US1763013A - Telephone system - Google Patents

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Publication number
US1763013A
US1763013A US375715A US37571529A US1763013A US 1763013 A US1763013 A US 1763013A US 375715 A US375715 A US 375715A US 37571529 A US37571529 A US 37571529A US 1763013 A US1763013 A US 1763013A
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Prior art keywords
repeater
circuit
line
lines
relay
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Expired - Lifetime
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US375715A
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English (en)
Inventor
Skillman Thomas Samuel
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AT&T Corp
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Western Electric Co Inc
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Publication of US1763013A publication Critical patent/US1763013A/en
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    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04M—TELEPHONIC COMMUNICATION
    • H04M3/00—Automatic or semi-automatic exchanges
    • H04M3/40—Applications of speech amplifiers

Definitions

  • This invention rela-testotelephone systems.
  • repeaters are provided for insertion into the lines which may require them, it is usual that-either a repeater or a group of repeaters are 7 permanently connected with the lines or that the insertion of the repeaters is controlled manus ally by an operator.
  • the insertion ofthe repeaters in theline maybe effected partially bysennautomatic means as may be seen from U. S.
  • a feature of the invention resides in the means provided for arresting the said movable member on said worked contact which means may compr se a transformer the secondary winding of which is connected in series with the said movable member so that y when said member reaches the said worked contact, the said'secondary w nding is short which is suflicienttooperate a relay connected in the circuit of said primary winding.
  • the scheme may also have advantages when used v oircuited thusoausing an increase of current in the primary winding of said transformer above mentioned relay may be directly conn'ectedm the circuit of sald'movable member.
  • the 'A feature of the presentinvention is a system in which a repeater may be insertedinto a line entirely automatically and according to the requirements of the line. 7 f l
  • the invention maybe regarded as a telephone systemin" which an established connection between two polnts 1s utilized for transmitting current for determining whether or not arepeater should be interconnected there betweem this discrimination being utilized for automatically governing the insertion of a repeater.
  • an alternating" current is transmitted over the talking circuit to determine whet-her or not a repeater should be interconnected in said circuit.
  • transmission circuit may besent thereover, means being provided responsivezto said alternating. cur'rentsfor governing the insertion of a repeater inthe transmission circuit.
  • a discrimination is made between the nature of a plurality of lines (e. g. theirattenuation characteristic or whether they are short orlong lines etc.) by meansof alternate mg current of difl'erent frequencies orof altern atmgcurrent ofdlfi'erentamplltude or of i alternating current modulated or interrupted at different speeds.
  • a further feature of the invention provides facilities for using any one of a group of lines for repeater working and at the same time picking up one of a preferably much smaller group of balancing networks.
  • connection of cord circuit repeater is controlled entirely by the line equipment and the repeater equipment so that any form of manual cord or automatic switch may be used in the connection.
  • the line equipment individual to the transmission lines are adapted to perform the function of signalling that is to say to transmit dial impulses ringing currents etc. and also to control the insertion of a repeater in the transmission circuit. This is a very important feature of the present invention.
  • Another feature of the present invention resides in the provision of means for gain regulation which may be efiected by means of an alternating current (e. g. voice frequency) transmitted over the signalling circuit for controlling the gain of the amplifier.
  • an alternating current e. g. voice frequency
  • the gain of the repeater interconnected in the line may be controlled by means of a plurality of marginal relays or by means of attenuating pads adapted to be inserted in the circuit.
  • Fig. 1 shows the signalling and line equipments at the incoming end of a toll line
  • Fig. 2 shows an operators cord circuit
  • Fig. 3 shows the signalling and line equipments at the outgoing end of a toll line.
  • Fig. 4 shows the equipment associated with I the repeater.
  • Fig. 5 shows schematically an arrangement embodying the invention for switching a toll line L1 to a toll line L2 over automatic switches S1, S2 and S3; 7
  • Fig. 6 shows schematically the working system according to the present invention.
  • Fig. 7 shows a method of applying the invention for controlling a repeater over a junction circuit.
  • Figs. 1 show the detailed circuit of a particular embodiment of the invention and Figs. 5 and 6 are simplified diagrams illustrating the working of the circuit.
  • FIG. 5 shows equipment located at a central otfice upon which converge a number of long telephone lines referred to as toll lines.
  • toll lines are used for traffic into and out of the control of fice and its local area, and are also used for traffic through this area.
  • two or more toll lines will be connected in tandem, and since in most cases this will cause a high attenuation of the speech currents, a repeater will be necessary between the two lines.
  • the equipment TLl and TLO may include devices responsive to alternating current, such as vacuum tube detectors, or voice frequency relays. Signalling between TLl and TLO is used to decide whether a cord circuit repeater is necessary, the alternating current devices discriminating between alternating currents of diflerent character which are transmitted between TLl and TLO over the talking circuit.
  • voice fre quency relays are used, and the discrimination is obtained by using different frequencies, but alternative methods such as the use of diiferent amplitudes or of interruptions at different speeds will readily occur to those skilled in the art.
  • TLO to send a pulse signal to TLl and if this signal is such that a repeater is needed TLl initi ates the operation of connecting the repeater.
  • This pulse may be sent at any time when a talking circuit between the two line equipments is assured and the simplest way of providing for this is to wait until the called subscriber replies, since a talking current between TLl and TLO will always be present at this time whether manual or automatic connections are used.
  • the attenuation of the two lines for operators conversations occurring before the subscriber replies will not be excessive, owing to the absence of subscriber loops and the slight delay before the called subscriber isv able to talk, would not be noticed.
  • TLO to send out tone continuously until the peaters may beallowed to hunt simultanecalled subscriber replies,- and for TLl to respond to this and to pickup the repeater;
  • TLO could easily be made continuous by the addition of suitable small condensers TLO could send. out a pulse or pulses immediately it is picked up and this would be sure-to reach TLl, but where operators may interrupt the connectnig circuit this cannot be done.
  • T L1 to send a pulse ora continuous tone to TLO and for TLO to pickup the cord circuit repeater firstQ.
  • ()ther arrangements such as starting the signal from TLO by a preliminary pulse from TLl reccived only when the connection is completed, will readily occur to those skilled in the art and need not be elaborated.
  • TLO sends a signal to TLl to initiate the insertionof the repeater.
  • TLO is a line of highattenuationwhich will require a repeater whencver connected to another toll'line, a signal (B) will be sent... If,
  • a repeater may be needed only when otherlinesof high attenuation are connected and in this case TLO sends out a signal (A).
  • the equipment inTLl will be arranged to respond therefore either to signal (B) or to signals (A) and (B) depending on the attenuation of the Line L and thus discrimination is obtained between connections which require repeaters and connections which do not.
  • the response of the apparatus TLl causes it to pick up a free repeater over the line finders LF and LF (for smaller groups of lines, of course, only one. finderwill be. required).
  • the repeater apparatus REP must then pick up the line L over the finders LF and LF and special arrangements will be needed to do this since it'will not be normally-possible to provide a special markingcir'cuit over the automatic switches or the cord circuit connecting TLl and TLO. It would of course 1 be easy to do this by. providing special cord 7 circuits or special. automatic switchesbut such an arrangement is extremelyuneconomical,'in view of the small numberofconnec-.-
  • the short circuit can only be elfecti-ve' overthe correct connection and not over'cross connections. InZcases where preventionof cross connection. is not required, as in very small offices, the voice'frequencyrelay may be connected-directly in theta-lking circuit.
  • a master switch may be'provided for distributing the cord circuit re-:
  • FIG. 6 the banks of contactsof line finder vLFand of network finder NFl are shown.
  • a group of toll lines such as L, connected to line finder LF are dividedinto groups, for instancein three groups A, B, C, to which correspond on the network finder NF three groups A 13 ,0 of suitable balancing networks;
  • L leads to the line circuit of the repeater
  • Marking potential applied by way 'of GMl fromthe repeater enables NF to pick up the required group of networks by means of;
  • incoming and outgoing toll lines may be located in diflerent places through calls being connected either manually or automatically over a junction circuit. It will be clear that in this case the arrangements described above may be used. A typical instance is shown in Fig. 7 in which a repeater may be connected in series with the existing connections instead of in shunt.
  • Fig. 7 shows a method of working over a junction circuit utilizing the principle of controlling the repeater connection by the line equipment and using the interconnecting talking circuit to provide signalling between the line equipments.
  • the operation of the arrangements of Fig. 7 is as follows L1, L2, TLi, TLO, s3, s1, s2, 0, N1,-LF1, LF& and REP are the same as before. L2 however is now reached over a junction circuit and switch S4 and the repeater REP is connected in series with the connection.
  • N2 is used for balancing the line over LF.
  • Sl/Vl and S W2 are relay groups to introduce the repeater. Signalling between TLl and TLO takes place as before and TLl picks up the repeater.
  • Figure 1 shows the signalling equipment at the incoming end of toll line 101 which is connected to an operators cord circuit shown in Figure 2.
  • the operator in this case is a switching operator who connects through to any required exchange requested by the operator at the distant end of the line 101.
  • Figure 3 shows the signalling equipment at the outgoing end of line 301 which is operated on the same basis as the line 101.
  • Figure at shows the equipment associated with a repeater in order that a connection between the lines 101 and 301 may be made by way of repeaters when necessary.
  • the method of working used by the operators is as follows
  • the operator at the distant end of the line 101 plugs into the line and thus lights the switching operators lamp 201.
  • the switching operator then enters the circuit by throwing her key 202 and plugs the line through i to the required exchange. In most cases this will be over comparatively short lines to local subscribers and no repeater will be needed.
  • a signal is sent back over the line 101 to extinguish the distant supervisory lamp, thus to inform the operator.
  • a further signal is sent back to light the supervisory lamp and the distant operator then pulls out the plug to release the connection.
  • the removal of the plug sends back a signal to the switching operator of Figure 2 by lighting lamp 201 and the operator then pulls out her plug and the line is ready for another call.
  • the switching operator plugs into this line and the train of operations are repeated, another operator being called at the distant end, the subscriber replying and eventually releasing and then the originating operator and the switching operators tak ing down as before.
  • the line 301 used in this case will of course be available also for local calls, so that a control operator similar to the operator at the distant end of the line 101 as well as the switching operator may pick up the line 301 and complete calls over it.
  • Figure 8 therefore, with the omission of the special relays used for introducing the cord circuit repeater, represents also the equipment at the outgoing end of line 101, while Figure 1 gives a good idea of the equipment which will be located at the distant end of line 301.
  • Relay 117' is arranged to senda pulseof voicefrequency current out of one'combination on to the line Whenever it energizesand Itwill be seen that the cycle of operations is just the same as in the case described above where a switching operator is used in place of the automatic apparatus.
  • relay116 releases, thejdistant supervisory lamp lights,'the originating operator takes .down and thus a pulse of voice frequency current is received to o'perate lease the connection.
  • the removal fof the jack releases 115 and thus The above description assumes that no cord circuitrepeater W as'necessa1"y. Similar conditions forlline 301' will-now be-described' This is the case when301'ispickedup by an originating operator directly and not over another long line.
  • lmown metl1od of signalling can be use'ol.
  • the ack 203 or more probably. anothena'ck fin parallelwith203 on the'other. operators position, will be. picked upto call the distant switching operator or lto prepare, distant the line; *These sending relays are operated when the lineis released to send the combination'WY'to give a release signal'at the dis-' tant end.
  • the trelays308 to 317 are similar 115, automatic apparatus. This will energize re 3 lla'y 302 and'will cause the circuit consisting j at relays 303, 304, 305, 306'and 307 to func v tioninprecisely the. same way as the correspending relays in Figure 1. A shortpul'se.
  • relay 316 being released bythecombination *WX rec'eived ever the line to' .eiz-tingui'sl ftlie supervisory lamp and relay 317 being 'released by the combinationW-Y to light the 90, relays 102 and 104.
  • Line 101 is assumed to be a long line which has'a high attenuation and which therefore needs a repeater when connected to any other It is provided consequently with two relays 110 and 111 which respond to either signalling code.
  • Line 301 is assumed to be a short line and therefore sends out combination XZ. If 101 were also a short line relay 110 would not be provided and therefore no repeater would be inserted, but since it is a long line it responds to either i XZ or VZ, the release of either 110 or 111 thus functioning to lock up 123.
  • Relay 123 places battery on the starting circuit of the finder switch 402; this energizes the high resistance relay 401 to start all the free finder switches such as 402 hunting for a line.
  • relay 404 in its associated repeater circuit is energized. This relay opens the stepping magnet 405 to stop the finder. It also shunts relay 401 and the latter falls off to stop the other finders hunting.
  • Relay 404 places earth on a circuit to start the network finder 406 and the other line finder 407 searching for network 440 and for line 301 respectively.
  • the stepping magnet 408 on the network finder is energized over an obvious circuit and the finder 406 hunts until the first of the terminals marked on brush 0 of 402 is reached. At thispoint the transformer 448 is short circuited and the current in its primary is thus increased sufficiently to operate the voice frequency relay 409.
  • the free network is indicated by battery potential on brush and this energizes relay 411 to open the stepping circuit.
  • the low resistance relay 411 renders the circuit busy. Any standard circuit stopping the switch when all networks in the'group are busy, can be used (e. g. last contact to have permanent battery).
  • switch 407 has been hunting for line 301, the stepping magnet 412 being energized over a circuit via the contacts of relays 413, 414 and 415 to ground from relay 404.
  • the ground from relay 404 also closes the filament circuit of the repeater.
  • the line 301 is marked on brushes (Z and e of 407 by the voice frequency current applied from the source 416 through the transformer 417 to brushes cl and e of 402 and thence to the line circuit of 101, plug 204, jack 203, line circuit of 301. hen the correct terminals are found relay 418 energizes relay 414 to open the stepping circuit and the repeater is then completely connected.
  • transformers 448 and 417 to control the hunting of 406 and 407 in order to avoid cross connection between hunting switches.
  • the voice frequency current in the primary circuit will only increase sutliciently to operate the relays on a complete short circuit and not on a cross connection.
  • Other means are available for carrying this out on finder 406, but the described method is probably the most satisfactory way in the case of switch 407. If the transmission bridgesin Figures 1, 2 and are of the repeating coil type an effective short circuit can still be obtained by a proper polling of i the connections.
  • the test relay 413, and relay 414 lock up relay 415 to maintain the stepping circuit open after the release of 414 and also to switch in the cord circuit repeater.
  • the latter is done by earth from 415 over the contact of relay 411 to brush 9 of finder 402, to relay 419, and to relay 420.
  • Relays 419 and 420 remove the voice frequency testing circuit of transformer 417 from the line and connect in the repeater at the same time removing short circuits designed to prevent one repeater from singing.
  • Earthover brush 9 of switch 402 energizes relay 124 to remove the signalling apparatus from line 101 (in order to reduce imbalances and to prevent false operation of the apparatus by high level currents from the repeater) and connects through. the line circuit from the operators position to the monitoring windings 421 and 422 of the repeater.
  • the repeater consists of two amplifiers 423 and 424 together wlth two hybrid coils and 426 of which the windings 421 and 422 the selection of the repeater IS in progress.
  • Relay 43s maintains earth on a commonlead for ashort time to energize relays 418 and 139.
  • Relay 413 unlocks 415 and removes earth from brush 7 of switch 407 to release relay321. It also closes the circuit of magnet 4:12 overthe oil normal springs and the switch returns to normal.
  • the release of relay 415 removes earth from brush 9 of switch 402 and from relays 419 and 120.
  • the cord circuit repeater thus returns to normal and relay 124 is also released I thus opening the energizing circuit of relay 402. Interference due to tone placed on the talking-circuit is avoided by therelease of relay lO-i or by. choosing the proper timing constants for the different relays.
  • the invention enables oneto use gain regulation apparatus for controlling the amplit'cation of the repeaters.
  • this may be done by means of a series of marginal relays in the circuit line repeater controlled I by the line equipment apparatus TLl' (and TLO) or by means of attenuatingpads con nected in the lead from the line to the repeater equipment REP.
  • the gain regulation may beunder the control of a local operator and in this case theuoper ,ation may be carried out over a connecting switch RP or the line equipment TLl or TLO by means of alternating current (e. g. :v'oicev frequency).
  • alternating current e. g. :v'oicev frequency
  • "Gain control may also be in the hands'of the distant operator by means ofthe signalling equip- 1 ment TLl. I y I
  • the circuit may .bearrangedto release also the line equipment apparatus TLl and TLO, thus improving the balance of the circuit.
  • A'group of vo ce frequency relays provided in-the repealter equipment REP can then be arranged ii to adjust the gain regulation apparatus by means of alternating current received either from a local operator in the case of manual switching, orfrom a distant operator in the case of .automatic switching. This latter relay group would also be used to release the connection.
  • Gain control by voice frequency means can I Either operator may be provided with a key or-keys which place a certain combination or z...
  • lines each including a pair of talking conductors, means for interconnecting said lines, a repeater, and means controlled over the talking conductors of an established connection between two of said lines for inserting said repeater in said established connection.
  • lines means as sociated with each of said lines for selectively'transmitting and receiving alternating currents of different frequencies over the talking conductors thereof, means for interconnecting said lines, a repeater, and means selectively responsive to said alternating currents controlled over the talking conductor of an established connection between two of said lines for inserting said repeater in said established connection.
  • lines of different character means associated with each of said lines for transmitting alternating currents corresponding to the characteristics of said lines over the talking conductors thereof, means for interconnecting said lines, re-
  • lines of different character means associated with each of said 'lines for transmitting alternating currents corresponding to the characteristics of said lines over the talking conductors thereof, repeaters of different characteristics, means for interconnecting said lines, and means responsive to said alternating currents controlled over the talking conductors of an established connection between two of said lines for selecting an appropriate repeater, adjusting said selected repeater, and for inserting said selected and adjusted repeater in said established connection.
  • lines of different character means associated witl'i'each of said lines for transmittii'ig and receiving alternating currents of different frequency over the talking conductors thereof, each said means being arranged to transmit alternat ing .currents corresponding to the charact ristics of the said associated line, means for interconnecting said lines, repeaters of chi ferent' chracteristics, andmeans responsive to alternating currents transmitted by one of said lines over an established connection to another of said lines and received-by the said other said line for selecting an appropriate one of said repeaters and inserting it in said established connection.
  • lines each including a pair of talking conductors, means for interconnecting said lines, a plurality of repeaters, a switch for selecting one of said repeaters controlled over the talking conductors of an established connectionbetween two of said lines, and means for inserting said selected repeater in said established connection.
  • lines each including a pair of talking conductors, means for interconnecting said lines, a plurality of repeaters, a switch for selecting one of said repeaters, means controlled over the talking conductors of an established connection between two of said lines for starting said switch, and means for inserting said selecting repeater in said established connection.
  • lines each including a pair of talking conductors, means for interconnecting said lines, a plurality ofrepeaters, an incoming and an outgoing switch for each of said repeaters, means controlled over the talking .conductors of an established connection between two of said lines for starting said incoming switches to select one of said repeaters, means controlled over the talking conductors of an established connection between two of said lines for stopping the outgoing switch of a selected repeater, and means for inserting said selected repeater in said established connection.
  • lines each including a pair of talking conductors, means for interconnecting said lines, a plurality of repeaters, incoming and outgoing switches at the incoming and outgoing connections of said repeaters, means controlled over the talking conductors of an established connection between two of said lines for starting said incoming switches to select one of said repeaters, a plurality of adjusting networks, an auxiliary switch for selecting one of said networks and connecting it to a selected one of said repeaters, means controlled over the talking conductors of an established connection between two of said lines for stopping said outgoing switches, and means for inserting said selected repeater in said established connection.
  • lines each including a pair of talking conductors, means individual to each of said lines for transmitting and receiving alternating currents over different frequencies, means for interconnecting said lines, a plurality of repeaters, an incoming and an outgoing switch for each of said repeaters, alternating current responsive means controlled over the talking conductors of an established connection between two of said lines for starting said in coming switches to select one of said repeaters, alternating current responsive means controlled over the talking conductors of an established connection between two of said.
  • V p In witness whereof I hereunto subscribe my name this twelfth day of June, 1929.

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  • Engineering & Computer Science (AREA)
  • Signal Processing (AREA)
  • Interface Circuits In Exchanges (AREA)
  • Cable Transmission Systems, Equalization Of Radio And Reduction Of Echo (AREA)
US375715A 1928-07-20 1929-07-03 Telephone system Expired - Lifetime US1763013A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
GB21064/28A GB324328A (en) 1928-07-20 1928-07-20 Improvements in telephone systems

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US1763013A true US1763013A (en) 1930-06-10

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Application Number Title Priority Date Filing Date
US19741D Expired USRE19741E (en) 1928-07-20 Telephone system
US375715A Expired - Lifetime US1763013A (en) 1928-07-20 1929-07-03 Telephone system

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Application Number Title Priority Date Filing Date
US19741D Expired USRE19741E (en) 1928-07-20 Telephone system

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US (2) US1763013A (en))
BE (1) BE362519A (en))
DE (1) DE636403C (en))
FR (1) FR680025A (en))
GB (1) GB324328A (en))

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2550755A (en) * 1947-09-24 1951-05-01 Automatic Elect Lab Toll switching telephone system
US2564084A (en) * 1946-11-02 1951-08-14 Automatic Elect Lab Telephone system having repeater insertion on long distance lines
US2601302A (en) * 1941-05-02 1952-06-24 Int Standard Electric Corp Two-way wire telephone repeater circuit

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2601302A (en) * 1941-05-02 1952-06-24 Int Standard Electric Corp Two-way wire telephone repeater circuit
US2564084A (en) * 1946-11-02 1951-08-14 Automatic Elect Lab Telephone system having repeater insertion on long distance lines
US2550755A (en) * 1947-09-24 1951-05-01 Automatic Elect Lab Toll switching telephone system

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Publication number Publication date
FR680025A (fr) 1930-04-24
BE362519A (en))
USRE19741E (en) 1935-10-22
DE636403C (de) 1936-10-13
GB324328A (en) 1930-01-20

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