US2422700A - Reciprocal signaling trunk telephone system - Google Patents

Reciprocal signaling trunk telephone system Download PDF

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Publication number
US2422700A
US2422700A US599537A US59953745A US2422700A US 2422700 A US2422700 A US 2422700A US 599537 A US599537 A US 599537A US 59953745 A US59953745 A US 59953745A US 2422700 A US2422700 A US 2422700A
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Prior art keywords
relay
current
line
signal
signaling
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US599537A
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English (en)
Inventor
Norman A Newell
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AT&T Corp
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Bell Telephone Laboratories Inc
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Priority to NL78127D priority Critical patent/NL78127C/xx
Priority to BE479847D priority patent/BE479847A/xx
Priority to FR959395D priority patent/FR959395A/fr
Application filed by Bell Telephone Laboratories Inc filed Critical Bell Telephone Laboratories Inc
Priority to US599537A priority patent/US2422700A/en
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Publication of US2422700A publication Critical patent/US2422700A/en
Priority to CH281613D priority patent/CH281613A/de
Priority to GB5098/48A priority patent/GB640108A/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
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04Q—SELECTING
    • H04Q1/00—Details of selecting apparatus or arrangements
    • H04Q1/18—Electrical details
    • H04Q1/30—Signalling arrangements; Manipulation of signalling currents
    • H04Q1/44—Signalling arrangements; Manipulation of signalling currents using alternate current
    • H04Q1/444—Signalling arrangements; Manipulation of signalling currents using alternate current with voice-band signalling frequencies
    • H04Q1/446—Signalling arrangements; Manipulation of signalling currents using alternate current with voice-band signalling frequencies using one signalling frequency
    • H04Q1/4465—Signalling arrangements; Manipulation of signalling currents using alternate current with voice-band signalling frequencies using one signalling frequency the same frequency being used for all signalling information, e.g. A.C. nr.9 system

Definitions

  • Objects of the invention are the provision of 5 more reliable signal transmitting and receiving means in systems employing voice frequency signaling, the provision of such signaling means for the transmission of signals over four-wire lines,
  • This invention is a signaling system in which the termination of current of a particular frequency normally transmitted over a line constitutes a first signal, in which an impulse of ticular frequency are transmitted over a line, in
  • a feature of the invention is a signaling system in which the termination of current of a particular frequency normally transmitted over a line constitutes a first signal,-in which the transmission, of an impulse of current of said particular frequency and of a particular limited duration constitutes a second signal, in which the continued transmission of current of said particular frequency constitute a third signal, and in which the current of said particular frequency is reduced in amplitude when continued beyond a predetermined interval of time.
  • Another feature of the invention is a signaling system in which the termination of current of a particular frequency normally transmitted over a line constitutes a first signal, in which means normally efiective to prevent response to current of other frequencies or to current of the signaling frequency in combination with current of other frequencies is disabled by the response to said first signal, in which the transmission of an impulse of current of said particular frequency constitutes a second signal, and in which the continued transmission of current of said particular frequency constitutes a third signal.
  • a voice freparticular frequency constitutes a seizure or supervisory signal, in which short impulses of current of this particular frequency constitute selective or supervisory signals, and in which the continued transmission of current of said particular frequency constitutes a disconnect or supervisory 5 signal.
  • Another feature of the invention is a telephone and voice frequency signaling system in which the transmission of voice and signaling current is effected over four conductor lines,one pair of conductors being used for transmission in one direction and the other pair of conductors for transmission in the other direction, current of a particular frequency being normally transmitted over each pair as long as the line is idle, the termination of the normally transmitted current constituting a seizure or supervisory signal, the transmission of impulses of current of said particular frequency constituting selective or supervisory signals, and the continued transmission of current of said particular frequency constituting a disconnect or supervisory signal.
  • Another feature of the invention is a telephone and voice frequency signaling system in which voice current and signaling current of a parwhich the talking circuit over the line is normally closed and signaling current of said particular frequency is transmitted over the line while idle, and in which the talking circuit is opened for a predetermined interval of time each time the transmission over said line of current of said particular frequency is initiated or terminated.
  • Another feature of the invention is a voice frequency signaling system in which voice current and signaling current of a particular frequency are transmitted over a line, in which the talking circuit over the line is normally closed and signalin current of saidparticular frequency is transmitted over the line while idle, in which termination of the transmission of current of said particular frequency constitutes a seizure or supervisory signal, in which the transmission of an impulse of current of said particular frequency constitutes a selective or supervisory signal, and in which the continued transmission of current of said particular frequency constitutes a disconnect or supervisory signal, the amplitude of the signaling current transmitted over the line while idle being smaller than the amplitude of the signaling current transmitted as selective, supervisory or disconnect signals.
  • Another feature of the invention is the control of an amplifier by two networks energized by the output of the amplifier, the voltage across the two networks being rectified and applied to the control grid to effect operation of a signal relay responsive to voice frequency signaling current, to prevent operation of the relay responsive to voice current, and to effect release of the relay responsive to termination of the signaling current.
  • Figs. 1 and 2 represent a first toll office com prising an operators position OPI, an outgoing trunk circuit OTI, a two-way trunk circuit TWT l, a selector TSI, an incoming trunk circuit ITI, a signal transmitting circuit STI, and a signal receiving circuit SRI;
  • Figs. 3 and 4 represent another toll oiiice comprising an operators position P2, an outgoing trunk circuit 0T2, a two-way trunk circuit TWTZ, a selector T52, an incoming trunk circuit 1T2, a signal transmitting circuit ST2 and a signal receiving circuit SR2; and
  • Fig. 5 shows the relative positions of Figs. 1 to 4 inclusive, to form an operative arrangement.
  • the system represented in the drawings includes a plurality of toll ofiices each of which comprises a toll board with operators positions and "cords for answering calls incoming from manual or dial local offices, from toll subscribers lines; from community dial oftices, or from other toll offices; and for connecting-calling intertoll trunks with switching trunks leading to called manual or dial local offices, to called toll subscribers lines, to trunks to community dial offices, and to intertoll trunks to other toll oflices.
  • Outgoing jacks are connected to switching trunks, toll subscribers lines, trunks to community dial offices and intertoll trunks.
  • Answering jacks are connected to recording trunks, toll subscribers lines, trunks from community dial offices and intertoll trunks.
  • Intertoll firstselectors, and intertoll second selectors are provided for use on calls incoming over intertoll trunks to establish connections with other-toll, local or community dial ofiices.
  • the operators"positions are provided with dials for use in controlling the operation of intertoll selectors in other toll offices and for controlling the operation of selector and connector switches in local or community dial offices.
  • and GT2 incoming trunk circuits ITI and 1T2, two-way trunk circuits TWTI and TWIZ; and the toll route selector circuits TS I- and TS2 are all similar to corresponding circuits of the aforementioned King-Miller and Walsh" patents.
  • the two toll ofiices shown in the drawings are interconnected by four-wire lines, one being shown in the drawings as consisting of two twooffice and to receive and transmit voice current incoming over toll line TLI to these trunk circuits.
  • Balancing networks BNI and BN2 are connected to hybrid coils HCI and HCZ in usual and wellknown manner.
  • the signal transmitter STI comprises a generator 230 of alternating current of a particular voice frequency, for instance 3,200 cycles per secend, a relay 200 responsive to seizure, selective, supervisory and disconnect signals which are to be transmitted over the toll line TLI, an auxiliaryrelay 220 and a cut-off relay 2H] for disconnecting the toll line TLI from the hybrid coil HCI during the transmission of signals outgoing over toll line TLI.
  • the generator 230 is normally connected through resistors 21 and 233, resistors 232 and 23, back contacts of relay 200, conductors 2M and 242- and repeating coil 24!] to the con ductors of toll line TLI, the continued presence of a tone of 3,200 cycles on the toll line indicating that the line is idle.
  • a one-way amplifier Al connecting toll line TLZ to the hybrid coil HCI, prevents the transmission of signaling current from signal transmitter ST! over toll line TL2.
  • the signal transmitter ST2 associated with toll line Th2 in the second toll oflice is similar to the signal transmitter STl, corresponding elements having reference characters with the same tens and units digits.
  • signaling current from generator 330 is normally-transmitted over toll line TLZ; and. the amplifier A2 is efiective to prevent the transmission of signaling current from generator 330 over toll line TLI.
  • the signal receiver SRI- comprises an input transformer 253 which is connected by conductors 25H. and 2 52 to the repeating coil 2511 of toll line TLZ in parallel with the input side of amplifier A! through which voice currents are transmitted to the hybrid coil HCI.
  • the signal receiver SRl' further comprises a thermionic amplifier 260, an output transformer 2M, a detector 2'10, an output transformer 21 l two tuned circuits connected in series across. the output of transformer 2-H, a signalrelay 290 connected in the plate circuit of tube 210 and an auxiliary relay 285.
  • the amplifier 260 is arranged for negative feedbackfrom the plate circuit through condenser 254 and varistor 25 5 so as to limit the level of signal applied through transformer 26-!
  • (-)ne of the aforementioned tuned circuits consists of an inductance coil 214 connected parallel with condenser 2-13 and the other tuned circuit consists of'the'cond'enser 217 connected in series with the inductance coil 21 8.
  • Both of'these tuned circuits are tuned to the signali-ngfrequencyso that the parallel tuned circuit has a very high impedance at the-signaling frewire lines TLI and TL2 associated with trunk I circuits OTI and TWTI in the first toll 'ofiice and with trunk circuits 0T2 and TWTZ in the second toll oifice.
  • the line TLI is used to, transmit voice and voice frequency signaling current from the first toll ofiice t the second and the line TL2 is used to transmit voice and voice frequency signaling current from the second toll office 'to the first,
  • a hybrid coil HCI individual to trunk circuits OTI and TWT! is arranged to transmit voice current from these trunk circuits overt'oll line TLI to the second tollofiice and to receive and transmit voice current incoming over toll line TL2 to these trunk circuits.
  • the detector 2:10 is biased substantially to cut-oifand the alternating component in itsoutput circuit is applied through transformer 211 across. the two tuned circuits.
  • the voltage thus developed across the; parallel tuned circuit. is, rectified. by rectifier 212 and applied through, resistor 216 to the grid of tube 2. 20 Produce a positive reaction.
  • Relay 290 requires about .010 second for operation' thereby affording additional protection against false operation in response to a signaling frequency component in speech.
  • the signal receiver SR2 is similar to the signal receiver SRI in that it responds to the same signals but constitutes an alternative arrangement. Both of the signal receivers connected to lines TLI and TL2 may be arranged the same as receiver SRI in Fig. 2 or both may be arranged the same as receiver SR2 in Fig. 3. Signal receiver SR2 comprises an input transformer 353 which is connected by conductors 35I and 352 to the repeating coil 350 of toll line TLI in parallel with the input side of amplifier A2 through which voice currents are transmitted to the hybrid coil H02.
  • the signal receiver SR2 further comprises a thermionic volume limiting amplifier 355, an out put transformer 359, a thermionic detector 310, a signal relay 314, an auxiliary relay 315, a voltage dividing network and two tuned networks normally connected in series across the output of transformer 359 to control the bias of the grid of detector 310.
  • Resistor 354 included in the grid circuit of amplifier 355 limits the level of signal transmitted through transformer 359; and the varistor 360 connected across one side of this transformer also limits the voltage applied to the voltage dividing network and tuned networks aforementioned.
  • the voltage dividing network comprises rectifier 363, resistor 364, condensers 365 and 366, resistor 361 and rectifier 368.
  • One of the tuned networks consists of condenser 38I and induction coil 382 in parallel and the other consists of condenser 383 and coil 384 connected in series.
  • the voltages developed across the tuned circuits are applied through the voltage dividing network and conductor 369 to the grid of detector 310, which is normally biased by the voltage drop in resistor 312.
  • the rectifiers 363 and 368 are poled so that the grid of tube 310 becomes more positive when signaling current is being received and becomes more negative when current of a frequency other than the signaling frequency is being received over line TLI, the impedance of the parallel tuned circuit being a maximum at the signaling frequency and the impedance of the series tuned circuit being a maximum at other frequencies.
  • Condenser 31I delays a change in the grid bias of tube 310 thereby giving further protection against response to voice current having a signaling frequency component.
  • Resistor 385 connected in parallel with the series tuned circuit limits the voltage developed thereacross,
  • Condenser 316 delays the operation of relay 315 andresistor 311 discharges condenser 316 when relay 315 operates.
  • Relay'314 controls the connection of ground to signaling conductor 410; and the auxiliary relay 315, when operated, shortcircuits the series tuned circuit so that voice or interference current is ineffective to cause the release of relay 314 on calls routed to an intercept operator.
  • the plug API of the cord CDI at the position OPI in the first toll office is inserted in an answering jack to answer a call incoming over a recording trunk or an intertoll trunk or a, trunk from a community dial olfice, that the operator has determined the destination of the call and that the plug CPI of this cord is inserted in a jack associated with an outgoing trunk circuit over which the call may be extended, and that the trunk 0TI is associated with the jack J I into which the plug CPI is inserted.
  • the insertion of plug CPI in jack J I closes a circuit for operating relay I04, thereby causing the operation of relay IIO as described in the aforementioned King et al.
  • relay IIO disconnects the signaling conductor I10 from conductor I69 thereby to prevent the operation of relay I003 of two-way trunk circuit TWTI when ground is connected to signaling conductor I10, connects answering supervisory relay I05 of the trunk circuit OTI to conductor I10 and connects ground to conductor I68 to operate relay I004 of twoway trunk circuit TWTI.
  • Relay I004 locks to conductor I68 independent of relay I003 and further opens the connection between the winding of relay I003 and the signaling conductor I10.
  • relay I 40 connects signaling battery to conductor I64 to operate the signal relay 200 of the signal transmitter STI.
  • the operation of relay 200 of signal transmitter STI terminates the transmission of signaling current of 3200 cycles per second fromthe generator 230 over toll line TLI thereby causing the release of the normally operated relay 314 of signal receiver SR2.
  • Relay 200 also closes a circuit through its inner lower front contact for operating cut-off relay 2").
  • Relay 2I0 disconnects the repeating coil 240 of toll line TLI from conductors 20I and 202 leading to the hybrid coil HC I, connects the repeater termination comprising resistor 2I3 in series with condenser 2I4 across the repeating coil 249, connects ground to conductor I68 to hold relay I004 operated independent of relay H0, and closes a circuit for operating relay 220.
  • Relay 220 locks under the sole control of relay 200, opens the operating circuit of relay 2I0 and opens a shunt circuit through resistor 235 across the generator 230 thereby to increase the voltage applied to conductors MI and 242 when relay 200 releases as hereinafter described. The release of relay 2I0 disconnects the repeater termination and closes the talking connection between coil 240 and hybrid coil HCI.
  • the termination of the signaling current normally transmitted over toll line I'LI effects the release of relay 314 of signal receiver SRI, therevby connecting ground to signaling conductor 410 to cause the operation of relay 503 of trunk circuit TWTZ.
  • the circuit for operating relay 503 is traced from ground at the back contact of relay 314, through conductor 410, lower back contact of relay 4I0 of trunk circuit 0T2, conductor 469, back contact of relay 504 of trunk circuit TWT2,
  • Relay 503 connects ground to conductor 460 to guard the outgoing trunk circuit T2 from being seized on an outgoing call.
  • Relay 503 closes a circuit for operating relay 505, this circuit being traced from ground at the back contact of relay 314, through conductor 410, lower back contact of relay 4! 0 of outgoing trunk circuit 0T2, conductor 469, back contact of relay 504 of two-way trunk circuit TWTZ, winding of relay 505, uppermost front contact of relay 503, conductor 461, thence in simplex through resistors 42! and 422, backcontacts of relay 420 of outgoing trunk circuit 0T2, windings of retard coil 465, conductors 45!
  • Relay 501 also closes a circuit through resistor 506 for holding relay 503 operated, opens the operating circuit of relay 503 and connects ground to conductor 553 of selector TSZ to hold the selector T82 and any additional selector through which the connection is extended in the second toll office until the connection is released at the first toll oflice'.
  • relay 140 Whenthe calling operator at the first toll office operates the dialing key (not shown) the upper winding of relay 140 is controlled by the impulse contacts of the dial at position OPI.
  • generator 230 When relay 200 releases responsive to the first impulse of a digit, generator 230 is reconnected through resistors 23L, 232, 233 and 234, back contacts of relay 2-00 and conductors 24! and 242 tothe repeating coil 2'40, whereby an impulse of 3200-cycle current is transmitted over toll line TL! during the interval that relay 200 is released.
  • This impulse of current is amplified by tube 355 of signal receiver SR2 and effects the operation of relay'314.
  • generator 230 is disconnected from conductors 2-4! and 242 thereby terminating the impulse of current of the signaling frequency to effectthe release of relay 314.
  • Each release and reoperation of relay I40 in response to the dialing of the first digit of the called number opens and closes the circuit through conductor I64 to cause a corresponding release and reoperation of relay 200, whereby a series of impulses of current of signaling frequency is transmitted over toll line TLI-, each impulse causing the momentary operation of relay 314.
  • relay 314 momentarily disconnects ground from conductor 410 as many times as there are impulses in the series received over toll line TLI, and relay 505 of trunk circuit TWT2 and line relay 551 of'selector TS2 are thereby alternately released and reoperated a like number of times. Since relay 501' is slow in releasing, the response of relay 505 to dial impulses is ineffective to cause the release of relay 501. Each release of relay 551 causes the operation of the vertical stepping magnet (not shown) of selector TSZ' whereby the brushes 51!, 512, 513 and 514 are tepped up to the level corresponding to the digit dialed.
  • the brushes are advanced step by step in the selected level until a set of terminals connected to an idle trunk or succeeding selector are encountered; whereupon relay 560 is operated to extend the connection to the selected switch or trunk, all in usual and well-known manner.
  • Each succeeding train of dial impulses created by operation of the calling operators dial is repeated by relay I40 to relay 200 and a corresponding train of impulses of voice frequency signaling current is transmitted over toll line TL! to operate relay 314; and the operation of relay 314 effects the transmission of corresponding trains of impulses, through brushes 51! and 512 and the selected terminals of selector T82, to operate suc ceeding switches through which the connection is extended or to operate digit registers.
  • the dial key (not shown) is restored to normal and relay R30 is operated in the manner described in the aforementioned King-Miller and Walsh patents to complete the talking connection between cord CD! and hybrid coil HC'I.
  • the call in question is one which is routed through selector T82 and a selected idle incoming trunk circuit to a toll operator position in the second toll onice and that the selected trunk circuit is the trunk circuit 112 terminating at jack J8.
  • the operation of relay 560 of selector TSZ closes a circuit for operating the line relay 6 05 of trunk circuit IT2.
  • This cir cuit is traced from groundat the .back contact of relay 314, through conductor 410, lower back contact of relay 4I0 of outgoing trunk circuit 0T2, conductor 460', back contact of relay 504, winding of relay 505, outer upper front contact of relay 503, conductor 461, thence in simplex through resistors 42!
  • vRelay 505 is operated by the current in this circuit, thereby to hold relay 501 and thus maintain the connection of ground to conductor 553. Relay 655 close a circuit for lighting lamp L8.
  • Relay 634 is operated in the manner described in the aforementioned P te t to J. G. Walsh and closes a circuit from ground through conductor 604, brush 514 of selector TS2, a, front contact of relay 560, and the winding of relay 5! of two-way trunk circuit I'WTZ. The operation of relay 5
  • relay 300 This circuit is traced from battery through conductor 466, front contact of relay 5, back contact of relay 5l0, conductor 455, back contact of relay 440, conductor 464 and the winding of relay 300.
  • the operation of relay 300 disconnects generator 3.30 from conductors 34! and 342 to terminate the transmission of signaling current over toll line TL2 and thereby cause the release of relay 290 of signal receiver SRI.
  • the operation of relay 300 also closes a circuit for operating cut-ofi relay 3l'0.
  • Relay 31-0 opens the talking connection between repeating coil 340 and hybrid coil H02, connects the repeater termination comprising resistor 3I3 and condenser 3I4 across coil 340, connects ground to conductor 468 to maintain a busy indication for trunk circuits T2 and TWT2 while a signal is being transmitted over line TL2, and closes a circuit for op erating relay 320.
  • the operation of relay 320 opens the operating circuit of relay 3 I 0'and opens the normally closed shunt circuit through resistor 335 across generator 330, thereby to increase the voltage applied across conductors 3M and 342 when relay 300 release to transmit a signal, for instance an on-hook or busy signal.
  • the release of relay 3I0 transfers coil 340 from the repeater termination to coil H02 and opens the operating circuit of relay 320; and rela 320 i then held operated under the sole control of relay 300.
  • relay 290 responsive to the termination of signaling current over toll line TL2 causes the release of relay 285 and connects ground to conductor I10, thereby operating supervisory relay I of trunk circuit 0T2.
  • Relay I05 disconnects ground from the low resistance winding of sleeve relay I04, thereby causing the calling supervisory lamp CS to be extinguished to indicate that the call has been answered in the called toll ofiice.
  • relay 634 releases and disconnects ground from conductor 604, causing the successive release of relay 5 of trunk circuit TWT2 and relay 300 of signal transmitter ST2.
  • relay 300 reconnects generator 330 to coil 340, thereby transmitting signaling current over line TL2 to cause the reoperation of relay 290 of signal receiver SRI.
  • the operation of relay 290 disconnects ground from conductor I'I0, releasing relay I05 and thereby causing the lighting of lamp CS to give th calling operator anon-hook signal.
  • the aforementioned release of relay 300 also causes the operation of relay 3I0 and the release of relay 320.
  • the release of relay 320 causes the release of relay 3 I 0 and again closes the shunt circuit through resistor 335 across generator 330, whereby the voltage applied across conductors MI and 342 is reduced and the signaling current transmitted over line TL2 is reduced to the normal, idle condition.
  • I of two-way trunk circuit TWT2 is alternately operated and released under the control of an interrupter (not shown) thereby causing the alternate operation and release of relay 300 of signal transmitter STZ.
  • Relay 300 alternately disconnects and reconnects generator 330 to coil 340, whereby signaling current is intermittently transmitted over line TL2 to cause the alternate release and reoperation of relay 290 of signal receiver SRI.
  • the alternate release and reoperation of relay 300 causes the alternate operation and release of supervisory relay I05 of trunk circuit OTI whereby the supervisory lamp CS of cord CDI is intermittently extinguished and lighted, thus giving the calling operator a busy signal.
  • relay I 04 releases; but if relay I05 is operated at this time, relays H0 and I 40 are held operated. With relay I 05 released, or as soon after the release of relay I04 as relay I05 releases, relays H0 and I40 are also released.
  • the release of relay I40 causes the release of relay 200 whereby generator 230 is reconnected across conductors 24I and 242 thereby to effect the transmission of signaling current over line TLI to effect the reoperation of relay 314 of signal receiver SR2.
  • the release of rela 200 also causes the operation of relay 2 I 0 and the release of relay 220.
  • the operation of relay 220 causes the release of relay 2I0 and closes the shunt circuit through resistor 235 across generator 230 whereby the voltage applied to conductors MI and 242 is reduced to the normal level.
  • the operation of relay 314 disconnects ground from conductor 410 causing the release of relay 505 of trunk circuit TWT2 and line relay 605 of trunk circuit 1T2.
  • relay 505 causes the release of relays 501 and 503 of trunk circuit TWT2 and the release of relay 560 of selector TS2 whereby selector TS2 is restored to' normal in usual and. well-known manner.
  • the release of relay 503 also disconnects ground from conducto 46B, thereby terminating the busy marking of trunk circuits 0T2 and TWT2.
  • a line a first means operated responsive to current of a particular frequency normally transmitted over said line, means normally eifective to prevent the operation of said first means responsive to current of frequencies other than said particular frequencyor to current of said particular frequency and other frequencies, means operated responsive to th release of said first means upon the termination of current of said particular frequency and efiective to disable said preventing means, means responsive to the reoperation of said first means by an impulse of current of'said particular frequency, and means responsive to the operation of said first means by current of said particular frequency for more than a predetermined interval of time.
  • a line,signa1 transmitting means at one end of said line comprising a generator of alternating voltage of a particular frequency for use in transmitting signals over said line, a trunk circuit comprising talking conductors over which voice current is transmitted, means normally connecting said line to. said talking, conductors and to said generator,
  • a signaling system comprising a line for transmitting voice current and signaling current of a particular frequency in the voice frequency range, signal receiving means connected to said line, said signal receiving means comprising a relay, means for operating said relay responsive to current of said particular frequency, means re sponsive to current of frequencies other than said particular frequency for preventing the operation of said relay when voice or interference current which has a component of said particular frequency is transmitted over said line and means rendered efie'ctive by the operation of said relay for disabling said preventing means, and signal means controlled by said relay.
  • a line a trunk circuit comprising talking conductors normally connected to one end of'saidline, a generator of alternating voltages of a particular frequency for use in transmitting signals over said line, means normally connecting said. generator to said one end of said line, signal receiving means connected to the other end of said'line comprising a signal relay, means responsive to current of said particular frequency for operating said relay, means responsive to current of frequencies other than said particular frequency for preventing the operation of said relay in response to voice or interfering current which includes a component of said. particular frequency, means rendered effective by the operation of said relay to disable said preventing means, and means responsive to seizure of said trunk circuit for momentarily disconnecting said talking conductors from said line and for disconnecting said generator from said line to cause the release of said signal relay.
  • a signaling system a line, a trunk circuit comprising talking conductors normally connected to one end of said line, a generator of alternating voltage of a particular frequency for use in transmitting signals over said line, means comprising contacts of a signal transmittingrelay connectingsaid generator to said one end of said line, signal receiving means connected to the other end of said line comprising a signal receiving relay, means responsive to current of said particular frequency for operating said signal receiving relay, means responsive to current of frequencies other than said particular frequency'for preventing the operation of said relay in response a to voice or interfering current which includes a component of said particular frequency, means rendered efiective by the operation of said relay to disable said preventing means, means responsive to seizure of said trunk circuit for operating said signal transmitting relay to disconnect-said generator from said line thereby to effect the release of said signal receiving relay, means for momentarily releasing said signal transmitting relay to effect the operation and release of said signal receiving relay, means for releasing said signal transmitting relay to effect only the operation of said signal
  • a line a trunk circuit comprising talking conductors normally connected to one end of said line, a generator of alternating voltage of a particular frequency for use in transmitting signals over said line, means comprising contacts of asignal transmitting relay connectingssaid generator to said one end of said line, signal receiving means connected to the other end of said line comprising a signal receiving relay, means responsive to current of said particular frequency for operating said signal receiving re lay, means responsive to current of frequencies other than said particular frequency for preventing the operation of said relay in response to voice or interfering current which includes a component of said particular frequency, means rendered effective by the operation of said relay to disable said preventing means, means for operating said signal transmitting relay to disconnect said generator from said line thereby to effect the release of said signal receiving relay, means for momentarily releasing said signal transmitting relay to eifect the operation and release of said signal receiving relay, means for releasing said signal transmitting relay to efiect only the operation of said signal receiving relay, means rendered effective by each operation and each release of
  • a line a trunk circuit comprising talking conductors normally connected to one end of said line, a generator of alternating Voltage of a particular frequency for use in transmitting signals over said line, means comprising contacts of a signal transmitting relay connecting said generator to said one end of said line, signal receiving means connected to the other end of said line comprising a signal receiving relay, means responsive to current of said particular frequency for operating said signal receiving relay, means responsive to current of frequencies other than said particular frequency for preventing the operation of said relay in response to voice or interfering current which includes a component of said particular frequency, means rendered effective by the operation of'said relay to disable said preventing means, switching means, means responsive to seizure of said trunk circuit for operating said signal transmitting re lay to disconnect said generatorfroni said line thereby to effect the release of said signal receiving relay to prepare said switching means for op eratio-n, means for momentarily releasing said signal transmit-ting relay to effect the operation and release of said signal receiving relay to selectively operate said switchingmeans
  • a line a trunk circuit comprising talking conductors normally connected to one end of said line, a generator of a1- ternating voltage of a particular frequency for use in transmitting signals over said line, means comprising contacts of a signal transmitting relay connecting said generator to said one end of said line, means for operating said signal transmitting relay to terminate the transmission of current of said particular frequency over saidline, means for momentarily releasing said signal transmit ting relay to effect the transmission of impulses of current of said particular frequency over said line, means for releasing said signal transmitting relay thereby to continuously transmit current of said particular frequency over said line, and
  • a four-conductor line one pair of the conductors for transmitting voice and signaling current in one direction and the other pair of conductors for transmitting voice and signaling current in the other direction
  • a trunk circuit at one end of said line havmg a pair of talking conductors, for transmitting voice current in both directions
  • means comprising a hybrid coil connecting said talking conductors to both pairs of conductors of said line
  • signal transmitting means associated with the pair of conductors of said line used to transmit voice current from the talking conductors of said trunk circuit and signal receiving means associated with the pair of conductors of said line used to transmit voice current to the talking conductors of said trunk circuit
  • said signal transmitting means comprising a generator of alternating voltage of a particular frequency used for signaling, means normally connecting the generator to the pair of conductors used to transmit voice currents from the talking conductors of said trunk circuit and a signal transmitting relay controlling the connection between said generator and pair of conductors, the operation of said signal transmitting relay being effective
  • a four-conductor line one pair of the conductors for transmitting voice and signaling current in one direction and the other pair of conductors for transmitting voice and signaling current in the other direction, current of the same particular frequency being used for transmitting signals in both directions
  • trunk circuits one at each end of said line, each of said trunk circuits having a pair of talking conductors for transmitting voice current in both directions
  • means at each end of said line comprising a hybrid coil connecting the talking conductors of the associated trunk circuit to both pairs of conductors of said line, and signal transmitting means and signal receiving means at each end of said line, the signal transmitting means at each end being associated with the pair of conductors of said line which transmits voice and signaling current to the other end and the signal receiving means at each end being associated with the pair of conductors of said line which receives Voice and signaling current from the other end,'each of said signal transmitting means comprising a generator of alternating voltage of a particular frequency for use in transmittin signals over
  • said signal receiving means comprisin a signal receiving relay, means responsive to current of said particular frequency for effecting the operation of said signal receiving relay, means responsive to current of other frequencies for preventing the operation of said signal receiving relay in response to voice or interfering current which has a component of said particular frequency and means rendered effective by the operation of said signal receiving relay to disable said preventing means.
  • a signalin system comprising a line, a generator of alternating voltage of a particular frequency for use in transmitting signals over said line, a signal relay for controlling the transmission of signals over said line, means including contacts of said relay normally connecting said generator to said line thereby to transmit current of said articular frequency over said I line while idle, means for limiting the amplitude transmission of current of said particular frequency as a disconnect signal, and means for disabling said amplitude limiting means during the transmission of selective, supervisory and disconnect signals.
  • a signaling system comprising a line, a generator of alternating voltage of a particular frequency for use in transmitting signals over said line, a signal relay controlling the transmission of signals over said line, means including contacts of said relay normally connecting said generator to said line thereby to transmit current of said particular frequency over said line while idle, the operation of said signal relay being effective to terminate the transmission of current of said particular frequency as a seizure or supervisory signal, each momentary release of said relay being effective to transmit an impulse of current of said particular frequency as a selective or supervisory signal and the continued release of said relay being effective to initiate the continued transmission of current of said particular frequency as a disconnect sisnal, and means efiective to increase the amplitude of the current of said particular frequency nect signals as compared with the current normally transmitted, over the trunk when idle.
  • a trunk line, agenerator of alternating voltage of a particular signaling frequency used in transmitting signals over said line means normally connecting said generator to said line thereby to transmit current of said signaling frequency over said line 16 while idle, means comprising a signal relay controlling the connection of said generator to said line, the operation of said relay being eifective to terminate the transmission of signaling current over said line as a seizure or supervisory signal, each momentary release of said relay eil'ecting the transmission of an impulse of signaling current as a selective or supervisory signal, and the continued release of said relay effecting the transmission of signaling current as a disconnect signal, means for limiting the amplitude of the signaling current transmitted over the line while idle, means for increasing the amplitude of the signaling current transmitted as selective, supervisory and disconnect signals and means effective a predetermined interval of time after the release of said relay to reduce the amplitude of the signaling current transmitted as a disconnect signal over said line to that of the signaling current transmitted over said

Landscapes

  • Engineering & Computer Science (AREA)
  • Computer Networks & Wireless Communication (AREA)
  • Signal Processing (AREA)
  • Devices For Supply Of Signal Current (AREA)
  • Sub-Exchange Stations And Push- Button Telephones (AREA)
  • Interface Circuits In Exchanges (AREA)
US599537A 1945-06-15 1945-06-15 Reciprocal signaling trunk telephone system Expired - Lifetime US2422700A (en)

Priority Applications (6)

Application Number Priority Date Filing Date Title
NL78127D NL78127C (xx) 1945-06-15
BE479847D BE479847A (xx) 1945-06-15
FR959395D FR959395A (xx) 1945-06-15
US599537A US2422700A (en) 1945-06-15 1945-06-15 Reciprocal signaling trunk telephone system
CH281613D CH281613A (de) 1945-06-15 1947-12-13 Signalanlage.
GB5098/48A GB640108A (en) 1945-06-15 1948-02-20 Improvements in or relating to signalling systems

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
US599537A US2422700A (en) 1945-06-15 1945-06-15 Reciprocal signaling trunk telephone system

Publications (1)

Publication Number Publication Date
US2422700A true US2422700A (en) 1947-06-24

Family

ID=24400029

Family Applications (1)

Application Number Title Priority Date Filing Date
US599537A Expired - Lifetime US2422700A (en) 1945-06-15 1945-06-15 Reciprocal signaling trunk telephone system

Country Status (6)

Country Link
US (1) US2422700A (xx)
BE (1) BE479847A (xx)
CH (1) CH281613A (xx)
FR (1) FR959395A (xx)
GB (1) GB640108A (xx)
NL (1) NL78127C (xx)

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1449644A (en) * 1919-12-30 1923-03-27 Western Electric Co Telephone system
US1512907A (en) * 1924-10-28 Assig-nor to western electric com
US2005836A (en) * 1933-08-29 1935-06-25 American Telephone & Telegraph Signaling system
US2387525A (en) * 1943-07-21 1945-10-23 Automatic Telephone & Elect Telephone or like system

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1512907A (en) * 1924-10-28 Assig-nor to western electric com
US1449644A (en) * 1919-12-30 1923-03-27 Western Electric Co Telephone system
US2005836A (en) * 1933-08-29 1935-06-25 American Telephone & Telegraph Signaling system
US2387525A (en) * 1943-07-21 1945-10-23 Automatic Telephone & Elect Telephone or like system

Also Published As

Publication number Publication date
GB640108A (en) 1950-07-12
CH281613A (de) 1952-03-15
FR959395A (xx) 1950-03-29
BE479847A (xx)
NL78127C (xx)

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