US1455827A - Selective circuit for multiplex transmission - Google Patents

Description

May 22, 1923.

H. A. AFFEL SELECTIVE CIRCUIT FOR MULTIPLEX TRANSMISSION Filed Sept. 24, 1919 INVENTOR.

Patented May 22, T1923.

M A. AFFEL, OE BROQKLYN, NEW YQRK, ASSIGNOB TO EC TELEPHONE TELEGRAPH COMPANY, A CQRPOBATION OF N YORK.

' instant rray SELECTIVE CIRCUIT FOR MULTIPLE TRANSMISSION.

Application filed September 24, 1919. Serial Ito. 325,841.

To all whom it may concern: 1

Be it known that I, HERMAN residing at Brooklyn in the county of Kings and State of New York, have invented certain Improvements in Selective Circuits for Multiplex Transmission, of which the following is a specification.

This invention relates to signaling systems and more particularly to systems in which a plurality of signals are simultaneously transmitted over the same conductor.

One of the principal features of the invention resides in the provision of an arrangement whereby a plurality of signals may be transmitted over a grounded conductor such as a submarine cable.

Still another feature of the invention relates to the provision of arrangements whereby a channel for the transmission of ordinary voice currents and a number of channels for the transmission of telegraph signals or additional telephone channels by the use of carrier currents maybe simultaneously superposed upon a grounded conductor such as a submarine cable.

The above features, together with other features of the invention more fully hereinafter appearing, are realized by superposing upon the ordinary voice currents transmitted over a submarine cable, a plurality of carrier currents having frequencies in some instances above and in some instances below the voice range, together with ordinary Morse currents, the several channels beingseparated by means of frequency selectivity.

The invention may now be more fully understood by reference to the following description when read in connection with the accompang drawing. Referring to the drawing, t? r designates'a transmission C11- cuit such as a submarine cable, which forms one'conductor of a transmission circuit employing a grounded return. An artificial line or net work MN is provided for balancing the cable MN and a plurality of parallel signaling paths, 1-1, 2-2, 3-3, 4-4 and 5-5 are provided for interconnecting the cable and artificial line. Morse transmitting ap aratus T and Morse receiving apparatus 1 is associated with the junction points of the paths 1 and 1", the polar receiving relay having its windings so arranged that one-half 18 included in each of the paths 1 and 1, while transmitted our- A. Arena,

rents from the transmitter T are applied to the midpoints of the windings 11. An alternating current telegraphic transmitting apparatus T is applied to the midpoints of the windings of a balanced transformer 12, connected in the path 2-2, while an amplifying and detecting arrangement 1), and

a receiver R, is inductively associated with the path through said transfdrmer. Atelephone transmitter T is arranged to apply telephonic currents to the midpoint of the windings of a transformer 13 in the path 3-3, while a tele hone amplifier A, and telephone receiver 3 are inductively associated with said path through said transformer 13. In a similar manner carrier transmitting arrangements T and T are connected to the midpoints of the windings of transformers 14 and 15 included in the paths 4-4 and 5-5. Detecting and amplitying arrangements D, and D havin receiving devices R, and R, associated t erewith are inductively coupled to said paths through the transformers 14 and 15 respectively.

It will be observed that the arrangement above described is such that all of the transmitting devices are conjugate with respect to all of the receivi devices' and viceversa, so that there wil be substantially no interference between oppositely directed transmissions, regardless of the frequencies. In order to provide for frequency. separation between transmission in the same direction, filters or selectin circuits F F F,,, F, and F are provide in the paths 1, 2,

3, Land 5, respectively. These filters may be of any well-known character, but are preferably band filters of the type disclosed in the U. S. Patents to George A. Campbell,

Nos. 1,227,113 and 1,227 ,114, dated May 22, 1917.

illustrated, is designed to transmit a range of frequencies extending from zero to 100 cycles, this range being suiiicient to take The filterF may be a low filter and, as

In order to balance the filters F to F inelusive, balancing networks should be provided in the corresponding halvesof the signalin paths designated 1' to 5' inclusivc. iese balancing arrangements may comprise any suitable form of networkwhose electrical characteristics simulate those of the filter to be balanced. As illustrated, however, duplicate filters F F F F andF, are provided for balancing the selective filters F, F, inclusive. The filters F to B, should each transmit the same band or frequencies as the filter which it is intended to balance. lit will be understood, of course, that the various frequencies above referred to are given merely for purposes of illustration and that in actual practice other frequencies than those indicated may be used.

It will be seen that by means of the arrangements above disclosed it is possible to utilize the full frequency capacity of an expensive conductor such as a submarine cable, so that in addition to the ordinary Morse signals ordinarily transmitted a telephone channel as well as a number of additional carrier telephone or telegraph channels are provided. 0

It will'be obvious that the general principles herein disclosed may be embodied in many otherorganizations widely different from those illustrated, without departing from the spirit of the invention as defined in the following claims.

What is claimed is:

1. In a multiplex system, a transmission circuit, balancing means therefor, a plurality of signaling paths connected in multiple between said transmission circuit and balancing means, said balancing means simulating the impedance of the transmission circuit at the frequencies transmitted over each of said paths, means whereby telephone currents of voice frequencies may be transmitted from one of said paths. over said transmission circuit, means whereby signal ing currents having frequencies below the lower voice limit may be transmitted over certain other of said paths, means whereby signaling or carrier currents having frequencies above the upper voice limit may be transmitted over said transmimion circuit through still other of said paths, and means to substantially prevent in each of said paths the transmission of frequencies from the other paths.

2. In a multiplex signaling system, a

transmission circuit, balancing means therefor, a plurality of signaling paths connected in multiple between said transmission circuit and said balancing means, said balancing'meanssimulating'the impedance of the transmission circuit at the frequencies transmitted'ovcr each of said paths, means associated with one of said paths for transmitting and receiving Morsecurrents, means associated with another of said paths for transmitting and receiving alternating carrier currents whose frequency is less'than that of the lowest frequency employed in ordinary telephonic transmission, means associated with a. third of saidpaths for transmitting and receiving ordinary telein multiple between said transmission cir cuit and balancing means, said balancing means simulating the impedance of the transmission circuit at the ire uencies transmitted over each of said pat is, telephonic transmitting and receiving apparatus associated with one of said paths and telegraphic transmitting and receiving apparatus associated with the remaining paths, certain of said apparatus being arranged to transmit and receive frequencies above the upper voice limit, other of said apparatus being arranged to transmit and receive frequencies below the lower voice limit, and means to substantially prevent in each of said paths the transmission of frequencies from the other paths.

4. In a multiplex signaling system, a transmission circuit, comprising a grounded cable conductor, an artificial line or network, a plurality of signaling paths connected in multiple between said transmission circuit and artificial line, said artificial line simulatingthe impedance of the taransmission circuit at the frequencies transmitted over eanh of said paths, and selective means in said paths for providing frequency discrimination between alternating currents transmitted overthe paths.

5. In a multiplex signaling system, a transmission circuit comprising agrounded cable conductor, an artificial line or network, a plurality of signaling paths connected in multiple between said transmisessee? sion circuit and artificial line, said artificial line simulating the impedance of the transmission circuit at the frequencies transmit-' ted over each of said paths, selective means in said paths for providing frequency dis-i crimination between the paths, the selective means associated with one of the paths permitting the transmission of ordinary voice currents, the selective means associated with other of said paths permitting the transmission only of signaling frequencies below the lower limit of voice transmission and theselective means associated with still other ofsaid paths permitting the transmission only of signaling or carrier frequencies above the upper llfllllilllgLVOlCQ frequency.

6. In a multiplex transmission system a transmission circuit comprising a grounded cable conductor, an artificial line or network, a plurality of signaling paths connected in multiple between said transmission circuit and artificial line, said artificial line eiated with still other of said paths, said carrier current apparatus employing frequencies above the upper limiting telephonic frequency, and means to substantially prevent in each of said paths the transmission of frequencies from the other paths.

In testimony whereof, I have si ed my name to this specification this 23r day of September 1919.

HERMAN A. AFFEL.

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