US2225648A

US2225648A - Printing telegraph system

Info

Publication number: US2225648A
Application number: US310504A
Authority: US
Inventors: George A Locke
Original assignee: Bell Telephone Laboratories Inc
Current assignee: AT&T Corp
Priority date: 1939-12-22
Filing date: 1939-12-22
Publication date: 1940-12-24
Anticipated expiration: 1957-12-24

Description

Dec. 24, 1940. G. A. LocKE I PRINTING TELEGRAPH SYSTEM Filed Dec. 22, 1939 V 2 Sheets-Sheet 1 e r .ql

/NvE/vroR G. A. LOC/(E By Z 0l ATToR/vfr Dec. 24, 1940. G, A. LocKE PRINTING TELEGRAPH SYSTEM l Filed DSC. 22. 1959 2 Sheets-Sheet 2 MON illwml,

/NVEN TOR G. A L OCKE Bj www HQQN Y A T TORNE Y Patented Dec. 24, 1940 UNITED STATES PATENT OFFICE PRINTING TELEGRAPH SYSTEM Application December 22, 1939, Serial No. 310,504

7 Claims.

This invention relates to a communication system for transmitting signaling impulses vover telegraph lines or channel of toll lines and more particularly to a telegraph system for connecting an outlying telegraph subscribers station to a central switching oice over a telegraph line or channel.

A telegraph ssytem of this character permits the extension of telegraph lines, each of which may be connected to a plurality of subscribers stations.

An object of the invention is to permit one of a plurality of subscribers stations to be connected to a line extending to a repeater station which in turn is connected to a telegraph exchange oiiice.

Another object of the invention is to lock out, or prevent, a subscribers station from using a line when another subscribers station is operatively connected to the same line.

According to the present invention, two or more subscribers telegraph stations may be connected to a relay arrangement located in a switching center at a local telephone central ofce, the switching arrangement being connected to a toll line extension circuit that extends to one or more repeater stations connected to a distant telegraph exchange oflice. The relay arrangement is controled either over a line circuit which extends from a repeater station, or from either of the subscribers stations, dep-ending upon the direction in which the call originates. The relay arrangement at a local telephone central oiiice provides a combination of relay operated circuits whereby the subscriber at one station is prevented from establishing a connection to the exchange ciiice when the other station is busy.

A feature of the invention is locating the switching equipment at a local telephone central cnice for maintenance purposes.

Another feature is the provision of lock-out relays in the switching arrangement for preventing one subscribers station from seizing a line when the line is engaged by another subscribers station.

The invention will now be described with respect to the accompanying drawings which illustrate the telegraph exchange system to which an embodiment of the invention may be satis- 'factorily adapted. The drawings are arranged into two gures:

Fig. 1 shows a distant telegraph exchange cf.- fice connected on one side to a single telegraph subscribers station and on the other side to a toll line extension circuit extending through a repeater at a distant point and a single conductor line outgoing to a telephone central cnice.

Fig. 2 shows the switching arrangement at a local telephone central oice whereat the single conductor line terminates, and two subscribers lines connected thereto vand extending to their respective subscribers stations.

Referring to Fig; 1 of the drawings, a subscribers teletypewriter set at station A comprising the transmitting contacts |02 and printer magnet |03 of a teletypewriter is connected over a line |04 which terminates in jack |05 of the subscribers line circuit equipment at the teletypewriter exchange cnice. The equipment vat the subscribers station A and at the termination of the line may be similar to that shown in Fig. 5 of U. S. Patent 2,143,000 granted to W. W. Cramer et al. on January 10, 1939. Line |04 may be one of a plurality, as shown, terminating at the switchboard at the teletypewriter exchange.

By means of the operators cord circiut |08, the operators position circuit |01 and jack |08, the subscribers line |04 may be extended over a toll line extension` circuit, the toll line extension circuit including jack |08, together lwith the terminating equipment adjacent thereto, repeater |09 and toll line ||0. The repeater |00 may be located at a point distant from the exchange cnice. The operatcrs cord circuit |06 and the operators position circuit |01 may be similar to those shown in Figs. 3 and 4, respectively, of U. S. Patent 2,143,000, supra. The terminating equipment connected to jack |08 at the exchange office may be similar to Fig. 8 or U. S. Patent 2,143,000, supra. The repeater |09 may be similar to the left side of Fig. 7 of U. S. Patent 2,143,000, supra.

The toll line ||0 terminates in two parallel paths 20| and'20l for preparing connections to one or the other of the transmission circuits which respectively extend to the subscribers station X and Y. The toll line extends also through the winding of relay J, contact and inner left armature of relay 203', inner left armature and contact of relay 203, condenser C to ground.

The ringing current generally applied at the switchboard at the distant teletypewriter exchange oiiice when a connection is established, operates the alternating current relay J. Relay J, upon operating, closes an obvious operating circuit for relay R. Relay R operates and thereby, over its left armature and contact, applies ringing current from ringing generator RG to message line 204 and over its right armature and Contact applies ringing current from the same generator to message line 204. Code ringing, which is well known in the telephone art, is employed, that is, one pulse ci ringing current is transmitted to call the subscriber at station X and two pulses to call the subscriber at station Y. The equipment at stations X and Y are identical. A description of the equipment at station X will suffice for a description of that at station Y. Corresponding parts of the equipment located'at the local telephone central office and at stations X and Y will hereinafter be designated by like reference characters, except that the parts associated with and located at station Y will be further designated by prime marks.

Relays J and R'successively respond to the ringing current transmitted from the switchboardat the distant teletypewriter exchange oice and relay R, in turn, supplies ringing current locally to both subscribers stations. X and Y. Assume that one pulse only of the ringing current is received. The subscriber at station X answers by turning on power switch 205 to close a circuit extending from ground through the winding of alternating current relay 201, control wire 206, through the winding of relay 202, right armature and back contact of relay 203 to grounded battery 2|2'. Relays 201 and -202 operate. Relay 201, upon operating, causes lamp 208 to light indicating to the subscriber at station X that a circuit through the local telephone central ofdce has been obtained. Relay 202, upon operating, closes an obvious operating circuit for relay 203. Relay 203, upon operating, opens at its inner left armature and contact the incoming ringing current circuit forv operating relay J and connects at its outer left armature and contact the message line wire 204 -to the toll line IIO. Also relay 203, upon operating, closes at both of its right front contacts, a circuit extending from grounded ringing generator RG, conductor 209, the two right front contacts of relay 203, conductors 2|0' and 206', through the winding of alternating current relay 201', condenser 2| I to ground. Relay 201 operates to cause lamp 208 to operate indicating to the subscriber at station Y that toll line I I0 is busy.

A lock-out feature is provided by relay 203 which, upon operating, opens at its right armature and back Contact the operating circuit for relay 202 and therefore the subscriber at station Y cannot seize the toll line I I0 because relay 203 cannot operate to provide a transmission path. The subscribers teletypewriters at stations X and Y at which the message line wires 204 'and 204V respectively terminate are ofthe type disclosed in Fig. 1 of U. S. Patent No. 2,143,000, supra.

METHOD or OPERATION Subscribers station originates a connection The system will now be described from the viewpoint of originating a call at station X. The subscriber at station X operates the power switch 205 -to thereby close a circuit hereinbefore traced for

operating relays

202 and 201. Relay 202, upon operating, operates relay 203 and operates and closes at its upper left armature and contact, a connection between the message line wire 204 and toll line H0 whereby a line lamp (not shown) associated with line I-I0 is lighted at the switchboard at the distant teletypewriter exchange ofce. The lighting of aline lamp in `a switchboard at a teletypewriter exchange office is well known in the telephone art and is accomplished in the same manner as with single party operation or as shown and described in U. S. Patent 2,143,000, supra. Also relay 202 operates to there- -by close an obvious operating circuit for slow release relay 203. Relay 203 operates and at its right front contacts closes a circuit from grounded ringing generator RG, conductor 209, the two right front contacts of relay 203, conductors 210 and 206', through the winding of alternating current relay 201', condenser 2l I to ground. Relay 201' operates and lamp 208', in turn, lights to indicate to the subscriber at station Y that toll line IIO is connected t-o subscribers station X. In addition to the busy lamp, such as that designated 208' at station Y, the idle subscribers station, such as station Y in this case, is prevented or locked out from establishing a connection by the disconnection of the grounded battery, such as that designated 2|2, from the start circuit closed by the operation of the power switch at the idle station.

The operator at the distant teletypewriter exchange oice, upon observing the usual signal indicating an incoming call, inserts the answering plug of her cord circuit into the jack associated with the operated signal and challen-ges the subscriber at station X .by typing OBR on the teletypewriter at the operators position circuit. The subscriber upon observing the letters OPR operates the teletypewriter at station X to transmit signals to the operator indicating the name or number of station X and the number of the called station. The operator then by means of the calling end of the operators cord circuit connects the calling line to the line of the called party and transmits ringing current to the station of the called party. All lthese functions are well known in the art.

Call originating at distant teletypewriter exchange olice` Assume that a call originates at a distant subscribers station, such as station A connected directly to a distant teletypewriter exchange o'ice, ringing current i-s received over single conductor toll line I I0 at. the local telephone central oiiice lto operate relay J as hereinbefore described. Relay J upon operating causes the ringing relay R to operate and to thereby connect ringing generator RG over the right-hand armature and contact of relay R to conductor 204 and over the left armature and contact of relay R to conductor 204.

Inasmuch as stations X and Y are arranged for code ringing, the operator at the exchange ofce would transmit one pulse of ringing current to call the subscriber at station X and two pulses to call the subscriber at station Y. The ringer at each of the teletypewriters at stations X and Y would ring, but only that subscriber who would identify his code call would respond by operating his power switch such as that designated 205 at station X or 205 at station Y. The subscriber upon operating his power switch, say that designated 205', closes a circuit extending from ground, switch 205', through the winding of relay 201', conductor 206', through the winding of relay 202', right armature and back contact of relay 203 to grounded battery 2I2. Relays 201' and 202 operate. Relay 202', upon operating, operates relay 203'. Relay 203', upon operating, causes the message line wire 204 to be connected Ito toll line I I0, opens the operating circuit for relay J and connects the ringing generator RG over conductor 209 and right front contact-s of relay 203' to conductors 2I0 and 206 whereby alternating current relay 201 is operated to light busy lamp 208 indicating to the subscriber at station X that toll line I I0 is connected to station Y.

The subscriber at station Y upon operating the power switch 205 also operates a start switch (not shown) to start the teletypewriter motor and to replace the teletypewriter in condition for the transmission and reception of signals. The '15.

teletypewriter at station Y is now prepared to transmit and receive signals.

Break, recall and disconnect features The break, the recall and the disconnect features are not alected by two-party operation and a recall from either station does not provide a means whereby the other station may take over the circuit providing a recall key rather than the power switch is employed at each station for recalling. The operation of the recall opens the message line circuit but does not cause the release of relay 2M or 202 in the local telephone central oilice and therefore the circuit to subscriber station X or subscriber station Y respectively remain locked out.

What is claimed is:

1. In a telegraph system comprising a teletypewriter exchange office, a switch center, a signal transmission circuit interconnecting said oiiice and said switching center, a switching device for normally terminating said circuit at said switching center, a plurality of teletypewriter stations connectable to said device, means in said device responsive to signals incoming over said transmission circuit for controlling connections to each of said stations, operable means at each of said stations for causing one of said stations to be operatively connected through said device to said signal transmission circuit for telegraphic communication purposes, and means responsive to the operation of the operable means at one of said stations to exclude the other station from a connection to said transmission circuit.

2. In a telegraph system comprising a teletypewriter exchange oce, a source of signals at said oiice, a switching center, a signal transmission circuit interconnecting said oce and said switching center, a switching device comprising a source of signals for normally terminating said transmission circuit at said switching center, a plurality of teletypewriter stations, a plurality of circuit means, normally deenergized, for respectively connecting said plurality of stations to said device, circuit closing elements responsive to signals from the inst-mentioned source to cause the second-mentioned source to intermittently energize said plurality of circuit means, operable means at each of said stations, electromagnetic means included in said device and respectively responsive to said operable means at said stations, other electromagnetic means included in said device and respectively responsive to the rst-mentioned electromagnetic means, circuit closing elements controlled by said other electromagnetic means for respectively connecting said stations to said transmission circuit for telegraphic communication purposes, another circuit closing element controlled by each of said other electromagnetic means for causing one only of said stations at a time to be operatively connected to said transmission circuit, and an indicating instrument at each of said stations responsive to signals transmitted from the secondmentioned source for giving an indication at the other of said stations when -said one station is operatively connected to said transmission circuit.

3. A telegraph system according to claim 2 wherein each of said circuit means for connecting said plurality of stations to said device comprise for each station a control line controlled by one of said operable means and for controlling one of said electromagnetic means and one of said other electromagnetic means, and a message line arranged to be connected to said transmission circuit, only one message line at a time being connected.

4. A telegraph system according to claim 2 wherein said switching device which effects connection of said transmission circuit to any one of said stations, comprising relays responsive to signals from the first-mentioned source for causing signals from the second-mentioned source to be transmitted overeach of said plurality of circuit means to operate an audible signal at each of said stations.

5. A teletypewriter exchange system comprising a central oii'ice, a switching center, a plurality of outlying stations, a transmission channel interconnecting said central olce and said switching center, a plurality of channels interconnecting said switching center and said outlying stations, respectively, a source of signals at said central oice, at said switching center and at each of said outlying stations, switching means at said switching center responsive to signals from the source at said central oflce for connecting said source at said switching center to each of the channels of said plurality, indicating means at each of said outlying stations responsive to said sources at said switching center, manually operable means, operative at will at each of said outlying stations for operating said indicating means, and electromagnetic means at said switching center responsive to the operation of said manually operable means at one of said outlying stations for connecting said one of said outlying stations through said switching center to said central office for communication purposes and for preventing the connection of another of said outlying stations to said central o'ce while said one of said outlying stations is busy.

6. A system of party line telegraphic service to a telegraph exchange comprising a central oilce, a pair of stations, a main line extending from said central oce to the region of said station over which said stations are to be given service, a switching point at which said main line is interconnected with local lines individual to said stations, means for calling said stations over said main line, and means operable by assumption of operative positions by one of said stations to lock out the local line of the other station from operative association with said main line at said switching point.

7. In a telegraph system comprising a teletypewriter exchange oflice, a switching center, a signal transmission channel interconnecting said office and said switching center, a switching device for normally terminating said channel at said switching center, a plurality of teletypewriter stations connectable to said device, said device being controllable to connect, under the control of current supplied over said transmission channel all said teletypewriter stations to said transmission channel, and an instrument at each of said stations operable to disconnect the other of said stations fromV said transmission channel during the operation of said instrument.

` GEORGE A. LOCKE.