US2407150A - Telephone or like signaling system - Google Patents

Telephone or like signaling system Download PDF

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Publication number
US2407150A
US2407150A US502884A US50288443A US2407150A US 2407150 A US2407150 A US 2407150A US 502884 A US502884 A US 502884A US 50288443 A US50288443 A US 50288443A US 2407150 A US2407150 A US 2407150A
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relay
contacts
exchange
incoming
signal
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Gillings Charles
Beale Charles Edmund
Terroni Teseo Bruno Dante
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Automatic Electric Laboratories Inc
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Automatic Electric Laboratories Inc
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    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04Q—SELECTING
    • H04Q3/00—Selecting arrangements
    • H04Q3/0016—Arrangements providing connection between exchanges

Definitions

  • the numerical direct current impulses received at the sending end of the trunk are converted into voice frequency coded signals which are transmitted over the trunk and re-converted at the terminal end into' numerical direct current impulses.
  • each voice frequency coded signal is preceded by a prefix signal which is the same for all codes and serves the purposeof testing the incoming equipment and also switching any echo suppressor in the route into the correct direction of transmission preparatory to the sending of the coded signal which is characteristic of the D. C. train of impulses to be transmitted.
  • the apparatus measures such signals as regards their frequency, their duration and, their spacing.
  • the sequence is such that it is connected in circuit withthe trunk line leading to'a following exchange, said blocking device by introducing considerable attenuation into the speaking circuit preventing the code signal from actuatingflapparatus at said .following exchange.
  • Figs. 1-4 show the circuit arrangements of a sleeve-controlled outgoing relay set
  • Figs. 5 and 6 show the circuit arrangements of an incoming relay set
  • Figs. '7 and 8 form a trunking diagram of various combinations of trunk routes to Which the invention maybe usefully applied
  • Fig. 9 show an alternative circuit arrangement including certain modifications which are necessary if the incoming relay set is required to respond to 'busy flash signals.
  • Each train of impulses received at the outgoing relay set is re-transmitted over the trunk in coded form made up of a combination of four voicefrequenc'ies, hereinafter referred to as W, X, Y and Z.
  • Each coded digit transmitted is preceded by a preparatory signal comprising all four frequencies, W, X, Y and Z which are effective "in the incoming relay set 170 to prepare the voice frequency receiver thereat for operation.
  • the prepare pulse also takes control of any echo suppressors in the route to turn them .into the correct direction for transmitting.
  • the 'W','X Y, Zfrequencies used are of 900, 750, 600 and 500 cycles respectively.
  • the coded digit comprising not more than three of the frequencies W to Z is decoded at the incoming relay set and converted into a marking on the bank of a uniselector which counts the sending out of a corresponding train of loop impulses to set the automatic switches in exchange C.
  • the second prepare and code signals are transmitted and are dealt with similarly.
  • the calling operator When all digits have been dealt with and the switching equipment at exchange C has been set to connect with the required subscriber, the calling operator will receive ringing tone, busy tone, or iNU tone to denote the state of the called line.
  • repeated Y pulses of .140 m. s. duration spaced 36.0 m. s. apart are sent back from th incoming relay set in exchange C to bring about the extinguishing of thesupervisory lamp inthe operators cord circuit at exchange B. Vhen this is done, an acknowledgment signal is transmitted back from the outgoing relay set comprising a single Q40 m. s. pulse of X frequency which serves to terminate the sending of the repeated Y pulses from the incoming relay set. Conversation now takes place and when the called party clears, repeated Y pulses similar to those forming the answer signal are transmitted from the incoming relay set back to the outgoing relay set where they bring about the lighting of the operators supervisory lamp.
  • the outgoing relay set sends forward to the incoming relay set a clear signal comprising a two-seconds X pulse followed by a 300 m. s. Y pulse which causes the incoming relay set to clear down and release the train of automatic switches at exchange C.
  • the clear signal In case the operator has to clear in face of ringing, busy or NU tone, the clear signal under these circumstances is lengthened to a six-seconds X 'pulse followed by a 300 m. 5. Y pulse. The object of the long X pulse is to ensure that the clear signal will get through in face of NU tone which is interrupted at the source for one second after the tone has :been transmitted for 'five seconds.
  • the proposed voice frequency nal code is as follows:
  • the outgoing relay set may be taken into use from any one of three sources, namely, manual board, automatic local subscriber, or incoming relay set from a distant exchange.
  • the operations are substantially similar to those already described for seizure from the manual board, except that resistance battery is connected to the sleeve of the manual board jack to busy the outgoing relay set against seizure from this source.
  • the VF signals from the outgoing relay set of exchange B can find a circuit 'by way of the condenser bridge in the auto-toauto relay set of exchange E to the incoming relay set of exchange H and this would bring about the generation of two trains of impulses for each train of impulses transmitted from the outgoing relay set in exchange B.
  • the incoming relay sets are provided with blocking devices in the line circuit which function almost instantaneously upon reception of the VF prepare signal precedin each code and thus prevent the code signals reaching the incoming'relay set at a dis- &
  • Relay MM at contacts mm I, Fig. 1 connects flicker earth to the upper low resistance winding of relay M to flash the lamp in the operator's circuit to provide an indication that she is connected to a dialling trunk, and at contacts mm2, Fig. 4, connects earth to the P conductor incoming from selector levels to guard the relay set against seizure over this path and also operates relay SR.
  • Relay SR- at contacts srl causes the switch TS to self-drive from its home position to position l where relay CO is operated over the oil-normal bank TSI and relay FXY is operated over bank.
  • Relay FXY in operating, at contacts fang l brings up relay CS and at contacts fats/2 causes the switch TS toselfdrive over its bank TS3 to the third position.
  • X frequency is applied to transformer VXF via contacts fc2, fxyl and cal and terminatin resistance VTR and then extends via contacts csl and 082 and contacts col and 002 to the trunk line to form a seizing signal to the incoming relay set at the distant exchange.
  • relay FXY releases to terminate the X pulse after a period of the order of 100 m. s. and at contacts h2g3 operates relay FC which looks and at contacts I03 causes the switch TS to step to position 4-from which it drives to position 6 over bank T and interrupted earth connected to conductor 13.
  • Relay RR at contacts rrl operates relay A which in turn'o-perates relay B, Fig. 3,1;0 prepare certain impulsing circuits and operate relay BR, Fig. 4.
  • relay A When the dial isturned off-normal, balanced battery on the lines is replaced by a loop through the dial impulse springs and relay A continues to hold.
  • relay A When the dial is released, relay A responds to the impulses which it repeats at contacts al, Fig. 3, via relay C to the driving magnet DSAM of the first digit storing switch DSA so that wipers of this switch are stepped to a corresponding position.
  • Relays B and C hold operated during the impulsing and the latter at contacts 02, Fig. 4, operates relay OS to prepare the VF signaling circuit at contacts csl and 082, Fig. 2.
  • Relay C also at contacts cl, Fig. '3, energises the driving magnet DDM of the digit distributor switch DD, but as this switch is of the reverse drive type its wipers are not moved at this time.
  • relay A At the end of the first series of impulses, relay A remains energised and relay C releases after its slow period and at contacts 0! completes a circuit over bank DSAI, Fig. 3, for operating relays CNA and CNR in series. If the digit dialled is 5 or less, relay CNA operates over its left-hand winding and as a result a short interdigital pause is provided between the retransmitted digits as will appear subsequently.
  • Relay CNR at contacts cnr2 advances the: sending control switch SC from its home position to position I where relay ST is operated over its two windings in series. Relay approximately 160 ms. .holds relay CS and at contacts s3, Fig.
  • the duration of the prepare pulse is thus meas- .ured by the time takenfor the switch SC to step from contact i to contact '4 plus the slow release period of relay ST which ,gives a total figure of Relay S at contacts s5 nectsthe code pulse to the line, this pulse being dependent for its composition on the setting of the switch DSA as fully described in the previously mentioned specification so that it is thus characteristic of the digit dialled.
  • Relay S also at contact 81 short-circuits its high resistance left-hand winding to self-drive the switch SC to contact :9 where relay Z operates over its high resistance lower winding and at contacts 24 disconnects the code pulse from the trunk line.
  • duration of the code pulse is measured by the time taken for switch SC to self-drive from contact 4 to contact 9 which is approximately 100 ms.
  • Relay Z holds relays CNA and CNR at contacts 2] and at contacts 22 causes the switch DSA to self-idrive to its home position where relay Zreleases and at contacts 22 causes the switch SC also to drive to its home position, while at contacts 23 relay-CS is released.
  • relay CNR will be maintained operated in series with a relay CNB, .not shown, and accordingly when the switch SC comes into its home position it will again self-drive to contact -I where relay ST will re-operate to-send out the prepare pulse of WXYZ frequency followed by the code pulse which .is picked up from the setting of the Wipers of the switch DSB which is assumed to besimilar to the switch DSA already described.
  • relay EP would operate and lock to earth over Accordingly, when the switch DSA reaches its home position, thus measuring 01f part of the interdigital pause, relay EP will hold during the slow period due to its shortcircuited upper winding and at contacts 6102 will cause the switch DSA to make another revolution. During this revolution relay EP releases but relay Z holds to bring 'about a substantial increase in the interdigitalpause. 'For example, if the digit O had been dialled, the .interdigital pause would be made up as follows: fourteen steps of the switch DSA plusan additional revolution making 39 steps all gives a period of approximately 780 ms. To-this must be added sixteen steps of the switch SC say 320 ms. plus a further 260 ms.
  • relay CNR When all stored digits have been transmitted in code, relay CNR finally releases and at contacts cnrZ opens the kick-on circuit for the sending control switch SC, while at contacts curl, Fig. 4, it brings up relay BS, Fig. 2, which has no functionat this stage.
  • the DSA switch on which the fifth digit is received, will take precedence and so will up- This trouble may be simply overcome by providing, in the CNR relay individual battery feeding circuits to the three relays CN-A-CNC, break contacts of relay CND which are paralleled by make contacts of each relay concerned. As regards relay CND this will remain directly connected to relay CNR as shown in Fig. 3. With these arrangements the operation in turn of the relays CNACNC is not interfered with and on operating they will lock independently of relay CND, but as soon as relay CND is operated in response to the fourth digit, none of the preceding relays can be operated in response to a fifth and subsequent digits. This condition obtains until the fourth digit has been sent out in coded V. F.
  • Relay KR, Fig. l thereupon operates and locks up at contacts lcrl while at contact lcrZ it releases relay A.
  • Relays B and BR in turn restore after their slow periods and the former at contacts b3 advances thedigit distributors-witch DD to its mid positionpreparatory to the operation of relay AA at a later period.
  • Relay BR at contacts br3 connects the earthed low resistance lower winding of relay RR into the sleeve circuit and though relay RR receives insufiicient currentto operate the supervisory lamp again glows under this condition.
  • Relays M, MM, KR, CO, .FC and BS remain operated and the line condition is now such that the operator may listen to tones and if necessary speak without the necessity for a calledparty answer signalg but no supervision is given.
  • the sleeve circuit current is increased. to a value sufficient to operate relay RR and this relay at contacts rr2, Fig. 1, maintains a suitable V. F, termination on the trunk line, in place of the operator's telephoneset.
  • the incoming relay set at the distant exchange transmits 140 m. s. of Y frequency over the trunk followed by a, space period of 360 m. s. and this signal is repeated until acknowledged by the transmission of an X signal from the outgoing relay set.
  • relay Y operates in the YF receiver VFR shown schematically as a dotted rectangle in Fig. 2 and opens the circuit to relay BS which releases after a slow period of 80-110 m. s. To release relay BS therefore the Y frequency must be applied for a sufficient period and. when relay BS has released, relays MS and MT are operated inturn and hold for the remainder of'the Y pulse.
  • relay BS When the Y pulse is finished, relay BS re-operatesand at contacts bsl opens the circuit for relay MS which has a release timeof 300-400 m. s.
  • Relay MT has a release time of 200-300 m. s. If the break period is of the correct duration, namely 360 In. s.,then thisperiod plus'the 80-110 m. s. release time of relay BS, which releases in response to he next Y pulse, will be. suflic-ient to cause relay MS to release but not relay MT.
  • relay SB which has been short-circuited hitherto operates in series with relay SA and locks.
  • Relay SB operates relay AA, Fig. 3, in the selfdriving circuit of theswitch DD and relay AA at contacts aa2, Fig. 4, reoperates relay CS and at contacts aal, Fig. 2, applies an X pulse acknowledgment signal to the outgoing trunk.
  • the duration of this acknowledgment signal is measured by twelve steps of the switch, DD plus the release time of the relay AA which releases when the DD switch reaches the home position and which in turn releases relay CS.
  • relay SA at contacts sa3, Fig. 1 connects battery via resistances YP and YQ to the ring of the jack for through supervision and alsoatcontacts safi, Fig. 1, removes the short-circuit by way of the lower winding of relay RR from the high resistance winddistant exchange transmits Y pulses of the same typegas for thecalled party answer signal.
  • relays M, MM, KR, CO, FC, BS, SA and SB are held operated and the switch TS is in position 6. Accordingly the first m. s. pulse of Y frequency releases relay BS and operates relays MS and MT as already described.
  • relay BS is operated and releases relay MS but not relay MT so that when the next Y pulse is received and relay BS again releases, during the slow release period of relay MT relay SY operates over contacts $172 and at contacts syl completes a locking circuit for itself-for the remainder of the Y pulse.
  • Relay SY also at contact sy3 operates relay SZ and at contacts syZ releases relay SA which at contacts sa3, Fig. 1, disconnects battery fromthering of the jack for backward supervision, and at contacts saB restores earth via the low resistance winding of relay RR to the jack sleeve circuit to re-light the operators calling supervisory lamp.
  • relay SY remains held because its release time is 400-450 m. s., i. e. longer than the 360 m. s. breakperiod and consequently if the called subscriber should again remove his receiver, the Y pulses will cease and after its slow period relay SY releases and disconnects relay SZ.
  • relay SA re-operates and locks in series with relay SB to restore the speaking conditions.
  • relays M and M in the sleeve circuit release and the latter releases relay KB.
  • the release of relay MM at contacts mm2, Fig. 4 steps the switch TS from position 6 to position 1 by way of bank TS3, whereupon relay BR operates in series with relay SR over bank TS4.
  • Relay SR on operating at contacts. sr3 re-operates relay CS and these relays together bring about the application of an X frequency pulse forwardly over the trunkby way of contacts sr2, csl and 082.
  • relay SB Since relay SB is operated, the switch TS continues to self-drive from position I to position I5 via bank TS3 and contacts sb4 and then steps by means of interruptedearth on lead 13 from position I 5 to position [9 via bank TS5.
  • Relay FXY is then uperated over bank 'I'Sfl, contact l9, and serves to disconnect the X frequency at contacts .fxyl, Fig. 2, after a period of application of two seconds and at the'same contacts to connect up Y frequency to the trunk.
  • relays SR and BR are causedto release after their slow periods and on the release of the latter, earth is extended over bank TS3 to step the switch to position 20.
  • Relay FXY then releases after its slow period and thus terminates the Y signal after a period of application of 300 m. s. and also releases relay CS.
  • Switch TS then steps from position 20 to position 23. via bank TS3 and contacts acl, and then slow -steps from earth on lead l3 over contacts 23 and 24 via bank TS5 to reach its home position where relays CO, FC and SB release.
  • Relay QQ disconnects the busy condition from the sleeve of the jack at contacts 005, Fig. 1, and; as earth is also removed from the P conductor leading to the selector levels when the TS switch reaches its home position the relay set is free for further use.
  • the object of the long X pulse under these con- 13 ditiOns is to ensure that the clear signal will be received at the distant incoming end when, for example, NU tone is being transmitted backwardly.
  • the NU tone is transmitted for five seconds and disconnected for one second and this :7
  • the call may have been originatedeither by a subscriber on the same exchange or via an incoming V. F; relay set from a distant exchange, say 13
  • relay-SR earth extended forward overthe private conductor? operates relay-SR, Fig. 4, which causes the switchTS toself-drive over bank TS3 to the first position where'it-operatesrelays CS and Relay C0 operates relay BS; and drops relay SR, while relayFXYextends a 100 m. s. X seizing-pulse forwardly over the trunk to the distant incoming relay set.
  • Relay FXY also causes switch TS to self-drive-to-position 3 where relayFXY isdisconnected and after itsslow period-releases toterminate the X pulse.
  • Relay FC is then operate-d and-locks up and serves'to step TStopositionA from which it slow steps from interrupted earth on conductor; l3; to positionfi Relay FC also brings about-the operation of relay A, Fig. 1, over the calling subscriber s loop-and relay A in turn brings up relaysB- and-BRto prepare the circuitforthe reception of thedialled impulses. From this point thecall proceeds as for an operator call alreadydescribed; that is-to say, relay-A responds to-thedialled-impulses which are stored-via the digit distributor switch-DD on the coding switches DSA--DSD. Subsequently under the control ofthe sending 'sw-itchSC the coded digits-aretra-nsmitted toline in.
  • Relay CO under these, conditions busies the manual board jack by. connecting. resistance battery to the sleeve-cir 1 2 cuit.
  • relays Ms and MT check the length and spacing of the pulsesand ifthese are correct allowrelays SA and SB to operate.
  • Relay SA at contacts saA and sa5, Fig. 1, reverses the A relay connections towards the call-- ing partyfor; supervision, while relay SB operatesrelay AA to cause an X pulse acknowledgment signal to be transmitted forwardly to the distant exchange.
  • This signal lasts fora period measuredby the homing time of the switch DD-via thelow resistance relay plus the slow release period of relay AA which is disconnected when switch DD arrives at its home position.
  • the reception of the X" pulse acknowledgment signal at the distant exchange causes the backward Y" answer signal tobe disconnected and conversation may now takeplace.
  • earth is connected toboth the negative andpositive lines and serves to operate relay AG; Fig. 1, while the normal forward earth on the P conductor operates relay-- SR.
  • Relay FXY extends a 100 m. s. Xseizing pulse for-.
  • relay- FXY is disconnected and when it re-- leases after-its slow period the X seizing pulse is terminated. Sincerelay AC isoperated, switch TS self-drives-- to position 20 via bank TSZ and remains; there until the end of the call so that as it leaves position l while relay FXY is still'operated, relay F6 is not operated.
  • the incoming- VFprepa-re and code pulses are thus extended directly throughthe outgoing; relay set to the distant exchange; Relay CQ busies thejack by connecting battery to the sleeve circuit, whileswitch TSat bankTSd holdsearth'on the P wire to busy the outgoing; relay set against seizure oventh'e selectorlevels.
  • repeated Y pulses are extended from'the' distant exchange directly through theoutgoing-relay set andare; acknowledgedby-a 440m; s.
  • switch TS will; run homefromposition 6 to extend the clear signal of two seconds'X followed by 300 In, s;,Y'
  • the first Y pulse operates relays MS and MT and during the first 360 m. s. break period relay MS releases so that at the commencement of the next 140 m. s. Ypulse relay SA is operated and at contacts 3012, Fig. 4, causes the switch TS to step from its home position to contact I.
  • Relay SB is operated and locked when the Y pulse isfinished and from then on the switch TS makes a complete revolution during which the clearing signal comprising a two-second X pulse followed by a 300 m. s. Y pulse is transmitted to the trunk line to release the distant equipment. It should be mentioned that during the revolution of the switch TS the X seizing pulse is again transmitted while the switch is passing over the early contacts of the bank, but under these circumstances this signal produces no switching function at the distant exchange.
  • relay IX when the 100 m. s. X seizing pulse is received over the trunk line from the outgoing relay set, relay IX, not shown but assumed to be located in the valve receiver IVliRyoperates and in turn brings up the relief relay XR.
  • Relay XR at contacts m3 operates relay K which locks upat contacts kl, at contacts k2 operates relay PY, Fig. 6, and at contacts k4 extends earth forwardly over the P conductor to the incoming selector to busy this switch.
  • relay IX in the valve receiver releases and in turn drops relay XR which at contacts :rr4 operates relay NN.
  • Relay NN at contacts nnfi further earths the P conductor extending to the incoming selector, at contactsnnl operates relay KK over the negative line in series with one winding of the A relay in the incoming selector and at'contacts nn3 operates relay GX, Fig. 5.
  • Relay GX at contacts 9034, Fig. 6, connects battery by way of a high resistance YF to the centre point of the repeating coil which finds a circuit to earth at the centre point of the transformer which connects the valve receiver IVFR to line. A small current is thus causedto flow by way of various relay contacts connecting with the line circuit which are thus wetted to prevent coherer trouble. No further operations take place at this stage and the incoming selector is now ready to receive the train of impulses.
  • relays IW, IX, IY and IZ operate in the V. F. receiver and in turn bring up their relief relays WR, XR, YR and ZR.
  • yrd, 213 and wr3 relay CA is now operated, whereupon the botliway line termination comprising resistances YB, YC, YJ, YD and YE and condenser QA which normally imposes a loss of the order of 3 db, is converted into a combined line terminationand infinite attenuation loss pad which prevents the passage of signals so that the line is blocked at this point.
  • the purpose of this arrangement will be described later in connection withtandein calls.
  • Relays WR to ZR have a pyramid chain of contacts (not shown)v connected to the bank SS2 of the sender switch SS, and since the code relays WR and ZR are operated at this time, earth is connected to the sixth contact of the'bank SS2 in order to terminate the sending after five impulses have been transmitted to the incoming selector as will appear subsequent: 1y.
  • Relay CB also at contacts c225 releases relay GK and operates relays PC and P, the latter looking over its own contacts.
  • Relay PC at contacts pcI operates relay CC which at contacts ccI prepares a circuit for relay IG which operates when the constantly driven impulse springs 66%M next open.
  • Relay IG at contacts z'g2 drops relay K and at contacts igI extends the impulse springs 66%M to the driving magnet SSM of the sender switch.
  • Relay IG also at contacts ig2 transfers the forward, holding loop extending to the selector to the impulse springs 33%M which are closed at this time, since they are out of phase with the magnet impulse springs 56%M'which have just opened to bring about the operation of relay IG. Accordingly, the sending sWitchSS now steps its wipers until they encounter the marking earth connected to the sixth contact of bank SS2 over contacts of the coding relays WR and ZR, while at the same time the impulse springs 33 %M transmit five impulses to the incoming selector as described in the previously mentioned specification.
  • Relay 45 SZ operates when wiper SS2 comes into its sixth position and locks over contacts seI to the homing. bank SSI.
  • Relay SZ also at contacts s22 short-circuits the 33%M springs to terminate the impulses to the selector and at contacts 823 50 releases relays CA and CB which have been held in series.
  • Relay CB at contacts cbt drops relayIG which at con-tacts ig4 causes the sending switch SS to.,-home, while the holding circuit for the selector is again transferred to relay KK 55 which re-operates.
  • Relay CB also re-operates relay GX and releases relays WR and ZR as Well as relay PC after its slow period which is followed by the release of relay CC also after its slow period.
  • Relays K, PY, NN, KK, GX and P 60 remain held.
  • connection is thus fully set up and the called party is rung.
  • battery is reversed over the forward trunk so that relay KK releases and relay EE operates.
  • Relay EE at contacts eeZ brings up relay IR which at contacts irZ-ir4 alters the connection to the loss-pad to render it inefiective and at contacts irl drops relay K.
  • Relay K opens the circuit of relay PY and during the slow release period of the latter, relay MA is operated and locks up over contacts mal and gx'l.
  • Relay MA at contacts WW3 and mad, Fig. 5., connects up the secondary winding of the transformer VSF to the backward trunk and at contacts ma2 connects relay FY, Fig.
  • the X acknowledgment signal is measured against the release time of relay GX (300-400 m. s.) to provide the required degree of immunity against spurious X frequencies on the line.
  • relay GX 300-400 m. s.
  • Relay EE at contacts eeZ drops relay IR to re-introduce the line termination and also operates relay MA.
  • Relay MA connects interrupted earth to relay FY which pulses to send back to the outgoing relay set the clear signal comprising 140 m. s. Y pulses with 360 m. s. spacing.
  • this signal results in the release of relay SA which disconnects battery from the ring of the outgoing jack and lights the calling supervisory lamp at the operators position.
  • Relays NN, KK, GX, P and MA remain held,-while relay FY is slowly pulsing;
  • the outgoing relay set sends a clear signal comprising a two-seconds X pulse followed by a 300 m. s. Y pulse;
  • the X pulse operates relays 1X, XR and GY in the incoming relay set and the latter opens the circuit for relay F'Y to terminate the transmission of the called party clear signal.
  • Relay XR also opens the circuit of relay GX sufficiently long for it to release whereupon it drops relay MA and operates relay CC over contacts 9333.
  • relays IX, XR and GY release and relay CC commences to release slowly.
  • Y pulse now follows and serves to operate relays IY, YR and CR
  • Relay CR locks to the earthed contacts 172' and transfers the hold ing circuit for relay NN to the Y pulse and also connects earth to the P conductor extending for- Wardly to the automatic switches.
  • relay NN releases and drops relays P and K which open the holding circuit for relay CR, The forward holding loop is opened and the earth on the P conductor is removed on the release of relays N and CR thus initiating the release of the operated automatic switches, and the incoming relay set is now free for further use.
  • tones which may be encountered during the setting up of the call such as ringing, busy and NH
  • these are passed back along the trunk line in the normal manner except that the line termination which is in circuit under these conditions imposes a 3 db loss but this does not seriously reduce the tone level.
  • the NU tone is broken at the source for one second in every six to allow the release signal to obtain control of any echo suppressors which may be in circuit and thus get through to its destination.
  • the release signal comprises 6 seconds of X frequency followed by 300 m. s. of Y frequency. This long signal insures a certain break-in during the I second silent period of the NU tone.
  • relay K since the called party has not answered, relay K will still be operated and hence the X signal operates relay PC which brings up relay CC and from this point the release procedure is identical with that previously described for the normal operator clear.
  • relay IR With relay IR operated the loss pad and line termination are removed at contacts ir2-ir4 while any circuit for relay CB is disconnected at contacts 2'15' so that the following VF' signals pass directly through the incoming relay set without any conversion or repetition. Under these conditions before the in-' coming relay set can be releasedr it must receive a long X pulse to drop relay GX followed at the proper interval by a short Y pulse to operate enough to bring about the-release of relay GX.
  • the 440mm; X pulse acknowledgment signal which is sent from the originating end in response to the called party answer signal will bring about the release of relay GX, but as this is not followed by a Y signal thetemporary release of relay GX brings about no material change in the condition of the incoming relay. set.
  • the release signal comprising along X pulse followed by a short Y. ulse is received, the incoming relay set releases as already described.
  • relay CA when the VF prepare impulse is received at the incoming relay set at the second exchange (C), relay CA operates almost immediately and provides an infinite attenuation loss pad which in effect-short-circuits the trunk across a resistance bridge to prevent the passage of V. F. signals beyond the incoming relay set.
  • relay CA in the incoming relay set at the fifth exchange (H) may operate but will at once release when the CA relay at the first incoming relay set has operated and inserted the loss pad in the trunk. It will be recalled that relays CA and CB lock in series during the reception of the code pulse and while the loop impulses are being transmitted so that neither the prepare nor the code VF signals are transmitted to the incoming relay set in the fifth exchange.
  • this shows the modifications necessary to the incoming relay set to instead of negative, relay TH is operated via the metal rectifier MBA and locks up.
  • Relay IR is also operated from relay EE and with all four relays operated the line termination and loss pad is disabled and a straight through connection is provided.
  • relay KK will be operated while the call is being set up. If a busy line is encountered, busy tone is returned as explained and if this is accompanied by busy flash batteryon the positive line relay EE is also operated. Since however, relay TH is not operated under these conditions since the battery in question is a negative battery, relay IR in operating does not disable the line termination and loss pad, so that balanced conditions are maintained to the line amplifier which is prevented from singing during the busyflashcondition.
  • a connection is extended over a trunk in which the functional operations including superyisory and, releasing Q 'LS l Q 031 8 3 0 2 are cQ ll d y s snals r a plurality of sources of alternating currents of different frequencies, means in said connection to transmit; impulses of said currents of deterin d: f equen y dur tion and spa n over d trunk in accordance with said functional operations'controlled thereover, a signal comprising impulses one of said frequencies repeated at a determined rate to control the supervisory functional operation, a second signal comprising another frequency of determined duration, means in said trunk to transmit said second signal to stop said supervisory signal and means in said connection to transmit a subsequent pulse of said; first signal within a determined spacing, after said stoppage signal is effective to control the functional operation of releasing said connection.
  • a connection includinga trunk line over which voice frequency signals are transmitted to establish a connection and in which a clearing signal of voice frequency is normally sent tothe calling end when thecalled station hangs up and a release si al of Voice frequency is then transmitted from the calling end to release the connection, the provision of means responsive to a release signal transmitted from the calling end before a. clearing signal. is received for causing the transmission of the clearing signal to act as a release signal to release the connection.
  • a plurality of voice frequency responsive equipments each associated with a trunk line and each normally responsive to received voice frequency coded signals to translate the same into direct current impulses to operate automatic switches to extend a connection
  • a trunk line means for transmitting over said line a plurality of coded signals each'comprising impulses of a plurality of different voice frequency sources and a varying number of said frequencies in accordance with received signals and other control signals of varying number of impulses of determined frequency duration and spacing in accordance with other received signals, a plurality of receivers connected successively to said line and responsive to a received signal for translating it to a signal corresponding to said received.
  • a blocking means controlled from each of said receivers to prevent the further passage of said received signal current over said line to the successively connected receivers, means in each receiver effective on certain of said coded signals for translating said signal and operating said blocking device to prevent said other receivers from effectively completing said particular code translation and means in each receiver responsive to other received signals to complete the corresponding translation without operating said blocking means.
  • a trunk line including voice frequency responsive equipment, means for extending av connection thereto and for transmitting coded digit signals of voice frequency currents thereto to extend a. connection thereover and for transmitting other coded voice frequency signals thereto, a blocking device in said trunk, each digit signal including a portion effective to include the blocking device in the trunk to block further progress of voice frequencies over the connection, and each other signal passing over the connection without blocking.
  • a voice frequency signaling trunk terminated on a responsive repeater including means for transmitting and receiving over said trunk a signal to seize said repeater and another signal to release said repeater, a. switch operating line controlled from said repeater, means responsive to the seizure of the repeater to connect said line to said trunk, said repeater responsive to other voice frequency Signals received over the trunk to control a connection, and to repeat said release signal thereover, holding equipment in said repeater controlled over said connected line to prevent a false release of said trunk before said line is disconnected, means effective in the event of a short circuit on said line whereby said holding equipment and said other signals are disabled, means insaid repeater effective only when said equipment is disabled to disconnectsaid line from said trunk to permit said release signal to be effective to release said repeater.

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  • Engineering & Computer Science (AREA)
  • Computer Networks & Wireless Communication (AREA)
  • Interface Circuits In Exchanges (AREA)
  • Sub-Exchange Stations And Push- Button Telephones (AREA)
  • Telephonic Communication Services (AREA)
US502884A 1942-10-15 1943-09-18 Telephone or like signaling system Expired - Lifetime US2407150A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
GB14466/42A GB560794A (en) 1942-10-15 1942-10-15 Improvements in telephone or like systems

Publications (1)

Publication Number Publication Date
US2407150A true US2407150A (en) 1946-09-03

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ID=10041694

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Application Number Title Priority Date Filing Date
US502884A Expired - Lifetime US2407150A (en) 1942-10-15 1943-09-18 Telephone or like signaling system

Country Status (3)

Country Link
US (1) US2407150A (fr)
FR (1) FR931977A (fr)
GB (2) GB560794A (fr)

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2530815A (en) * 1949-02-02 1950-11-21 Automatic Elect Lab Mobile radiotelephone system having a single channel and a single frequency
US2566009A (en) * 1947-12-12 1951-08-28 Automatic Elect Lab Interexchange switching telephone system
US2594719A (en) * 1945-05-19 1952-04-29 Automatic Elect Lab Voice-frequency telephone signaling system
US2651679A (en) * 1947-02-07 1953-09-08 Int Standard Electric Corp Electric signaling system
US2721901A (en) * 1951-10-16 1955-10-25 Automatic Elect Lab Telephone systems incorporating bankposition marking in switching stages
US2890282A (en) * 1953-01-30 1959-06-09 Gen Dynamics Corp Automatic telephone system

Families Citing this family (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2579530A (en) * 1947-04-29 1951-12-25 Int Standard Electric Corp Four-wire to two-wire connecting circuit
BE482466A (fr) * 1947-04-29
DE1021016B (de) * 1955-04-29 1957-12-19 Standard Elektrik Ag Schaltungsanordnung fuer Fernmelde- und Fernwirkanlagen zur Signaluebertragung nach einem Frequenzkodesystem

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2594719A (en) * 1945-05-19 1952-04-29 Automatic Elect Lab Voice-frequency telephone signaling system
US2651679A (en) * 1947-02-07 1953-09-08 Int Standard Electric Corp Electric signaling system
US2566009A (en) * 1947-12-12 1951-08-28 Automatic Elect Lab Interexchange switching telephone system
US2530815A (en) * 1949-02-02 1950-11-21 Automatic Elect Lab Mobile radiotelephone system having a single channel and a single frequency
US2721901A (en) * 1951-10-16 1955-10-25 Automatic Elect Lab Telephone systems incorporating bankposition marking in switching stages
US2890282A (en) * 1953-01-30 1959-06-09 Gen Dynamics Corp Automatic telephone system

Also Published As

Publication number Publication date
GB560807A (en) 1944-04-20
GB560794A (en) 1944-04-20
FR931977A (fr) 1948-03-09

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