US2241896A - Telephone system - Google Patents

Description

May 13, 1941'. E. WOCHINGER TELEPHONE SYSTEM Filed Aug. 5, 1938 2 Sheets-Sheet 1 INVENTOR: EDUARD WOCHINGER I I l ATTORNEY? y 1941- E. WOCHINGER 2,241,896

TELEPHONE SYSTEM Filed Aug. 5, 1938 2 Sheets-Sheet 2 bit v INVENTOR: EDUARD WOCHINGER ATTORNEY.

vu D Ra to Patented May 13, 1941 UNITED STATES PATENT OFFICE TELEPHONE SYSTEM Verwaltung und eselang, near Berlin, Gerdes Gesellschaft fiir die Schutzrechten mit beschriinkter Haftung, Berlin, Germany Application August 5, 1938, Serial No. 223,208 In Germany August 17, 1937 9 Claims.

nation of length of conversation in such systems and this is attained in that with connections between sub-exchange subscribers which do not extend over the principal exchange switch means become effective at certain time intervals under the influence of a time Switch arranged in the connecting path, and send out information to a central set in the principal exchange over connections not included in the existing path.

The present invention attains special importance in semi-automatic telephone systems with small country centres, in which the connectionbetween sub-exchange subscribers are made by an operator. An advantage of this system over known arrangements consists in that after the making of such a connection and removal of the plug by the operator all connecting devices and lines not completely necessary for the conversation are free and available for other connections, thus the operator is also completely out off from the connection which she has just made.

The reckoning of the fees for such connections corresponding to the value is possible without any further means, since the operator can ascertainthe distance, i. e., the zone from the number of the calling and of the called subscriber. The subject of the present invention now permits in addition to a stepping off of the conversation, fees according to the duration of the conversation by transmitting time signals to the operator.

In the drawings an embodiment of the invention is shown. Fig. l is a trunking diagram for the five exchanges A, B, C, D and E, while Fig. 2 shows in detail the circuit arrangements in ex change C.

The principle of the invention can for example be used in systems with the network as shown in Fig. 1. Diagrammatically a small country centre is shown with the sub-exchange B, C, E

and a principal exchange A, in which latter, is

the operator, by whose aid connections for semiautomatic trafiic are made and supervised.

The principal exchange A with the operators position is connected with the sub-exchange connecting lines Ll, L2, L3. The connecting system VA in the principal exchange serves to make the connection with the operator over the connecting lines. In the operators position there is a lamp board with the signal lamps Zl, Z2, Z3, Z4 which are switched in by impulses from a sender over one of the lines Ll to L3 and taken up by one of the receivers El, E2, E3, E4 situated at the other end of this line.

The exchange B is assumed to be completely automatic. Subscribers who are connected to this exchange can therefore by means of an impulse series sent out from their selection dial, make the desired connection inside their own exchange without the help of the operator, and also make automatic connections with subscribers of other exchanges. Since in this automatic working the fee is determined in known manner with attention to the time by means of meters influenced by metering stepping on devices, in connections which proceed fromsubscribers of the exchange and sending out of time signals to the operator is not necessary. From the exchange B a connecting line L5 also extends to the exchange D While over line L4 the exchange C, and from this exchange over the connecting line L6 the subexchange E, can be reached.

The particular operations should now be considered which are made to transfer the time signals by means of the different possible connections.

.If, for example, a subscriber N2 of the exchange C wishes to make a connection with a subscriber of the automatic exchange B when the subscriber N2 lifts up his receiver and operates the crank, the call finder ASC is started up and sets itself on the calling subscriber. Over the transferrer UEC and the secondary line switch MWC the connecting line L4 is reached. From here the call is passed on over the transferrer UEBI of the exchange B and the connecting link VAI to the connecting line LI and to the connecting link VA in the principal exchange A. A call signal lies up in the operators position in known manner so that she is informed of the presence of a call. She connects herself with the calling subscriber and makes an enquiry. The operator then makes the connection to the desired subscriber NI of the exchange B so that the two subscribers are connected as follows: subscriber N2 of the said exchange C, call finder ASC, transferrer UEC, secondary line switch MWC, line L l, transferrer UEBI, group selector GW, line selector LW, subscriber Ni, devices for determining the particulars of the conversation and for sending out data for the purpose of transferring a time signal are situated for this connection in the transferrer UEBl. Here in dependence on a time switch a release relay is energized which stimulates the sender Si to send out the high frequency impulse over line Ll at definite times during the connection. The impulse is taken up by the receiver at the principal exchange A which brings about the connection of the corresponding signal line ZI. The operator has the conversation tickets to hand in a compartment by the lamp Zl, and can now draw up the conversation period and hence the value of the fee from the signal transmitted.

If an internal connection in the exchange C is required i. e., a subscriber N2 of this exchange wishes to speak with a subscriber N3 connected to the same exchange, then when the receiver at the callingset N2 has been lifted and the crank operated the same path is built up to the operator as in the first case. By the setting of the direction selector RWC in the exchange C and the line selector LWC by the sending out of determined impulse series by the operator the desired connection is then made. For sending out the time signal to the operator the time switch in the transferrer UEC now comes into efiect. At definite time intervals it stimulates the sender in the exchange C and the high frequency impulse is now sent over the connecting line L4 and the loop I) coupled with the connecting line L3. From the connecting line L3 the receiver E3 in the principal exchange A takes up the impulse and connects the corresponding signal lamp Z3. The operator can therefore register the conversation time for this connection on a ticket in the compartment situated by this lamp.

The coupling lead b as already mentioned connects the connecting line L4 with the connecting line L3. It is so constructed by the inclusion of frequency filters or the like that only the transmission of high frequency impulses is possible over this lead and not other switching operations so that disturbances by this lead in the connecting and speaking trafiic are avoided with certainty. If the subscriber of the exchange C wants to make a connection with the subscriber N1 of the sub-exchange E the connecting path extends after the connection has been made by the operator from the subscriber N2 over i the call finder ASC, transferrer UEC, direction selector RWC, connecting line L6, secondary line switch MWE, transferrer UEE, direction selector RWE, line selector LWE, subscriber N1. In the same-way as for internal connections between two subscribers of the exchange C the time switch in the transferrer UEC now comes into effect for these connections and stimulates the sender S3 to send out high frequency impulses at definite time intervals. The transferring of the high frequency impulses results in the same manner as for interval connections between subscribers of the exchange C.

If a subscriber of the exchange C wishes to make a connection with a subscriber of the exchange D the connection extends after the setting of the different connecting devices by the operator as follows: subscriber N2, call finder ASC', transferrer UEC, secondary line switch.

MWC, connecting line L4, transferrer 'UEBI,

definite intervals during the connection.

group selector GW, transferrer UEB2, connecting line L5, secondary line switch MWD of the sub exchange D, transferrer UED, direction selector RWD, line selector LWD, subscriber N5. In the same way as in a connection between a subscriber of the exchange set C with a subscriber of the exchange set B, the sender Si by means of time switches arranged in the transferrer UEBI is stimulated to send out high frequency impulses over the line Ll to the operator at definite time intervals. These impulses are taken up by the receiver El in the principal exchange and connect a signal lam 2! in normal manner.

If a subscriber of the sub-exchange E wishes to make a connection with a subscriber of the same exchanges, then after the subscriber N5 has initiated a connection and a connecting path to the operator: subscriber N 5, call finder ASE, transferrer UEE, secondary line switch MWE, connecting line L6, call finder ASC in the exchange C, transferrer UEC, secondary line switch MWC, connecting line L4, transferrer UEBI, connecting link VAI, connecting line Ll, connecting link VA in the principal exchange A, the operator sets the direction selector RWE and the line selector LWE- in the sub-exchange by sending out certain impulse series so that the subscriber N! has called and the speaking connection between the two subscribers in the sub-exchange E is made, The time impulse is now given to the operators position by means of a sender S4 which is stimulated by the time switch in the transferrer UEE of the sub-exchange E after The time impulse extends from the sender S4 over the connecting line Lt, coupling line 0 (this line 1 also has frequency filters which only permit the transferring of high frequency impulses) connecting line L l, coupling line b, connecting line L3, to the principal exchange A. The high frequency impulses sent out by the sender S4 extend therefore, from. exchange C in exactly the same way over the line L3 to the principal exchange as with internal connections over the exchange C. Since in both exchanges twoconnections can now exist at the same time the operator must receive different time signals. For this reason the sender S 'l sends a time signal with a difierent frequency to: that sent by the sender S3 in the exchange C. By means of the impulses sent out by the sender S4 with a different frequency over the connecting line L3, not the receiver E3 in the principal exchange, but the receiver E4 is influenced so that by it the lamp Z2 is connected corresponding to the time signal. By this lamp, therefore, the time signal is transferred to the operator by internal connections inside the sub-exchange E.

If the subscriber of the sub-exchange E wishes to speak with a subscriber of the exchange C the connection extends as follows after the setting of the selector in the exchange C by the operator: subscriber N6, call finder ASE, transferrer UEE, secondary line switch MWE, connecting line L6, call finder A in the exchange C, transferrer UEC, direction selector RWC, line selector LWC, subscriber N3. By this connection the time signal is passed through the sender S3 in the sub-exchange C and this is stimulated at definite time intervals by the time switch arranged in the transferrer UEC. The time impulses extend then from the sender S3 over connecting line L4, coupling line B, connecting line L3, receiver E3 in the principal exchange. By means of the receiver E3 the time signal is transmitted to the operator through the lamp Z3.

A connection from a subscriber of the subexchange E to a subscriber of the automatic exchange B extends in a similar manner to an already described connection from a subscriber of the exchange C to a subscriber of the exchange B. Time impulses are sent over the line Ll to the receiver El in the principal exchange through the sender SI of the exchange B which sender is stimulated by the time switch provided in the transferrer UEBI at definite time intervals to send out impulses. By means of the receiver El in the principal exchange A the signal lamp Zlis switched in.

Also in a connection from a subscriber of the sub-exchange E to a subscriber of the sub-exchange D, the sending out of time impulses follows in the same way through the sender SI working together with the time switch arranged in the transferrer UEBI. When the dial impulses have been sent out by the operator such a connection extends as follows: subscriber N6, call finder ASE in the sub-exchange E, transferrer UEE, secondary line switch MWE, connecting line L6, call finder ASC in the exchange C, transferrer UEC, secondary line switch MWC, connecting line L4, transferrer UEBI in the exchange B, group selector GW, transferrer UEBZ, connecting line L5, secondary line'switch MWD of the sub-exchange D, transferrer UED, direction selector RWD, line selector LWD, subscriber N5.

Finally the operations for connections going out from the subscribers of the sub-exchange D should be mentioned. If a subscriber of a subexchange D wishes to make a connection with a subscriber of the automatic exchange B then after initiating the connection he reaches the operator by the following path: subscriber N4, call finder ASD, transferrer UE D, secondary line switch MWD, connecting line L5, transferrer UEB2, connecting link VA2, connecting line L2, connecting link VA of the principal exchange A. After the setting of the connecting devices by the operator the connection exists as follows: subscriber N4, call finder ASD, transferrer UED, secondary line switch MWD, connecting line L5, transferrer UEB2', group selector GW, line selector LW, subscriber NI Over this connection the time impulses are transferred to the operator by means of the sender S2 which is stimulated to send out impulses at definite time intervals by means of a time switch arranged in the transferrer UEB2. The time impulses pass from the sender S2 over the connecting line L2 and are taken up by the receiver E2 which connects the signals to the operator by lighting up the signal lamp 2.

I If a subscriber of the sub-exchange D wishes to make a connection with a subscriber of the subexchange C, this connection after the setting of the connecting devices concerned by means of the operator exists as follows: subscriber N4, call finder ASD in the sub-exchange D, transferrer UED, secondary line switch MWD, connecting line L5, transferrer UEB2, group selector GW,

transferrer UEBI, connecting line L4, secondary line switch MWC in the sub-exchange C, transferrer UEC, direction selector RWC, line selector LWC, subscriber N3. By means of this connection as in the preceding the time signal is sent out by the sender S2 to the operators position and the sender S2 is stimulated to send out impulses at definite time intervals by means of the time switch arranged in the transferrer UEB2.

A connection from a subscriber of the subexchange D to a subscriber of the sub-exchange E extends in similar manner to the connections described above. Also in this connection the time signal is transferred in the same way by means of a sender S2 over the connecting line L2 to the operator.

If several links are present in the same exchange several connections can exist at the same time, or if several connecting lines pass between two exchanges, and between these exchanges several connections can be made at the same time, it is thus not only necessary to have a sender with different frequency for each link but also to acquaint the operator with the manner in which the signal lamps and connections are related. For this purpose the individual links are so made that at the reply of the desired set and withdrawal of the plug the corresponding sender is stimulated to send out a signal impulse. At the operators position, therefore, after the withdrawal of the plug a lamp immediately lights up so that the operator knows that by means of this lamp the directly made connection is supervised with regard to the conversation length.

For the rest it should be recommended that this starting impulse should be transmitted to the operator every time in order to save her from mental work and avoid error.

In Fig. 2 part of the exchange C is shown in detail, i. e., part surrounded by dotted lines.

After the initiating of the connection by a calling subscriber of this exchange i. e., after the receiver is removed and the crank operated, a call relay AN, not shown, is energized and-connects the relay N over: earth, contacts wan, 20p, winding of the relay N, battery, earth. The relay N operates two contacts 8n and ZI-n which are so arranged that the contact 8n is closed somewhat before the contact 2ln. When the call finder AS stands on the contact on which the calling line is connected the test relay P immediately operates and by opening the contact 20p prevents the call finder from moving any further. If this is not the case, however, by means of contact 2111. the circuit for the magnet Da of the call finder is closed: earth, contact Klan, 20p, 2 In, 231', magnet Da, battery, earth. The magnet at Da has a contact 22da after the operation of which relay R is connected over resistance Wz'5. Relay R opens at contact 231', the circuit indicated above for the magnet Da so that the contact 221111 is closed and a short-circuit thus made for the winding of the relay R. The contact 231' istherefore closed after a short while so that the magnet Da of the call finder is again connected. The interplay between the magnet Da and the relay R continues until the call finder has found the calling connecting line and the following circuit is made: earth, wiper dz5 in its rest position, contacts 90, 8n, windings II and I of relay P, wiper da3, lead 0, and battery, which is not shown. The relay P operates in this circuit. stops the call finder by opening the contact 2111), locks the calling line by disconnecting its high resistance winding II at the contact 1p, and

switches through the speaking leads by closing its contacts lp and 2p. By the opening of contact 20p the relay N releases. The relay P further closes its contact 4513 and connects the lead 02 with battery. In this way the secondary line switch MWC (Fig. 1) is started up and comes to a stop when the leads a2, b2 and 02 have been found. Over connecting line L4 and devices of the sub-exchange B and line Ll the connection to the to lift up his receiver).

operator in the principal exchange A is now made in the. known manner. By means of a signal the operator is made aware of the presence of a call while a signal is also transmitted to the calling subscriber over lead a2 and the condenser Col and 002, contacts 5p, 3k, Ip, wiper dal. The operator now enters the connection'inthat she puts the plug in the call jack so that at the same time a battery potential is laid on the lead a2 and the relay I operates.

If the calling subscriber has given the calling impulse by turning the crank, without lifting his receiver, the relay Y is not energized, consequently the contact 46y is open and thus the battery is not connected to the lead b2 over contact 397th, resistance WiB, (the connection of the battery over Wit? at this moment would connect a signal to the operator from which she would recognize that the calling subscriber is waiting The operator may now call the subscriber desiring the connection. She operates the call key and thus sets the battery to the lead b2; in this way the relay E is energized over contact My. By the closing of the contact IllSe the following circuit is made for the relay W: earth, contact lllfie, winding of the relay W, resistance WiS, battery, earth. By closing of the contact 3320 the call machine RM is connected to the line I) lead to the subscriber by which the calling devices at the subscribers set is operated. When the subscriber lifts his receiver the following circuit is made: earth, battery, resistance WM, winding of the relay X, contact 282', 47c, 37c, lp, wiper dal, lead a, subscribers loop, lead I), wiper da2, contacts 2p, 6k, 32w, 36c, winding of the relay Y, earth. In this circuit the relays X and Y operate. I'fthe subscriber has lifted his receiver during the sending out of the call this circuit cannot be made since the contact 33w is closed thus relay X alone operates and by closing itscontact 188x makes a shortcircuit for the winding of the relay W. Relay W therefore releases immediately so that by the closing of the contact 32w the relay Y is also connected. The relay Y closes its contact 431/ and 1 thus lays battery potential over contact 397% and resistance Will to thelead b2 connected to the operators position. In this way the operator receives a signal which makes her aware of the reply of the subscriber. closed a circuit for the relay C by closing its contact Eli: earth, contact Elli, winding of relay C, resistance Will, battery, earth. The relay C closes a holding circuit for itself at contact 550.

Therefore it makes the energizing circuit for relay P (Winding I) independently of the setting of the wiper ($25 of the time switch.

The operator now makes an inquiry to the subscriber and sends out an impulse series affecting the relay I by which if an internal connection, i. e., the connection with a subscriber of the same exchange is required, the direction selector RWC consisting of an auxiliary selector (with a magnet De) and the principal selector (with the magnet Dh) is set on the leads 0.3, 123, c3. The:

The relay I has contact 550.

a eless selector has a contact 43de by means of which the relay His connected: earth, contact 43de, winding of the relay H, battery, earth. At the end of the first impulse and repeated energizing of relay I the following circuit for the relay K is made: earth, contacts 731', 12h, winding of the relay-K, battery, earth. RelayK opens its contacts 3k, 4k, 6k, whereby the speaking leads are interrupted and relays X and Y are released. After the release of the relay Y the following holding circuit for the relay K is closed: earth, contact 690, wiper rid, the first two contacts set on one another (setting of De on these con tacts only by local subscribers), winding I of the relay Kh, contacts Mk, I ly, winding of the relay K, battery, earth. In this circuit the relay Kh also operates.

At the end of the impulse series the relay I remains energized for some time, so that-with the contact 861' remaining open, relay VI as well as relay V is released. After the release of relay VI the following circuit is made for the magnets of the principal selector Dh: earth, battery, magnet Dh, contacts H370, Ht'vl, wiper (263 in its working position, wiper (M5 in its rest position, contacts Illlh, 54m, earth. By means of the contact l ldh of the magnet Dh the relay H is switched in and interrupts the above-mentioned circuit for Dh at the contact Hllh. In this way the contact 441th is opened again and relay H is released. By the closing of the contact Him a circuit for the magnet Dh is closed again, now over the following path: earth, contacts 54121, llllh, wiper dhE in its operated position, magnet Dh, battery, earth. The alternate play between the magnet D71. and the relay H continues until a free lead 03 has been found and the wiper dhd has been set on the contact, over which earth potential is connected by means of wiper del and Then the following test circuit is mader'earth, contact 550, wiper del and wiper dhd in its fixed position, winding I of the relay PI, wiper dh3, lead 03 and battery. The relay P] by closing its contact Eilpl locks itself in the following circuit: earth, battery, winding II of the relay Pl, contact Ellpl, wipers (m4 and de! in their fixed'positions, contact 55c, earth. By the closing of the contact 49p! direct earth potential is layed to the lead 03 over contact 550 and thus the subsequently arranged connecting device seized is locked against any other seizing.

The operator now sends out impulse series to set the following line selectors, by which impulses the relay I is impulsively energized, and which impulses are transferred to the line selector over contact 282 and the lead a3. A further influencing of the magnets De and Dh is not possible since the contact 5410! is open. Should the line selector be set on the desired subscriber, calling current is sent out to him in the following manner: by the closing of the contact 53p! the following circuit is closed. for the relay F: earth, contacts 53101, 52x, Moi, winding of the relay F, battery, earth. The relay F closes its contact I64 and thus makes a circuit for the magnet Dz of the time switch: earth, contacts IiMf, 99kh, 102M, I832, magnet Dz, battery, earth. The

magnet De moves its wipers rial-(Z25 forward by one step. At the same time it closes its contact Hilde and thus the following circuit for the relay Z: earth, contact illld'z, winding of the relay Z, resistance Wi'l, battery, earth. The relay Z interrupts at the contact I032 the circuit for the'magnet D2, so that this restores.- The following holding circuit is closed for the relay Z:

earth, battery, resistance Wi'I, winding of the relay Z, contacts 962', 91th, 997th, I041, earth. By the closing of the contact 922, the following circuit is closed for the relay RI :'earth,'battery, Winding of the relay RI, contacts 922, lls,'99kh, I04 earth. The relay RI closes its contact I 0071 and thus makes a short-circuit for the winding of the relay Z, which releases and also by opening its contact 92.2 brings the relay RI to release. The circuit indicated above for the magnet D2 is now closed again by contact I032, so that a further stepping on of the wiper takes place. The magnet Dz and the relays Z and RI form an interrupting device by which the wipers of the magnet D2 are stepped on in a stepwise fashion. Each time the wiper dz2 reaches the contacts connected with one another the following circuit is closed for the relay W: earth, wiper dz2, contacts connected with one another, contact I01 winding of the relay W, resistance Wit, battery, earth. The relay W closes its contact 33w and thus lays calling current to the lead b3 leading to the desired subscriber whereby his calling device is operated.

When the called subscriber replies a circuit is made for the relays X and Y over his loop: earth, battery, resistance Wi l, winding of the relay X, contacts 281', pl, wiper dhI, leado3, loop over the called subscriber, lead 193, wiper dhZ, contacts 48pI, 32w, 36c, winding of the relay Y, earth. If the subscriber has replied directly during the laying on or the calling current only relay X operates, and by closing its contact I081: makes a short-circuit for the relay W and stops the sending out of the calling current, at the contact 32w; on the closing of the contact the relay Y then operates. By the opening of the contact My the above mentioned holding circuit for the relay K is opened so that by the closing of the contacts 370, 47c and 67s the speaking leads are switched through and the conversation between the two subscribers can begin. Relay F is brought to release by the opening of the contact 523:, so that an influencing of the magnet Dz in the described manner can no longer result by the interruptions at the contact IMf.

If at the time of replying of the called subscriber the wiper of the magnet Dz was not in the rest position, then, by the opening of the contact 'IIy, the relay Kh, which, as has previously been indicated is energized together with the relay K, does not release, since it has closed for itself the following holding circuit: earth, wiper (123 in its operated position, contact 467th, winding II of relay Kh, battery, earth. As a result the contact 931th. is closed so that earth is layed to the wiper de l. As a consequence the following circuit is made for the magnet De: earth, battery, magnetDz, contacts I032, I02rI, II -is, 9Ie, wiper dad in it's operated position, contact 937th, earth. By the closing of the contact Illldz a previously mentioned circuit fol-the relay Z is closed, so that by the opening of the contact 1032 the above mentioned circuit for the relay D2 is opened. By the opening of the contact IUIdz the relay Z is again deprived of current, so that by the closing of the contact Ill3z the magnet D2 is again switched in. In this way by means of the magnet Dz the wipers of the time switch are stepped on, and actually more quickly than previously since the relay RI does not now come in. The play between the magnet D2 and the relay Z continues until the wipers of the magnet Dz have reached their rest position. Then the holding circuit for the winding II of the relay Khl is opened at the wipers 1123, so that this releases and among other things opens its contact 937th and, by disconnection of earth potential from the wiper de i a further influencing of D2 is prevented. The relay Kh. has further closed its contact 397071.. In this way, over contacts 40y, 391th and resistance Wi9, battery potential is layed to the lead b2 leading to the operators position, and hence a signal is connected at the working position from which the operator recognizes that the speaking connection between the subscribers is made. Hence she withdraws the plug from the jack, so that the relay I is brought to release. Thus the relays V and VI operate again over contacts 662' and 650. Then the following circuit arises for the relay S: earth, contacts ZBpI, 2611,2411, winding of the relay S, battery, earth.

The conversation metering now begins, for which the switch mechanism D2: is used again. After the opera-tion of the relay S the following circuit is made for the magnet Dz: earth, contacts 690, 94s, 91th., IIl2rI, I032, magnet Dz, battery, earth. The switch mechanism De thus switches its wiper to the first contact. At the contact IIlIdz the relay Z is again connected, and interrupts the circuit indicated above for De at the contact Ill-32. Hilde does not bring about, however, the release of the relay Z, since this has in the meanwhile locked itself in the following circuit: earth, battery, resistance Wi'I, winding of the relay Z, contacts 962, 948, 59c, earth. At the same time the contact 882 is closed and thus a thermo-relay Th. is heated. After some time the contact 98th. is closed, whereby a short circuit is made for the Winding of the relay Z over contact 98th. The

relay Z thus releases and opens the circuit for the thermo-relay at the contact 682. After a definite cooling off period the contact 91th is closed again and thus the circuit mentioned above for the magnet D2 is closed again. The resistance ratio in the above-mentioned switch mechanism is so arranged that the interval between the individual steps should amount to about one minute. The wiper dzl is therefore brought to the fourth contact when the conversation has lasted 3 minutes. The following circuit then exists for the relay AR: earth, contact Ms, wiper dzl on contact 4, contact 15hr, of an auxiliary relay HR, winding of the relay AR, battery, earth. By the closing of the contact I8ar there follows the laying of earth potential to the lead going to the sender S3 for the first time. The sender is induced for the first time to send a high frequency impulse over the connecting leads LI and L3 (Fig. 1) to the operators position in the principal exchange, which is taken up by the receiver E3 and the signal lamp Z3 thus switched in. The operator recognizes that the internal conversation in the exchange C has lasted more than the 3-minute limit. She notes it down on the conversation form which is in the compartment corresponding to the lamp Z3.

The laying of earth to the lead passing to the sender S3 through contact I800 lasts only for a short time. On the energizing of the relay AR the contact liar and thus the following circuit for the auxiliary relay HR is also closed: earth, contact Ms, wiper dzl on contact 4, contact Tim, winding of the relay HR, battery, earth. The relay HR locks itself in a holding circuit so long as the wiper dal rests on the contact 4 (i. e., one minute), by closing its contact 16hr. By the opening of the contact 15hr the energizing cir- The opening of the contact operator.

cuit for the relay AB is opened and thus at contact l8wr the impulse 'for the sender S3 is com-' pleted.

The same operations take place when after 3 minutes the wiper dzl reaches the contact 1 and after further time intervals the contacts In and I3. The operator thus receives the time signal at intervals of 3 minutes and can thus note the duration of the conversation and subsequently determine the fee for the conversation on the reckoning form.

- minute from step i of the time switch onwards.

If for reasons given earlier it is necessary to send out impulses immediately after the reply of the called subscriber, in'order for the purpose of eliminating cases of doubt to indicate at once to the operator the signal lamp, which allows her to supervise the time of,the connection which has just been made, then the contact! of the contact bank of the time switch must also be wired, so that immediately after the stepping on of the wiper dzl to the first contact there results a sending out of impulses to the Also a forced separation of the connection is arranged after the lapse of a certain period, namely if the wipers (125 have reached the contact I3, i. e., the conversation has lasted 12 minutes, a short circuit is made for the relay Y so that it releases. The release of the relay Y initiates the release, which then occurs if before the expiration of the 12 minutes the connected subscriber gives the clearing signal. On the release of the relay Y the contact 25y opens the circuit for the relay S which immediately releases. By the closing of the contact 585a short-circuit for the winding of the relay C is formed over the contact 571) still closed, s'o'that this restores.

It opens its contact Hlc over which the relay P would be maintained energized on the stepping of the wiper (Z25 from its rest position, so that now "the relay P is brought 'to release. By the opening of the contact 55c the holding circuit for the relay PI is also opened so that this releases. For the magnet Dh the following circuit is closed: earth, contact 53111, 'Hfih, wiper (171.5 in its operated position, magnet Dh, battery, earth. The magnet Dh operates its contact db and thus closes a circuit for the relay H, which operates and at the contact Hilh interrupts the circuit indicated above for Dh. By opening the contact d ldh the relay H is disconnected, so that by the closing of the contact I Hlh the magnet Dh is energized again. In this waythe wipers of Dh are stepped on to their rest position. Then the following circuit exists for the magnet De: earth, contacts "5410!, mm, wiper 11715 in its rest position, wiper de3 in its operated position, contact I I I0, magnet De, battery, earth. Also this magnet with the aid of its contact 43de acts together with the relay H as an interrupter and switches its wipers to the rest position. Then the following. circuit is made forthe magnet Dz: earth, contacts '54171,

Huh, wipers ens, see, both in their rest position, wiper dad in its operated position, contacts 9lz, 5s, IHZ I, I032, magnet Dz, battery, earth."

selector D6 is set in another manner and'actually' the wiper (262 sets itself on the last two contacts to which the resistanc'e'WiHl is connected. The principal selector Dh sets itself then on the direction given by the auxiliary selector De, so that the wipers 'dhldh3 are set on the leads at, b4, 04, and thus on the connecting lines L6. The operator by sending out further impulse series sets the connecting devices of the subexchange E in such a' manner that the desired subscriber N! is reached over the line selector LWE '(Fig. 1).

When the required subscriber replies, the relays and Y operate in the manner described and in the same way as already described there begins the transferring of the time signal to the operator's position, in that the time switch Dz'of' the exchange C dispatches impulses to the sender at definite conversation time intervals,

which brings about the connection of the signal lamp Z3 at the operators position by sending out high frequency impulses over the connecting lines L4 and L3.

The release of the-connection follows in man-- her already described. I

A difference in the method of working to that in the previously described exchange connection consists only in that the relay causing the call sending at the contact 931th remains uninfluenced, since in this case the sending out of calling current is controlled by devices of the required exchange.

As. previously described connections from asubscriber of the sub-exchange to a subscriber of thesub-exchange C are supervisedas regards time by the time switch in the exchangeC.

In such'connections the calling subscriber N6 reachesover the call finder ASE, the transferrer UEE, the secondary line switch MWE, connecting "line L8 to the call finder ASC of the subexchange'C, where the call relay AN, not shown, operates and closes its contact 191m. The call finder is stepped on in the decribed manner until it has been set'on the leads a-l, bl, cl.

Calling of the operator, 'buildingof the con nection, calling of the required subscriber, etc., results in the manner already described. The direction selector RWC is set in the same "way as describedf'or local connections, i. e., the wiper 1162 of the auxiliary selector is broughtto a con tact on which the winding I of the relay Kh is connected.

The making of the conversation connection results in the manner already described, as also the indicating of the'time signal to the operator in the main exchange and the release of the co'nnecting'path. 1

Should the requirement be satisfied that en internal-connections no supervision as regards timebe undertaken but onlyon connections 'between subscribers of difierent exchanges, devices must be provided which difierentiate between internal connections and prevent the sending out of time signals to the operator at the main exchange in the case of internal connections.

In Fig, 2a such an additional arrangement is shown. In addition to the devices represented in Fig. 2 an additional wiper da l of the call finder A50 is here necessary and de l of the auxiliary selector De. These two Wipers are situated with their specially wired contact banks between the contact 15hr and the impulse relay AR. A circuit for the relay AR can only be made with a definite setting of the wipers dal and de l.

For internal connections, therefore, inside the exchange C, the wipers dad may rest, for example, on one of the contacts I or 2. For the impulse relay AR no circuit can be made, so that the sending out of time signals is suppressed.

If a subscriber of the exchange E calls a subscriber of the exchange C, the wiper (1:14 of the call finder ASC stands on the contact 5 which by the action of the wiper de l stands in direct connection with the impulse relay AR. Therefore, the sending out of time signals takes place.

If a subscriber of the exchange C calls and if he is connected with a subscriber of the exchange E, the wiper dad rests on the contact 3 and the wiper (led on one of the contacts 3 or 4. Over these contact settings an influencing of the impulse relay is possible so that with such a connection also a time signalling is undertaken.

What is claimed is:

1. In a measured service telephone system, a local exchange, a calling subscribers line and a called subscribers line each terminating at said exchange, a local connection in said exchange joining said two lines for conversation, a distant exchange, an inter-exchange connection between said distant exchange and said local exchange, and means in said distant exchange operated variably over said inter-exchange connection in dependence upon the length of time said local connection is maintained in said local exchange.

2. In a measured service telephone system, a first exchange, a second exchange, an inter-exchange connection between the exchanges, a pair of subscribers lines terminating at the first exchange, a local connection in the first exchange joining said lines for conversation, and timing means in said first exchange operated to transmit to said second exchange over said inter-exchange connection a timing signal for each unit period of time that said local connection is maintained.

3. In a measured service telephone system, a first exchange, a second exchange, a calling subscribers line terminating at the first exchange, a called subscribers line terminating at the second exchange, means for completing a connection between said lines, a third exchange not included in said connection, an auxiliary connection between said third exchange and one of said first two exchanges, and means in said third exchange controlled over said auxiliary connection in accordance with the length of time that said connection between the subscribers lines is maintained.

4. In a measured service telephone system, a first exchange, a second exchange, a calling subscribers line terminating at the first exchange, a called subscribers line terminating at the second exchange, means operated to complete a connection between said lines, a third exchange not included in said connection, an auxiliary connection between said third exchange and. one of said first two exchanges, and timing means associated with said connection between the subscribers lines effective to transmit to said third exchange over said auxiliary connection a timing signal for each unit period of time that said connection between the subscribers lines is maintained.

5. In a telephone system, two exchanges, subscribers lines terminating at the first exchange, an operators position at the second exchange, means controlled over a calling one of said subscribers lines for extending a connection to said operators position, means controlled by the operator at said position for completing a connection local to said first exchange between said calling line and the line of a called one of said subscribers, and timing means associated with said local connection thereafter operated to transmit to said operators position a timing signal for each unit period of time that said local connection is maintained.

6. In a telephone system, three exchanges interconnected by trunk lines, a calling subscribers line terminating at the first exchange, 2. called subscribers line terminating at the second exchange, an operators position in the third exchange, means controlled over certain of said trunk lines by the operator at said position for completing between the lines of said subscribers a connection which does not pass through said third exchange, and timing means associated with said connection for transmitting to said operators position over certain of said trunk lines a timing signal for each unit of time that said connection is maintained.

'7. In a telephone system, two exchanges, an operators position at the first exchange, subscribers lines terminating at the second exchange, an inter-exchange trunk line, a plurality of link circuits in the second exchange each controlled by the operator at said position over said trunk line to complete a local connection between the lines of a calling one of said subscribers and a called one of said subscribers, and timing means individual to each of said links for causing a timing signal characteristic of that link to be transmitted to said operators position over said trunk line for each unit period of time that the connection over that link i maintained.

8. In a telephone system, two exchanges, a calling subscribers line terminating at the first exchange, an operators position at the second exchange, means controlled over said calling line at times for extending a connection to said operators position, means controlled by the operator at said position for completing at difierent ones of said times from the line of said subscriber talking connections of different classes which do not pass through or terminate in said second exchange, and timing means associated with each of said talking connections for transmitting to said operators position,'for each unit period of time that the connection is maintained, a signal characteristic of the class of said connection.

9. A telephone system as claimed in claim 8, having a plurality of inter-exchange trunk lines terminating at the second exchange, and wherein the signals corresponding to different classes of connections are transmitted to the operator at the second exchange over different ones of said trunk lines.

EDUARD WOCHINGER,

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