US1619060A - System of multifrequency circuits - Google Patents

Description

March 1 1927.

R.- W. DEARDORFF SYSTEM OF MULTIFREQUENCY CIRCUITS Filed Feb. 8. 1924 ATTURNEY Patented Mar. 1, 1927.

1,619,060 s PATENT oFFICE.

RALPH W. DEARDORFF, OF KENSINGTO N, CALIFORNIA, ASSIGNOR TO AMERICAN TEL- EPHONE AND TELEGRAPH COMPANY, A CORIQRATION OF NEW YORK.

SYSTEM F MUL rirnnennncr ciRcUrrs;

Application flied February s, 1924. serial No. 691,455.

The principal object of to provide apparatus particular frequency range to another.

quency currentspart way and transmitting them the rest of the way a part of another low These and other other phantom circuit. p

will become appar jects of my inventionl on consideration of a Vlimited number of sy cific embodiments which I have chosen illustratein the accompanying drawings.

will be understood that the following speciparticularly to ythese examples of my invention, leaving the scope defined in the appendfication`v refers more ofthe invention to be ed claims.

`In the drawings, Figure means for transferring rents from a part of one such circuit a party vof the other `such* circuit. fFig. pairs of side to a phantom circuit, with meansv to transfer high fre-` 2 is a diagram showing two circuits,l each pair belonging quency currents from a part *ofy each s circuit" of taining the normal transmission' side and phantom circuits o-f both pairs.

' In the transmission filter 13 is interposed'asY shown in Fig.

filter consists of reactance elementsV arranged asshown, and in the par-KV ticular' instance here disclosed, the reactanceV the following table.Y

Ythe table 'also 4U This low pass in the foregoing Y m11. L1=532 L27-65.8 1132329 11,216.4

llith the values given the critical frequency 13 is 8,(190 cy les per4 second.

my invention is new and improved method and for the transfer of currents of a fromv one circuit Another object of my invention isfto provide for transmitting high freon a part of a low frequency circuit and then transferring them frequency circuit. Still another object of my invention is to provide for transferring currents of a certain frequency range from the side circuits of a phantom circuit to the side circuits of an- Y 1 isa diagram'of twov low frequency circuits provided 'with highV frequency curone pair tov'a part of a respective side Vcircuit Vof the other pair, while mainover the line 11, 12, a'low pass comprises all the reactance values'in; Figs. 1l

l table, l for the low pass filterV vThat is, frequencies below this value will be transmitted between the lines 11, 12 and frequencies above this value will be shunted out.

At 14, 15 a similar transmission line is shown with a similarly interposed low pass filter 16.

The high pass wave filter 18 is connected at 17 and v21 between the parts 11 and 15 of the respective lines 11,12 and 14, 15. This high passlter 18 is made up of reactances arranged as shown inthe drawing and with the particular values given in the foregoing table.V Its critcial frequency is 3,000 cycles Vper second, meaning that frequencies above this value will be transmitted between 11, 17V and 15, 21 but that frequencies below this value will not be transmitted.

Voice frequency currentsY on the line 11, 12 will pass readily .through the filter 13 and will not be diverted at 17. Similarly, voice frequency currents will'pass on the line 14, 15 without diversion at 21. But high frequency currents on the part 11 of the line 11,12 will not pass to the part 12 but will pass at 17 through the filter 18 to the part from 15 to 11. v

VIt will be seen that at. any place where -two voice frequency transmission lines pass in proximity, filters like 18 and 16 can lt-.erposed and another filter like 18 can beconnected across so that high frequency lcurrents may be transferred from one part 11 of one line to one part 15 of the other line.

In Fig. 2 I have shown two side circuits 11, 12 and 11, 12 phantom circuit. Similarly, 14, A15 and 14', 15 Vare the two side circuits of another phantom circuit. In each sidecircuit there is interposed a respective low pass filter 13, 13, 16 and 16. v l18 'are connected across between parts of respective side circuits in a manner similar to that described for Fig. 1. At the middle points 19 and 19 of the terminal shuntcoils '11 connections are made across from one high pass filter 18 to the other high pass filter Y 18. These connectons 19 and 19 are made through interposedv condensers C5. The l middle coils L, have their middle points dirrectly connected at 20. v It will be seen that the four side circuits shown in Fig. 2 will each carry voice frequency currents, the respective low pass filters LP transmitting these currents freely.

ide

bein.- 8

which together make a` High pass filters 18 and:v

Also, for voice frequency currents on any side circuit, the high pass filters 18 and 18 will not transmit, the principle being the same as in Fig. 1. This is not altered by the connections at the middle points of the coils L4 in Fig. 2, because these points are neutral points on the side circuits.

High frequency currents on the side circuits will be blocked by the low pass filters LP and will be transmitted by the high pass lters 18 and 18'. I-Iere again the connections at the middle points of the coils L4 will not affect this result, because these points are neutral points on the side circuits.

Low frequency currents on the phantom circuits will be readily passed by the low pass filters as may be seen from Fig. 1, Where the inductances L, are non-inductive for currents the same way in both conductors. In the absence of the connections 19-I 19 and 20, phantom currents, though of low frequency, would get through the condensers C3 and C4 in some degree between the lines 11, 1l' and 15, 15. But the cross connections 19-19 and 2O shunt out such phantom currents so that no substantial phantom current gets across between 11, 11' and 15, 15. The capacities C5 are given a compromise value; if too large, they would shunt out so much current across 11, 11' or 15, 15 as seriously to attenuate the phantom current along the phantom circuit 11, 12, 12', 11' or 15, 14, 14', 15'. On the other hand, if the capacities C5 were made too small, there would be an appreciable transfer of phantom current between 11, 11' and 15, 15'. By putting condensers of proper value at C5, it is possible to put a direct connection at 2O so that substantially no currents are transferred across from one vpliantom circuit to the other.

It should be noted that by making the connections at the middle points of the coils L4, these coils become non-inductive to phantom currents, so that they oeriio impedance whatever in Vthe cross connections 19-19 and 20.

I have shown the reactances at C5 in Fig. 2 in the form of capacities but it will be understood that any substantial reactancesy for the voice frequency range'might be employed at these points. Instead of the capacities represented by the condensers C5, inductances or resistances may be interposed as indicated in Fig. 2 by throwing the switches S to the proper contacts. If the switches S are thrown so as to substitute the inductances for the condensers C5, the combination of which these inductances are apart would act as a high pass wave filter to the phantom circuit 11-11-- 15-15'.

It will be seen that if the phantom circuit` comprising the side circuits 11, 12 and l1',

12 passes in proximity to the phantom circuit comprising the side circuits 14, 15 and 14', 15', then it becomes possible to superpose high frequency currents on parts 1l, 11 of the side circuits of one pair and the parts 15, 15' of the side circuits of the other pair and to transfer these high frequency currents across either way.

I claim:

1. In combination, two phantom circuits each comprising a pair of side circuits, low pass filters interposed in said side circuits, and connect-ions between the parts of the side circuits one way of one pair to the parts of the respective side circuits one way of the other pair, these connections each comprising a high pass wave filter and means to shunt out phantom currents across said high pass filters.

2. rllwo phantom circuits, each comprising a pair of side circuits, low pass filters interposed in each said side circuit, high pass filters connecting each side circuit on one side in each phantom with a corresponding side circuit on one side in the other phantom, and connections between the midpoints of corresponding shunt elements of the said last mentioned filters, the connections for the end shunt elements comprising switches and various impedance elements which may be interposed by means of said switches.

3. In combination, two phantom circuits passing in proximity and each comprising a pair of side circuits, low pass lters inter-f posed in the respective side circuits, connections across from one part of each sidecircuit of a pair to a part of a respective side circuit of the other pair, high pass wave filters interposed in these connections, said high pass wave filters comprising the. usual shunt and series reactances, and connections from the middle oints of the shunt vreactances of one hig pass Wave filter to the corresponding points of the other high pass wave filter.

4. In combination, two phantom circuits passing in `proximity and each comprising aV pair of side circuits, low pass lters interposed in the respective side circuits, connections across from one part of each side circuit of a pair to a part of a respective side circuit of the other pair, high pass wave filters interposed in these'connections, said high pass wave filters comprisingseriescon-l densers balanced in pairs and alternately disposed shunt inductances, the Vterminal shunt inductances, of each filter being connected at their middle points through condensers to the like and the intermediate inductances beingconnected at their middle points directly to the like points of the other filter.;V Y 1 5. In combination, ytwo phantom circuits each comprising apair of side'circuits 'all adapted for through transmission Ofcurpoints of the other filter,

rents of a certain frequency range, means to transfer currents of another frequency range between a side circuit of one pair and a side circuit of the other pair, and means to prevent current of said first frequency range from getting across from one phantom circuit to the other.

6. In combination, two phantom circuits each comprising a pair of side circuits and adapted for through transmission of currents of a certain frequency range, means to transfer currents of another frequency range between a part of each side circuit of one pair and a part of a respective side circuit of the other pair, and means to prevent current of said first mentioned frequency range from getting across from one phantom circuit to the other.

7 In combination, two phantom circuits each comprising a pair of side circuits, low pass filters interposed in the respective side circuits, high pass filters interposed between a part of each side circuit of one pair and part of a respective side circuit of the other pair, and means to prevent low frequency currents on either phantom circuit from getting across through the connections afforded by said high pass filters.

8. In combination, two phantom circuits passing in proximity and each comprising a pair of side circuits, low pass filters interposed in the respective side circuits, connections across from one part of each side circuit of a air to a part of a respective side circuit o the other pair, high pass wave filters interposed in these connections, said high pass wave 4filters comprising series condensers balanced in pairs and alternately disposed shunt inductances, the terminal shunt inductances of each filter' being connected at their middle points through impedance elements to the like points of the other filter, and the intermediate inductances being connected at their middle points directly to Ythe like points of the other filter.

In testimony whereof, I have signed my name to this specification this 29th day of January, 1924.

RALPH IV. DEARDORFF.

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