US2024580A - Communication system - Google Patents

Description

F. $.KINKEAD ET AL COMMUNICATION SYSTEM Filed- April 19, 1933 2 Sheets-Sheet 2 E s. KIN/(E140 T. L. CORW/N lNVE/V TORS SUB. SET

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A TTOR/VE Y Patented Dec. 17, 1935 umrso S'iT rATENT OFFICE COMMUNICATION SYSTEM Application April 19, 1933, Serial No. 666,828

1 Clain'l.

This invention relates to that type of communication system in which a subscribers station is provided with dual service in the form of two communication lines connected thereto, one line being for one type of service, such as leased wire service, and the other line being for another type of service, such as exchange service. I

Heretofore in a communication system, if a subscriber wished to be supplied with two different types of service, he was forced to equip his station with a separate set of station apparatus for each type of service. This duplication of apparatus is objectionable from a cost standpoint as it is practically double the cost of one set of station apparatus, This duplication is also undesirable from the'viewpoint of space considerations because the extra apparatus takes up space which could be used for other purposes. Another objection is found in the cost of maintaining' and operating two sets of station apparatus.

All of these objections are done away with by means of the present invention, the objectv of which is to supply dual service over either open or closed loops to a subscribers station having only one set of station apparatus.

Another object of this invention is to provide switching apparatus at a subscribers station (provided with dual service) for quickly switching its station apparatus from transmission and/or reception over one communication line totransmission and/or reception over another communication line.

Still another object of this invention is to enable a calling station to give a non-continuous audible signal and a continuous visible signal to 'an operator at a subscribers station provided description will be set forth with reference to V the drawings in which: 7 r

Fig. 1 represents a subscribers station having only one set of station apparatus is conopen loop'to another station I02.

'run under these conditions.

nected by a normally open loop to another station;

Fig. 2 represents a somewhat similar subscribers station but which is provided with dual service over normally open loops;

Fig. 3-'represents a subscribers station having only oneset of station apparatus which is connected by a normally closed loop to another station; and V Fig. 4 represents a somewhat similar subscribers station but which is provided with dual service over normally closed loops.

Ordinary service over a normally open loop As has been stated above, Fig. 1 shows a subscribers station IIII- which has only one set of' station apparatus (teletypewriter and associated apparatus) and which is connected by a normally The loop is rendered normally open'by means of double pole double throw switch I03 which is normally in its open position as is shown in Fig. 1. When in this open position, the left po-rtion'of switch I03 opens the loop so that current from station I 02 would go to station 1 0| and then pass through line relay I04, sending contacts I05, break key I06, and then through switch I03 to ground. Station I02 may be either a single subscriber's station, like station l0l, or it may be a central ofiice, such as the central office disclosed in Patexit 1,804,548 granted May 12, 1931 to G. S. Vernam. If it is a single subscribers station, it

. may have station apparatus similar to that of station 10!.

' The right portion of switch I03 opens a path from the source of power supply I01 through motor generator I08 and motor I38 of the subscribers printing telegraph set. Since, under these conditions motor generator I08 will not be operated, it will not supply energizing current 40 to printer magnet I09. Also, motor I38 will not The transmission or reception of signal impulses by station IIll can not now take place because of the fact that neither printer magnet I09 nor motor I38 is energized.

For the transmission or reception of signal impulses, switch I03 is put in its closed position which is opposite to that shown in'Fig. l. The

cordingly be closed. Likewise, the path from power supply I01 through motor generator I08 armature of line relay I04 and energize printer 3 magnet I00. When line relay I04 is now successively energized and deenergized in response to the transmission or reception of signal impulses, its armature will successively open and close thereby successively opening and closing the energizing circuit for printer magnet I00.

If station I02 is a single subscribers station, it may be said that station I02 and station I0! are provided with leased wire service. If station I02 is a central oflice, then it should be stated that station 'IOI is provided with exchange service. With the arrangement shown in Fig. 1, if the subscriber at station IOI wishes to be supplied with dual service, that is, with both leased wire and exchange service, it is necessary for him to equip station IOI with a separate set of station apparatus for each type of service. As has been stated above, this duplication of apparatus is objectionable for several reasons.

Dual service over normally open loops However, by means of the special switching arrangement of this invention, a subscriber's station having only one set of station apparatus may be provided with dual service over normally open loops as is shown in Fig. 2 where subscribers station Bill is connected by means of normally open loops to station 202 and station 2| 0. It may be assumed for the purpose of illustration that station 202 is a central olfice, such as the central oflice disclosed in Patent 1,804,548 granted May 12, 1931 to G. S. Vernam, and that station 2 I0 is a single subscribers station.

The station apparatus (teletypewriter and associated apparatus) at station 20I is rendered normally non-operated by means of double pole double throw switch 203 which is normally in its open position as is shown in Fig. 2. While in this open position, the right port-ion of switch 203 opens a path from the source of power supply 201 through motor generator 208 and motor 230 of the subscribers printing telegraph set. Since motor generator 208 is not operated now, it will not supply energizing current to printer magnet 209. Also, under these conditions motor 238 can not run. As was the case with station IOI under similar conditions, the transmission or reception of signal impulses by station 20I can not now take place because of the fact that neither printer magnet 209 nor motor 2-38 is energized.

The left portion of switch 203 opens the subscribers loop to central oflice 202 and provides current from central oilice 202 with three paths to station 20L The first path leads from central ofiice 202 to station 20I by passing through an upper left pair of contacts of key switch 2I I, down through line relay 204, sending contacts 205, break key 206, through middle and bottom left sets of contacts of key switch 2H, and finally through switch 203 to ground. The second path leads from central ofiice 202 to station 20!, through ringer 2 I2, through the bottom left set of contacts of key switch ZII, and then through switch 203 to ground. The third path is similar to the second path-except that, instead of passing through ringer 2I2, current will pass through relay 2I3.

If an operator at central oflice 202 wishes to communicate with the subscriber at station 20!, the operator momentarily impresses a preassigned ringing voltage on the line. This ringing voltage will follow the second and third paths described above. By following the second path, the ring-v ing voltage will cause the operation of an alarm device (ringer 2I2) Since ringer ZIZ is operated only during the time ringing voltage is impressed upon the line, a non-continuous audible signal will be given to the subscriber at station 20 I. By following the third path, the ringing voltage will operate relay 2I3. The operation of relay 2E3 closes a path for current from power supply 202' to pass through switch 203, through both another alarm device (signal lamp 214) and relay 7H5, through the armature of relay 2 I3, and then back to power supply 25?. As soon as relay EH5 opcrates, current from power supply 201 will pass through its armature and lock relay 2I5. This will cause continuous operation of the second alarm device (signal lamp 2M) thereby giving a continuous visible signal to the subscriber. Therefore, calling apparatus (ringer 2 i 2 and lamp 2M) at subscribers station 2%! is capable of being actuated by another station, such as central ofiice 292, for informing subscribers station 2e! that it desires attention.

If the subscriber at station 20 i' wishes to answer a call from central ofiice 282, he closes switch 203. The right portion of switch 203 opens the path through relay 2I5 and lamp 2M thereby extinguishing lamp 254 and releasing relay 2I5. At the same time, a path is closed from power supply 201 through motor 238 and motor generator 208. This will energize printer magnet 209. The left portion of switch closes a path for current from central ofiice 202 to pass through the subscribers line relay 20 as described above but, instead of passing through switch 203 to ground, the current will now pass back to central ofiice 2G2. Transmission or reception of signal impulses may now take place between subscribers station 20I and central oflice 202.

If the subscriber at station 2H3 wishes to communicate with the subscriber at station 20I, he momentarily closes the loop leading from station 2i0 to station 20L This enables current to pass through relay 2H5 and energize it. When station 20! is connectedto central office 202, the line current is applied at central office 202, but when station 20i is connected to station 2 I 0 one of them must apply line current. For the sake of simplicity, it may be assumed that it is applied at station 2 Hi. When relay 2 I0 operates, its armature closes a path for current from power supply 201 to pass through and operate an alarm device (ringer 2 I1). Also, a path is closed through the armature of relay 2!. 8 through both relay 2 i8 and another alarm device (signal lamp 2 I9) and then back to power supply 207. When relay 2%?! operates, its armature closes a locking-up circuit leading from power supply 20? through the top right set of contacts of switch 2! I, the armature of relay 2I8, through both relay 2| 8 and alarm device Bit, and. then back to power supply 20?. When relay 2H3 releases, ringer 2!! will become unoperated but, due to the locking-up circuit, lamp 2I0 will remain lit. This procedure gives a non-continuous audible signal and a continuous visible signal to the subscriber at station 20!. Therefore, calling apparatus (ringer ZI I and lamp 2I0) at subscribers station EDI is capable of being actuated by another station, such as subscribers station ZIQ, for informing subscribers station 20l that it desires attention.

It is to be understood that the invention is not to be limited to the particular kinds of alarm devices described above. Ringers 222 and 2H and signal lamps 2H, and 259 could be interchanged if desired thereby giving the subscriber a noncontinuous visible signal and a continuous audible signal. Also, any other type of alarm device of the difference.

could-be substituted for ringers'2 I 2 and .211 and/ or signal lamps 2M and .2l9.

If the subscriber at station 26! wishes to answer a call from the subscriber at station 2 l 0,-he closes switch 293 and operates switch 2 to the left which is the position opposite to that shown on the drawings. As has been described above,.the right portion of switch 203 closes a path from power'supply 2B7 through motor238-and motor generator 238 thereby energizing printer magnet 299. When switch 2! I is put into position at the left, the top right set of contactsrof switch 2 will open thereby opening the locking-up path from power supply 291 through lamp 219. This will extinguish lamp 2 I9. At the same time, the

path from subscribers station 2H) through relay H6 will be opened by the top left set of contacts.

of switch 2| I; The path from central office 202 through the subscribers line relay 204 will now be changed so as to lead from central office 202 through the middle left sets of contacts of switch 2 down through the bottom left sets of contacts of switch 2H to ground. In the path for ringing current from central ofiice 202, the ground connected to the lower left set of contacts of switch 2 l I will now be substituted for the ground associated with switch 283. The path will now be closed for current from subscriber's station 2H) to pass through the middle right set of contacts of switch 2H, down and around through break key 205," sending contacts 285, line relay 204, upper left set of contacts of switch 2| I, and then back to stationZ l9. Transmission or reception of signal impulses may now take place between subscribersstations 23! and 2H3;

The current used for communication between stations Ziil and subscribers station 2 I!) may not always be equal to the current used for communication between station Zlil and central ofiice 202; To take care of any difference between these two currents, a biasing circuit is provided for line relay 204. For the'sake of illustration, let it be supposed that, the current in the loop leading to central ofiice 232 is less than the current in the loop leading to subscribers-station.2H1. Let it also be assumed that the amount of the difference between these two currents is known and that resistance 22!! compensates for the amount. Now, when switch 2| I is in the position shown in the drawings, resistance 228 will reduce the biasing current from motor generator 208. When switch 2| l is in the opposite position to that shown in the drawings, resistance 225i will be sho-rt-circuited out of the biasing circuit thereby increasing the biasing current.

Ordinary service over a. normally closed loop then through special delay key 339, break key 306,]

sending contacts 335, line relay 3G4, and back over the loop to station 332. Station 392 may be either a-single subscribers station like station 30L orit may be a central .ofiice, such as the central office disclosed in Patent 1,804,548 granted May 12, 1931- to G.-S-. Vernam. If it is'a single subscriberszstation, it may have station apparatus similarto that of station 38!.-

' When no signal impulses are being transmitted or received at station 3i! l, power switch 303 is kept .in. its .open position, as is shown in the drawings.

In. this open position, switch 303 opens a path from the source of 'power supply 301 through motorgenerator 303 and motor 338 of the subscribers printing. telegraph set.. Since under these conditions motor generator 308'will not be operated, it will not supply energizing current to printer magnet 309. Also, under these conditions motor 338 can not run. The transmission or reception ofsignal impulses by-station 3M can not now take place because of the fact that 1 neither printer magnet 369 nor motor 338 is en- 7 ergized.

For the transmission or reception of signal impulses, switch 303 is put in its closed position which is opposite to that shown in Fig. 3. The 1 path from power supply 307 through motor generator 308 and motor 338 will now be closed. Currentfrom motor generator 388 may now pass through the armature of line relay 3% and energize printer :magnet 399. When linerelay 304 2 is now successively energized and deenergized in response to the transmission or reception of signal impulses, its armature will successively open and close thereby successively opening and closing'the energizing circuit for printer magnet 369. A dis- 2 connect signal may be given by the subscriber at stationiiill by operating the special delay key 339 which causes a long break signal to be transmitted. Key 330 is so arranged that that portion oi the loop which is at station 30! will be held 3 closed during the transmission of the long break signal.

As was the casev with the arrangement shown in Fig. 1, if the subscriber at station 3% wishes to be supplied with dual service, that is, with both 3 leased wire and exchange service, it is necessary for him to equip station 33! with a separate set of station apparatus for each type of service. As has been stated above, this duplication of apparatus is objectionable for several reasons. 4

Dual service over normally closedloops However, bymeans of the special switching arrangement of this invention, a subscribers station having only one set of station apparatus (teletype- 4:

writer and associated apparatus) may be provided with dual service. over normally closed loops as is shown'in Fig. 4. In Fig. 4, subscribers station to: is connected by means of normally closed loops to stations 4B2 and ilil. It may be assumed for the 5 purpose of illustration that station 462 is a central ofiice, such as the central ofiice disclosed in Patent 1,804,548 granted May 12, 1931 to G. S. Vernam, and that station Mil is a single subscribers station. According to this assumption, station Mil is now provided with dual service comprising exchange service to central office 402' and leased wire service to subscribers'station s l 9. Under the normal conditions shown in Fig. 4, current from central office 462 passesover the loop to station 43 I, then through special delay key 438, through relay M3, through a middle left set of contacts of key switch 4H to break key 3%, sendingcontacts fibjline relay eats, up through another middle left set of contacts of switch 4! i, 6 and'then back'over the loop to central office 432. At the same time, the loop leading to subscribers station 4! 3 is short-circuited by the top left set of contacts-of switch 4! l. Under normal conditions,

path from power supply tillthrough motor generator 433 and motor .38 is opened by reason of switch 133 being in its open position.

If an operator at central office' 432 wishes to communicate with the subscriber at station dill, 7

the operator momentarily opens the loop to station 40|. The opening of the subscribers loop will cause relay M3 to release. The top contact of relay 4|3 will now close a path to operate an alarm device (buzzer 4|2). This path leads from power supply 401, the top armature of relay 4|3, through buzzer 4|2, the armature of buzzer M2, the bottom left set of contacts of switch 4| the left portion of switch 403, and then back to power supply 401. However, buzzer 4|2 will operate when current passes through it and its armature will be drawn away from its contact thereby opening the path just described. When this path opens, buzzer 4 I2 will release and its armature will fall back thereby closing the circuit and causing this procedure to be repeated during the time that relay 4 l3 remains unoperated. The effect of this action is the generation of a buzzing sound by the armature of buzzer 4|2.

At the same time, the bottom armature of relay 4 I3 will close a path to operate another alarm device (signal lamp 4|4). This path leads from power supply 401, through the right portion of switch 403, through both lamp M4 and relay M5, the bottom armature of relay M3, and then back to power supply 401. This will light lamp 4 4 and will cause the operation of relay 4|5 which will result in its armature closing a locking-up circuit for relay 4|5.

When the operator at central oflice 402 closes the loop to subscribers station 40| relay 4 I3 will be operated again. The top armature of relay 4 3 will open the path to buzzer 4 I 2 thereby causing it to cease operating. However, since relay 4|5 is provided with a locking-up circuit, lamp 4|4 will remain lit. In summary, it may be stated that calling apparatus (buzzer 4| 2 and lamp M4) at subscribers station 40| is capable of being actuaated by another station, such as central oiflce 402, for informing subscribers station 40| that it desires attention by giving a non-continuous audible signal and a continuous visible signal to the subscriber at station 40|.

It is to be understood that this invention is not to be limited to the particular kinds of alarm devices described above. Buzzer M2 and signal lamp 4|4 could be interchanged if desired thereby giving the subscriber a non-continuous visible signal and a continuous audible signal. Also, any other type of alarm device could be substituted for buzzer 4|2 and/or signal lamp 4|4.

If the subscriber at station 40| wishes to answer a call from central office 402, he closes switch 403. The right portion of switch 403 opens the path through lamp 4| 4 thereby extinguishing it. At the same time, a path is closed from power supply 401 through motor 438 and motor generator 408. This will energize printer magnet 409. The left portion of switch 403 opens the path from power supply 401 to buzzer 4 l2. Transmission or reception of signal impulses may now take place between subscribers station 40| and central ofiice 402.

If the subscriber at station 40| wishes to extinguish lamp 4M without holding communication with central ofiice 402, he could do so by momentarily operating switch 403 to its closed position. The momentary closure of switch 403 would open the path from power supply 401 to lamp 4|4. This would cause relay 4 l5 to release thereby opening its locking-up circuit.

If the subscriber at station 40| wishes to communicate with subscriber at station 4 I0, he closes switch 403 and operates switch 4| to the left which is the position opposite to that shown in the drawings. As has been described above, the right portion of switch 403 closes a path from power supply 401 through motor 438 and motor generator 408 thereby energizing printer magnet 409. When switch 4| is put into the position at the left, the top left set of contacts of switch 4|| will open thereby removing the short-circuit across the loop to subscribers station 4|0. Current from central ofiice 402 is now provided with a path over the loop to subscribers station 40|, through special delay key 430, through relay M3, the middle sets of contacts of switch 4| and then back over the loop to central ofiice 402. Buzzer 4 2 is provided with a path from power supply 401 through the armature of relay 4|3 (when relay 4 |3 has released), through buzzer 4| 2, the armature of buzzer 4|2, the lower set of contacts of switch 4| and then back to power supply 401. This enables central ofiice 402 to signal the subscriber at station 40| by means of buzzer 4| 2.

Current from subscribers station M0 is now provided with a path over the loop to station 40| through the right set of contacts of switch 4| I, break key 406, sending contacts 405, line relay 404, the upper left set of contacts of switch 4| and then back over the loop to station 4|0. Transmission or reception of signal impulses may now take place between subscribers stations 40| and 4H].

For the sake of simplicity, no alarm device has been shown at station 40| which can be operated by the subscriber at station 4|0. If desired, such calling apparatus may be added to the station apparatus at station 40| in a manner similar to that in which it was added to the station apparatus of station shown in Fig. 2. Also, for the sake of simplicity, it has been assumed that the current used for communication between station 40| and subscribers station M0 is equal to the current used for communication between station 40| and central oiiice 402. If there should be any difference between these two currents, a biasing circuit could be provided for line relay 404 which would be essentially the same as the biasing circuit provided for line relay 204 shown in Fig. 2. Also, station 4| 0 could be connected to station by means of a normally open loop if desired.

Stations 20| and 40| have been shown to be supplied with dual service; If it were desired to supply them with multiple service of several different types by means of a plurality of transmission lines connected to a plurality of difierent stations, this could readily be done in a manner similar to that shown in the drawings. In fact, it is to be understood that the arrangements shown in the drawings and described above are illustrative of the operation of the invention and will serve to assist in interpreting the claim.

The claim is not to be restricted to the precise construction described above, but is intended to include all changes and modifications employing the principles and features of operation of the invention. 5

What is claimed is:

In a, printing telegraph system, a subscribers printing telegraph station supplied with multiple service in the form of a plurality of transmission lines connected thereto for communication with a plurality of different printing telegraph stations connected to the transmission lines, the transmission lines being for different types of service with line current of diiferent amounts,

7 said subscribers printing telegraph station having only one printing telegraph set for the transmission and reception of messages over the transmission lines, and switching apparatus for switching the printing telegraph set from operation over one transmission line to operation over another transmission line; said printing telegraph set including only one line relay, a biasing circuit for enabling the line relay to operate correctly with current of any amount that is used lines in accordance with the amount of current I in the particular transmission line which is being used for communication purposes at a given time.

FULLERTONS. KINKEAD. THOMAS L. CORWIN.

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