

At the exchange B the signaling current is received in the receiver RE" through normally closed switches 42' and 45'. Asan incidentto the application of this current to the device RE', one terminal of relay I' is grounded energizing its lower winding. This relay is retarded by the short circuited winding. After a short period, however, the relay is fully energized and operates the movable contacts of switches I I' and I3 to set up a new and more direct circuit from the line LI-L2 to the receiver equipment RE'. this time switch I5 is open taking the short circuit off the retarding winding of the relay. The closing of switch I4' partially completes a circuit to shunt the winding of magnet 2' which is no1'- mally energized through the resistance R I The f'.,

closing of switch I6 partially completes the signaling circuit FDE which, however, at the moment, is open at switch 2I'. Finally, switch I2' is closed to complete the circuit of one energizing winding of the magnet 4' which in turn opens L switches 44', 45', 42 and 4I' and closes switches 46' and 43'. This will disconnect trunk LI, L2 from the local line ZI and Z2 at exchange B. Switch 4l' closes completing the short circuit for As a result, at exchange A it will be magnet 2 so as to cle-energize it, whereupon,

switch 2 Il closes. A predetermined period must pass before these latter operations occur in view of the fact that magnet 2' is retarded in its deenergization. At the end of the impulse which energized RE', the lower winding of magnet I' is de-energized and it immediately drops back opening switches I4', I 6 and I2'. Switches II' and I3 swing back to the position shown in the drawings. The opening of switch I6', of course, breaks the control or signal circuit connectedto wire FDE'. i

It will be noted that in order that an impulse received at exchange B shall be effective, that is, be operative to provide the signal or control through the circuit FDE', it is necessary that its i duration be greater than the sum of the operating times of relays I' and 2.

It will now be assumed that the exchanges A and B are connected over the line LI-L2 and that the different relays of the system are ln the 'position shown in the drawings. Thus theline to the equipment RE and also through switches 44', 45', 42 and 4I to the equipment RE',l

Two conditions are now to be considered. In the rst place, if the length of this impulse is less than the operating period of relays I and I', then the lower windings thereof are energized but the impulse ceases before these relays become energized. Therefore, the communication equipment as well as the associated auxiliary equipment is not operated. On the other hand, if the length of this impulse is greater than the operating period of the relays I and I' and assuming that their operating times are the same, it will be seen that the relays will be energized simultaneously. liowever, as soon as relay I is operated it closes `switch I2 completing the circuit to the lower winding of relay 4 which immediately operates, and, through its switches 44 and 4I, disconnects the conductors lI-l2 from the conductors LI- L2. The relays I and I' will therefore deenergize, and this will occur before the relays 2 and 2' may operate to complete the control or signaling circuits on the wires FDE and FDE and to operate signal indicating devices SI and SI'. The same cycle of operations, namely the holding of relays I and I', the holding of relay 4 and the f release of relays I and I is repeated throughout the time during which the accidental signal is transmitted on conductors ZI and Z2. It will be noted-V that it is not necessary that the relays I and I' should operate simultaneously to obtain this desired result. If we assume that relay I is energized before relay I' it holds during the time which elapses between the energization of relay I' and the release of relay 2'. Therefore, relay 4 cuts off at 4I and 44 the transmission'of the signalV and by this means causes relay I' to drop -before relay 2' has dropped and has been able to set up the circuit for the wire FDE'.

Thus, it will be seen that with proper timing of the relays, an undesired signal, similar to a control or signal impulse, originated at one exchange, will not be effective to accomplish an improper signal or control at the other exchange. However, a desired and intentional signal or control originated at one exchange will get through.

From theabove description it will be apparlent to those skilled in the art that the principles of this 'invention may take other physical forms than have been disclosed by way of example and vthat it is possible without departing from the scope of the invention to replace all or part of the members by equivalent members or assemblies to give the same result. I do not, therefore, de sire to be strictly limited to this disclosur'e but rather to the scope of the appended claims.

What is claimed is:

1. In a communication system, a rst and a second exchange, a plurality of lines leading to each exchange, a trunk interconnecting said exchanges, a signal receiver at each exchange, a signaling circuit at each exchange for sending -signals of a predetermined duration, two alternative connections between each receiver -and the trunk at its exchange, switching means normally vclosing the rst of said alternative connections r'associated receiver responds `to a signal of said vpredeterminedduration, means for operating the switchingA means when the receiver responds to `3111 of predetermined duration for actuatted through the switches`44 and 45 and'lll and l,7,5 ingv said switching means to open the normally closed connections at the exchange, a control circuit at each exchange closed when the receiver at the associated exchange responds to an impulse of said Vpredetermined durationfand a connection between the signaling circuit andthe i trunk closed by said switching means when` the receiver at the associated exchange is inactive or is operated by an impulse of shorter than said predetermined duration. j

2. In a communication system, a rst and a second exchange, a plurality of lines leading to each exchange, a two-wire trunk interconnecting said exchanges, an impulse receiver at each exchange, a signaling circuit at each exchange for sending impulses of a predetermined duration, twohalternative connections between each receiver and the trunk at its exchange, switching means normally closing the first of said alternative connections and normally connecting a line at the associated exchange with the trunk, slow operating means at each exchange for closing the second connection only when the associated re ceiver responds to an impulse of said predetermined duration, means for operating the switching means controlled by said slow operating means for actuating said switching means to open the normally closed connections at the exchange, a

control circuit at each exchange closed when the receiver at the associated exchange responds to an impulse of said predetermined duration, and a connection between the signaling circuit and the trunk closed by said switching means when the receiver at the associated exchange is inactive or is operated by an impulse of shorter than said predetermined duration.

3. In a communication system, a first and a second exchange, a trunk interconnecting said exchanges, a signal receiver at each exchange, three relays associated with the receiver at each exchange, the first being relatively slow to energize and the second being relatively slow to deenergize, two alternative connections between a receiver and the trunk at its exchange, one of said connections including iront contacts of the associated rst relay and the second connection including back contacts of the associated third relay, an energizing circuit for the rst relay closed while the associated receiver is op erated by a signal, two energizing circuits for the third relay, one controlled by means at the exchange at which the third relay is located and the second by a front contact of the associated first relay, a normally closed energizing circuit for each second relay, a short circuit for each second relay including front contacts 0f the associated iirst and third relays, a control circuit at each exchange including a front contact of the first and a back contact of the second relay at the exchange, and a signaling circuit at each exchange to which the receivers are responsive connected with the trunk over front contacts of the associated third and back contacts of the associated second relay.

4. In a communication system, a iirst and a second exchange, a plurality of lines terminating at each exchange, a trunk interconnecting said exchanges, at each exchange a signaling circuit on which impulses of a predetermined duration are sent, a control circuit, an operating circuit and an impulse receiver, a first relay associated with each receiver, said relay being slow to energize and having an energizing circuit closed While the receiver responds to an impulse, a second relay at each exchange, said second relay being normaily energized and being slow to deenergize,

a third relay at each exchange'having two ener giz'ing circuits, one closed under the control of said operating circuit and the second upon the energization vof the associated first relay and, thus, only if the receiver is operated by an impulse vof predetermined duration, means for conn necting a line at an exchange with the trunk including back contacts of the third relay, a normally closed connection between the trunk and the impulse receiver at each exchange including back contacts of the associated third relay, an alternative connection between each receiver and the trunk including front contacts of the associated rst relay, a short circuit for each second relay closed in front contacts of the associated rst and third relays, means for completing a control circuit at an exchange including a front contact of the associated rst and a back contact of the associated second relay and, thus, only if a signal received by the associated relay is of greater duration than the sum of the operating times of said first and second relays, and means for connecting the signaling circuit at an exchange with the trunk including front contacts of the third and back contacts of the first relay at the exchange, whereby said connection is closed only when no signal is received by the receiver at the exchange and the operating circuit is closed.

5. In a communication system, two exchanges, lines leading to each exchange, a trunk interconnecting said exchanges, means at each exchange for connecting a line terminating thereat with the trunk, receiver means at each exchange normally connected to said trunk to respond to signals thereover, means at each exchange for applying a signal to said trunk and for simultaneously disconnecting the' trunk from the receiver and from the line at the exchange where the means is operated, means operated by each receiver when responding to a signal of a given duration for thereafter closing a control circuit if the signal lasts for a predetermining additional duration, and means also operated by the lastmentioned receiver-operated means for operating the impulse-applying and disconnecting means to disconnect the trunk from the impulse-applying means after the operation of the receiveroperated means for the said duration only, whereby an impulse originating at one exchange will operate the control circuit at the other exchange if it lasts for said predetermined duration and the additional duration, but if the signal originates on a line then neither control circuit will be completed irrespective of the length oi such signal.

6. In a communication system, two exchanges, lines terminating at each exchange, a two-Wire trunk interconnecting said exchanges, means at each exchange for connecting a line terminating thereat with the trunk, receiving means at each exchange normally connected across said trunk to respond to impulses thereover, means at each exchange for applying an impulse to said trunk and for simultaneously disconnecting the trunk wires from the receiver and from the line at the exchange where the means is operated, means operated by each receiver when responding to an impulse of a given duration over the trunk for thereafter closing a control circuit if the impulse lasts for a predetermined additional duration, and means also operated by the last-mentioned receiver-operated means for operating the impulse-applying and disconnecting means for simultaneously disconnecting the trunk wires from REFERENCES CITED The following references are of record in the file of this patent:

Number UNITED STATES PATENTS Name Date Whistlecroft Oct. 18, 1927 Davis June 10, 1930 Chauveau July 12, 1932 Mathias Oct. 8, 1929 Torcheux Mar. 10, 1942 Koenig Oct. 14, 1941 Black Apr. 16, 1929

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