US2022053A - Combined telephone and telegraph system - Google Patents

Description

Nov. 26, 1935. H U E 2,022,053

COMBINED TELEPHONE AND TELEGRAPH SYSTEM Filed Dec. 30, 1932 2 Sheets-Sheet 1 INVEN7UR H. M PRUDEN ATmRA/EV Patented Nov. 26, 1935 UNITED STATES PATENT OFFICE COMBINED TELEPHONE AND TELEGRAPH SYSTEM Application December 30, 1932, Serial No. 649,477

1 Claim.

This invention relates to the combined telephone and telegraph systems and particularly to arrangements for switching telegraph apparatus into association with a telephone circuit 5 when it is not being used for telephone transmis- SlOIl.

An object of the invention is to utilize a fourwire radio telephone system for transmitting telegraph signals when the system is not being used for telephonic transmission.

Another object is to utilize a plurality of relay groups at a central ofiice for automatically con" necting to a radio telephone circuit the receiving unit of a telegraph set immediately after its associated sending unit has been connected to the circuit at a toll switchboard.

Heretofore in systems of the type herein described the selection by an operator, at a switchboard, of a telegraph transmitter of a printer set for operation over the transmitting side of a telephone channel, automatically connects the associated telegraph receiver of the set to the receiving side of the same channel by means of a rotary selector switch comprising three contact banks as disclosed in U. S. Patent 1,828,823, granted to E. R. Taylor on October 27, 1931.

According to the present invention, the selection of a telegraph receiver corresponding to a selected telegraph transmitter is accomplished by means of a group of relays. There are provided for each printer set in the system as many groups of relays as there are telephone channels.

Four-wiretelephone systems are usually provided with voice-operated arrangements for suppressing echoes and preventing singing over the four-wire circuit. In a well known arrangement of this type, voice-operated relays are provided whereby when transmission takes place from the two-wire terminal out over the transmitting side of the four-wire circuit, the normally disabled transmitting channel will be cut through for transmission and the receiving circuit will at the same time be disabled. Similarly, when telephone transmission is being received over the receiving side of the circuit, voice-operated relays will disable the transmitting side as well as the voiceoperated equipment associated therewith to prevent any interference with reception.

When such a, circuit is to be used for full duplex telegraph transmission, if the telegraph transmitter is to be applied to the two-wire terminal it is necessary to actuate the voice-operated relay which cuts through the transmitting side of the circuit. This may be done automatically upon the connection of the telegraph transmitter to the circuit but necessarily results in disabling the receiving side ofthe circuit at the same time, Therefore, the telegraph receiver must be associated with the receiving side of the four-wire circuit beyond the point at which it is disabled 5 in order that telegraph signals may be freely received.

When several four-wire circuits are provided and one or more telegraph sets are available, the present invention provides an arrangement 10 whereby, when the transmitting apparatus of a telegraph set is connected to the two-wire terminal of a particular four-wire circuit, its corresponding telegraph receiving apparatus is automatically switched into connection with the re- 15 ceiving side of the four-wire circuit.

The invention will now be more fully understood from the following description when read in connection with the accompanying drawings of which: 20

Fig. 1 illustrates the connections of three telephone channels to three radio channels respectively, and nine groups of relays whereby the receiving unit of three telegraph printers may be automatically connected as desired, but one at a 25 time, to any one of the three telephone channels;

and

Fig. 2 shows in schematic layout the equipment provided for a telephone channel and equipment provided for a printer set. Two additional tele- 30 phone channels and two additional printer sets are shown in diagrammatic form.

Referring to the drawings, the terminal arrangement of a four-wire system comprising a transmitting line H0 and a receiving line I II is 35 illustrated in detail. In practice, the transmitting line may be associated with the radio transmitter of a trans-Atlantic telephone circuit and the receiving line with the corresponding radio receiver of such a system. Such a system is illus- 40 trated in the drawing as the preferred embodiment of the invention.

The ends of the transmitting and the receiving lines are connected through a hybrid coil 210 to a two-wire terminal ending in a jack 2 45 through which connections may be established by means of a cord circuit to various telegraph circuits. In order to prevent singing over the fourwire part of the system, the transmitting line I III! is normally disabled by a contact at the 50 With relay 2 I2 operated, transmission may take place from the two-wire terminal over the transmitting line Hi! but current can not be transmitted from the receiving line III to the two-Wire terminal. place in the opposite direction, an amplifier-detector 2I5 is associated with the receiving line I I I and controls the relay 2 I6 which, when actuated, closes a short circuit across the transmitting line H0, this short circuit at the same time disabling the amplifier-detector H3 and preventing any interference with reception over the line III. It will thus be seen that transmission may take place in only one direction at a time.

The telephone system above described may be used for telegraph transmission when it is not being employed for telephony and preferably the telegraph signals would be transmitted and received as audible tones modulated or controlled 1 in accordance with the telegraph message. When a telegraph transmitter is connected to the twowire terminals of jack 2! I, it is obviously necessary to actuate the relay 2 I2 to remove the short circuit from the transmitting line I I0. This results in disabling the receiving line III at the same time by means of the right-hand armature and contact of relay 2I2. Consequently, it has been the practice heretofore to permanently connect the receiving telegraph apparatus with the receiving line III at a point beyond the short circuit controlled by the relay 2I2.

Where a number of such telephone circuits are provided and one or more sets of telegraph equipment are available, an arrangement, such as above described, becomes impracticable as flexibility in the connection of the telegraph equipment to the idle telephone line is impossible.

To avoid this diificulty, the present invention provides an arrangement whereby, when a. telegraph transmitter is connected to the two-wire terminal at jack 2| I, the corresponding telegraph receiver will be automatically associated with the receiving line I I I.

In the drawings, three telephone channels T1, T2 and T3 are shown arranged to be accessible to three printing telegraph circuits P1, P2 and P3. Any one of the telegraph circuits may be con- I nected by means of cord circuits C1 and C2 to any one of the telephone channels when the channel selected is not being used for telephonic transmission. The three telephone channels are shown respectively connected to three radio channels R1, R2 and R3 each of which is equipped with a retransmitter t and a repeating receiver 1'. For the purpose of illustration, it is assumed thatthe telephone channel T1 is not being used for telephonic transmission at the time it is desiredto connect printer circuit P1 to it by means of cord circuit C1. The telegraph transmitting and receiving equipment of the printer circuits P1, P2 and P3 are identical. The equipment shown for printer circuit P1 comprises a transmitter 2I'l which is arranged to send direct current pulses through the winding of a transmitting relay 2l8 In order that transmission may take to control the transmission or a tone of frequency from a generator 2I9 to the transmitting jack 220. The receiving equipment of printer circuit P1 comprises a tone amplifier 22!, a receiving filter 222 for selecting the receiving telegraph f 5 and a detector 223 in whose output circuit is included a receiving relay 224. The receiving relay 224 sends direct current pulses to the receiving unit, or printer 225.

The telegraph transmitter may be associated with the two-wire terminal of the telephone circuit by inserting the plugs 10' and p of the cord circuit C1 in the jack 2Il of the two-wire terminal of the telephone circuit and in the jack 220 of the telegraph transmitter, respectively. When this connection is established the operating circuit of relay 226 associated with the telegraph transmitter of printer circuit P1, and that of relay 22? associated with the two-Wire telephone terminal will be completed from battery, over the tip spring of jack 22d, tip of plug p, tip conductor of the cord 01, tip of the plug :0 and tip spring of jack 2| I, through the winding of relay 22'I, over the ring spring of jack 2H and ring of plug p, ring conductor of cord C1, ring 25 of plug 50, ring spring of jack 228, through the winding of relay 226, to ground. Relays 22'i and 226 operate. The operation of relay 22'! connects ground to the winding of the voice-operated relay 2| 2 which operates to disable the receiving line I I I and at the same time removes the normal short circuit from the transmitting line I Id. The system is now in condition to transmit telegraph, signals from the printer circuit P1 over the cord circuit C1 and thence over transmitting line III Relay 22'I, in operating, connects ground to a circuit traceable over conductor 22%, contact and armature of relay I I 2, conductor I I 3, through the winding of relay H4, to grounded battery. Relay I operates and completes the circuit traceable from ground, armature and contact of relay 226, contact and armature of relay 229, conductor 230, armature and contact of relay H4, through the winding of relay H5, to grounded battery. Relay H5 operates and closes at its inner lower armature and contact, a locking circuit for itself raceable over conductor H6, contact and armature of relay 22 5 to ground. Also relay H5, in operating, connects at its inner upper armature and contact an operating circuit for relay H2 which opens the operating circuit for relay II I. Relay I I4 releases. Relay H5, in operating, closes at its outer upper and outer lower armature and contacts a communication circuit extending from the receiving line I I I to the receiving equipment of printer circuit P1. Relay H5, in operating, closes in parallel with its locking circuit, a path extending over its innermost lower contact a circuit extending through the winding of relay 229, to grounded battery. Relay 229 opcrates and removes ground from the contact of relays H4, IE4, EM" associated with printer circuit P1 in order to prevent ground from being connected by a relay corresponding to relay 22'! of telephone channel T1, in one of the other telephone channels for operating relays H5 or H5" whereby a second telephone channel will be connected to the printer circuit P1. In a similar manner, relay H2 operates to open the operating circuit for relay H6 and the corresponding relay for each of the other printer circuits P2 and P3 thereby preventing circuits P2 and P3 from being connected to the receiving line I I I.

Relay H5 is held operated Lmder control of relay 226 as long as the cord circuit 01 interconnects jacks 2H and 220. When the cord circuit C1 is removed from the jacks, relay H releases to restore the circuit to its normal condition. It will be noted, therefore, that a relay, such as relay H2, is provided for each of the telephone channels and that each of these relays is common to all the printer circuits.

When it is again desired to use the telephone circuit for telephonic transmission the plugs p and p" are withdrawn thereby releasing relays 226 and 221. The release of relay 226 releases relay I I5 which in turn causes the release of relay I 12. The operating circuit for relay l M closes at the armature and contact of relay H2 but this circuit is now opened because of the release of relay 221. The release of relay 221 causes the release of relay 2l2 whereby the telephone channel T1 is restored to normal. The release of relay H5 disconnects the receiving unit of printer circuit P1 from the receiving line I l I.

Printer circuit P1 may be connected in a similar manner to either of telephone channels T2 or T3 by interconnecting jack 220 by means of a cord circuit with a jack, corresponding to jack 2H, of the desired channel. Should telephone channel T2 beselected for connection to printer circuit P1, then relay group TzPi would be employed for connecting the receiving unit of printer circuit P1 to the receiving line III of telephone channel T2. Should telephone channel T3 be selected then relay group T3P1 would be employed for connecting the receiving unit of printer circuit P1 to the receiving line III" of telephone channel T3.

Should it be desired to use printer circuit P2 said telegraph sets.

phone channel. A' connection thus established 5- would cause to be engaged the relay group of groups T3P2, T2P2 and T1P2, depending on which telephone channel was selected'to connect the receiving unit of printer circuit P to the receiving line of the selected telephone channel.

In like manner printer circuit P3 may be connected to the receiving line of one of the telephone channels, but in this case a relay group of groups T3P3, T2P3 and TIPS will be engaged to complete the connection.

What is claimed is: a

In a transmission system, a plurality of fourwire telephone circuits each comprising a transmitting line and a receiving line, a two-wire terminal for each of said telephone circuits, a plurality of telegraph sets each comprising a telegraph transmitter and a telegraph receiver, a link circuit for connecting any one of said telegraph transmitters to the two-wire terminal of any one of said telephone circuits, and a plurality of relay groups corresponding in number to the numerical product of said plurality of telephone circuits multiplied by said plurality of telegraph sets, each of said groups comprising two relays only which when operated in response to a connection established by said link circuit, complete a connection for communication purposes between one of said telephone circuits and one of HAROLD M. PRUDEN.

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