US1564391A - Telephone-repeater monitoring system - Google Patents

Description

TELEPHONE REPEATER MONITORING SYSTEM Dec. 8, 1925-.

R. s. WILBUR Fild June 18, 1921' 4 5 LW. 7 5W W hven/ar: Ray 5. W/Yfiur.

2 Jim.

Patented Dec. 8, 1925.

iiNlTED STATES BAY SETH WILBUR, OF LYNDHURST, NEW

PATENT OFFICE.

JERSEY, ASSIGNOR TO WESTERN ELECTRIC COMPANY, INCORPORATED, OF NEW YORK, N. Y., A CORPORATION OF NEW YORK.

TELEPHONE-BEPEATER MONITORING SYSTEM.

Application filed .l'une 18,

To all whom it may concern:

Be it known that I, RAY S..W1LBUR, a citizen of the United States, residing at Lyndhurst, in the county of Bergen, State of New Jersey, have invented certain new and useful Improvements in TelephoneRepeater Monitoring Systems, of which the following is a full, clear, concise, and exact description.

The present invention relatesto monitoring circuits for telephone repeating stations and like purposes.

An object of the invention is to provide a simplified type of monitoring circuit suitable for listening in on transmissions passing through a repeating station, without disturbing the normal operation ofthe repeater. A further object is to provide a combined monitorin circuit and communication channel, or example over either line section coming into atwo-way repeating station, and particularly between two separated repeating stations, over which channel an at: tendant at a distant station may be called into conversation from another station on the line.

For this purpose the system of the invention provides preferably at each repeating station on a line one or more sources of suitable ringing current, talking and listening sets and simplified switching arrangements, by which listening, talkin and signalling can be carried on over eit er or both'sections of the line with facility and despatcli.

A. feature of the invention is theslmple and economical way in which the monitoring and signalling apparatus is coupled to one or the several'line circuits. It is desirable to associate. monitoring equipment with the output circuit as then a satisfactory volume of monitoring current maybe secured without appreciably reducing thev'norm'altransmission. Heretofore listening-in or monitoring sets designed for use with repeater circuits in which the output transformer is made the balanced coil, have required extra re eating coils insertedfin the line sections. hese are expensive tdggbuild and have the disadvantage t at they must be 1921. Serial No. 478,194

balanced in the same way that the other elements of a line must be balanced. Furthermore the primary windings of such coils are always in the line Whether the monitoring sets are being used or not, with the necessary resulting. transmission loss and complications.

The present invention, however, employs simply a few turns of wire on the usual balanced repeater coil itself to serve as an extra winding. for the monitoring apparatus. This wmdingcan be applied readily during the manufacture of the coil, and in fact it a .coil is not the balanced coil but is used in brid e. In that case it saves the use of an auxi iary coilto avoid metallic connection between the repeater circuit and the monitoring set.

For a more com lete disclosure of the invention and its mo e of operation, a description' of a typical repeater circuit embodying the invention will now be iven, reference bein had to the accompanying drawing in whic Fig. 1 shows a schematic circuit arrangement of the repeating station'for one line; Fig. 2 shows an alternative manner of associating the monitorin windingwith the line; and ig. 3 shows a ifl'erent manner of applying the monitoring winding.

The line is shown as divided into the usunl east-west sections LE and LW associated with each other through two one-way rePeat- -ing paths RE and RW. To prevent circulation of energy around the repeating paths the line sections are provided with the usual balancing circuits BE and BWand with the balanced repeating coils comprising the series line windings 1, 2, 3 and 4 associated with the repeater output coils 5, 6. All of this apparatus is well known in the art and it is clear that with proper line balances transmissions may, pass from section. LE through the repeater RW and on to the line LW without finding their way into the input of the repeater RE and similarly transmissions inay pass in the opposite direction through repeater RE.

According to the form of the invention shown in Fi 1 an extra winding comprising sections 1 and'8 is applied to the balanced repeating coil to serve for monitoring and signalling. In construction this winding may comprise a relatively small number of turns of fine wire and may be situated next-to the core or between the primary and secondary windings or outsidev of the primary and secondary'windings. It thus occupies little space and its presence. does not therefore interfere with the eflicient design of the output transformer for its usual an normal function. y

The terminals of the windings 7," 8 are brought out to the respective jacks JE and JW to connect the monitoring apparatus with the line. The plugs 9 and 10 will be inserted into their respective jacks and for normal listening over both lines the key K will be thrown to its upper position where it may if desired be locked thus holding its springs in their separated positions. A circuit then exists including the monitoring windings 7 and 8 of line LW, springof jack JW, tip of plug 9, contact 11 now clesed, contacts 12 and 13 normally closed, the .resistance R, attendants receiver 20, contacts 14 and 15 normally closed, contact 16 of key K, sleeve contacts of plug 10 and jack JE, windings 7 and 8 of line LE, spring and tip of plug 10. contact 17, sleeve contacts of plug 9 and jack JW to the opposite terminal of monitoring windings 7 and 8 of line LW. With this circuit established the attendant can listen to transmissions passing over either line section. The windings 7 and 8 are related to the line windings 1, 2, 3, and 4 in the same manner as are the repeater output windings 5 and 6, and the windings 7 and 8 serve, therefore, to receive currents incoming over the line, or to transmit current over the line, or to receive currents from the repeater output windings 5 and 6. Current impressed on the windings 7 and 8 from the monitoring circuits will not, however, affect the input of the repeater, since they are applied to the line side and line-balance side of the input terminal in the same manner as "are the repeater output coils 5 and 6. With the circuit established as above traced, therefore, if the repeaters are operative, the attendant hears signals due to received unamplified current over one line section and the same current after it is passed through a repeater and therefore become amplified, since the two monitoring coils are connected in series.

The object of the resistance R is to make the impedance of the receiver circuit,-as used in the monitoring connection, so high that only a small fraction of the outgoing transmission is drawn ofl into the monitoring receiver through the windings 7-8. If only one hundredth of the outgoing energy is drawn off through this circuit the volume of monitoring transmission will still be as great as that heard on the average by the subscriber at the distant end. When this is done the impedance of the monitoring circuit is relatively high as compared to that of windings 78 and the connection of the monitoringmircuit changes conditions only slightly from that of leaving this winding open circuited. On the other hand the impedance of the talking sets should be designed to match that of the monitoring connection to afford an veflicient communication channel for the repeater attendants.

If the attendant desires to talk over both line sections at oncehe leaves the key K in its up position and throws the double throw key DK to the right in the drawing. This separates the key springs opening contacts l3 and 14 and closes contacts 21 and 22. This alters the circuit previously traced by establishing a path from contact 11 through contact 21, secondary of microphone repeating coil 23, contact 22, contact 16 and from thereon as previously traced. Speech currents set up by the microphone T therefore pass to both line sections but do not afiect the input of either repeater as' described.

When the key DK was thrown 'asdescribed the receiver 20 was cut 011' at contacts 13 and 14 but is connected across one half of the secondary of repeating coil 23 thereby providing side tone in the receiver and furnishing an eflicie'nt'circuitfor receiving over .either line section.

If 1t is desired to transniit ringing current over both line sections at the same time, the key DK is thrown to the left in the drawing separating the left hand springs and opening the contacts 12 and 15 ot' the normal listening circuit and closing contacts 24 and 25'leading to a, source of suitable ringing current RC. From contacts 24 and 25 the circuit is as previously traced to the monitoring windings of the two line sections in series. During ringing the attendants transmitter and receiver are dis connected at contacts of key DK,

If it is desired to listen, talk or ring over line section LE the key K is thrown to the down position to open its sprin s and the key KE is thrown to the upor c osed position. A circuit then exists from the jack and keys K and KE are opened a circuit is established from the monitoring coil of the line LW, jack JW, plug 9 through the key contacts and 31 to the, common leads 28, 29, for connecting any of the monitoring apparatus desired to the line section LW.

In Fig. 2 isshown a method of positioning telephone repeater stations employing a baland utilizing the monitoring windings 7 and 8 which often proves convenient. The wind ings 'i" and8 are positioned between the line windings 1, 2, 3, and 4 and the repeater output windings 5 and 6 and the mid-point of the windings 7 and 8 is connected directly to ground. This provides an eflective electrostatic shieldand acts very much as if a groundedmetallic sheath were inserted between the primary and secondary windings of the balanced repeating coil. If both monitoring windings are arranged in this manner a tendency oi the repeater to sing due to electrostatic differences of potentials around the repeater circuit isopposed.

,In each of the Figures 1 and 2 the output of the repeater is associated with the outgoing line through the inductively related windings of the balanced repeating coil. In

some cases the arrangement is to connect the output circuit of the repeater to the bridged circuit of the repeating coil as shown in Fig. 3, where the output of repeater RE is connected through transformer 40, 41 to the bridged circuit 42. In such a case the moni-' toring winding may be applied to the output transformer 40, 41, the monitoring winding being indicated at 43.

It will be understood that the apparatus I shown at the monitoring station and the keys for controlling the various connections are illustrative of only one of many possible arran ements and that the principal object of idle invention once having been shown it will be obvious that these circuit arrange-- ments may be widely changed to meet varying conditions without departing from the spirit of the invention the scope of. which is defined in the appended claims.

What is'claimed is:

1. In a monitoring and signaling system for a telephone repeater station, said repeater station having line sections interconnected through oppositely directed repeaters, a balanced repeater coil for each of the interconnected line sections, and monitoring .and signaling coils each comprising an extra anced repeating coil in the line, said circuit comprising an extra winding inductively re-. rated to the line winding of said repeating coil but out of conductive relation to the circuit, a receiver, a circuit of such high impedance as to have negligible reaction on the normal repeater action for closing said ex-- tra winding through said receiver, a talking set for enabling the monitoring operator to communicate over the line through said extra winding, said talking set being proportioned to such an impedance as to give efiicient transmission to the connected transmisslon hnes.

4. In a repeater circuit including balanced ;repeater output windings mounted on a common core, a supervisory winding mounted on said core and in inductive relation to said repeater output windings and circuit arrangements for utilizing said coil for talking and listening purposes. I

5. In a repeating arrangement for a line, a balanced transformer winding including in the line circuit, a repeater having its out-- put circuit inductively. coupled to the bal-- anced transformer winding, an auxiliary winding inductively associated with said transformer and supervisory apparatus connected in circuit with said auxlliary wind mg.

ancing circuit, a repeater input circuit con-- nected to the mid-points of said windings, a

repeater ouzcl-put circuit inductively related to said win i no A line, a balancing circuit therefore, transformer windings :n said line and batngs, an auxiliary winding inductively associated .with said windings and supervisory apparatus connected in circuit with said auxiliary winding.

7. A line, a balancing circuit therefor,

transformer windings in said line and bal ancing circuit, a repeater input circuit connected to the midoints of said windings, a repeater output circuit inductively relatedv to said windings, and an auxiliary winding inductively associated with said windings and connected in circuit with supervisory apparatus, said auxiliary winding being balanced, whereby energy from said an rvisory apparatus divides substantially equally 4 Ma awi between said line and said balancing circuit. circuit, and means for utilizing saicl moni- 8'. A monitoring and signaling circuit for toring and signaling Winding for signaling telephone repeater stations en'lploying a baland talking purposes. 10 anced repeating coil comprising a monitor- In witness whereof, I hereunto subscribe ing and signaling Winding inductively remy name this 15th day of June A; D, 1921. lated to the line windings of said repeating coil but out of conductive relation to the line RAY SETH WILBUR.

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