US1501693A - Telephone transmission system - Google Patents

Description

July 15 1924. 1,501,693

R. S. WILBUR TELEPl-iOIEA TRANSMISSION SYSTEM Filed Nov. 25 1919 y @in Patented July 15, 1924.

UNITED STATES PATENT carica.

RAY S. WILBUR, DE LYND'HURST, NEW JERSEY, ASSIG-NOR TO- WESTERN ELECTEIC COMPANY, INCORPORATED, OF NEW YORK, N. Y., A CORPORATION O F NEW TELEPHONE TRANSMISSION SYSTEM.

Application fried November 25, 191e. serial No. 340,480.

To allzu/wm t may conce/1h71:

Be it lfznown that I, RAY S. l/TILBUR, a citizen of the United States, residing at Ljfndhurst, in the county of Bergen, State of ew Jersey, have invented certain new and useful Improvements in Telephone Transmission Systems, of which the following is a full, clear, concise, and exact description. Y'

i This invention relates to improvements in telephonesystems, and has particular reference toy the four-'wire repeater circuit therefor.

In transmission lines, it is common to pro- Y vide amplifying means for reinforcing currents of low frequency, such as employed in signalingbetween operators or subscribers. It is also desirable to impress upon a metallic circuit, simultaneously with the transmission of ringing current, other signaling current such as employed for the Morse code.

'It has been customary, in four-wire repeater circuits, when transmitting ringing current, for instance, from a terminating` circuit over an outgoing line, to operate an electromagnetic device for the urpose of supplying ringing current to sait line. rThe operation of this device opens and unbalances the outgoing line while ringing current is being applied and thereby prevents the transmission of metallic Morse signaling current.

An object of this invention is to prevent unbalancing of the outgoing circuit when applying ringing current thereto, whereby other signaling current may be impressed upon the line or metallic side of said'fcircuit simultaneously with said ringing current.

The drawing illustrates diagrammatically a four-wire repeater circuit showing the application of the invention thereto.

' 1n the drawing, A designates an incoming line, B a terminating circuit and C an outgoing line. Ringing current transmitted over the incoming line A is induced into the secondary winding of the repeating coil l, from thence to the back' cont-acts and up per and middle armatures of relay 2, the back contacts and armatures of relay 8, and

then to 'the'primary' winding of the repeating coil Il; A low frequency filter consisting of condensers 5 and a bridged induct-ance 6 is employed to lter out ringing and voice currents below a certain range of frequency -so that all ringing current will be diverted to the primary winding of the repeating coil el., as before stated. This ringing current-is respond to this amplified current is ener` gized. This causes the energization of relay 9 which is made slow to release so that the same will remain energized during any momentary deenergization of relay 'SYdu'e'j toia decrease in the amplification ofthe current passing through the Winding thereof.` Energization of relay 9 connects a source of ring'- ing current 10, preferably of 1623- cycle frequency, to the terminating circuit B, through the middle and lower armatures and front conta cts of relay 9, resistances Ofanto-transformer 11 and primary vwindings ofwth'e three-winding transformer 12.` The attraction of the upper armature of relay9 closes a bridge Vacross the line Afthrough're'sistance 13 and thus prevents unbalancingof the line. Voice currentswithin "the usual range of frequency willvpass from one line to another through the' normal contacts `of relays 2, 3 and 9 after the latter relay has released its armatures at the termination'of the application of ringingcurrent to the circuit B.

Ringing current of the usual 16% cycle frequency transmitted from the terminating circuit B passes to the middle lpoi-nts of the three-winding transformer 12, the autotransformer '11, normal `contacts of the middle and lower armatures of relay 9 and the windings of the ringing response relay 14. This relay is responsive to the ringing current and, by its energization, opensfthe energizing circuit of relay 15 which releases'its armature. A circuit is then closed from grounded battery, through the windings of relays 2 and 3 in parallel, and the armature and contact of relay 15, to ground. Relays 2 and 3 are energized. Relay 2, by attracting its armatures, disconnects the incoming line A and bridges said line through resistance 16, to prevent unbalancing of the line during the application 'of ringingcurrent. Relays 2 and 3 connectV ringing current, preferably of a frequency of 133 cycles, from a source 17 through alternate contacts of said relays, and from'th'ence to thek Windings of a transformer 18 which'is connected The current is here amplified in the usual manner and a relay 8 tuned* to` transn'iitted from. the secondary windings of the three-winding transformer, overthe sides of the outgoing line C, through the re 3eatmg coil 19. inasmuch as line C is not opened during the transmission of ringing current thereover, as is apparent from the foregoing, the line Awill remain balanced or continuous to permit of the application of other signaling current thereto, wnile said ringing current is being applied. Voice currents will be transmitted from circuit B directly through the primary and secondary windings of three-winding transforme-r l2 to the line C.

The advantage of the feature just mentioned, of not opening line C during the transmission of ringing current thereover will be apparent if we consider that line C inha'ddition to beingemployed for transmitting speech currents is also employed for two-wayY metallic telegraph operation. The usual method of duplexing a two-wire line for telegraph signals is to shunt the line by a suitable bridge 30, connections therefrom being talen to the usual telegraph relay and balancing' network. This balancing network is, of course, adapted to match the impedance of the line as seen from leads 32 and which would be the combined iinpedance of outgoing line C and the impedance looking in the direction of line B whereby the local receiving` equipment will not be actuated by the outgoing telegraph signals. lt would, therefore, follow that if in applying the ringing currents from generator 17 to outgoing line C, the line were temporarily opened, the impedance of the system connected to leads 352 and would be changed, thereby unbalancing the telegraph equipment and preventing the successful. duplex operation thereof.

TFilliat is claimed is:

l, in a telephone system, a two-wire circuit., a four-wire circuit, a three-limb transformer for coupling one side of said fourwire circuit to said two-wire circuit, a source of ringing currents, and means responsive to ringing currents in said twowire circ-uit for impressing currents from said source upon said side of said fourivire circuit iviiile maintaining fixed thereonnections of said side to said transformer.

2. ln combination, a local station comprisingterminals of a terminating circuit, terminals of an outgoing line, an artificial balancing line for said circuit, a three-wind- ;ing transformer having a winding in said circuit, a winding in said balancing line and a. third winding in said outgoing line, a local4 generator of ringing currents, and means responsive to ringing currents from a distant station for impressing ringing currents from said generator upon the mid points of the first two windings of said transformer to transmit said currents to said terminating circuit.

.9i signaling station, a plurality of lines terminating at said station, a network for balancing one of said lines, a three winding transformer having a. winding in circuit 1with said first line, a second winding in circuit with said balancing network and a third winding in circuit with a second line, a third line being connected to the mid- A points of said first two windings, a local generator of ringing currents, and means responsive to ringing currents in said third line for impressing ringing currents upon the midpoints of said first two windings.

el. ln combination, a signaling station, a foiuf-wire circuit and a two-wire circuit terminating at said station, said station comprising means for coupling said circuits, a source of ringing currents, and means responsive to ringing currents in said twowire circuit for disconnecting one side of said founwire circuit from said coupling means and for impressing ringing currents from said source upon the other side of said four-wire circuit.

)i telephone signaling station, fourwire circuit and a two-wire circuit terminating at said station, means for coupling s id circuits, means in one side of said fourwire circuit for prevent-ing ringing currents from the said one side of said four-wire circuit from being impressed directly upon said two-wire circuit, a plurality of sources of ringing` current, means comprising movable contacts in the said one side of said four-wire circuit and responsive to ringing currents in said two-wire circuit for connecting one or" said sources to the other side of said four-wire circuit, and means com.- prising movable contacts in the said one side of said four-wire circuit and responsive to ringing currents in said four-wire circuit for connecting another of said sources to said two-wire circuit.

6. A telephone signaling station, a twowire circuit and a four-wire circuit terminating in said station, said station compris ing means for coupling said circuits, a plurality of movable contacts included in the speech transmission path of one side of said four-wire circuit, means responsive to ringing current originating in said two-wire circuit for operating certain of said contacts, and means responsive to ringing current. originating in one side of said fourwire circuit for operating other of said contacts.

7. ln combination, a three-winding transformer, a line in circuit with one winding lll() llO.

of said transformer, a balancing network.

for said line in circuit with a second Windlll ing of said transformer, a second line in circuit with the third winding of said transformer. a second transformer having a winding in circuit with said second line, a source of signaling currents, and means responsive to signaling currents in said first line for connecting said source to said sccond transformer.

8. signaling station. a four-wire circuit and a two-wire circuit terminating at. said station. connections coupling both sides of said four-wire circuit to said two-wire circuit, said connections being traversed by ringingcurrents from said two-wire circuit, a local source of ringing currents, and means responsive to ringing currents in said two-wire circuit for impressing ringing currents from said source upon one side of said four-wire circuit while maintaining fixed the connections of the said one side to said two-wire circuit.

9. In combination, a three-winding transformer, a line connected in circuit with one winding of said transformer, a balancing network for said line in circuit with the second winding of said transformer, a second line in circuit with the third winding of said transformer, a third line connected to the midpoints of said first two windings, a local source of signaling currents, and means responsive. to signaling currents originating in said first line for impressing currents from said source upon one of said other lines while maintaining fixed the connection of said last-mentioned line to said transformer.

10. In combination, a line for the transmission of signals of one type in either direction. a second line for the transmission of signals of one type in onedirection only, a signaling station comprising means for coupling said lines, movable contacts in said second line, means controlled by currents in said first line for controlling certain of said contacts. and means controlled by currents in said second line for Vcontrolling other of said contacts.

11. In combination, a line for the transmission of signals of one type in either direction. a second line for the transmission of signals of one type in one direction only, a signaling station comprising coupling means for said lines, and means comprising movable members responsive to signaling currents from said first line for impressing signaling currents upon said second line while maintaining fixed the connections of said second line to said coupling means.

12. In combination, a line for the transmission of signals of one type in either direction, a second line for the transmission of signals of one type in one direction only, a signaling station comprising means for coupling said lines, a local source of ringing currents. and means responsive to ringing currents in said first line for impressing ringing currents from said source upon said second line whiie maintaining fixed the connections of said second line to said coupling means.

13. In combination, a two-wire line, a four-wire line, means for coupling said lines, a source of signaling currents, a local network having an impedance approXimating the impedance of one side of said fourwire lines, and means responsive to signaling currents in said two-wire line for applying signaling currents from said source to one side of said four-wire line, for breaking` the connections between said coupling means and the other side of said four-wire line. and for connecting to said network that part of said b-roken side away from said coupling means.

14. In combination, a two-wire line, a four-wire line, coupling means for said. lines, a source of signaling currents, a local network having an impedance approximating the impedance of one side of said fourwire line, and means responsive to signaling currents in one side of said four-wire line for applying signaling currents from said source to said two-wire line, for breaking the connections between said coupling means and the said one side of said fourwire line, and for connecting said network to the part of said broken side located away from said coupling means.

15. In a telephone system. a two-wire circuit, a four-wire circuit, means coupling one side of said four-wire circuit to said two-wire circuit, a source of ringing currents, and means responsive to ringing currents in said two-wire circuit for impressing currents from said source upon said side of said four-wire circuit while maintaining fiXed the connections of said side to said two-wire circuit.

In witness whereof, I hereunto subscribe my name this 21st day of November A. D.

RAY S. IVILBUR.

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