US1386321A - Charles s - Google Patents

Description

c. s. DEMAREST. TELEPHONEREPEA TER EQUIPMENT.

APPLICATION FILED MAY 9. i919.

Patented Aug. 2; 1921.

WEB YER SHUNT INVENTOR ficfiflemasrl ATTORNEY transmission line in order to preventthe repeaters.

1 lii R fis MA ES .OF'BROOKLYNQ New Year, ss ca o answer PHONE Ann TELEGRAPH COMPANY, n conronarion or NEW-$03K,

'rnnnrnonn nnrnaf'r'nn EQU'IPMENT.

To all whom it may concern:

Be it known'that I, CHARLns S. DEMAREST,"

residing at Brooklyn, in the countvof Kings and State of New York, have invented certain Improvements in Telephone Repeater Equipments, of which the following is a specification.

This invention relates to transmission cir-' cults which include repeaters and more particularlyto a means for testing such re- When a transmission line includes repeater apparatus it is customary to associate withthe repeater artificial lines'or net works suitable for balancing the sections of the peater from singinnx To test the transmission gain due to the repeater, the repeater apparatus including the artificial lines is disconnected from the transmission line and connected to a standard form of testing apparatus. This testing apparatus will have .a constant impedance which in all probability will not-be the same as that of are interconnected by the repeater 'appara-' tus. Accordingly when the testing apparatus is connected to the repeater, the artificial lines will not balance the testing apparatus a.

and will nolonger maintain the repeater in ajbalanced condition and singing in the repeater will result. 7

It, is an object of the invention to avoid or obviate the above described difficulties when testingrepeater apparatus and accordingly, the said invention provides testing apparatus'which may be associated with rewith the switching means, whereby the repeaters are disconnected from the transmission line and connected to the testing apparatus, means for disconnectingfrom the repeaters the balanoingartificial lines normally associated with the repeaters and for associating with the repeaters artificial lines suitable for balancing the testing apparatus.

and drawing of the invention;

' i In the drawing is illustrated a preferred form of the arrangements embodying this in.-

wvention. The two sections L and L of a transmission line are shown interconnected Specification of Letters Patent. Patented Aug. 2, 192 1. Application filed May 9, 1919. Serial Nb. 295,912. i

by repeater apparatus. The repeater appa ratus includes the repeater elements R and R, which are shown as of the mechanical type, although any other type, such asthe well known vacuum tube repeater, may be employed. Normally associated with there-' peater apparatus are the net works N and N adapted for balancing the sections L and L respectively of the transmission line, in order I to prevent the repeater from singing. Associated with sections'L and L of the line are the jacks J and J When the plugs P and P of patching cords are inserted in the jacks J and J respectively, the repeater apparatus may be disconnected from the line and connected with the testing apparatus. The patching cords are associated with the testing apparatus by means of the jacks J and J When the repeater apparatus is disconnected from sections L and L of the line, the net worksN and N are disconnected from the repeater apparatus and the" net works N and N 4 are connected to the repeater apparatus. The net works N and N are of a value suitable for balancing the impedance of the testing ap paratus. Associated with the jacks J, and

J 4 of the testing apparatus are conductors 12 and 13, respectively. Included in these conductors are the-net works N and N which are of a value adopted as a standard for purposes of comparison and testing. The conductors l2 and 13 are normally associated with the contacts of the key K When the key K is operated, the generatingapparatus 35 which is adapted to generate currents suitable for testing purposes, such, for example, as currents of telephonic frequency, will be started in operation. Testing current may then be applied either over condu'ctors 12, through the repeater apparatus and over conductors 13, to the receiver shunt 31 and the operators telephone set 32, or

from the generating apparatus 35 over conductors 13, through the repeater apparatus :and overcondu'ctors 12 to the receiver shunt 31 and the telephone receiver 32. A keyK is provided in the testing apparatus upon the operation of :which the testing current may be transmitted from the generating apparatus 35 through the net work N and tothe telephone receiver 32. By means of comparing the transmission efliciency, as indicated by a scale on the receiver shunt appa ratus, between the circuitincluding the net work N, and the circuitincluding the re-' peater apparatus, ameans is afforded for measuring thegain in transmission over a circuit due to the includlng thereln of the re eater apparatus.

, he operation of the invention is as fol lows: V transmlsslon due to the includlng 1n the l ne If it is desired to test the gain in of the repeaters R, and R the plugs P and P areinserted, in the jacks J and J and connected with the section L of the line over the make contacts of jacks J and J and over conductors 3 and 4. 'When the V =ment1oned c rcuit as the operatlon of key K,

plugs P, and P are inserted in the jacks ,J and. J the following circuit is closed:

from ground, sleeve contacts of jack J and plug P sleeve conductors of the patchlng cord, sleeve contacts of plug P and jack J,,

I sleeve conductors of jack J over conductor 516, winding of relay 1, to battery and.

ground, The closing of this circuit will 0perate the relay 1 which will pull up its armatures and will disconnect from the repeater R, the net Work N,, which is normally connected thereto, and will connect the net Work N, over conductors 10, contacts of relay 1 .andover conductors 6 to the windings of the usual transformer 5 of the repeater apparatus. When the-plugs P and P, are 1n- 4 serted in the jacks J 3 and J respectively,

the following circuit is closed: from ground,

T sleeve contacts of jacks J and plug P sleeve conductors of the patching cord, sleeve v contacts of plug P and jack J over the sleeve conductors of jack J 3 and over conductor 47, winding of relay 2, to battery and ground. The closing of. this circuit will energize relay 2 which will pull up its armatures and disconnect from the repeater R the net workNj which is normally connected thereto and will connect the net work N over conductors 11, contacts of relay 2, andoverconductors 7, to the windings of the usual transformer 45 associated with the repeater apparatus. The keys K and K will now be thrown. The operation of the key K, closes the following circuit: from ground, make contact of key K conductor tion of the key K, will close the following circuit: from ground, upper make contact.

of key K conductor 18, winding of relay '17, to battery and ground. The operation of key K will also close the following circuit: from ground, lowermake contact of (key K conductor 19, winding of relay 16,

' to battery and ground. The closing of these two last mentioned circuits will operate the relays 16 and 17. WVhen the generating ap-' paratus 35 is Started in operation and when the relays 16' and 17 are operated, testing current will be applied from the generating V apparatus 35 over the following circuit, the 7 key K, being thrown to the left: over con ductors 22, over conductors 61, left hand make contacts of key K over conductors 20, contacts and armatures of relay 16, over conductors 14, net work N, over conductors 15, armatures and contacts of relay 17, over conductors 21, right hand'normal contacts of keyK over conductors 25 and 26,. from conductor-25 to the receiver 32, and from conductor26, over conductor 28, make con-' tact of key K over conductor 27, to the reso 7 ceiver 32. It is pointed out that the receiver shunt 31 is not included in this last closesthe short-circuit about the series resistance 34 and opens the path including the shunt resistance 33. By-means ofthe re ceiver 32, the volume ofthe sound transmittedv over this last mentioned circuit may be observed. The key It, will now be restored to normal. The testing current from the generating'apparatus 35 will now be transmitted over the following circuit from the generating apparatus 35, over conductors 22, over conductors 61, left hand make con-V tacts of key K over conductors 2'0, net'95 work N over conductors12, tip contacts of jack J 2 and plug P tip conductors of patching cord, tip contacts of plug P andjack J through the repeater apparatus in the usual manner, to the tip contacts of j ack J and plug P over thetipconductors of the patching'cord, tip contacts of plug P and jack J over conductors 13, net work N normal contacts of relay 17, conductors'21, right hand normal contacts of key K over conductors 25 and 26, through the receiver shunt 31, to the telephone receiver 32. By now adjusting the receiver shunt until the same tone is heard in the receiver as in the' case of the formerly traced circuit through the net work N it will be possible to ob-. serve and measure from the graduated scale on the receiver shunt the gain due to the including in the circuit of the repeater apparatus. By throwing the key K in the opposite direction, a testing current may be transmitted through the repeater apparatus in the opposite direction. By this :means the gain in transmission over the transmission line in either direction, due to the repeater apparatus, may be observed and measured. As has been previously pointed out,

the net works N and N which are associ-. ated with the repeater apparatus, when the testing apparatus is associated therewith, are adapted for balancing the impedance of the testing apparatus and a condition of balance in the repeater apparatus Willbe maintained with respect to thetesting apparatuswhen the testing apparatus is connected thereto.

Accordingly, the transmission of testing current from the testing apparatus through the repeater apparatus will not cause fsinging to take place in the repeater apparatus.

While the invention has been disclosed as embodied in certain specific arrangements which have been deemed desirable, it is understood that it is capable of embodiment in many and widely varied forms without departing from the spirit of the invention as defined in the appended claims.

What is claimed is:

1. A transmission circuit including lines interconnected by repeater apparatus, networks normally connected to said repeater apparatus for balancing said lines, apparatus for testing said repeater apparatus, networks associated with said repeater apparatus for balancing said testing apparatus, and means responding when said testing apparatus is connected to said repeater apparatus for disconnecting said first mentioned networks from said repeater apparatus and for connecting said second mentioned networks thereto.

2. A transmission circuit including lines interconnected by a telephone repeater, networks normally connected to said repeater for balancing said lines, apparatus for testing said repeater, networks associated with said repeater for balancing sa1d testing apparatus, switching means associated with said lines and said testing apparatus, means controlled by said switching means for disconnecting said repeater from said lines and for interconnecting said lines over auxiliary conductors, and -means controlled by said switching means for disconnecting said first mentioned networks from said repeater and for connecting said second mentioned networks thereto.

3. A transmission circuit including lines interconnected by a telephone repeater, networks normally connected to said repeater for balancing said lines, apparatus for testing said repeater, networks associated with said repeater for balancing saidtesting apparatus, jacks associated with said lines and said testing apparatus, patching cords adapted to cooperate with said jacks and connect said testing apparatus with said repeater, relay means associated with the jacks of said lines and responding when said testing apparatus is connected to said repeater for.

disconnecting said first mentioned networks from said repeater and for connecting said second mentioned networks thereto.

In testimony whereof I have signed my name to this specification this 5th day of May, 1919.

CHARLES S. DEMAREST.

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