US1472451A

US1472451A - Phantomed signaling circuits

Info

Publication number: US1472451A
Application number: US407972A
Authority: US
Inventors: Milton K Akers
Original assignee: Western Electric Co Inc
Current assignee: AT&T Corp
Priority date: 1920-09-03
Filing date: 1920-09-03
Publication date: 1923-10-30
Anticipated expiration: 1940-10-30

Description

Oct. 30, 1923. 1,472,452

M. K. AKERS PHANTOMED S IGNALING- CIRCUITS Filed Sept. 5. 1920 //7 van for: /7/7f0/7 A. Akers Patented Oct. 30, 1923.

MILTON K. AKERS, OF EAST ORANGE. NEW JERSEY, ASSIGNOR TO WESTERN ELECTRIC COMPANY, INCORPORATED, OF NEW YORK, N. Y., A CORPORATION OF NEW YORK.

PHANTOMED SIGNALING CIRCUITS.

Application'filed September 8, 1920. Serial No. 407,972.

To all whom it may concern:

Be it known that I, MILTON K. AKERs, a citizen of the United States, residing at 41 South lVa-lnut Street, East Orange, in the county of Essex and State of New Jersey, have invented certain new and useful Improvements in Phantomed Signaling Circuits, of which the following is a full, clear, concise, and exact description.

This invention relates to transmission systems and more particularly it relates to signaling, lines, such as telephone lines, which are capable of being phantomed.

As is well known, in the art of telephony for example, an additional signaling circuit may be derived by phantoming two side circuits in which thesignaling currents for the third or phantom circuit pass in one direction over the two wires in parallel of one side circuitand return over the two wires in parallel of the other side circult. For ef- .ficient operation of such a derived phantomed circuit it is essential that the phantomed circuit currents be substantially equal in each of the two wires of each side circuit. Any inequality in the division of the phantomed currents will give rise to cross-talk, a result which is highly undesirable. This inequality of the phantomed currents in the two side circuit wires is due to some impedance irregularity in one or the other of the side wires and lines have frequently been encountered having such irregularities that it has not been found feasible to phantom them.

In accordance with this invention it has been found possible to phantom side circuits with considerable impedance irregularities therein by deriving a current proportional to the amount of unbalance between the two wires of each side circuit and impressing this current on each wire in such a manner as to substantially equalize the currents in each pair of wires. Such a method of equalization of the phantomed currents is over a wide range substantially independent of the frequency.

This invention will be better understood by reference to the following detailed description taken in connection with the accompanying drawing which represents this invention as embodied in a telephone system.

The telephone system illustrated in the drawing comprises two side circuits composed of conductors 5, 6, and 7 8 respectively. Connected at one end of side circuits 5, 6 is a substation set A comprising a transmitter 10, receiver 11. transformer 12, and battery 13. The opposite ends side circuit 5, 6 has a similar substation set B comprising a transmitter 14, receiver 15, transformer 16. and battery 17. Side circuit 7, 8 is provided with similar substation sets C and D.

Shunted across the terminals of the two side circuits 5, 6, and 7. 8 are the

phantom coils

19, 20, 21 and 22 from intermediate points of which

connections

24, 25, 26 and 27 are taken to the two substation sets E and F for the derived phantom circuit. The phantom circuit currents in such a system may be considered for example, as passing over wires 5 and 6 in one direction and returning over wires 7 and 8 in the opposite direction.

As is well-known in the art, such a phantom is feasible only when there is a substantial equality in the phantom circuit currents in wires 5 and 6 and in wires 7 and 8. Any inequality in a division of the phantom circuit current between the two wires of each side circuit pair, gives rise to cross talk between the side circuit currents and the phantom circuit currents, a result which is highly objection-able.

The manner in which side circuits may be phantomed, according to this invention, regardless of the tendency of one wire of each part tending to carry more than its proportion of the phantom circuit currents, may be explained as follows: Connected in shunt to the side circuit 5, 6 at the end adjacent substation A is a transformer 35 having the three

windings

30, 31 and 32, which are preferably mounted on a single coil structure. Inductively associated with the phantom coil 19 is an inductance element 33 which is in circuit with winding 31 of the transformer 35.

Windings

30 and 32 of transformer 35 are connected in series with the phantom coil 19. A similar arrangement at that end of side circuit 5, 6 adjacent substation B is shown comprising a trans former 36 having

windings

37, 38 and 39;

windings

37 and 39, of which are in series with phantom coil 20, the other winding 38 is in circuit with an inductance element 40 which is associated with the phantom coil 20.

Suppose, for the purpose of illustration that line 5, due to impedance irregularities tends to carry more than half of the phantom circuit current. The phantom circuit current flowin r through connection 24 will therefore ten to divide between the two halves of phantom coil 19 and in proportion to the length, for example, of the arrows shown adjacent coil 19. Since that part of coil 19 in circuit with line 5 tends to carry the majority of the current, the current induced in winding 33 will be in the direction of and proportional to the length of the arrow adjacent coil 33. The current in coil 33 will flow through coil 31 and will produce in

windings

30 and 32 current components in the direction of the arrows adjacent these two windings. It will be observed that the current induced in coil 30 is in a direction opposite to the flow of the phantom circuit current and will therefore tend to diminish the proportion of the phantom circuit current carried by wire 5. The current induced in coil 32, however, is in such a direction as to aid the phantom circuit currents in line 6 and therefore increase the amount of phantom circuit current carried thereby. It follows therefore, that this arrangement of these inductive windin with respect to the phantom coil 19 Wlll. serve to substantially equalize the phantom circuit currents carried by wires 5 and 6, regardless of differences in impedances of the two wires 5 and 6. Such an arrangement, furthermore, is independent of the frequency, and therefore will produce a substantial equalization of the currents over the whole telephonic range.

It is evident that the above described method cannot produce" an absolutely perfect balance between the two wires 5 and 6 since such a condition would make the current in winding 33, zero and consequently no current would be produced to create the corrective action necessary. The arrangement however, reduces the cross talk between the phantom circuit and the side circuits.

The action of

windings

37 and 40 inclusive which are associated with phantom coil 20 is similar to that described for the system associated with phantom coil 19.

In case the side circuit 7, 8, which is employed in connection with side circuit 5, 6 also tends to carry the phantom circuit currents in unequal proportions, arrangements similar to those described for phantom coils 19 and 20 may be associated with the

phantom coils

21 and 22. Thus in thedrawing, transformer 42 having windin s, 43, 44 and 45, is shown at that end of side circuit 7, 8 adjacent substation C and a winding 46 is shown inductively related to phantom coil 21 and in circuit with winding 44 of transformer 42. Similar

inductive windings

49, 50, 51 and 52 are shown associated with the phantom coil 22 at that end of side circuit 7, 8 adjacent substation D. However, if the side circuit associated with side circuit 5, 6 in order to produce a phantom circuit, is of such a nature as to carry the phantom circuit currents equally without the necessity of any correcting means, the phantom coils for the second circuit will not require the inductive windings associated therewith as shown in the drawing.

Although this invention has been described specifically in connection with a telephone system, it is to be understood that this invention is applicable to other types of signaling systems such as telegraph systems, composite systems, carrier current systems, and the like.

\Vhat is claimed is:

1. In combination, a line, a transformer having a winding in series with said line, a phantom tap connected to the midpoint of said winding, a second transformer having a winding in circuit with a second winding of the first transformer, and having other windings connected in series with said line on opposite sides of said tap.

2. In combination, a two-wire line, a transformer winding in series with said line, a phantom circuit tap connected to the midpoint of said winding, a second winding inductively associated with said first winding, a third winding and a fourth winding connected in series with said first winding on opposite sides of said phantom tap, and a fifth winding inductively associated with said third and said fourth windings, and connected in series with said 'second winding.

In witness whereof, I hereunto subscribe my name this 27th day of August, A D. 1920.

MILTON K. AKERS.