US1619058A - Telephone repeater station - Google Patents

Description

March 1, 1927. 1,619,058

G. cRlssoN TELEPHONE REPEATER STATION Filed Feb. '7, 192

[ 2 v -INVEN'T'OR; 7 w 6'. 622129013 BY W ATTORNEY rammed Mar. 1, 1927.

GEORGE CRISSON,

OF HACKENSACK; NEW JERSEY, ASSIGNOR TO AMERICAN TELE- PHONE AND TELEGRAPH COMPANY, A CORPORATION OF NEW YORK.

TELEPHONE REPEATER STATION.

Application filed February 7, 1922. Serial No. 534,721.

This invention relates to arrangements for establishing a three-way telephone connection at a repeater station. With the arrangements of the invention, three-way com- 6 munication may be established between the two ends of a long telephone line and one or more intermediate stations, such as repeater stations, in connection with demonstrations of long distance telephony or in 1v connection with the distribution of public speeches in which at one or more points on a line it may be desirable to permit audiences to hear speech coming from a single point and which may at the same time permit talking into the line from these various stations. The invention might find further application in other fields, such as on leased wire telephone lines in which service is to be distributed to a number of stations along the line in a manner to permit any one station to talk to any other station. The arrangements might also be utilized for monitoring purposes where it is desirable for the supervisor to talk into the line as well as to listen on the line.

The arrangements of the invention pro- -vide novel means for connecting talking and listening loops to a through telephone line whereby provision may be made for talking with equal volume in each direction from the repeater on the through line, or, if desired, with any given difference in volume in the two directions; for listening with equal efliciency to the conversation in either direction over the through line or with any desired efficiency in either direction; for unimpaired transmission through the repeater of conversation between the terminals of the line; and for an adjustable volume or side tone in the receiving loop. Other'features and advantages of the invention will appear more fully from the detailed description hereinafter given.

The invention may be more fully understood from the following description together'wit-h the accompanying drawing, in the Figure 1 of which is illustrated a circuit diagram embodying the principles of the-invention and in the Fig. 2 of which is shown a'modification thereof.

- In Fig. 1 is shown a conventional form of two-way two-element repeater interconnecting the two line sections L and L This repeater may be either of the cord circuit type or the through-line type and ineludes the usual net works N L and N for balancing the lines L and L the threewinding transformers 1. and 2, the vacuum tube elements 3 and 5 and other appa ratus, such as the filter 4 and (3. Connected with the input circuits of the tubes 3 and 5, by means of the circuits 17 and 18, is a talking circuit L, to which may be connected talking apparatus. The talking circuit L includes the potentiometer 7, the transformer 8, a vacuum tube amplifier 9, the series resistance elements 10, 11 and 12, the transformers 13, 14 and 15. The resistance 12 is provided with an adjustable contact 16 so that it can function as a potentiometer. The resistance elements 10 and 11 are arranged in a manner similar to 12. Associated with transformer 15 is a side-tone circuit 19, which will he more fully described later. Bridged across the network conductors of the repeater are the circuits 23 and 25. These circuitsare connected through the transformers 20 and 21 to a receiving circuit L which may include telephone receiving apparatus. This receiving circuit also includes the vacuum tube amplifier 22. The side tone circuit 19 is associated with the input circuit of the tube 22.

Transmission between the lines L, and L takes place in the usual manner and without interference from any of the added apparatus.

When it is desired to talk from the line L over the lines L and L the voice currents arriving over line L enter potentiometer 7, the drop in which is stepped up by the input transformer 8 and applied to the vacuum tube 9 in the usual manner. The output current of the vacuum tube traverses the resistances 10,11 and 12 in series. Transformers 13 and 14 transfer the voltages across the resistances 10 and ll to the two grid circuits of the vacuum tubes 3 and 5 of the line repeater to send speech currents in each direction through the line. Due to the very high grid-filament impedance of the vacuum tubes 3 and 5, no currents of appreciable magnitude are caused to flow in the grid circuits, and no interference between the two sides of the repeater occurs;

The volume of speech currents repeated from the talking loop L, to the through line depends upon the design of the apparatus associated with line L 1 It can be adjusted by means of the potentiometer 7 is usually the case, it is desired to send equal speech currents in both directions from the repeater, the resistances 10 and 11 are equal, and transformers 13 and 14 have the same ratio. In this case a single resistance and a single transformer with two equal secondary windings could be used instead of'the arrangement shown. By giving r unequal values to the resistances 10 and 11,

or by using transformers of different ratio, the speech currents transmitted in the two directions from the repeater may be made to differ from each other by any desired ratio. If the speech currents in the talking i circuit L are strong enough, it is possible to dispense with the amplifier 9 and transmit the currents directly to the resistances 10, 11 and 12. i

The operation of the arrangements in receiving voice currents coming in over the lines L or L is as follows: If voice currents arrive over the through line, for example, from the line L little or none of the disturbance will reach the network N and the input transformers 20 of the listening circuit will be substantially unaffected. The speech currents will be amplified by the line repeater 3 and transmitted to the line L and the network N The'voltage set up across the'ter'mina-ls of the network N is impressed upon the primary winding of the input transformer 21 of the listening amplifier 22. This transformer steps the voltage up or down as may be necessary and impresses it upon the grid of the vacuum tube 22 of the listening amplifier, which repeats the speech currents into the listening circuit L in the usual-manner. Speech currents from the section L of the through line reach the listening circuit L in the same way, except that the input transformer 20 transfers the voltage across the network N, to the grid of the vacuum tube 22, while transformer 21 is unaffected. By this arrangement, the effects produced in the listening circuit L depend only on the output voltage of the line repeater. If the transformers 20 and 21 were connected across the line terminals of the line repeater, it will readily be seen that both the input and output voltages of the line repeater would act in producing speech currents in the listening circuit L and the resulting current would be the sum or difference of the currents, due to the input and output voltages of the repeater considered separately, depending upon the arrangement of the transformer connections. This would'lead to some uncertainty as to the volume of the speech currentsin the lis- When, as

toning circuit L and probably would cause distortion of these currents. These effects would become more harmful as the gain of the line repeater is reduced.

Ordinarily the two transformers 20 and 21 would have equal turn ratios, in order that the listening circuit L would receive with equal efiiciency the speech passing in either direction through the line repeater. By using transformers having different ratios, or by making the ratio of one or both transformers adjustable, the receiving efficiency could be made different for transmission in the two directions over the through line. This would make is possible to compensate for differences in the transmission level in the two directions and so cause each terminal of the line to .be heard L,. The high impedance of the grid circuit .of the "acuum tube 22 insures that there will be no interference between the two sides of the line repeater through the trans formers 20 and .21. The primary windings oftransformers 20 and 21 are wound to such high impedance that they do not appreciably affect the balance of the line repeater.

When speech currents reach the transmit produced by speech'between the ends of the through line. To overcome this effect, con

motions of the transformers 20 "and 21 are so arranged that the voltages of their secondary windings caused by speech, currents from the talking circuit L oppose each other, and little or no current is produced in the listening circuit L,. In order that person listening to the receiving apparatus connected with circuit L may hear what is said on the talking circuit L the side-tone circuit 19 is provided. This consists of the potentiometer device 12 previously mentioned and a transformer 15 whose primary winding has impressed upon it an adjustable voltage from the potentiometerand whose secondary winding is connected in"ser ies with the secondaries of the input trans formers 20 and 21 to the grid of the vacuum tube 22. Speech currents in the talking circuit L thus produce speech currents in the listening circuit L whose volume can be adjusted by means of the potentiometer contact 16 to be equal to'that received from the through line, or to'any other desired value.

similar reference characters are used to denote like parts with respect to Fig. 1. The supervisory apparatus is denoted as X and may include both talking and listening apparatus. The talking apparatus will be connected in substantially the same manner as in Fig.1 by the circuit L to the circuits 17 and 18"which are connected in series .in the grid circuits of the tubes 3 and 5. A relay 51 controlled by switching means 'K at the set X is provided whcreby'the talking set at X may be operatively disconnected from circuits 17 and 18 when desired. The listening circuits 23 and :25 are connected to line L and thence to the apparatusat X.

The listening circuits 23 and 25 are coupledto the lines L and L in a different manner than in Fig. 1 being related inductively thereto by additional windings on the hybrid coils 2 and 1. As the operation would be substantially similar to the arrangements H of Fig. 1 no further description thereof will be given.

While the invention has been disclosed as embodying certain specific arrangements which are deemed desirable, it is understood that it iscapable of embodiment in many and widely varied forms without departing I from the spirit and scope of the appended claims.

What is claimed is:

1. In combination with a transmission. line includin a two-way repeater and networks for ba ancing the sections of the lines interconnected by the repeater, a listening circuit, and circuits bridged across the terminals of the networks associated with the line sections for associating said listening circuit with said repeater.

2. In combination with a transmission line including a two-way repeater and networks for balancing the sections-of the lines interconnected by the repeater, a listening circuit having a vacuum tube included therein, and circuits bridged across the terminals of the networks associated withthe'line sections for associating said listening circuit with said repeater.

3. In a transmission system including a two-wa vacuum. tube repeater and networks or balancing the sections of the lines interconnected by the repeater, a talking I circuit, a transformer having a plurality of secondary windings, the primary windings of said transformer being connected to said talking circuit and the secondary wmdmgs a plurality of windings,

of said transformer being connected in series in the grid circuits of said vacuum tubes, a listening circuit, and circuits bridged across the terminals of the networks associated with the line sections for associat-- ing said listening circuit with said repeater. 4. In a transmission system including a two-way vacuum tube repeater and networks for balancing the sections of the lines interconnccted by the repeater, a talking circuit, a transformer having a plurality of windings, the primary windings of said transformer being connected to said talking circuit and two of the secondary windings being connected in series in the grid circuits of sai vacuum tubes. a listening circuit including a vacuum tube amplifier, circuits bridged across the terminals of the networks as'sociated with the line sections for associating said listening circuit with said repeater,an a slde tone circuit mterconnectmg said talking and listening circuits, said side tone circuit being connected in series in the grid circuit of said amplifier in said listeningcircuit and being inductively related to said talking circuit.

5. In a transmission system including a two-way vacuum tube repeater, a talking circuit including a otentiometer, an amplifier, a plurality of resistance elements. in series in said circuit, transformer windings in parallel withsaid resistances, and secondary windings inductively related to said first mentioned transformer windings, said secondary windings being included in series in the grid circuits of said vacuum tubes.

6. In a transmission system a two-way repeater comprising two one-way vacuum tubes for a talking circuit, and a transformer having the primary windings of said transformer being connected to said talking circuit and the secondary windings of said transformer being connected the input circuits of respectively in series in the vacuum tubes of said repeater. I

7. In a transmission ,system a two-way repeater, a talking circuit, transformers having their primary windings connected to said talking circuit, the secondary windings ofsaid transformers being connected respectively in series in the input c rcuits of said repeater whereby transmisslon ma take place from said talking circuit simu taneously over .both of the line sections interconnected by said repeater, and means for adjusting the volume. of transmission from said talking circuit to said line sections, said means comprising lndividual variable resistance elements connected 1n said talking circuit in parallel with each of the primary windings of said transformers.

8. In a transmisslon system including a two-way vacuum tube repeater and networks transmission in opposite directions, 7

dividual transformers with theirsecondary windings in series in the grid circuit of said amplifier, the primary windings of said transformers being. bridged across the terminals of the networks associated with said line sections, and means for varying the condition of said transformer- .windings whereby the volume of transmission from 1 either of said line sections to said listening circuit may be independently adjusted. y

In testimony whereof I have signed my name to this specification this 4th day of February, 1922. a

- GEORGE CRISSON.

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