US2423087A - Impulse signal transmission system - Google Patents

Description

J y 7- c. DE-VRIENDT EEMPULSE SIGNAL TRANSMISSION SYSTEM Filed Marh 24, 1945 INVENTOR Can: 42s 1: Vex/m7- ATTORNEY Patented July 1, 1947 IMPULSE SIGNAL TRANSMISSION SYSTEM Charles De Vriendt, Antwerp, Belgium, assignor to International Standard Electric Corporation, New York, N. Y., a corporation of Delaware Application March 24, 1943, Serial No. 480,418 In the Netherlands June 21, 1941 The present invention relates to improvements in signal transmission systems in general and has reference in particular to impulse transmission systems.

It is common practice to incorporate in telephone systems, or similar systems for establishing connections, improvements or additional facilities for the service. These require an additional signalization either between different switching stages in the same exchange, or between different exchanges in the same area or in different areas.

One of the main difiiculties encountered in this connection resides in the fact that it is necessary to provide new signalling paths, because the existing conductors of the junctions between switching stages or between exchange are usually not available for this purpose.

The principal object of the invention is to pro vide a signalling system for impulse transmission which utilizes an existing conductor without interrupting or interfering with the purposes for which this conductor is normally used. In brief, I accomplish this and other objects of the invention, as will become more apparent hereinafter, by providing for continuous transmission of an alternating current over the signalling wire during each complete train of impulses. According to another feature of the invention, synchronized stepping mechanisms are provided at the sending as well a at the receiving end. According to a further feature of the invention, a cold-cathode tube is used at the receiving end as relay control means, whereby the signalling system according to this invention may be operated with a minimum of energy.

An embodiment of the present invention is illustrated, by way of example, in the accompanying drawing.

In the drawing, numerals I, 2 represent any kind of connecting wire having a certain impedance X. Same consists of any combination of resistances, capacities and inductances. Normally, this wire is used for signalling purposes on a direct current or alternating currentbasis.

Condensers C1 and C2 serve to separate any existing direct current signals from the signalling system according to the invention. Condensers C1, C2 in conjunction with impedance X and primary winding p of transformer T are tuned to resonance with frequency 1, which usually comes within the voice frequency range employed in the signalling system according to the invention. 7

Letters SS designate the power magnet of a step-by-step selector switch of well known type,

20 Claims. (01. 179-16) for instance such as are used in telephone or like systems for establishing connections. The two terminal banks a and b are shown with their respective brush members a1 and b1.

Switch SS serves two purposes, viz.: (l) for connecting a continuous alternating current of frequency f to thesignalling wire via level a; and (2) for disconnecting said alternating current via level 1), when the complete train of impulses which corresponds to a particular signal, is terminated.

Relays B1, B2, B3 and B4 perform various functions, as will be explained hereafter.

The cold-cathode tube L, used according to the invention, is of well known type, requiring a specific control gap between potential Vx to ignite the control gap between the two electrodes c1 and 62, while a substantially higher main gap breakdown potential Vy is needed for igniting the main gap between the anode A and either one of the two electrodes 61 and ez. Once the control gap has been ignited however, a sustaining potential Vz, which may be considerably lower than Vy, suffices to maintain a current across the main gap.

As shown in the drawing, secondary winding 8 of transformer T is inserted between a connecting point on potentiometer P and control anode c1 of cold cathode tube L, while anode A is connected in series with relay B4. The latter reproduces the impulses produced at the sending station. The anode circuit can be closed only by the control action of relay B3, whose armature steps in synchronism with stepping relay B1 of the sending station. The control relay B2 of the sending station operates over a marking wire when a predetermined number of impulses has been transmitted.

Elements IMP1 and IMPz are two mechanical or electrical impulse generators. If located in the same exchange, these two generators may comprise impulse cams mounted on the same shaft. Synchronization is thus obtained without special means. If the two impulse generators are located at different exchanges, they may be synchronized by any number of methods, known per se. These methods will not be further described as not coming within the scope of the present invention.

Generator IMP1 may be provided for a plurality of circuits and/or exchanges in common, which results in a considerable economy in line plant.

Starting key Sir is closed when impulse transmission is to be started. Key Sh may be opened again at any convenient time after the signalization has been completed. Starting contact Sta 3 is closed as soon as the circuit at the receiving end has been seized and is ready for the reception of impulses.

On the basis of the foregoing explanation of the character and function of the various devices shown in the drawing, a detailed description of th operation of the system is given in the following.

Let us assume that the receiving end circuit has been seized and the starting contact St: is closed. In that event, relay B: will operate in synchronism with the impulses from generator IMPi, but nothing further will happen.

When the sending station is ready to start the transmission of impulses, starting contact Sti is closed. Relay B1 operates as soon as the impulse sender IMPZ grounds for the first time its rotating brush member, causing the energization of power magnet SS. As soon as the ground connection of generator IMPz is broken, relay Bl releases and the brushes of the switch complete the first step. At this moment, an alternating current of frequency f is sent out over the line to the receiving end.

At the receiving end, tube L is normally not ignited because the biasing potential of control anode 61 is such, that the potential difference between 61 and (22 is lower than the control gap breakdown voltage.

However, upon receipt of the alternating current from the sending end, a certain potential is induced in the secondary winding of transformer T and the peak of one half-wave of this potential is then added tothe biasing potential of c1, with the result that the control gap is ignited and remains ignited as long as the alternating current continues.

The next time when generator IMP2 connects relay B1 to ground, this relay is actuated and energizes element SS. Simultaneously, relay B3 is grounded and hence put in operation. As a result, the anode circuit of the tube L is closed. Since th control gap is ignited, the main gap is now likewise. ignited and relay B4 is operated, closing the local stepping circuit (not shown).

However, as soon as the ground connection of the impulse senders is broken, relays Bi and B3 release, the brushes of the switch take another step and relay B4 opens its stepping contact. One impulse is thus transmitted in the manner described above.

Each subsequentv impulse is. transmitted in exactly the same manner.

If it is desired to transmit a signal comprising four impulses, for instance, the following connections are established:

When the ground connection of the impulse senders is broken after relay B4 has closed its stepping contact four times, the brushes of switch SS take a further step and stop on terminal 5.

Relay B4 then becomes de-energized. However,

at the beginning of the operations, the impulse transmission control device caused terminal 5, in bank I). of switch SS, to be connected to ground, thereby determining that the complete train of impulses constituting the signal shall consist ofbut four impulses.

As a result, as soon as the switch, arrives at terminal 5,, relay B2 operates via bank I), and the alternating current is cut off from the; line.

Since at this moment the anode circuit of the tube L is opened, the control gap of the same is extinguished and no further impulses can be received until the sending circuit. is again, ready to transmit some subsequent signals- Special attention is directed to the great advantages produced by this invention from the point of View of electrical interference. While the impulses are being transmitted, the impedance of the signalling conductor remains unchanged and, when relay B2 operates, this conductor is connected to ground, which, practically speaking, does not alter th impedance, because the impedance of the A. C. generator in itself is very small.

I am aware of the fact that many changes may be made in the signalling system according to the present invention without departing from the spirit and scope of the same. I therefore do not wish to be understood as limiting myself to the exact details of construction and arrangement shown and described herein.

I claim:

1. In a signalling system, a sending station, a receiving station, and a transmitting line interconnecting said stations, first impulse producing means associated with said sending station, second impulse producing means associated with said receiving station, supply means for supplying electric energy to said transmitting line, operative means at said receiving station associated with said second impulse producing means, said operative meansbeing adapted to respond only to the combined action of said second impulse producing means and the electric energy supplied over said transmitting line, whereby the efiect of said second impulse producing means may be controlled from said sending station, by supplying or discontinuing the supply of electric energy at the sending station.

2. In a signalling system, a sending station, a receiving station, and a, transmitting line interconnecting said stations, first impulse producing means associated with said sending station, second impulse producing means associated with said receiving station, supply means for supplying electric energy to said transmitting line, control means associated with said first impulse producing means and said supply means, said control means being adjustable for various numbers of impulses representing predetermined signals, and adapted to automatically disconnect said supply means from said transmitting line after delivery by said first impulse producing means of the number' of the impulses for which said control means has been adjusted, operative means at said receiving station associated with said second impulse producing means, said operative means being adapted to respond only to the combined action of said second impulse producing means and the electric energy supplied over said transmitting line, whereby the effect of said second impulse producing means may be controlled from said sending station, by supplying or discontinuing the supply of electric energy at the sending station.

3. In a signalling system, the combination with a sending station, a receiving station, a transmitting line interconnecting said stations, a first impulse circuit associated with said sending station, first impulse producing means in said first impulse circuit, a second impulse circuit associated with said receiving station, second impulse producing means in said second impulse circuit, said first and second impulse producing means operating synchronouslywitheach other, whereby corresponding impulses are produced in both said impulse circuits of the sending station and the. receiving station, of control means disposed at the sending'station and electrically connected with said transmitting line, said control meansceiving station, a second impulse generator in said second impulse circuit, said impulse generators operating synchronously with each other, whereby, upon creation of an impulse or of a group of impulses in the first impulse circuit, a corresponding impulse or roup of impulses is simultaneously created in said second impulse circuit, control means associated with said first impulse circuit, a source of electric energy associated with said sending station and adapted to be connected to said transmitting line by said control means, the latter being adjustable for a certain number of impulses and, adapted to open said first impulse circuit and disconnect said source of electric energy from said transmitting line when the number of impulses for which it is adjusted, has been delivered; cooperating means at the receiving station associated with said second impulse circuit, said cooperating means being electrically connected to said transmitting line and adapted to respond only to the combined action of said impulses in said second impulse circuit and the energy supplied from said source of electric energy, said impulses in said second impulse circuit being ineffectual when transmission of energy over said transmitting line is discontinued by said control means, whereby only the number of impulses selected at the sending station and constituting a particular signal, will be delivered at the receiving station, irrespective of whether or not said second impulse generator continues to create impulses in said second impulse circuit.

5. The system claimed in claim 1, in which said means for supplying electric energy is a source of alternating current.

6. The system claimed in claim 1, in which said operative means includes a cathode tube fed by the electric energy supplied over said transmitting line.

7. The system claimed in claim 1, in which said means for supplying electric energy is a source of alternating current, and said operative means includes a cathode tube and a transformerhaving a primary and a secondary, said cathode tube being connected to said secondary, and said primary being connected to said transmitting line.

8. The system claimed in claim 4, in which said source of electric energy is an alternating current source, and said cooperating means comprises a transformer having a, primary, same being connected to said transmitting line.

9. The system claimed in claim 4, in which said source of electric energy is an alternating current source, and said cooperating means comprises a transformer having a, primary, same being connected to said transmitting line, said transformer also comprising a secondary and said cooperating means including a cathode tube, said secondary being connected to said cathode tube.

10. The system claimed in claim 4, in which said control means comprises a step-by-step selector switch controlled by said first impulse circuit, whereby each impulse causes said switch to advance one step.

11. The system claimed in claim 4, in which said control means comprises a first step-by-step selector switch controlled by said first impulse circuit, a second step-by-step selector switch being associated with and controlled by said cooperating means, whereby each impulse in said impulse circuits causes said switches to advance one step in synchronism, operation of said second switch discontinuing upon disconnection of said source of electric energy from said transmitting line, irrespective of whether or not impulses continue to be created in said second impulse circuit.

12. The system claimed in claim 4, in which said first impulse circuit includes a first relay and said control means includes a switch circuit, a step-by-step selector switch in said switch circuit, the latter being controlled by said first relay, whereby each impulse delivered by said first generator is transmitted to said first relay causing said step-by-step selector switch to advance one step, a first and second terminal bank, a first and second contact member associated with said terminal banks respectively, said contact members being controlled by said first step-by-step switch, whereby each step of said first switch causes each contact member to advance to the next terminal of the respective bank of terminals, the terminals of the first bank being connected to said transmitting line, said first contact member being connected to said source of electric energy; a control circuit connected to said second contact member, a second relay in said control circuit, adjusting means adapted to be moved to any desired terminal of said second bank of terminals, said adjusting means being grounded, whereby said second relay is energized when said second contact member is moved by said first switch into contact with a terminal grounded by said adjusting means, said second relay being adapted to disconnect said source of electric energy from said transmitting line.

13. The system claimed in claim 4, in which said first impulse circuit includes a first relay and said control means includes a switch circuit, a step-by-step selector switch in said switch circuit, the latter being controlled by said first relay, whereby each impulse delivered by said first generator is transmitted to said first relay causing said step-by-ste-p selector switch to advance one step, a first and second terminal bank, a first and second contact member associated with said terminal banks respectively, said contact members being controlled by said first step-by-step switch, whereby each step of said first switch causes each contact member to advance to the next terminal of the respective bank of terminals, the terminals of the first bank being con nected to said transmitting line, said first contact member being connected to said source of electric energy; a control circuit connected to said second contact member, a second relay in said control circuit, adjusting means adapted to be moved to any desired terminal of said second bank of terminals, said adjusting means being grounded, whereby said second relay is energized when said second contact member is moved by said first switch into contact with a terminal grounded by said adjusting means, said second relay being adapted to disconnect said source of electric energy from said transmitting line, and being further adapted to simultaneously break said first impulse circuit. v

14. The system claimed in claim 4, in which said cooperating means includes a cathode tube 7 comprising a pair of electrodes and an anode, a tube circuit, said electrodes being disposed in saidt'ube circuit, an anode'circult for said anode,

said anode circuit being grounded, a first relay, the latter being disposed in said second impulse circuit, said first relay being adapted to open and close said anode circuit, a second relay, same being disposed in said anode circuit and adapted to control a step by-step switch circuit.

5. The system claimed in claim 4', in which said cooperating means includes a cathode tube comprising a pair of electrodes and an anode, a tube circuit, said electrodes being disposed in said tube circuit, an anode circuit for said anode, said anode circuit being grounded, a first relay, the latter being disposed in said second impulse circuit, said first relay being adapted to open and close said anode circuit, a second relay, same being disposed in said anode circuit and adapted to control a step-by-step switch circuit; a transformer having a primary and a secondary, said secondary being disposed in said tube circuit and said primary being connected to said transmitting line.

16. The system claimed in claim 4, in which said cooperating means includes a cathode tube comprising a pair of electrodes and an anode, a tube circuit, said electrodes being disposed in :said' tube circuit, an anode circuit for said anode, said anode circuit being grounded, a first relay, the latter being disposed in said second impulse circuit, said first relay being adapted to open and close said anode circuit, a second relay, same being disposed in said anode circuit and adapted to control a step-by-step switch circuit, a second source of electric energy, same being disposed in said tube circuit and feeding said tube.

17. The system claimed in claim 4, in which said cooperating means includes a cathode tube comprising a pair of electrodes and an anode, a tube circuit, said electrodes being disposed in 'said tube circuit, an anode circuit for said anode, :said anode circuit being grounded, a first relay, the latter being disposed in said second impulse circuit, said first relay being adapted to open and close said anode circuit, a second relay, same being disposed in said anode circuit and adapted 'to control a step-by-step switch circuit, a second source of electric energy, same being disposed in said tube circuit and feeding said tube, and a potentiometer associated with said tube circuit and said second source of electric energy, whereby the voltage supplied to said tube by said second source of electric energy may be varied.

13. The system claimed in claim 4, in which :said cooperating means includes a cathode tube comprising a pair of electrodes and an anode, a tube circuit, said electrodes being disposed in said tube circuit, an anode circuit for said anode, said anode circuit being grounded, a first relay, the latter being disposed in said second impulse circuit, said first relay being adapted to open and close said anode circuit, a second relay, same bein disposed in said anode circuit and adapted to control a step-bystep switch circuit, said pair of electrodes being spaced apart to form a control gap, a main gap being formed by said anode and said electrodes, the breakdown potential for ignitin said control gap being lower than the breakdown potential of said main gap, the breakdown potentials beingso chosen that the sustain- .ing potential required to maintain the current acros the main gap, once the same has been 8 ignited; is lower than the main gap breakdown potential. v

19. The system claimed in claim 4, in which said first impulse circuit includes a first relay and said control means includes a switch circuit, a step-by-step selector switch in said switch circuit, the latter being controlled by said first relay, whereby each impulse delivered by said first generator is transmitted to said first relay causing said step-by-step selector switch to advance one step, a first and second terminal bank, a first and second contact member associated with said terminal banksrespectively, said contact members being controlled by said first stepby-step switch, whereby each step of said first switch causes each contact member to advance to the next terminal of the respective bank of terminals, the terminals of the first bank being connected to said transmittin line, said first contact member being connected to said source of electric energy; a control circuit connected to said second contact member, a second relay in said control circuit, adjusting means adapted to be moved to any desired terminal of said second bank of terminals, said adjusting means being grounded, whereby said second relay is energized when said second contact member is moved by said first switch into contact with a terminal grounded by said adjusting means, said second relay being adapted to disconnect said source of electric energy from said transmitting line; said cooperating means including a cathod tube having a pair of electrodes and an anode, a tube circuit, said electrodes being disposed in said tube circuit, an anode circuit for said anode, said anode circuit being grounded; a third relay, the latter being disposed in said second impulse circuit, said third relay being adapted to open and close said anode circuit, a fourth relay, same being disposed in said anode circuit and adapted to control a step-by-step switch circuit; a transformer having a primary and a secondary, said secondary being disposed in said tube circuit and said primary being connected to said transmitting line; a second source of electric energy, same being disposed in said tube circuit and feeding said tube, and a potentiometer associated with said tube circuit and said second source of electric energy, whereby the voltage supplied to said tube by said second source of electric energy may be varied; said pair of electrodes bein spaced apart to form a control gap, ,9, main gap being formed by said anode and said electrodes, the breakdown potential fo igniting said control gap being lower than the breakdown potential of said main gap, the breakdown potentials being so chosen that the sustaining potential required to maintain the current across the main gap, once the same has been ignited, is lower than the main gap breakdown potential.

20. The system claimed in claim 4, in which said first impulse circuit includes a first relay and said control means includes a switch circuit, a step by-step selector switch in said switch cir cuit, the latter being controlled by said first relay, whereby each impulse delivered by said first generator is transmitted to said first relay causing said step-by-step selector switch to advance one step, a first and second terminal bank, a first and second contact member associated with said terminal banks respectively, said contact members being controlled by said first step-by-step switch, whereby each step of said first switch causes each contact member to advance to the next terminal of the respective bank of terminals,

9 the terminals of the first bank being connected to said transmitting line, said first contact member being connected to said source of electric energy; a control circuit connected to said second contact member. a second relay in said control circuit, adjusting means adapted to be moved to any desired terminal of said second bank of terminals, said adjusting means being grounded, whereby said second relay is energized when said second contact member is moved by said first switch into contact with a terminal grounded by said adjusting means, said second relay being adapted to disconnect said source of electric energy from said transmitting line; said cooperating means including a cathode tube having a pair of electrodes and an anode, a tube circuit, said electrodes being disposed in said tube circuit, an anode circuit for said anode, said anode circuit being grounded; a third relay, the latter being disposed in said second impulse circuit, said third relay being adapted to open and close said anode circuit, a fourth relay, same being disposed in said anode circuit and adapted to control a stepby-step switch circuit; a transformer having a primary and a secondary, said secondary being disposed in said tube circuit and said primary 10 being connected to said transmitting line; a second source of electric energy, same being disposed in said tube circuit and feeding said tube, and a potentiometer associated with said tube circuit and said second source of electric energy, whereby the voltage supplied to said tube by said second source of electric energy may be varied; said pair of electrodes being spaced apart to form a control gap, a main gap being formed by said anode and said electrodes, the breakdown potential for igniting said control gap being lower than the breakdown potential of said main gap, the breakdown potentials being so chosen that the sustaining potential required to maintain the current across the main gap, once the same has been ignited, is lower than the main gap breakdown potential; a pair of condensers in said transmitting line, one condenser being disposed at the sending station and the other condenser being disposed at the receiving station, said condensers serving to filter out any direct current signals in the transmitting line; and a starting key disposed in each of said first and second impulse circuits for controlling the operation thereof.

CHARLES DE VRIENDT.

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