US2173551A - Communication system - Google Patents

Communication system Download PDF

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Publication number
US2173551A
US2173551A US180075A US18007537A US2173551A US 2173551 A US2173551 A US 2173551A US 180075 A US180075 A US 180075A US 18007537 A US18007537 A US 18007537A US 2173551 A US2173551 A US 2173551A
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Prior art keywords
relay
contacts
circuit
station
winding
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US180075A
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English (en)
Inventor
Karl E Fitch
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AT&T Corp
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Bell Telephone Laboratories Inc
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Priority to BE131631D priority Critical patent/BE131631A/xx
Priority to FR847619D priority patent/FR847619A/fr
Application filed by Bell Telephone Laboratories Inc filed Critical Bell Telephone Laboratories Inc
Priority to US180075A priority patent/US2173551A/en
Priority to DEI63175D priority patent/DE742933C/de
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Publication of US2173551A publication Critical patent/US2173551A/en
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    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L12/00—Data switching networks
    • H04L12/02—Details
    • H04L12/04—Switchboards

Definitions

  • This Vinvention V relates to communication systems and more particularly to telegraph switching systems.
  • An object of this invention is to provide supervisory arrangements for long multisection subscribers lines in which ther supervisory signals r* ,20 are transmitted through the system without material delay.
  • Another object of this invention is to provide a supervisory system for long multisection subscribers lines in which the supervisory signals 25 at each end of the system are continuously controlled from the other end.
  • a further object of this invention is to provide supervisory arrangements for the intermediate sections of long subscribers line circuits in which 30 it is possible to distinguish between ringing signals, marking current, spacing current, break signals, disconnect signals and recall signals.
  • Another object of this invention is to provide supervisory signals over the usual well-known 35 types of telegraph circuits.
  • Another object of this invention is to provide terminal equipment for long multisection subscribers line circuits which cooperate with the switching apparatus at the central exchange in 40 the same manner as local line circuits cooperate therewith.
  • Another object of this invention is to provide an intermediate supervisory circuit arrangement which cooperates with the same subscribers stav.45 tion circuit and equipment as employed at local subscriber stations.
  • Another object of this invention is to transmit over a telegraph line arranged to transmit only two signaling conditions all the signals trans- 50 mitted over a connecting line which transmits at least three different signaling conditions.
  • Another object of this invention is to distinguish between break signals and supervisory signals by transmitting either ringing current or a 55 series of uniform length impulses over the system in at least one direction during break signals and to transmit continuous marking and spacing currents to indicate supervisory signals.
  • a multisection subscribers line circuit is provided 6 which employs the same subscriber station circuits and equipment as employed at local subscriber stations.
  • the long line circuit is arranged to cooperate with the switching apparatus or cord circuit at the central station in the same manner l as local subscribers line circuits cooperate therewith.
  • At least one intermediate repeater station is provided between the central exchange and the subscribers station. Between the subscribers station and the intermediate station substantially l the same types of signals are transmitted as are transmitted between the local subscriber station and the central exchange equipment.
  • full duplex telegraph channel Between the central station and the intermediate station one or more sections of a full duplex telegraph channel are provided.
  • Any form of full duplex telegraph channel is suitable including both diiferential and bridge type full duplex circuits arranged for operation over either open wire lines or cable circuits and which employ either a ground return or a full metallic circuit.
  • any type of full duplex carrier current channel is suitable for the intermediate section.
  • the carrier current channels may be either of the voice frequency or higher carrier current frequencies and may also include radio channels.
  • any suitable or available combination of the various types of full duplex circuits may be employed between the intermediate point and the central exchange.
  • the transmission of 85 break signals in at least one direction over the system is distinguished from supervisory signals by transmitting a series of signal impulses of uniform length over the full duplex channel during the break signal.
  • this series of impulses of uniform length is generated by applying alternating current and preferably 20-cycle ringing current to the terminal equipment of the full-duplex channel.
  • the relays of this equipment respond by following the alternations of the applied a1- ternating current and transmit a series of uniform signaling impulses of alternate marking and spacing current of substantially unit length.
  • Fig. 1 shows the manner in which Figs. 2, 3, 4, 5, 6, '7 and 8 are arranged to form a typical telegraph system embodying the present invention
  • Fig. 2 shows the circuit arrangement at the subscribers station
  • Fig. 3 shows the circuit arrangement at an intermediate station
  • Fig. 4 shows an intermediate line section
  • Fig. 5 shows a terminal circuit arrangement at the central exchange which cooperates with the cord circuit
  • Fig. 6 shows a circuit arrangement of the cord circuit
  • Fig. '7 shows the operators equipment
  • Fig. 8 shows typical local subscribers line circuit and station equipment.
  • the line circuit is open at the subscribers station during the idle condition, i. e., when it is not desired to communicate therewith.
  • the line circuit extends from the subscribers station to an intermediate station at which one of the conductors is normally connected to ground and the other to battery.
  • the intermediate sections of the full duplex channel extending between the intermediate station and the central station are normally maintained in the spacing condition in both directions and the circuit is disconnected at the central exchange.
  • This closure is repeated at the intermediate station by changing the signaling condition transmitted from the intermediate station to the central exchange, from a spacing condition to a marking condition.
  • the marking condition when received at the central exchange, causes the lamp associated with the subscribers line to light to attract the operators attention.
  • the operator answers the call by inserting the answering plug in the jack associated with the line circuit.
  • This causes the terminal equipment to transmit a markingr condition from Vthe central exchange to the intermediate station, which vcompletely establishes the transmitting circuits between the subscribers station and the central exchange.
  • An alternating ringing current is employed which has a frequency of 20 cycles. This ringing current passes over the intermediate telegraph lines and circuits as unit impulses of alternate marking and spacing current.
  • a subscriber transmits a recall signal by momentarily interrupting the line circuit at his station and connecting ground to one of the wires. This causes the equipment at the intermediate station to momentarily transmit a spacing signal over the intermediate sections to the central office.
  • the prolonged spacing signal causes the cord circuit supervisory lamp to light, and then ilash if automatic recall is provided, or to relight and then follow the operations of the recall key at the subscribers station.
  • Disconnect signals are transmitted from a subscribers station by opening the line at the subscribers station and connecting ground to one of the line wires. This causes the equipment at the intermediate station to transmit a ⁇ spacing current or condition over the intermediate section to the central office.
  • the prolonged spacing signal is received at the central oice it causes the cord circuit supervisory lamp to light continuously.
  • the cord circuit and transmits ringing current to the terminal equipment.
  • the ringing current is transmitted over the intermediate line sections as alternate marking and spacing impulses of unit length. When these impulses are received at the intermediate point, they cause ringing current to be applied to the line extending to the subscribers station and ring a bell to call a subscriber.
  • the operator holds the ringing key operated for a prolonged period of approximately nine or ten seconds. This causes a slow relay to operate at the subscribers station equipment after which a message can be transmitted to the subscribers station and recorded by his teletypewriter. During the transmission of the message to the subscribers station the circuits operate as described above. At the completion of the call it is necessary to send a motor stop signal over the system.
  • Idle condition The idle condition of the relays remain as shown in Fig. 2 except relay 24 which may be in either the position shown or in its right-hand' flowing through the lower winding in a circuit from battery through the lower break contacts of relay 55, through lower winding of relay 58 to ground.
  • Relay 59 may be either in its righthand or left-hand position when the circuit is idle.
  • the relays of the full duplex section shown in Fig. 4 are maintained in their spacing positions as shown.
  • Relays' 2DI and 283 are maintained in their left-hand positions by an obvious circuit through their lower windings. These relays serve to maintain relay 2I0 at the distant end in its spacing or right-hand position.
  • Relays 2I2 and 2I3 are maintained in the right-hand or spacing position by an obvious circuit through their lower winding and in turn cause relay 208 at the other end of the circuit to be maintained in its lefthand or spacing position.
  • , 203, 2 I 2 and 2 I3 maintains them in their spacing position because no current flows through their upper windings at this time.
  • Relay 232 is maintained in the position shown by current flowing in an obvious circuit through its lower winding.
  • Relay 229 is maintained in its right-hand position by current flowing through its middle winding, in an obvious circuit.
  • Relay 226 is maintained in its marking or left-hand position by current flowing in a circuit from ground through its lower winding and the upper break contacts of relay 221 to battery.
  • Relay 220 is maintained in its spacing or righthand position by current iiowing in a circuit from ground through its lower winding and the marking contacts of relay 226 to negative battery.
  • Relays 225, 22S and 232 are controlled by the current flowing through their lower windings at this time because no current flows through their upper windings.
  • Relay 233 is maintained in its right-hand position by current iiowing in a circuit from ground through its upper winding, upper break contacts of relay 235 and spacing contacts of relay 232 to positive battery. Current flowing through the lower winding of relay 233 in an obvious circuit tends to operate this relay to its left-hand position but is overpowered by the current flowing through the upper winding which holds it in its right-hand position.
  • Subscriber originates a call
  • a subscriber desires to originate a callhe momentarily operates key 12 to a position where it operates the right-hand contacts.
  • Relay 21 in operating completes a locking circuit from source of power 28 through the winding of relay 21, upper contacts lof relay 21, stop contacts I4 of key 12, motor control contacts I5 to ground.
  • Relay 21 in operating also completes an operating circuit for relay I2 from source of power 28 through the lower contacts of relay 21 to ground through the winding of relay I2.
  • Relay 21 in operating also connects source of power to motors 38 and 3l and to the motor generator set 29. Motor generator set 29 causes current to flow through the lower winding of receiving relay 24 which tends to operate this relay to its right-hand position.
  • relay I2 The operation of relay I2 and the restoration of key 12, which permits the right-hand springs to return to normal, clos-es the line circuit through the subscribers station.
  • relay 49 at the intermediate station (shown in Fig. 3) in a ⁇ circuit from battery through the winding of relay 49, the upper break contacts of relay 68, upper: break contacts of relay 5I, line Ill to the subscribers station circuit shown in Fig. 2, the upper operated contacts of relay I2, normal upper contacts of the lower set of contacts of key 12, normal contacts of recall key I6, upper winding of, relay 24, distributor I1, break key I8, transmit- Relay 5I) in operating completes an obvious cir-V cuit for the operation of relay 5I.
  • Relay 5I operating completes a locking circuit from battery through its winding and lower contacts to ground through the break contactsI of relay 10.
  • Relay 5I in operating completes an obvious circuit for the operation of relay 52.
  • Relay 5I in operating also transfers the circuit of lines I and II from ground and relay 49 to the windings of relay 51 and interrupts the operating circuit of relay 49, allowing this relay to release.
  • Relay 49 in releasing interrupts the operating circuit of relay I! which in turn releases.
  • the subscribers line now extends from negative battery through the lower winding of relay 51, and the upper inner operated contactsI of re-. lay 5I, line II to subscribers station equipment, through contacts of key 12, sending contacts I9, break key I8, tape transmitting distributor I1, upper winding of relay 24, normal contacts of recall key IS, contacts of key 12, upper inner contacts of relay I2, line .I0 to the intermediate station, middle set of upper operated contacts of relay 5 I upper winding of relay 51, upper winding of relay 59, choke coil 69 to the armature and transmitting contacts of relay 58.
  • Current howing in this path through the upper winding of relay 59 causes the armature of this relay to move to its marking contact if it had been resting on its spacing Contact.
  • Current flowing in this line circuit flows through the upper and lower windings of relay 51 in opposite directions so that they neutralize each other and produce substantially no magnetic eiTect upon relay 57.
  • Relay 51 accordingly remains in its normal position.
  • relay 24 Current iiowing through the upper winding of relay 24 in this circuit to the subscribers' station causes relay 24 to operate to its left-hand contacts and completes a circuit for the operation of printer magnet 32 from the positive terminal ci motor generator 29, winding of printer mag-- ⁇ net 32,1eft-hand contacts of relay 24 to the negative terminal of motor-generator 29.
  • Current iiowing through the upper winding of relay 24 is in the opposite direction and overpowers the current flowing through the lower winding of relay 24.
  • Relay 52 (Fig. 3) in operating, as described above, completes an obvious circuit for the operation of relay 53.
  • Relay 52 in operating also connects ground to the armature and of winding of relay 56.
  • Relay 56 operates to its left-hand position in a circuit from negative battery through the marking contacts of relay 59, winding of relay 55 to ground through the upper inner operated contacts of relay 52.
  • relay 5B completes a circuit for the operation of relay G5 to its right-hand position from battery through the winding of relay 5l), left-hand contacts of relay 53 to ground through the upper outer operated contacts. of relay 52.
  • Relay 52 in operating also interrupts the circuit of the right-hand Contact of relay 53 and transfers the circuit of the left-hand contact of relay 50 to the winding of relay 13.
  • relay 53 connects ground to the potentiometer comprising resistance 14 and network 1
  • the operation of relay 53 extends lines
  • Relay 54 does not operate this circuit because negative battery is connected to both of its winding terminals.
  • relay 53 When relay 53 operated as pointed out above it extended line
  • This circuit may be traced as follows: From positive battery through resistance 234, upper windings of relays 20
  • and 203 transmits marking current through the noise suppression filter 26
  • U responds to this marking condition and moves to its marking contact. This causes the operation of relay 232 of the terminal equipment shown in Fig. 5 in the circuit from positive battery through the marking or left-hand contacts of relay 2
  • Relay 232 in operating interrupts the circuit through the upper winding of relay 223.
  • condenser 253 starts to discharge through the upper winding of relay 233.
  • and condenser 25D are so arranged that the discharging current of condenser 25
  • this discharge current falls to such a value that the current owing through the lower winding of relay 233 overpowers it and causes the armature of relay 233 to move to its left-hand position.
  • a circuit is completed for the operation of relay 221 from ground through the lefthand contacts of relay 233, lower outer break contacts of relay 235, break contacts of relay 228 to battery through the winding of relay 221.
  • Relay 221 in turn completes a locking circuit from ground through its center set of lower operated contacts, the break contacts of relay 228, to battery through the winding of relay 221.
  • Relay 221 in operating completes a circuit for the operation of relay 225 from ground through the lower inner make contacts of relay 221, lower break contacts of relay 2
  • Relay 225 in operating completes an obvious circuit for lighting the answering lamp 224 associated with jack 223.
  • Relay 221 in operating transfers the lower or biasing winding of relay 226 from positive battery to the armature of relay 220 and prepares relay 226 for receiving telegraph signaling impulses from a subscribers station.
  • Relay 221 in operating also completes a circuit for the operation of relay 234 from ground through its lower outer make contacts, lower inner break contact of relay 235 to battery through the winding of relay 234.
  • Relay 234 in operating connects battery to condenser 252 and the upper winding of relay 233. This charges condenser 25B to battery potential and causes the armature of relay 233 to move to its righthand position where a circuit is completed for the operation of relay 235 from ground through the right-hand contacts of relay 233, lower contacts of relay 234, upper inner break contacts of relay 230 to battery through the winding of relay 235.
  • Relay 235 in operating interrupts the operating circuit of relay 234 which releases.
  • Relay 235 in operating completes a locking circuit from battery through its winding and inner lower make contacts to ground through the lower outer operated contacts of relay 221.
  • Relay 235 in operating also transfers the circuit of the upper winding of relay 233 to marking contact of relay 232. Inasmuch as relay 232 is now in its marking position a circuit is completed for maintaining relay 233 in its right-hand position from ground through its upper winding, the upper inner operated contacts of relay 235 to battery through the marking contacts of relay 232.
  • the rst operator to answer will und the circuit idle and Will insert the plug 83 in jack 223,
  • the other operators, if they start to answer the call, will iind that the jacks in multiple with jack 223 will test busy so that they know that the call has already been answered.
  • relay 84 completes an obvious circuit for the operation of relay 92 and conditions the cord circuit and extends the tip of the cord to the armature of relay 9
  • I in operating vinterrupts the operating circuit of relay 225 which in turn releases and extinguishes the lamp 224.
  • I in operating extends the transmission circuit from the tip of jack 223 through the upper winding of relay 220 to the armature of relay 226.
  • Current iiowing through this transmission circuit from negative battery connected to the mark ing contacts of relay 226 through the upper winding of relay 220, upper contacts of relay 2
  • causes relay 220 ⁇ to be operated to its marking icontact.
  • Relay 220 in operating to its marking contacty causes relays 2
  • relay 208 responds to this marking condition and moves to its marking position and completes the operating circuit of relay 54 described above since now negative battery is connected to one winding't'erminal and positive battery from the marking contacts of relay 208 to the other winding terminal of relay 54.
  • Relay 54 in operating completes a locking circuit from battery through its winding and upper break contacts to ground through the lower outer contacts of relay 53. Relay 54 in operating also completes an obvious circuit for the operation of relay 55.
  • Relay 55 in operating transfers the circuit of the lower winding of relay 58 from positive battery to the armature of relay 59.
  • Relay 55 in operating also completes a transmission circuit from negative battery through the upper winding of relay 53, the upper operated contacts of relay 55, upper operated contacts of relay 53, line
  • These circuits condition relay 58 for responding to telegraph signal impulses.
  • the circuits are now in condition to enable the subscriber to communicate with the opera tor and indicate the other subscriber with Which he wishes to be connected.
  • the operator will then complete the call by inserting calling plug
  • the called subscriber is connected to the central station by local line calling plug IliI will be inserted into the subscribers jack
  • the long multisection subscribers line circuits described herein operate inthe same manner when connected to all of these different types of called subscribers circuits. Hence, this description of typical local subscribers line yand station equipment will illustrate the features of the long multisection subscribers line circuits. Assume, then, that plug
  • 40 completes a circuit for the operation of relay
  • Relay I4I in operating connects ground through its lower contacts to the ring of jack
  • Relay 91 in operating completes an obviouscircuit for lighting lamp
  • Relay 244 in operating removesA the ground connected to the T lead and to the winding of ringer
  • Relay 244 in operating and removing ground from the T lead interrupts the operating circuit through the lower winding of relay I4
  • the subscriber shown in Fig. 2 may operate his station equipment in a number of different ways.
  • the subscribers station shown in Fig. 2 is provided with both a keyboard transmitter and a tape perforator and tape controlled transmitter. It is to be understood, however, that any suitable subscribers station equipment may be employed at the end of the long multisection line.
  • the equipment at the intermediate point is arranged to work with all the different subscribers station circuits usually employed at local stations.
  • the distant subscribers station may be provided with the equipment shown at the subscribers station illustrated in Fig. 8.
  • the arrangement shown in Fig. 2 illustrates that the subscribers station may provide all the services provided for a local subscriber.
  • the switch 33 is operated to the K position where it interrupts the circuit through the lower contacts. This interrupts the circuit through the start magnet 4I of the tape control transmitter distributor I1.
  • the subscriber In order to transmit, the subscriber must also operate the send-receive switch 20 to the position shown so the transmission circuit extends through the transmitting contacts I9.
  • transmitting contacts I9 transmit telegraph signaling impulses in accordance with the keys operated by the subscriber by opening and closing the line to the intermediate point.
  • the line relay 24 at the subscribers station will follow the signal impulses and repeat them to the printer magnet 32 which records the transmitted signals on the local teletypewriter and provides a home copy for the subscriber.
  • Relay 24 in its spacing position connects resistance 48 between the positive and negative terminals of the motor generator 29 to compensate for the load of the printer magnet 32 and thus maintain the load on the motor generator substantially constant and so the voltage output of the motor generator remains substantially constant when relay 24 is in both its marking and spacing positions.
  • remain open so that the brush arm 43 of the distributor I1 will remain at rest and not interfere with the transmission from the transmitting contacts I9.
  • Means is also provided for permitting the subscriber to perforate tape and then transmit from the perforated tape.
  • the subscriber wishes to merely perforate tape, he operates key 12 to the test position and leaves it in this position. With key 12 in test position, the power supply circuit is closed, as described above for the subscriber originating a call.
  • the line circuit extending to the intermediate station shown in Fig. 3, is interrupted and remains open so that the equipment at the intermediate station as well as at the central station remains in its idle condition.
  • the printed copy of the message perforated in the tape may be used for editing and correcting purposes so that the message may be edited before it is transmitted.
  • counter magnet 31 is operated to count the character.
  • the lever 80 moves in the direcion indicated and mechanically operates the counter contact 19 so as to interrupt the circuit of the counting magnet 31 since these particular signals do not cause any character to be printed on the teletypewriter.
  • counter contacts 19 are operated by lever 11 in response to a carriage return signal and cause the operation of release magnet 38 which restores the counter to zero.
  • the counter light 40 is provided which may be energized by closing the lamp control switch 39 and serves to illuminate the counter dial.
  • a supply of tape may be perforated without transmitting the information over the line to the central oice. If it is desired to return the equipment to normal without transmitting the information at this time key 12 is moved from the test position through the line position to the stop position and then to the normal or line position. This interrupts the locking circuit of relay 21. Relay 21 in releasing restores the apparatus at the subscribers station to its normal or'idle condition. It is to be noted that the equipment at the subscribers station cannot be deenergized so long as key 12 is in the test position. This arrangement tends to prevent the subscriber from leaving his equipment unattended with key 12 in the test position.
  • the transmission circuit is established as described above, and key 12 returned to its normal or line position without first being operated to the stop position.
  • Key 33 is operated to T position and switch 8
  • Start magnet 4l operates in this circuit and withdraws the stop latch 42 from engagement with the brush arm 43 carrying brush 44. This brush arm is driven through a friction clutch (not shown) from motor 33.
  • the line circuit extending to the central oflice is interrupted in accordance with the perforations of tape 41 under the tape control contacts So long as the supply of perforated tape is available, tape control contacts 46 remain closed and the transmitter distributor continues to transmit over the line to the intermediate station.
  • this transmission relay 211 which is in series with the line, as described above, follows the signals vtransmitted by the distributor I1 and repeats them to the printer magnet 32 of the teletypewriter where they are recorded.
  • telegraph signal impulses are transmitted from the subscribers station over the line extending to the intermediate station, shown in Fig. 3, as impulses of current and no-current, independently of how or what equipment is used to transmit the impulses.
  • Relay 51 at the intermediate station does not respond to these impulses, since they pass through both windings of the relay in opposite directions.
  • Relay 59 responds to the impulses transmitted from the subscribers station and repeats them to relays 293 and 29! in the circuit extending through its contacts, the
  • Relay 56 follows the signals repeated by relay 59 in a circuit from the contacts of relay 59 through the winding of relay 59 to ground through the upper operated contacts of relay 52.
  • relay 56 In response to spacing impulses transmitted by relay 59, relay 56 is operated to its right-hand position and in response the marking impulses transmitted by relay 59, relay 56 is operated to its leftwhand position. In the left-hand position relay 56 completes a circuit from ground through the outer upper operated contacts of relay 52, contacts of relay 56 to battery through the upper winding of relay 69.
  • Relay 65 is maintained in its right-hand position by current flowing in this circuit. When relay 58 is operated to its right hand position it interrupts this circuit. Condenser 6I then starts to charge from battery through the upper winding of relay 60.
  • Relay 225 repeats the signal impulses over the transmission circuit extending from its contacts through the upper winding of relay 220, upper' operated contacts of relay 2
  • Relay 90 repeats the signal impulses to the transmission Vcircuit extending to the subscribers station circuit shown in Fig.
  • relay 88 In case the operator has the printing key 89 operated, relay 88 will be operated, in an obvious circuit. With relay 88 operated, the transmission circuit extends from the tip of plug 83, through operated contacts of relay B4, the operated contacts of relay 88, and the operators position circuit to the repeating relays 90 and 9
  • 4 are provided to enable the operator to communicate with either subscriber without communicating to the other subscriber.
  • Signal impulses are transmitted, either from the subscribers station shown in Fig. 8 or from the operators equipment shown in Fig. '1 to the outlying subscribers station shown in Fig. 2,
  • relay 220 of the terminal circuit shown in Fig. 5 repeats the impulses over line 2
  • I-Iere relay 208 repeats the impulses through resistance 205, line
  • Relay 58 follows the signals and repeats them to the subscribers line.
  • At the subscribers station relay 24 follows the signals and repeats them to the printer magnet 32 of the subscribers teletypewriter which records the signals.
  • Break signals In case it is desired to interrupt the transmission being received at the subscribers station shown in Fig. 2, break key I8 is operated. This breek key is associated with the send-receive key 20 so that it is necessary to operate the sendreceive key first before the break key I8 can be operated. This merely short circuits the transmitting contacts I9 and interrupts the circuit of start magnet 4
  • relay ,55 will remain in its spacing position longer than the .3-second period required for relay 60 to operate to its left-hand position.
  • relay 60 operates to its left-hand position and completes a circuit for the operation of relay 13 from battery through the winding of relay 13, the lower outer make contacts of relay 52 to ground through the left-hand and armature contacts of relay 60.
  • Relay 13 in operating transfers the transmission path over lead
  • at the central station repeats these impulses to the terminal circuit shown in Fig. 5.
  • relays 232 and 225 respond by moving to their spacing positions.
  • Relay 228 repeats the break signal either to the operator or the subscribers station circuit shown in Fig. 8.
  • Relay 232 will remain in its spacing position over .2 second in this case and permit condenser 250 to become sufliciently discharged to allow relay 233 to operate to its lefthand position.
  • Relay 233 in operating to its left-hand position completes a circuit for the operation of relay 229 from ground through the left-hand contacts of relay 233, the lower operated contacts of relay 235, the lower normal contacts of relay 23
  • Relay 229 in operating removes the short circuit from its lower winding so that current may now ow from ground through the lower winding, resistance 249, the upper operated contacts of relay 235 to battery through the spacing contact of relay 232. Current flowing through this Winding tends to maintain relay 229 operated.
  • Relay 229 in operating also completes an obvious circuit for the operation of relay 230.
  • Relay 230 in operating completes a circuit for the operation of relay 234 from ground through its lower contacts, upper break contacts of relay 23
  • Relay 234 in operating completes a circuit through its upper contacts for charging condenser 250 and for operating relay 233 to its right-hand jposition. In the right-hand position the armature of relay 233 completes a circuit for the operation of relay 23
  • in operating interrupts the operating circuit of relay 234 and completes a locking circuit from ground through the lower operated contacts of relay 230, upper operated contacts of relay 23
  • Relay 232 follows the ringing current and during alternate half cycles, connects ground to the upper winding of relay 233 and fully charges condenser 250. This prevents relay 233 from moving to its left-hand position at this time.
  • Relay 232 at this time also tends to charge condenser 236 through resistance 249.
  • condenser 235 will discharge through the lower winding of relay 229 and maintain this relay in its left-hand position.
  • relay 230 when relay 230 operated it interrupted the transmission circuit to 'relay 226 so that this relay will remain in it spacing position and not receive or :follow the ringing current transmitted from the intermediate station.
  • relay 59 when the break signal is iirst received by relay 59, relay 59 operated to its spacing position during the next marking impulse transmitted by relay 58 to the subscribers station shown in Fig. 2. When relay 59 operates to itsv spacing position it reverses the bias current through the lower winding of relay 58 so thatit will tend to maintain relay 58 in marking position so long as the break impulses are received from the subscribers station. This insures the proper retransmission of the break signal to the central station and prevents the impulses being transmitted from a distant station yfrom interfering with the break signal.
  • the central exchange relay 226 is operated which relay in turn repeats it to the subscribers station shown in Fig. 8.
  • relay 90 With relay 90 in its spacing position it is impossible for the subscribers station shown in Fig. 8 to transmit marking signal impulses so that the line relay
  • the reception ofl the break signal by the teletypewriter 245 at the subscribers station shown in Fig. 8 causes the send-receive contacts
  • relays transmit a marking impulse over line 201 to the central station.
  • This marking impulse is repeated over line 2
  • Relay 232 operates toits marking position and remains in this position.v In the marking position, relay 232 completes a circuit through the upper winding of relay 233 for maintaining the armature of this relay in its right-hand position. Relay 232 in remaining in its marking position interrupts the locking circuit of relay 229 and permits condenser 236 to discharge, after which relay 229 will be operated to its right-hand position by current flowing in an obvious circuit through its center Winding.
  • Relay 229 in operating to its right-hand position interrupts the circuit for relay 230.
  • Relay 230 releases and in turn releases relay 23
  • Relay 230 in releasing reconnects the upper winding of relay 226 to lead 2
  • Relay 226 is then operated to its marking position by the marking impulse received over lead 2
  • Relay 226 will repeat this marking impulse to the local subscribers station shown in Fig. 8, whereupon the transmission circuits are restored to their normal condition and the subscriber at station shown in Fig. 2 may now transmit over the system as described above.
  • a break signal may be transmitted either by the operator or by the subscriber at the subscribers station shown in Fig. 8. This transmits a break or spacing signal over the tip of plug 83 to relay 220.
  • Relay 220 operates to its spacing position .during the transmission of the first marking impulse by relay 226 after the reception of the break signal and retransmits the break signal over line 2
  • Relay 220 in operating to its spacing position reverses the bias current through the lower winding of relay 226. This causes relay 226 to remain in its marking position and prevents it from interfering with the break signal received by relay 220.
  • 3 repeat the break signal over line 291 to relay 208 of repeater A.
  • Armature of relay 208 moves to its spacing position and repeats the break signal over line I 90 to relay 58.
  • the armature of relay 58 in turn moves to its spacing position during the first marking impulse repeated by relay 59 after reception of the break impulse and repeats the break signal to the subscribers line. With the armature of relay 58 in its spacing position relay 59 is maintained in its marking position so that if any succeeding impulses are transmitted by the subscribers station they will not interfere with the break signal.
  • Relay 24 at the subscribers station responds to the break signal by moving to its spacing position and remaining there independently of the o-peration of the transmitting contacts I9 or of the impulses transmitted by transmitting distributor I1. This indicates to the subscriber that the distant subscriber wishes to interrupt the transmission.
  • the teletypewriter also causes the sendreceive contacts 20 to be operated to the receive position at this time This interrupts the circuit of the start magnet 4
  • recall key I6 This interrupts the line circuit at the subscribers station and connects ground to conductor I I from the operated contacts of recall key I6 and interrupts the circuit through the upper winding of relay 51 and connects ground to the circuit through the lower winding of relay 51.
  • This circuit for the operation of relay 51 may be traced from ground through the operated contacts of recall key I6, the upper winding of relay 24, transmitting distributor I1, contacts of the break key I8, contacts of the transmitting device I9, contacts of the line test key 12, line I I, the inner upper operated contacts of relay 5I, lower winding of relay 51 to negative battery.
  • Relay 51 in operating completes a circuit for the operation of relay 10 from ground through the upper contacts of relay 50, contacts of relay 51 to battery through the winding of relay 1i).
  • Relay 10 operates and interrupts the locking circuit of relay 5 I.
  • thereupon releases and releases relay 52.
  • Relay 52 in turn releases relay 53 which causes the release of relays 54 and 55. 'Ihe release of these relays restores the circuit to its idle condition.
  • interrupts the operating circuit of relay 51 which in turn interrupts the operating circuit of relay 10.
  • Relay 10, however, is made slow in releasing so that relay 5
  • relay 232 responds to the spacing signal by moving to its spacing position. This causes the operation of relay 233 to its left-hand position after approximately .2 second. In the left-hand position relay 233 completes a circuit for the operation of relay 229 to its right-hand position.
  • Relay 229 in operating to its right-hand position removes the shunt from its lower locking winding so that it will lock in its left-hand position under control of the spacing contacts of relay 232.
  • Relay 229 also causes the operation of relay 230.
  • Relay 238 in operating interrupts the transmission circuit to relay 226 and also completes a circuit for the operation of relay 234.
  • Relay 234 in operating completes a circuit for the operation of relay 233 to its right-hand position through its upper winding.
  • Relay 233 in turn completes a circuit for Vthe operation of relay 23
  • locks operated under control of relay 239 and interrupts the operating circuit of relay 234 which then releases.
  • the operating circuits of these relays shown in Fig. 5 are the same as for a break signal described above. In.
  • relay 232 will remain upon its spacing contact at this time, since no ringing current is transmitted over the system.
  • the armature of relay 233 completes a circuit for the op-eration of relay 228 from ground through the left-hand contacts of relay 233, lower outer operated contacts of relay 235, the lower operated contacts of relay 23
  • Relay 228 in operating completes a locking circuit from battery through its winding and operated contact to ground through the middle set of lower contacts of relay 221.
  • Relay 228 in operating interrupts the locking circuit of relay 221 from battery through the winding of relay 221 and the break contacts of relay 228 to ground through the center set of lower operated contacts of relay 221. This permits relay 221 to release which in turn causes the release of relays 235, 228, 229, 239 and 23
  • relay 221 also connects ground through its inner lower break contacts to the ring of jack 223 and plug 83 which causes the operation of relay 85.
  • the operation of relay 85 causes the supervisory lamp 86 to light.
  • the operation of relay 85 also completes a circuit for the operation of relay 81 which locks operated through its upper contact.
  • recall signals may be sent by momentarily operating the line key 12 first to the stop position, then to the test position and finally restoring it to the line position.
  • the operation of key 12 to the stop position interrupts the locking circuit of relay 21 and permits this relay to release.
  • the release of relay 21 disconnects the power supply from the motor generator 29 and motors 30 and 3
  • the release of relay I2 interrupts the line circuit to the subscribers station and connects ground to lead II which extends to the intermediate station shown in Fig. 3 in the same manner the operation of recall key I6 connects ground to this lead. This causes the circuits at the intermediate station and central office to operate as described above when the recall key was operated.
  • recall key I 6 will only be provided when automatic recall is not provided at the central ofiice so that the subscriber can readily flash the supervisory lamp in the cord circuit at the cen-
  • recall key is not necessary and usually will not be provided because a single recall signal may be readily transmitted by line key 12.
  • I in releasing interrupts the transmission circuit through the upper winding of relay 220 so that the armature of this relay will move to its spacing position and transmit a spacing signal over line 2I8.
  • This spacing signal is repeated by relays 2l2 and 2I3 over line 201.
  • Relay 208 moves to its spacing position in response to this spacing signal.
  • Relay 208 in moving to its spacing position at this time performs vno useful function since the circuits have all returned to their normal or idle position.
  • a disconnect signal may be transmitted from the outlying subscribers station in response to a motor stop signal transmitted from the subscribers station or received by this station.
  • the motor stop signal operates contacts
  • Relay 220 will follow the ringing current and transmit alternate impulses of marking and spacing current of substantially unit length over line 2I8. Relays 2I2 and 2I3 repeat these impulses over line 201. Relay 208 of the intermediate station in turn repeats these impulses over line
  • Alternating current relay 63 responds to these impulses.
  • Condenser 64 is alternately charged and discharged through the windings of relay 63 from theV positive and negative batteries connected to the contacts of relay 208 over a circuit extending from the armature f relay ⁇ 208, resistance 206, lead
  • the same terminal of condenser 64 is also connected to negative battery through resistance
  • Relay 63 is an alternating current relay and tends to operate and remain operated so long as these impulses are received.
  • Relay 63 in operating completes an obvious circuit for the operation of relay 65.
  • Relay 65 in turn completes a circuit for the operation of relay 60 to its right-hand position from ground through -the upper operated contacts of relay 65, lower break contacts of relay 66 to battery through the upper winding of relay 60.
  • Current ilo-wing in this circuit opposes and overcomes the current ilowing through the lower winding of relay 66 so that relay 69 will operate to its righthand position.
  • relay 60 in operating completes a locking circuit from battery through its winding and inner upper operated contacts to ground through the inner upper operated contacts of relay 65.
  • Relay 66 in operating interrupts the operating circuit of relay 60 so that relay 60 starts to release at this time.
  • starts to charge through the upper winding of relay 60 at this time.
  • the charging current of this condenser is sufcient to maintain relay 60 in its right-hand position for approximately .3 second in the preferred embodiment of this invention.
  • relay 60 will be operated to its left-hand position by current flowing through its lower winding in an obvious circuit.
  • relay 61 With the armature of relay 60 in its left-hand position at this time a circuit is completed for the operation of relay 61 from ground through the armature and left-hand contacts of relay 60, lower break contacts of relay 52, upper operated contacts of relay 66 to battery through the winding of relay 61. Relay 61 in operating completes an obvious circuit for the operation of relay 68.
  • relays 61 and 68 connects the source of 20-cycle ringing current 15 to line l0 extending from the subscribers station in the following circuit: from ground through the source of ringing current 15, protective lamp 16, inner operated contacts of relay 61, operated contacts of relay 68, middle set of normal contacts of relay 5
  • Relay 63 When the operator releases ringing key
  • Relay 63 will not remain operated under this condition since condenser 64 will become fully charged. Hence, no current will flow through the winding of relay 63 so relay 63 will release and in turn release relay 65 which in turn releases relay 66.
  • Relay 66 releases relay 61 which in turn releases relay 68. The release of these relays disconnects source of ringing current 15 from the line extending to the subscribers station. Relay 68 is slow in releasing.
  • relay 01 will disconnect ground from the ring of jack ⁇ 221 and thus permit relay 01 to release.
  • the release of relay -91 allows the supervisory llamp
  • the subscribers may corninunicate between themselves and the operator at the central exchange, if necessary, as described above, and at the termination of the call, disconnect by operating the line key to the stop position for a short interval of time and then releasing it.
  • and relay 25 are connected in parallel with the condenser 23 and ringer 22.
  • the operator will hold ringing key
  • Relay 25 will operate at this time and complete a circuit for the operation of relay 26 from source of power 26 through the winding of relay 26 and the contacts of relay 25 to ground. Relay 26 is slow to operate and does not close its contacts for at least six or eight seconds.
  • Relay 25 in operating completes a circuit for the operation of relay 21 from source of power 28, winding of relay 21, contacts of relay 26 to ground.
  • Relay 21 in operating locks operated and energizes the equipment at the subscribers station, as described above when the subscriber initiates a call.
  • lay 2 is also operated when relay 21 operates and completes the line circuit through the subscribers station.
  • relays 63, 65, 66, 61, and 68 release whereupon, if the equip-ment at the subscribers station has responded as described above, relays 49, 50, 5
  • the operation of relay 221 removes ground from the ring of jack 223 which in turn permits relay 91 to release and in turn extinguish the supervisory light
  • a long subscribers line circuit comprising subscribers station equipment, an intermediate repeater station, central interconnecting station equipment, terminal equipment connected to said long subscribers line circuit at said interconnecting station, a telegraph line connecting said subscribers station and said intermediate station, a full duplex channel connecting said intermediate station and said central station, means at said subscribers station for continuously controlling supervisory signals at said central station comprising means for transmitting a series of signals of alternate character and of uniform length from said intermediate station during break signals which exceed the length of spacing signals encountered in transmitting code combinations of telegraph signaling impulses.
  • a method of supervising over a long multisection subscribers line circuit which comprises transmitting a break signal over the intermediate sections of said system for a short interval of time in response to a break signal transmitted from the subscribers station and then transmitting a series of uniform length impulses of alternate character over the intermediate sections during the remainder of the break signal transmitted from the subscribers station.
  • a telegraph exchange'system comprising a central interconnecting station, a plurality of local subscriber stations, lines connecting said subscribers stations to said central station, interconnecting means at said central station for interconnecting said local stations, a distant subscribers station, telegraph equipment similar to the telegraph equipment at said local stations located at said distant station, an intermediate repeater station, a line connecting said distant subscribers station to said intermediate station, a full duplex telegraph channel connecting said .intermediate station and said central station, terminal equipment located at said central station connected to said full duplex channel for cooperating with said switching equipment in the same manner that said local station lines cooperate therewith, and means at said repeater station for transmitting ringing current over said intermediate line section in response to break signals which exceeds a predetermined short interval of time.
  • a method of distinguishing between break signals and disconnect and recall signals transmitted over an intermediate section of a long subscribers line which comprises the step of first transmitting said supervisory signaling conditions oVer said line and then applying ringing current to said intermediate section in response to one of said signals which exceeds a predetermined minimum interval of time.
  • a telegraph system comprising a plurality of local subscribers stations, a central interconnecting station, telegraph lines connecting said subscribers station, means at each of said subscribers stations and said central station for transmitting and responding to at least three signaling conditions in addition to two signaling conditions employed for transmitting code combinations of telegraph signaling impulses, an outlying subscribers station and an intermediate repeater station, and apparatus located at said outlying subscribers station and said intermediate station for transmitting and responding to the same signaling conditions as transmitted between said local subscribers stations and said central station, a full duplex telegraph channel arranged to transmit only two dilerent signaling conditions connecting said intermediate station and said central station, and means for transmitting and receiving to all of said signaling conditions to and from said full duplex channel which comprises transmitting impulses of uniform length and of alternate character over said full duplex channel in response to one of said signaling conditions which exceeds a predetermined interval of time.
  • a first communication line circuit capable of transmitting three signaling conditions and a second communication line capable of transmitting only two signaling conditions, means for transmitting three signaling conditions in addition to code combinations of impulses of two of said signaling conditions over said first line circuit, and means for transmitting all -of said signal conditions over said second line circuit which comprises transmitting a series of impulses of uniform length and of alternate character over said second line in response to one of said signaling conditions transmitted over said first line circuit.
  • a multisection subscribers line circuit comprising a subscribers station, an intermediate repeater station, a line connecting said subscribers station and said intermediate station, a central telegraph exchange station, a full duplex telegraph channel connecting said intermediate station and said central exchange station, means for transmitting signaling impulses of substantially unit length and of alternate character over said full duplex channel from said intermediate station to said central station in response to break signals exceeding a predetermined minimum period transmitted from said subscribers station, and means for transmitting a series of impulses of subtantially unit length and alternate character over said full duplex channel from said central station to said intermediate station to call said subscribers station, and means at said intermediate station for responding to said series of impulses and for applying ringing current to a line extending to said subscribers station in response thereto.
US180075A 1937-12-16 1937-12-16 Communication system Expired - Lifetime US2173551A (en)

Priority Applications (4)

Application Number Priority Date Filing Date Title
BE131631D BE131631A (de) 1937-12-16
FR847619D FR847619A (de) 1937-12-16
US180075A US2173551A (en) 1937-12-16 1937-12-16 Communication system
DEI63175D DE742933C (de) 1937-12-16 1938-12-15 Vermittlungssystem fuer Telegraphie

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
US180075A US2173551A (en) 1937-12-16 1937-12-16 Communication system

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US2173551A true US2173551A (en) 1939-09-19

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Application Number Title Priority Date Filing Date
US180075A Expired - Lifetime US2173551A (en) 1937-12-16 1937-12-16 Communication system

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US (1) US2173551A (de)
BE (1) BE131631A (de)
DE (1) DE742933C (de)
FR (1) FR847619A (de)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2495773A (en) * 1942-12-30 1950-01-31 Bell Telephone Labor Inc Alternating current telegraph system
US2605347A (en) * 1949-04-29 1952-07-29 Bell Telephone Labor Inc Telegraph concentration board spare communication circuit

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2495773A (en) * 1942-12-30 1950-01-31 Bell Telephone Labor Inc Alternating current telegraph system
US2605347A (en) * 1949-04-29 1952-07-29 Bell Telephone Labor Inc Telegraph concentration board spare communication circuit

Also Published As

Publication number Publication date
BE131631A (de)
FR847619A (de)
DE742933C (de) 1943-12-16

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