US2201651A - Dial switching telephone system - Google Patents

Description

May 21, 1940. w. HATTON ET AL DIAL SWITCHING TELEPHONE SYSTEM 7 Sheets-Sheet 1 Filed April 7, 1938 WHAT TON INVENTORS LBHA/GH By L/(OZMA n llllllllll o L m EN N? Q L w m Mm U m Q Z i 59k m M A T TORNE Y y 1940. w. HATTON El AL 2,201,651

DIAL SWITCHING TELEPHONE SYSTEM Filed April 7, 1938 7 Sheets-Sheet 2 WHATTON INVENTORS. LB. A/G'h' LKOZMA A T TORNE Y FIG- 2 FIG. 3

May 21, 1940.

w. HATTON ET AL 2,201,651

DIAL SWITCHING TELEPHONE SYSTEM 7 Sheets-Sheet 3 Filed April 7, 1938 W HATTON LB. HAIGH L.I(0ZMA A 7'TORA/EY m/vavroxes M y 1, 1940. w. HATTON ET AL DIAL SWITCHING TELEPHONE SYSTEM Filed April 7, 1938 7 Sheets-Sheet 4 WHATTON I/Vl EN TORS LBHAIGH LJfOZM/i BY A TZORNEV May 21, 1940. w. HATTON ET AL 2,201,651

I DIAL SWITCHING TELEPHONE SYSTEM Filed April 7, 1938 7 Sheets-Sheet 5 SVL (r0 F/IG. 4)

W HATTON INVENTORS LB. HA/GH L. KOZMA ATTORNEY May 21, 1940. w. HATTON ET AL I DIAL SWITCHING TELEPHONE SYSTEM Filed April 7, 1938 '7 Sheets-Sheet 6 LKOZMA May 21, 1940. w. HATTON ET AL DIAL SWITCHING TELEPHONE SYSTEM Filed April 7, 1938 7 Sheets-Sheet 7 3 HATTON INVENTORS LB. HA/G/l L. KOZMA BY ATTORNEY m nu m 21, mo

P TENT o Fica DIAL TELEPHONE SYSTEM William Hattom Leslie Baines Bligh, and Ladislae Korma, Antwerp, Belgium, aesignors to Western Electric Company, Incorporated, New York, N. 1., a corporation of New York Application April 7, 1938, Serial No. 200,656

9 Claims.

This invention relates to electrical communication systems and more particularly, though not exclusively, to automatic ticketing equipment for use in such systems.

Oneobiect of the invention is to provide improved substation identifying equipment which allows identification of any substation of an exchange in an economical and expeditious manner.

With this object in view one feature of the invention comprises a telecommunication exchange system comprising subscriber identifying equipment, characterized in this, that two stages of subscriber identifying switches or the like look for marking conditions applied to a circuit connection terminating at one end ina subscriber's line to be identified.

Another object of the invention is to provide improved means for ensuring that operating procedure in interstation connections is not prejudiced bythe use of faulty equipment.

With this object in view a second feature of the invention comprises an electrical communication system comprising a number of-similar 25 equipments, any idle one of which can be used in a connection, characterized by automatic test circuits in said equipments which test certain devices therein for faults immediately the equipments are taken into use, and by circuits closed if a fault exists in an equipment to disconnect and busy the equipment, to cause another equipment to be connected up in its place, and to give an alarm.

According to another feature of the invention, the same calling line identification equipment can be used for identifying calling subscribers of a plurality of different hundred-line groups. The identification may be made in a plurality of stages.

According to a further feature, the calling partys number and the record of the duration of the connection can both be made without delaying the normal release of a connection.

According to a further feature of the invention, a minimum holding time for a completed connection is enforced unless before that time expires certain records incidental to charging for the connections have been made.

According to a further feature of the inven-' tion, common-equipment used temporarily (e. g.. for automatic ticketing purposes) is tested when seized, and, if defective, is dropped and replaced by a similar equipment which is also tested before use. For instance, a common voice-frequency signal-receiving valve circuit may be so tested.

Great Britain October 31, 1936 This test takes'place without prejudice to the correct progress of the call or the completion of a full automatic ticketing record for the call.

The invention will be more clearly understood from the following description of two embodiments of the invention shown in the accompanying drawings in which:

- Fig. 1 shows part of a subscriber's line circuit,

a first line finder, a second line finder, and a first group selector together with a complete identification line finder. The latter is one of a group of identical circuits and is adapted to have access to the subscribers lines served by a plurality of groups of first line finders;

Fig. 2 shows an identification control circuit which is one of a group of identical circuits and is adapted to have access through its finder CF to a plurality of identification finders belonging to one or more groups of such finders and through its finder IF to a plurality of groups of first line finders;

Fig. 3 shows a two-wire junction circuit outgoing to another automatic exchange and adapted to be associated with a printing register whereby a tangible printed record may be produced for each call established over the junction;

Fig. 4 shows a control circuit common to a plurality of outgoing junction circuits and adapted to be connected to the outgoing junction for a portion at least of the duration of its occupation by a call;

Fig. 5 shows an identification startingcircuit and distributor;

Figs. 6 and '7 which should be placed one above the other show alternative identification equipment.

The ticket printing machine to which the bracketed conductors of Fig. 3 extend may be of the type disclosed in British Patent 472,435 granted to L. Devaux.

Referring to Fig. 1, when a subscriber at substation S originates a call to a subscriber in another exchange reached over the outgoing junction shown in Fig. 3, a first line finder such as ILF is caused to rotate until its brushes a b c d rest upon the terminals of the calling line, a second line finder such as finder ZLF is caused to rotate until itsbrushes a, b, c, it rest upon the terminals individual to the aforesaid first line finder and a register circuit (not shown) is caused to associate itself with the aforesaid second line finder in a well-known manner. The calling subscriber then dials the number of the wanted subscriber and the register causes the first group selector IGS permanently associated with the second line iinder 2L1, to select an outgoing junction, Fig. 3, in response to one or more digits of the number dialed, e. g., the first two digits of a five digit number. The register is adapted to await the closure of a low resistance loop across brushes a, b, of the first group selector IGS before transmitting each of the remaining digits, e. g.. the last three digits of the number dialed.

When the outgoing junction circuit, Fig. 3, is seized, relay Cw energizes to earth on the 0 wire and energizes Jo. Contacts 105 remove earth from wire 6 extending to the ticketing machine. Relay Jc now operates via deZ, 112, sil, m. followed by Ri; Ri, idl, id, 1216, ml, to earth on wire 5 from the ticketing machine associated with the junction circuit. Relay Jd energizes via cs6, resistance RST, jsm'i, eel, riZ, xii, 102, and operates JSM via 0.04, mi, M3, dai.

Relay Jb energizes via 10!, jet, a loop circuit via the Junction and the incoming Junction circuit, iel and coil JA. Bb also operates via 116, esl, jbl, 192.

Js is now looped across the incoming a and b wires and operates followed by JI, and Je; Je, bbl, :iel, 7'32. Je locks via b123, jei, 1112. Jo also locks via jel, {02, 1.92.

On the first impulse of the hundreds digit, Js releases so that earth via isi', jet, bb2, Si, wire I extending to theticketlng machine operates Si and the printer magnet of the machine. Relay Jd is released followed by JSM so that switch JS takes one step.

The locking circuit for Jo is also opened by 582 and J0 releases opening'the loop circuit for .lb which releases.

An impulse is sent over the outgoing junction by the opening of the circuit of Jb, but on the release of Js at the end of the incoming impulse, battery is connected via 79, job, jsl, to the junction b wire, and earth via id to the junction 0 wire, to end the outgoing impulse.

Js repeats the remaining impulses of the first digit to the printer magnet and over the junction. Relay Si remains energized until the end of the digit, when ED is released at sii disconnecting 58 from the junction. to release J8 and to signal the register-controller. Jl is also released, together with Je. Contacts bbl maintain battery on the 12 wire when contacts :Isl open to prevent an extra impulse being sent.

Jd reoperates in the same circuit as before followed by J SM. Earth connected to wire 2 by the ticketing machine is now connected via 7222, 1%, to wire 3 to cause the digit to be printed and the digit wheel to be returned to normal.

Ri has been locked via ni, gig! to wire 5 of the machine from which earth potential is now removedduring the revolution of the operating shaft MCS of the machine (not shown) so that Ri releases, followed by Jd and JSM, and JS steps to its third position. 1

Jo now reoperates via je2, ri2, sil, 7'92, followed by Jb.

When earth is reconnected to wire 5, when the machine is ready for the next digit, Ri reoperates via ddi, 1'03, nit, jgl, wire 5, and locks via 11!, in! to wire 5. Jd and JSM again operate, and Bb energizes via 1%, esl, :ibi, 7'02.

Js is now connected to the incoming a and 12 wires to signal the register to send the tens digit. As before, J1 and Je are operated and- Jc locked.

The tens digit is transmitted andrepeated by Js to the machine and over the junction and switch JSM is stepped to position 4, after which the same switching operations take place as after the hundreds digit, JBM being stepped to position I. when the machine has printed the digit and signaled to the junction circuit, the latter in turn connects Js to the junction to signal the register. The units digit is transmitted and repeated in the manner before described.

Switch JS steps to position 8 during receipt of the units digit.

At the end of the digit, Si releases as before followed by Bb, Je, J8, and the circuit for J! is opened.

Jd re-energizes together with JSM, and at the same time N! is operated; N rid, esl, Tml, jam! in position t, est, ril, xii, 102. N! operates because resistance RST is no longer in its circuit as it was in positions l-I of JS.

Contacts nil connect earth continuously to wire 3 to the machine to inform it that no more wanted party digits are to be awaited. The machine prints the units digit, and removes earth from wire 5 to release R! which releases Jd, and JS steps to position 1. N! locks via nil and wire 4. Es operates via act, nil, jal.

Battery on the wire it from the preceding circuit operates Ew, via ps5, cs5, ill. J! is slow-to-deenergize and will not release its armature before Ew energizes. The incoming a and 1: wires are now connected via winding of Js to earth on owl and via ewi and winding of Js to battery. Ja reoperates and prevents J1 from releasing.

When the ticketing machine arrives in position 8, after printing the units digit, it removes earth from wire 4 to release Nf, which removes earth from wire 3. The machine'then self-steps to position l0 and again connects earth to wires 4 and I.

Jc is again energized via ae2, ri2, ail. 7'92.

Earth via wire 5, MI, 1178, 9'03, :idi operates Ri. which locks via ril, :fgl to wire 6. Es has been locked energized via e32, 7'02 and now Ac ener-- gizes; battery, left-hand winding, ps4, rii, nil, right-hand winding, e32, igZ. Ac locks; left-hand winding, act, right-hand winding, e32, igZ.

When the called party replies, J b energizes over the distant loop and earth via 10!, jbl, cal,

m2, art, energizes As.

Clock contacts CLC close and open every two seconds. At the first closure after As operates, earth via cs2, CLC, ssi, tsl energizes Fs.

When CLC open, F's remains operated in series with the left-hand winding of Se, jet to act. 8.! also operates. When contacts CLC close for the second time, earth via the right-hand winding of Se and the left-hand winding of Ts energizes T8 and holds $8, the left-hand winding of which is short-circuited via tsZ.

When contacts CLC open for the second time, earth via fsi, tsZ, Fs, ts3, right-hand winding of Ts holds Fe and T8. but 83 releases since its lefthand winding is short-circuited and its righthand winding has no circuit. On the third closure of contacts CLC, Fs is short-circuited and releases, but Ts holds via tsi, tel, ssi, CLC, cs2. JSM operates via fsl, tsl, 9'02.

On the third opening of contacts CLC, Ts releases, opening the circuit of JSM which steps switch JS to position I in which Wp operates via 71!, tml, a'sm2, eel, M2.

JSM is stepped in this manner after each six seconds of conversation starting from position 1.

If after one minute of conversation, the calling partys number has not been received by the ticketing machine, a facility governed by a manual key such as CRK may be brought into use to party's number positions.

If CRK is thrown, earth via ism! in position i'l, CRK, operates Ns, which connects N! to wire 4. N) energizes to earth on wire 4, looks and connects earth to wire 3 to indicate end of calling The ticketing machine steps partys number. forward to position 22.

When Ac operated after the called party's number had been registered, start and testbattery via ac operates relay Cs, Fig. 4, which in turn energizes Is.

Magnets CJM of all free ticketing control circuits' are operated and the, switches CJ hunt for the outgoing junction circuit, Fig. 3.

When a switch CS finds, relay Te energizes; earth, cdmi, Te, vpZ, cjmG, to start and test battery, Fig. 3. Double test is made by earth via tei, low resistance windings of Dt, Te, vpi, cimi.

Contacts dt2 connect earth to the filament circuit of valve RV via VPI. If the filament is in order it heats up. If the filament is broken, Vp

energizes and releases Te and Dt. The circuit of CJM is opened at UM, Vp looks at vpi, lamp L0 is flashed and an audible alarm may also be given. Vp may also be operated over its other winding I if the battery supply fails or if the circuit is held for an unduly long time, in which case battery via cam CM first operates Th and later VP.

If Vp does not operate, Cs is short-circuited and Is is released, Vt is energized via tc6, dtl, and contacts vt4 connect 500 cycle current to grid transformer AGT. The valve RV becomes conducting and An operates followed by Tc, which lights lamp LO steadily via vp3, tcl. Vt is released and 500 cycle current' removed from AGT so that Ap releases. When the ticketing machine is ready for tariff it energizes Ri over wire 5, followed by slow-release relay Pw via Z02, cgimi, n'Z, Fig. 3, sil, dgZ. Relay also operates via edi, p203, tji, dti, followed by Ed; earth, ccmZ, Bd, ed i, 1'02, battery. The circuit for Ed is only effective when interrupter INR removes earth from In. When INR removes earth, Bd energizes and connects INR to 11' which is operated when INR connects earth thereto. Earth via ir2, bcli energizes CCM until INR releases Ir when switch CC takes a first step.

During its operation Ir also connects earth from tfli via ir3, cjm3, wire i, Fig. 3, to the ticketing machine.

INR continues to impulse Ir which steps CC and. the printer magnet of the machine insynchronism for the first tariff digit.

When the digit has been sent Ed is energized via pwi, b113, ccmi, cdm3, nti, pii, The operating circuit for Ed was opened by ccm2 when CC stepped off normal, but earth via db! held Bd over back contacts ed until Ed has operated. Release of Bd disconnects INR from Ir so that no more impulses are sent. Relay I0 is also released. Switch CC is h'omed; CCM, bdi interrupter contacts, ccm2. CDM is operated via ed3. Earth via ed2, resistance THR, tc3, cjmZ, psi, operates Jd, Fig. 3, to signal to the ticketing machine that printing can take place. The machine releases relay Ri, Fig. 3. P10, Fig. 4, is then released followed by Ed, which releases Jd, Fig. 3, and CDM so that switch CD takes a first step.

When the machine is ready for thenext digit,

which operates when its circuit is closed via- Ic and Ed reenergize and a second cdml in position 2, and the cross-connection between the banks of 'cdmi and ccml Four digits are sent out inthis manner, switch 'CD being stepped to position 5 after the fourth digit is sent.

- When the machine is again ready after the ,fourthtarifl digit-is printed, Ri, Fig. 3, and Pw, Fig. 4, energize and this time T1 immediatelyoperates via tit, p102, cdmt, nti, mi, and opens the circuit of lo. Relay Ir energizes via tj3, pw2, cdml, nti, pii. Relay T locks in parallel with lamp LA via til, tci, cdmi.

Earth via tfl, th3, ir5, is connected to start lead SVL for the distributor circuit Fig.5 for the calling party identification control circuits. At the same time, 2000 cycle identification current is connected via 1'14, tf5, cjm5, to the conversational fourth wire d, Fig. 3, over which the current flows back to the first line finder circuit and the calling partys line circuit.

In the distributor circuit, Fig. 5, So is enersized and connects earth to the filament of valve DVi in parallel with relay Ad which will operate and give an alarm if the filament is faulty.

2000 cycle current passes over the conversational fourth wire, wipers d d, Fig. 1, lead i2, Figs. 2 and 5, adi to grid transformer RGT. Valve DVi becomes-conducting and .relay Rp is energized. Earth via rpi s02 energizes So, which in turn operates St.

Relay Ab is normally operated so long as DS has access to an idle identification circuit. If a call comes in while Ab is released, AI is energized to operate an alarm and a congestion meter.

Distributor switch DS is normally standing on an idle identification control circuit, Fig. 2. Earth via st5, dsml is connected to the filament of valve DV, Fig. 2, and winding of relay Vp in parallel, and 500 cycle current via sti, dsm2 is connected to the identification circuit.

If the valve DV is faulty, Vp energizes, locks via vpi, operates an alarm via 21122 and lead ALL, flashes lamp LO via V123, earths lead FTL to operate As, Fig. 5, via dsm3, and busies the identification circuit to group relay Ab, Fig. 5 by opening V125. If As operates and Ab is energized,

next identification circuit. If this is busy, earth via gfi back and scm3 or sdm3 off normal, or earth via gti front is connected to FIL to step DS, Fig. 5'on another step.

If the filament of DV, Fig. 2, is in order, the 500 cycle alternating current via dsm2, VFL, I, Fig. 2, lt2, gti, transformer GT renders the grid of DV less negative. Relay A operates in the anode-cathode circuit of DV. Earth via a'i, gt2, gjl, energizes Str. Earth is now connected from jtG via shit and lead RTL to operate D, Fig. 5. D operates DR which disconnects the 2000 cycle current from the transformer RGT. Relays Rp, So, St, therefor release and 500 cycle current is disconnected from lead VFL, Fig. 2. Relay D also operates magnet DSM.

Release of A due to the removal of 500 cycle current connects earth via ai, stri, gf3, gt3 to operate Gt which locks via yt i, gj4, str2.

Magnet CFM is now energized via gt3, gf3, strl, ai, and switch CF looks for the link circuit forming part of the conversational connection. When the link is found, 2000 cycle current via lead i2, Fig. 2,.jd, Fig. 5, wiper cfmB, Fig. 2, gti, GT renders the valve DV conducting and A again operates. G! is now energized via gt2, al and locks via all, str2. Gt is now released followed by A. Ft energizes via ftl. It}. 018, strl. al and locks via ft, stri. Earth via ltl, cfm'l energizes Fd, Fig. 5, to disconnect the 2000 cycle current from the banks of the switches CF. Relay Ft also releases D, Fig. 5, which in turn releases DSM and distributor DS steps on to another identification circuit.

Magnet IFM now energizes via ti, U6, fti and switch IF hunts for an idle identification line finder RI, Fig. 1, which has access to the lines connected to the link circuit to which CF is connected, under control of relay-T. When an idle RI is found, T energizes via #5, wiper cfml, z'JmO, cross-connection, ifma, lead 8, battery, Fig. 1. T disconnects IFM so that switch- IF stops. Lt operates via tl, U5, iii and connects busy earth via low resistance, left-hand winding of T and lt4 to busy the selected finder RI.

RI now hunts for the calling party's line; RIM, Fig. 1, lead I, ijmS, lt3, gj3, strl, ai.

When RI finds, the 2000 cycle current via wipers d d d Fig. l flows via one of wipers rima-rimc, lead 8, ID or H, cfmS, ifmT, ltl, Iii, gtl, GT. Valve DV becomes conducting and A again operates. Lf energizes via lt5, gt2, al, and locks via U6, strZ.

Direct earth via U3, connected to Um! and ifmO, short-circuits T which releases followed by Lt. 2000 cycle current is disconnected from GT and A releases. Earth via ml is now connected via 10, (U2, U2, to battery, so that Is energizes when short-circuiting earth via interrupter INT is removed. 10 then locks via ic3, energizes If, and connects INT to relay I.

On its first energization, I operates SCM, and 500 cycle current is connected via TR, i3, ifml, cfmfi, lead 9, H], or ii, one of wipers rima-rimc, wipers di, d2, d3, of the line finders and group selector back to the automatic ticketing equipment.

When the interrupter INT releases I, SCM releases and steps switch SC to its second contacts, and the 500 cycle signal is removed. While I was operated, earth via sdml, ii operated Si which looks via sii, iii.

Earth via scml, 2'02, sdmi, scml, Di, l/I operates D) which releases Ic to stop impulse sending. Switch SC homes; SCM, interrupter, ici, and icZ, scml.

Earth via scml short-circuits and releases D) so that magnet SDM which was energized via (U3 is released and steps SD to its second contacts.

By jumpering the home contacts of sdml to the third contact of scmi, two 500 cycle cancel impulses would be sent instead of one before operating D The 500 cycle current cancel pulse sent back over the conversational fourth wire passes via c7'm5, Fig. 4, US to grid transformer AGT. Valve RV becomes conducting, Ap operates, and earth via apl, vtl, Pi, tfG, thl energizes Pi which energizes CDM.

At the end of the impulse Ap, Pi, CDM release and switch CD steps to position 6.

Relay Th. now energizes via cdm3, ntl, ml, and locks via. th3, til. Relay IT is released when brush cdm3 leaves position 5 and lamp LA ceases to glow. The 2000 cycle signal over the conversational fourth wire is disconnected at in, and the start signal is disconnected at thi from lead SVL so that relay SV, Fig. 5, releases.

In the identification circuit 10, which was released when the cancel pulse had been sent, cannot reoperate to transmit the calling party's numher until relays If, Id have released in turn to connect earth via idl to lo.

When 10 reoperates, it again connects INT to I, so that simultaneously, under control of INT, 500 cycle impulses are sent back to the ticketing equipment and earth pulses are connected to SCM to step SC.

The first and second digits in the example given are exchange code digits and are therefore known. The second terminal of sdml is crossconnected to the required wire l-8.

When the required number of impulses have been sent, D is again energized via semi, Sdmi, and impulsing is stopped. 10, If, Id, release in turn to give an interdigital period, S0 is homed and D! is released stepping Sd to position 3. When 10 reenergizes, a second exchange digit is transmitted under control of a cross-connection between contact 3 of sdml and a contact of scml.

The thousands digit is then sent, the number of impulses being determined by a circuit via sdmi and its fourth contact, cjm2, and a contact of semi.

The value of the hundreds digit is determined by the connection via contact five of sdml, wiper cfml and the semi bank.

The tens and units digits are determined by the connection via the sixth and seventh contacts of sdml, z'fmS, and ifm5, leads 6 and 5, and wipers rimd and Time, Fig. l, in turn in the following manner.

There are four wires provided between RI and wipers ifmliim4 which connected to the arcs semi; scm2. These four wires are successively tested by relay Df, first for a direct ground and then for a ground through a resistance. In this way, one wire may indicate two different digits and the four wires provided sufiice, therefore, for eight digits. For odd figures I, 3, 5, and 'l the four wires are connected directly to the corresponding arc terminals on rz'md, rime, whereas for the even figures 2, 4, 6, and 8 they are connected over resistances of 1500 ohms. Relay D1, after one step of SC, is connected to wire 4 and operates if a full ground (digit 1) is connected to wire 4. Relay BI is shunted in this position by a 200 ohms resistance via scm2, fti, so that it is not able to operate if the ground on wire 4 is connected over a resistance. ground, however, the shunt mentioned has no effect. If D) does not operate SC advances on the next impulse to position 2, where Df remains connected over are scm2 to wire 4. The shunting resistance of 200 ohms is, however, disconnected and, therefore, if the wire I is grounded over a resistance of 1500 ohms (digit 2) D) will operate and stop sending. If this is not the case. SC continues to advance and the wires 2, 3 and 4 are consecutively tested in the manner described above. After eight steps, ground via sme l is disconnected from the brush of RI and Di now checks via terminal 9 of semi, whether the arc terminal of RI is grounded or not. In the former case Df operates (digit 9), whereas if the terminal in question is not grounded SC makes a tenth step and Dj now operates in any case by a ground on the tenth terminal of semi (digit 0).

After the sending of the last digit, earth via sdmZ short-circuits relay Str which releases and causes the release of all relays involved into the connection. SC homes; SCM and interrupter zcl and 1'02, scml, and SD homes; SDM and interrupter, sdml, stl, al. When SC and SD are home, the circuit is available for a new call.

In case of a full The trains of 500 cycle impulses identifying the calling partys number, impulse relay AP, Fig. 4. Earth impulses via apl, vtl, Pi, U6, t l, 071M, wire I, Fig. 3, to the ticketing machine step the digit printer for each digit in turn. Relay Pi remains operated throughouteach impulse train and energizes CDM.. At the end of the first digit Pi releases followed by CDM and switch CD steps to position I, in which earth via m'l, n'tl, cdm3, resistanceTHR, tc3, 07' 2, 98!, operates Jd, Fig. 3, to signal the machine to print the digit. The machine releases Ri which releases Pw. Fig. 4, until the machine is ready to receive the next digit when Ri, Pw reoperate. Pi operates during the second digit to release Jd, Fig. 3.

At the end of the second calling party's digit, CD steps to position 8, Jd reoperates and signaling between the control circuit and the machine takes place as before.

Three more digits are received and at the end of the fifth digit CD steps to position ll. Earth via pil, ntl, cd1n3, tc3, camZ, psi, operates Jd in the junction circuit, Fig. 3.

The earth via pi-I, ntl, cdm3, this time passes direct to tc3 and not via resistance THR. In consequence when Jd, Fig. 3, energizes, the same earth via ril operates N which locks via M5 and wire 4 to earth on the machine. Ps, Fig. 3, operates via ac3, nil, 172, and locks via ps3, 102. Contacts psi release Jd.

Earth via nil, wire 3 causes the machine to step to position 22 in which earth is removed from wire 4 to release Nf, removing the earth which had been connected via nfl to wire 3.

Earth via wire 5 from the machine via :igl, 1116, '03, ydl energizes Ri. The right-hand operating winding of Ac is now short-circuited via ps4 operated, 1'1'5 operated, M3 in normal position and Ac releases.

Removal of battery on ac5 releases Te and Dt, Fig. 4. Relay Tc, Fig. 4, also releases followed by T Th, Pw. CD homes; CDM and its interrupter, tcl, cdml. The ticketing control circuit, Fig. 4, is now back to normal and ready for use in another call.

In the junction circuit, the release of A is followed by operation of Ar, via nsZ, ac6, wpl, 7'92. As is released at M4 and Jd is operated via mp2, arl, to ground on terminal 3 of CLC, connecting earth from es3, via M2, 1 13, to wire 3 in re-- sponse to which three minute-holes are punched by the machine in turn on the ticket, and the date, hour, and serial number are printed in turn, one with the punching of each minute hole.

Ri is released during these operations by removal of earth on wire 5, and W1), which no longer has a locking circuit via 10173 since Ac is released and Jd is operated, is released since its locking circuit via wp4, H2 is also opened. The junction circuit is no longer held busy by the ticketing machine, Jd also releases.

It will be remembered that JS started counting conversation time from position I, taking one step per 6 seconds or ten steps a minute. Earth via MS has maintained the counting circuit operative in place of cs2, Ar, being locked via ar2, i9

When JS reaches position I on its second rotation, earth via jg2, esl, ism2, ar6 operates relay Tm which looks via tml, 7'92.

JS has 22 positions, and its thirty-first step after position I on the first rotation determines the beginning of the fourth minute of conversation, that is, when it reaches position (7+31-22) IS on its second rotation. In this position, Wp

is reoperated via jl2,'tm4, jsm2, cs4, 7'02, followed by Jd via mp2, arl. R2 has been energized via wire after the three minutes have been recorded, and earth is again connected via cs3, y'di, 1113, to wire 3 to initiate recording of the fourth minute. Ri is released by the ticketing machine and when JS steps to position ll, Wp which has no locking circuit releases followed by Jd. When the fourth minute has been recorded and Jd has been released Ri is reoperated to earth on wire 5.

With Tm energized, JS steps to its first position immediately it reaches position 2|; J SM and its interrupter, t1n3, y'sm2, cs4, :ig2. Thus after passing position IS on the second rotation, J S only takes 20 steps per rotation at six second intervals, and the beginning of each additional minute occurs when JS reaches positions fi and 16 during each further rotation, the recording being caused by operation of Wp as before.

When the calling party hangs up at the end of conversation, Js is released followed by Jl. Earth at 1'! I is removed from the locking circuit of Ew. This earth is the holding earth for preceding equipment in the exchange. If a record is being made on the ticketing machine, earth via wpfi Will hold Ew and the connection until the record is completed.

When Ew is released, the preceding equipment also releases and removes earth from lead 0 so that Cw releases followed by the main hold relay Jg which releases all operated relays. Switch JS homes JSM and its interrupter, ysm3, 1'95. The junction circuit is now ready for use in another connection.

If the tariff to be charged in slack periods, e. g., at night, is different from that charged at other times, a relay Nt is provided and is operated from clock-controlled contacts via vtB to substitute wiper cdmZ for wiper cdm3 in the tariff-signaling circuits.

Referring now to Figs. 6 and 7, the identification start impulse over conductor SVL from the junction circuit used in a connection energizes relay Gs, Fig. 6, which in turn energize G1) in series (via r14) with relay Ci of an identification control circuit of the group controlled by a relay Gb. If all the circuits of this group were busy relay Ng would be operated to extend the start circuit to another group of identification control circuits. Vd now operates via 1203 and oil and causes V0 and D0 to energize. The circuit of Vd is opened at v03 and it releases slowly, 2000 cycle current is connected during the time Vd is energized via vd2, doll, primary of transformer DT, dofl to earth. The current induced in the secondary of DT causes anode current to flow in valve DV if the valve is functioning and relay Ar energizes. Relay Ok then operates via 12b2, arl. Vc has locked via vc3, oil, and Ole locks via ok3, winding of Vb to col. Vb operates.

It will be noted that the circuit via Vd was opened when Vc operated and a test of-the valve therefore takes place during the slow-release time of Vd. If the valve is defective and therefore Ar and Ole do not energize, Va will energize via back contact 12413, when Vd' releases, front contact 002, to back contact old. The opening of contacts va2 would release relay 0t and thereby release the control circuit. Relay Va will lock up over its right-hand winding and flash lamp BAL.

Assuming that the valve is functioning correctly, when Vd releases Ar and Do release.

Magnet IMM now operates via ot2, fh2, okl, arl and switch IM hunts for the group lines comprising the calling subscriber. When the 200 line group is found, high frequency signal current via the third wire of the subscriber line and the condenser connected thereto passes via the,

current induced in the secondary of DT valve DV conducting and relay Ar operates. Earth via front contacts of arl and vb2 passes via back contacts of (:15 to operate relay Bt. A direct current test relay Mt is now connected to test for double connections; earth, of I, mtm2, muml, rZl, high resistance winding of Mt, btl, Zt3, immll to test battery. If no otheridentification control circuit has stopped on the same outlet Mt will operate and look over its low resistance winding in series Md which also energizes.

Relay Dc was energized when Bt operated via bt2, fhd.

If due to a double test, Mt does not energize, magnet IMM reoperates via 0282, dcl mtl and the finder IM resumes its search. Assuming that Mt and Md operate, the low resistance ground via Md, Mt on wiper immll busies the selected outlet of the IM switches.

When Md energizes, magnet IFM is operated via mdZ, fhl, jtl and IF hunts for an idle final selector in the group marked by the position of IM. When a selector is found Ft energizes: earth, 0102, imml3, ifml, Ft, mdl, z'fmii and wire 2 to idle battery potential on the final selector (FS) 0 wire. The double test is performed by Ed and Pt and if IF is the only switch testing the final selector FS, Fd also operates followed by Fh to ot3 and Do to fhd. Contacts jh4 open the circuit of De which releases slowly.

Relay A1- which has been energized by the 2000 cycle current via IM is released by the operation of Do and Ai energizes via dol, af2, fh2, okl, arl. A locks via dol, M2 and energizes Ta via 0J4, zt2.

A fundamental circuit is now completed: earth, arl, okl, fh2, af3, Os, ifmZ, wire i, b Wire of final selector FS and a relay Fl therein (not shown). Relays Os, Fl energize. Earth via osl, usl energizes magnet MTM of the 11-point digit storage switch MT.

The operation of Fl in FS causes the trip spindle to rotate and send back revertive' impulses over the fundamental circuit, in response to each of which Os is released to step switch MT.

Earth via dod, primary of DT, 1102, usd, mtm3 is connected in turn to wires l-ili connecting the bank of mtm3 to wipers imml-immlEL When the imm wiperto which 2000 cycle potential is connected is reached, relay Ar reoperates, opening the fundamental circuit to stop FS and MT. Relay It now energizes via aj5, vbZ, arl, followed by Us via i252, aft

Contacts usl open the circuit of Ar which releases and again closes the fundamental circuit. Us locks via us3, afd, and It is released. The circuit of the primary winding of DT now passes via dOZ, us4 operated, 125 cycle filter, Zt2, wiper ijml, wire 3 to the final selector test wiper.

The release of Fl in FS advanced the sequence switch in known manner into the position for units selection and its reoperation on the reclosure of the fundamental circuit causes the brush carriage to rotate.

This time the revertive impulses are repeated by Os, via Osl, usl to magnet MUM of 22-point storage switch MU. When the brush carriage the final selector FS reaches the terminal to the c wire oi which 125 cycle potential is connected, Ar is operated, whereupon 0a and Fl in F8 are released and the brush carriage stops. The marker MU has made the same number of steps as the brush carriage of the final selector F8. Relay It is reoperated and contacts itl connect battery via ifml and lead 4 to operate a special relay in PS to suppress private branch exchange hunting. If the calling tone persists for sumcient time It will release slow-release relay Ta. This arrangement ensures that the brush carriage has stopped on a marked terminal, and has not been stopped by potential kicks produced by changes in the direct current conditions on a subscriber's c wire.

Earth via an, vbZ, a/S, usl, tal, energizes relay Lt.

The identification circuit has been held by the earth potentials supplied by contacts of 0t during the above operations.

During sending, earth via a 125-cycle filter is connected via USS, mtm3, 1mm wiper to the multiple point connection of the twenty marking wires including that of the calling line. This prevents low-frequency interference between the individual marking wires, while allowing an identification circuit to deal with another connection in the group.

If a premature release had taken place, Ot would have released the circuit, unless there is another call at the same time.

If a permature release occurs while the final selector brush carriage is hunting, and the identification circuit is held by another call, FS will not find a marked outlet on the selected level and switch MU will take 21 steps. Relay Rl is therefore energized via mum2, ltl. RI locks via r12 and releases 0t and the other relays. Relay X operates via interrupters of MTM, MUM, mtmZ, oil, and closes a circuit via :cl, mtml, for MTM. Relay X interacts with MTM and MT homes. Relay X then interacts with MUM and MU homes. Earth is then connected via afl, mtmZ, muml, rll to short-circuit and release Rl.

Assuming that the conversation continues,

relay Cw energizes via lt2, ifml, lead 3, and the 0 wire of F3, in parallel with the calling subscriber's cut-oil! relay, and earth via cwl, holds 01.. If release takes place during transmission of the calling party's number, Cw and 0t will release, and the identification circuit will return to normal.

The various digits are determined in the following way and are transmitted in well-known manner. In a six-digit area, the first two digits are known from the ofllce. These two invariable digits are sent in positions I and 2 of a sequence switch respectively.

The 1000s digit is determined by the position of IF, or in other words, by the group to which the engaged final selector belongs. The 's figure is a function of the position of IF and that of the marker MU. As known, one group of final selectors gives access to 200 subscribers (odd-even hundreds). In the case of even hundreds, MU has received maximum 10 impulses only, during the units selection, whereas in case of an odd hundreds the final has sent 10 impulses more.

The 10's digit is indicated by the position oi MT.

The units digit is sent under the control of MU.

What is claimed is:

1. In a telecommunication system, calling lines having marking terminals, two groups of identifying switches of which one group is 'used for terminating connections on said lines, means for imposing a test condition on the terminal of one of said calling lines, and means responsive to the presence of said test condition on said calling line for operating a switch in each of said groups of switches to connect with said terminal.

2. In a telecommunication system, calling lines arranged in groups having both group and line marking terminals, a group of switches for line group identification, a group of switches for line identification, said last-mentioned group of switches being also used for extending talking connections to said lines when called, means responsive to a calling line initiating'a call for imposing a test condition in the group terminal and the line terminal of said calling line, means for operating one of said line switches for locating the terminal of said calling line, and means for operating one of said group switches for locating the group terminal of said calling line before said line switch locates said calling line terminal.

3. In a telecommunication system, calling lines arranged in groups, each of said lines having a marking terminal, a group identifying switch and a line identifying switch accessible to said terminals, and a common test device associated with said group identifying switch for controlling the operation of said group identifying switch and of said line identifying switch when operated to locate the marking terminal ofa calling line, said line identifying switch also serving to complete talking connections to said lines when called.

4. In a telecommunication system, calling lines having marking terminals, a called line, a group switch, switching selectors for establishing a connection between one of said calling lines and said called line, means for imposing a test condition on the terminal of said calling line, and. means responsive to the presence of said test condition on said calling line for operating said group switch to locate the group in which said calling line belongs and one of said selectors to locate the marked terminal in said group belonging to said calling line.

5. In a telecommunication system, calling lines arranged in 'groupsand having marking terminals, called lines, a group identifying switch, final selectors for" completing connection between calling lines and called lines, means for imposing a test condition on the terminal of one of said calling lines, and means responsive to the presence of said test condition on the terminal of said calling line for operating said group switch to locate the group in which said calling line belongs and one of said final selectors to locate the marked terminal in said group which belongs to said calling line.

6. In a telecommunication system, calling lines arranged in groups having both group and line marking terminals, a first group switch having access to said group marking terminals, a group of connector'switches having access to said line marking terminals, and a second group switch for engaging a free connector switch in said group of connector switches to connect withthe line marking terminal of a calling line.

'7. In a telecommunication system, calling lines having group marking terminals and line marking terminals, a group switch, final connectors for establishing connections to said lines when called, means for imposing a test condition on the group marking terminal of a calling line, means for imposing a different test'condition on the line marking terminal of said calling line, means responsive to the presence of said test condition on the group marking terminal of said calling line for operating said group switch to locate said group marking terminal, means respon sive to the engagement of said terminal by said group switch for seizing one of said final connectors to locate the line marking terminal ofsaid calling line, and means responsive to the test condition on said line marking terminal for stopping the operation of said final connector.

8. In a telecommunication system, calling lines having group marking terminals and line marking terminals, a group switch, final connectors for establishing connections to said lines when called, means for imposing a test condition on the group marking terminal of a calling line, means for imposing a different test condition onthe line marking terminal of said calling line, means responsive to the presence of said test condition on the group marking terminal of said calling line for-operating said group switch to engage said group marking terminal, means responsive to the engagement of said terminal by said group switch for seizing one of said final connectors, and a counting circuit for selectively operating said final connector by revertive impulsesincluding means responsive to said test condition on the group marking terminal for causing said connector to select the group marked by said test condition and other means responsive to said different test condition on the line marking terminal for engaging the terminals of said line.

9. In a telecommunication system, calling lines arranged in groups having a marking terminal for each group and a marking terminal for each line, a group switch,'groups of final connectors having access, respectively. to each of said groups of lines, means for imposing a test condition on the group marking terminal of a calling line. 1

means for imposing another test condition on of connectors, and means responsive to said test condition and to said other test condition for'sclectively operating said connector to engage the .terminals of said calling line.

WEI-1AM HA'I'ION. LESLIE BAINES HAIGH. LADISLAS KOZMIA.

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