US1466708A - Transmission system - Google Patents

Description

Sept. 4, 1923. 1,466,708

. L. ESPENSCHIED TRANSMI SS I ON SYSTEM Filed Sept. 26 1919 2 Sheets-Sheet 1 IN V EN TOR.

E5 ease/lied ATTORNEY Sept. 4, 1923. 1,466,708

L. ESPENSCHIED TRANSMISSION SYSTEM Filed Sept. 26, 1919 2 Sheets-5heet 2 nu on. 49 I I IN V EN TOR.

L. Espe/zschfed BY ATT RNEY Patented gent, 4, i923,

teams LIZOYD ESPENQQHIED, OF HOLLIS, NEW YORK, ASSIGNOR TO AMERICAN TELEPHONE AND TELEGRAPH COMPANY, A CORPORATION NEW YORK.

TRANSMISSION SYSTEM.

Application filed September 26, 1919. Serial No. 326,523.

To all whom it may concern:

Be it known that L'LLoYn ESPENSCHIED, residing at Hollis, in the county of Queens and State of New York, have invented certain Improvements in Transmission Systoms, of whichthe following is a specification. v a

This invention relates to transmission systems and more particularly to multiplex systems employing carrier currents.

Where multiplex transmission is attained by the use of carrier currents a plurality of carrier frequencies are transmitted over a common transmission'gline, the carrier frequenciesbeing separated sufficiently to prevent interference and each frequency being assigned for use as a separate channel of communicationyso that signals, such for instance, as telephonic variations, may be transmitted by impressing them upon the carrier frequencies. Several channels may thus be superposed upon a common transmission line and the line may be thus utilized for multiplex transmission, It is furthermore desirable to transmit over a transniission line in addition to the carrier currents impressed thereon for telephonic purposes a carrier current or channelwhich may be utilized for signaling, ringing or other purposes and also to provide arrangements whereby D. C, Morse or telegraphic currents may be simultaneously transmitted over the line with the carrier currents.

t is a general purpose of this invention to provide arrangements whereby a telephone transmission line of the well-known four-wire type may be utilized for the multiplex transmission of currents for telephonic purposes, signaling purposes, and telegraphic purposes. A feature of the invention consists in providingat the two-wire terminals of a four-wire line means for transmitting a low frequency signaling channel over the outgoing two-wire portion of the four-wire line and means for receiving a low frequency signaling channel transmitted over the incoming two-wire portion of the four-wire lines, these signaling channels in each instance causing no interference with the telephonic channels. A further feature of the invention consists'in the rovision of arrangements whereby D. C. orse 0r telegraphi currents may be transmitted and received over both the outgoing and incoming two-wire portions of the four-wire ' ductors 2 and 3.

line and without causing interference with the telephonic or signaling channels. Other and further features and objects of the invention will appear more fully from the detailed description hereinafter given.

The invention may be more fully understood with reference to the following description together with the accompanying drawing in the Figures 1 and 2 of which are illustrated circuit diagrams embodying a preferred arrangement of the invention and a. modification thereof. Similar referencenumerals have been used to designate like parts in both figures.

In Fig. 1 isillustrated a terminal twowire line of the well-known four-wire type of transmission line of which is shown a portion of the incoming line L, thereof and a portion of the outgoing line L thereof, the line L being coupled with line L by means of the three winding transformer 1, and the line L, being connected to the, mid points of windings of transformer 1 by con- Ass ociated with line, L is the artificial line N adapted to balance line L. Included in the lines L, and L are the filter devices F. These filters may be of the type illustrated in U. S. Patents No. 1,227,113, and 1,227,114 issued to G. A. Campbell, and are designed to readily allow the transmission of currents used for telephonic purposes but which attenuate and practically extinguish currents of other frequencies, such for purposes of illustration as currents from 0 to 300 cycles. Accordingly by means of the filters F currents otherithan telephonic currents are'prevented from being transmitted from lines L, and L to line L and.thus causing disturbance in the telephone apparatus associated with line Associated with line L, is a receiving circuit for the low frequency signaling currents coming in over line L. This receiving circuit is tuned by means of the arrangements 10 and 11 of inductance and capacity to he resonant to the frequency of the currents for signaling. Accordingly such currents may readily be transmitted over the receiving circuit and currents of other frequencies may not be transmitted thereover. In place of the tuning devices 10 and'll it'is possible to use band filters if desired. The receiving circuit includes the rectifier 13, which for purposesof convenience is shown as of the vacuum bulb type, and the direct current relay 14'whereby the signal receiving circuit 15 is controlled. Associated with line L is a circuit arrangement whereby low frequency currents for signaling purposes may be ap plied to line L for transmission thereover. This signaling current is applied to the signal transmitting circuit from'the generator 32 which is controlled by relay 31 and the includes the devices 10 and 11, similar .to-

circuit 28. The signal transmitting circuit lines L and L are telegraphic circuits whereby D. C'. Morse or telegraphic currents may be transmitted or received over either of the lines L,- or L The telegraph circuit associated with line L 'includes the composite sets, 16 and 17 and the polar relay 18. The composite sets 16 and 17 are adapted to readily allow the transmission a of currents having a frequency suitable for tiff telegraphic puroses but which serve to attenuate and shut outcurrents of other frequencies; The polar rela 18 controls the receiving circuit 19 for t e incoming telegraphic lmpulses andby means of its polarized operation may cause impulses of both positive and negative polarity to be transmitted over circuit 19. Associated with the telegraph circuit is the transmitting circuit 20 whereby D. C. Morse impulses may be transmitted to the telegraph circuit and'out over line L,. The telegraph circuit. associated with line L, is similar to the one associated with linell and includes the composite sets 16 and 17', the polar relay 27, the telegraph receiving circuit 30, and the telegraph transmitting circuit 29. ciated with lines L, and L are the networks N and N respectively which are adapted to balance said lines for purposes which will be pointed out later.

The operation of the arrangements illustrated in Fig. 1 is as follows. -Telephonic currents coming in over line L, will be transmitted through the filter F and over conductors 2 and 3 and thence over .line L.

'attentuate and practically extinguish such currents. Neither will these incoming tele phonic currents be transmitted over the tele f graph circuit associated with line L, as they will be extinguished by the composite sets 16 and 17. Tel phonic currents appl edto the ecepoe line L will be transmitted through transformer '1, through filter F, and out over line L These telephonic currents will not be transmitted over the telegraph circuit associated with line L as they will be extinguished by the composite devices 16 and 17 included therein. Accordingly telephonic currents either coming in over line L, or transmitted out over line L will cause no interference with the signaling or telegraph apparatus of the system.

The relatively low frequency currents used for signaling purposes coming in over line L, will not be transmitted through the filter F but will be transmitted over conductors 4: and 5 and thence over conductors 8 and9 of the signaling receiving circuit. As has been already pointed out the signaling receiving circuit is tuned to be resonant to currents of a frequency used for signaling and will readily transmit such currents. These signaling currents will then be transmitted over circuit 12 and through the rectifier 13. Connected to the output of the rectifier 13 is the direct current relay 14: which will be actuated by these signaling currents. The relay 14 serves to control the circuit 15 which in turn may control any desirable signaling apparatus (not shown).

If it is desired to transmit low frequency signaling currents out over the line L of the four-wire system, the circuit 28 may be 'closed by any suitable means and current transmitted thereover will operate relay 31. The operation of relay 31 will connect the generator 32 to circuit 33. The generator 32 may be of any desirable type which will generate current havinga frequency suitable for signaling purposes, but it is desirable to employ a generator giving out as pure a wave form as possible and Without har monies. This signaling current applied to circuit 33 will be transmitted, over conductors 25 and 26 of the signaling transmit ting circuit, which as has been already pointed out is tuned to be resonant to currents of such 'frcquenc and will hence readily allow, the transmission thereof, and will be 7 transmitted from conductors 25 and 26 over conductors 23 and 24 and out over line L This signaling current applied from conductors 25 and 26 to the conductors 23 and 2e 4 and the'conductors 21 and 22 will normally not be transmitted over the telegraph circuit associatedwith line L, as the composite sets 16 and 17 are designed to" shut out such current. However if the signaling current was of such a character that a portion thereof should leak through the composite set 17 each other and accordingly would not effect polar relay 27. Furthermore these signaling currents transmitted from conductors 25 and 26 to conductors 21 and 22 andthe conductors 23 and 24 would normally be extinguishedby the filters F in line L and hence would not be transmitted through transformer 1 and out over line L. However, if the signaling current generated contained harmonics of the original wave and such harmonics were of afrequency within the telephonic range, aportion of the signaling currents would be transmitted through both of the filters F. However these currents would be opposite and ap-' proximately equal and at'po'ints 36 and 37 would balance and neutralize each other and hence would notbe transmitted through trans former 1 and out over line L. In order to insure that these currents will be approximately equal the network N is rovided which is adapted to simulate line in impedance value. In a similar manner the con ductors (Sand 7 V are provided associated:

with the line L and the signaling receiving circuit associated with said line in order to neutralize andbalance any of the telegraph currents transmitted over line L which might leak through the filters F in sthh line. Accordingly the arrangements of the invention provide a means for receiving signaling currents coming in over one side of the four-wire line and transmitting signaling currents out over the otherfside of the fourwire line without causing any interference between them and telephonic or telegraphic circuits associated therewith.

If it is desired to transmit D. C. Morse or telegraphic currents out over line L,, such currents maybe applied to circuit 20-and thence to the telegraph circuit associated therewith. These currents will readily be transmitted over the telegraph circuit as the composite devices 16 and 17 aredesigned toallow the transmission of currents used for telegraph purposes. These telegraph currents will then be applied to the conductors 6 and 7 and to conductors 4 and 5. From conductors 4 and 5 the telegraph currents will be transmitted out over line L,. Normally these telegraph'currents will not be transmitted over: line L as they will be shut out' by filter F. -Neither will these currents be transmitted over the signaling receiving circuit as the tuning devices 10 and 11 therein will render such circuit an inetlicient path for the transmission of such currents. However an of such --telegraph currents which might. be asto-be transmitted from conductors 4 and 5 either through the tuning device 10 or the filter F would be neutralized by equal and opposite balancing currents which. would be transmitted from conductors 6' and and through the tuning device 11 or the leftof such a nature hand filter F. Accordingly'telegraphic currents may be transmitted out over line L without causing any disturbance with the telephonic or signal ng arrangements of the system.

Telegraphic currents coming in over line L would be attenuated and extinguished by filter F and tuning device 10 and would be transmitted over conductors 4 and 5 and through composite set 17 and-would actuate the polarized relay -18. The polarity of the incoming telegraphiccurrents would determine the operation of polar relay. 18 and upon the operation of this relay current of either polarity-may be transmitted over the circuit 19 to apparatus (not shown) associated therewith and adapted to receive the telegraphic impulses. Associated with the telegraph circuit are thebalancing conductors 6 and 7 which in the same manner as pointed .out with respect to the'signaling receiving circuit will serve to neutralize and balance any of the telegraphic impulses which may not be properly shut out by filter F or the tuning device 10, and accordingly an additional safeguard is provided. against interference with the telephonic-or signaling arrangementsv from the telegraph apparatus. As the arrangements for transmitting andreceiving telegraphic impulses over line L are sol substantially similar to those described with respect to line L no further description thereof will begi'ven.

In Fig. 2 is illustrated a modification of the arrangements illustrated in Fig. 1, in which a slightly difierent circuit arrangement is'shown, similar numerals indicating like parts in both figures o f.the.invention. The incoming twowire line L ofth fourwire system is coupled through trans ormer 39' to the conductors 2 and.3, which are connected to the terminal two-wire line. L. The line, L terminates in the network N,,

adapted to balance saidline. The outgoing two-wire line L,, of the four-wire system, is coupled to the terminal two-wire line L in the-usual manner through the three-wire transformer 1. Included in conductors 2 and 3, and in conductors 2' and 3-, are the filters F, adapted to readily allow thetransmission of currents having a frequency suit- .of. frequencies which may be applied either to the line L, or to the line L will not be transmitted over the line l), as they will be effectually attenuated by the filters F, and accordingly such currents will cause no interference with the telephonic apparatus associated with line L. Associated with line L is a low frequency signaling receiving circuit terminating in circuit 15, adapted to receive the low frequency signaling currents coming in over line L,. Associated with line L is a telegraphic circuit, with which are associated the circuits '19 and 20, whereby currents suitable for telegraphic purposes may either be received from the line L or transmitted out over the line L,. Associated with line L is a low frequency signaling transmitting circuit, terminating in the circuit 28, whereby low frequency signaling currents may be transmitted out over the line L Associated with line L is a telegraphic circuit, with which are associated the circuits 29 and 36, whereby currents suitable for telegraphic purposes may either here ceived over the line L, or transmitted out over the line L The low frequency signaling receiving circuit associated with line L includes the tuning devices 10 and 11, which serve to make the circuit resonant to the low frequency currents used for signaling purposes. Accordingly this circuit will readily allow the transmission of suchcurrents, but will attenuate and extinguish currents of other frequencies. In a similar manner the low frequency signaling trans- -mitting current associated with line 2 incordingly the signaling currents coming in over the L, will cause no interference with the telephonic apparatus associated with the line L. These incoming signaling currents, furthermore, will cause no interference in the telegraphic circuit associated with line L, as they will normally be attenuated and extinguished by the composite sets 16 and 17 included therein. Furthermore, the balancing conductors 6 and 7 are provided so that any of the incoming sig naling currents, which might be transmitted through the composite set 17, would be opposed and neutralized by equal and oppo site currents which would have been transmitted over the balancing conductors 6 and 7 and through composite set 16. Included in conductors 6 and i? is the tuning device essence 39, similar to the tuning device 10, in order to balance the tuning device 10. Low frequencies signaling currents transmitted over circuit 28, and thence out over the line L will normally cause no interference with the telegraphic apparatus associated with the line L as such currents will be extinguished by the composite sets 16' and 17. Furthermore, the balancing conductors 21 and 22 are provided, over which equal and opposite currents may be transmitted to neutralize any of the signaling currents which might be transmitted over conductors 23 and 24 and through the composite set 17. The conductors 21 and 22 include the tuning device 40, adapted to balance the tuning device 10. Associated with the telegraphic circuits are the additional compo'site sets 40.

and 41. In other respects the telegraphic circuits associated with the lines L and L, are substantially the same as already described with respect to Fig. 1, and no description thereof will be given.

While the invention has hen disclosed in certain specific arrangements which have been deemed desirable, it is understood that it is capable of embodiment in many and widely varied forms without departing from the spirit of the invention as defined by the appended claims. For example, the circuit which has been referred to above and is specified in the claims below as a signaling channel may be used for carrier or alternating current telegraph transmission as well as for signaling of the type incident to telephone operating.

What is claimed is:

1. The combination of a four-wire tran mission system including an incoming twowire line and an outgoing two-wire line and a terminal two-wire line and arrangements whereby said system may be utilized for the simultaneous transmission of currents for purposes of telephoning, telegraphing and signaling, said arrangements comprising a circuit associated with said incoming two-wire line and adapted to efficiently transmit signaling currents coming in over said line, signaling apparatus controlled by said circuit, means in said circuit for preventing telephonic currents coming in over said two-wire line from being transmitted over said circuit, and means in said incoming two-wire line for preventing signaling currents coming in over said line from being transmitted from said line to said terminal line.

2. The combination of a four-wire trans mission system including an incoming twowire line and an outgoing two-wire line and a terminal two-wire line and arrangements whereby said system may be utilized for the simultaneous transmission of currents for purposes of telephoning, telegraphing and signs-Ming, said arrangements comprising,

needs/cs a circuit associated with said incoming two wire line and adapted to efiiciently transmit signaling currents coming in over said line, signaling apparatus controlled by said circuit, means in said circuit for preventing telephonic currents coming in over said two-wire line from being transmitted over said circuit, means in said incoming twowire line for preventing signaling currents coming in over said line from being transmitted from said line to said terminal dine, a circuit associated with said outgoing twowire line and adapted to 'eflicien-tly transmit currents suitable for signaling purposes, means for applying signaling currents to said circuit for transmlssion out over said outgoing two-wire line, means in said circuit for preventing *telephonic currents transmitted over said outgoing line from being transmitted over said circuit, and means in said outgoing line for preventing the signaling currents applied thereto from bein transmitted from said line to said ter-' mina line.

3. A four-wire transmission arranged for' the simultaneous transmission over the four-wire portion thereof of currents for telephonic purposes, for signal-i ing purposes, and for telegraphic purposes, means associated with the four-wire portions said system at the terminals thereof for preventing the telephonic currents from interfering with the slgnaling or telegraphic apparatus of the system, means associatcd with the four-wire portions of said system at the terminals thereof for preventing the signaling currents from interfering with the telephonic or telegraphic apparatus of the system, and means associated with the four-Wire portions of said system at the terminals thereof for preventing the telegraphic currents from interfering with the telephonic or signaling apparatus of the system.

t. lhe combination of a four-wire transmissionsystem including an incoming twowire line and an outgoing two-wire line and a terminal two-wire line and arrangementswhereby said system may be utilized for the simultaneous transmission of currents for purposes of telephoning, telegraphing and signaling, said arrangements comprising a circuit associated with said incoming twowire line and tuned to be resonant to signalin currents coming in over said line, signa ing means controlled 'by said circuit, a secon circuit associated with incoming two-wire line, composite sets in said second circuit adapted to readily allow the transmission of telegra hic currents and to shut out currents use for telephonic or slgnaling purposes, a telegraph receiving circuit and a telegraph transmitting circuit associated with said second circuit, and a filter included in said incoming two-wire line adapted to readily allow the transmission of telephonic currents and to attenuate and extinguish telegraphic and signaling currents.

5. The combination of a four-Wire transmission system including an incoming two- Wire line and an outgoing two-wire line and a terminal two-wire line and arrangements whereby said system may be utilized for the simultaneous transmission of currents for purposes of telephoning, telegraphing and signaling, said arrangements comprising, a circuit associated with said incoming two wire line and tuned to be resonant to signalin currents coming in over said line, signaling means controlled by said circuit, a second circuit associated with said incoming two-wire line, composite sets in said second circuit adapted to readily allow the transmission of telegraphic currents and to shut out currents used for telephonic or signaling urposes, a telegraph receiving circuit an a telegraph transmitting circuit associated with said second circuit, a filter included in said incoming two-wire line adapted to readilyallow the transmission of telephonic currents and to attenuate and extinguish telegraphic and signaling currents, a circuit associated with said outgoing twowire line and tuned to be resonant to signaling currents transmitted out over said line, means for applying signaling currents to said circuit and out over said outgoing two-Wire line, a second circuit associated with said outgoing two-wire line, composite sets in said last mentioned second circuit adapted to readily allow the transmission of telegraphic currents and to shut out currents used for telephonic or signaling purposes, a telegraph receiving and a telegra h transmittin circuit associated with sai last mentione second circuit, and a filter included in-said outgoing two-wire line adapted to readily allow the transmission of telephonic current and toattenuate and extin ish telegraphic and signaling currents.

l rl testimony whereof, I have signed my name to this specification this 25th. day at September 1919.

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