US1502817A - High-frequency multiplex signaling system - Google Patents

Description

July 29 1924.

L. ESPENSCHIED HIGH FREQUENCY HULTIPL SIGNALING SYSTEM Original Filed Sea. 30 )919 mmtoz Patented July 29, 1924.

UNITED STATES PATENT OFFICE.

LLOYD E SPENSQHIED, OF QUEENS, NEW YORK, ASSIGNOR TO AMERICAN TELEPHONE AND TELEGRAPH COMPANY, A CORPORATION OF NEW YORK.

HIGH-FREQUENCY MULTIPLEX SIGNALING SYSTEM.

original application filed September so, 1919, Serial No. 327,500. Divided and. this application filed 1 m 16, 1921. Serial No. 461,969.

T0 on whom it may concern:

Be it known that I, Lnoro ESPENSGHIED, residing at Queens, in the county of Queens and State of New York, have invented certain Improvements in High-Frequency Multiplex Signalin Systems, of which the following is a specification.

This invention relates to high frequency multiplex signaling systems, and particularly to a terminal circuit arrangement embodying the use of a common translating circuit adapted both to modulate transmitted telegraph impulses and to demodulate the received high frequency tele graph signals.

This application is a division of my copending application, Serial No. 327,500, filed Sept. 30, 1919, entitled High frequency multiplex signaling systems.

In multiplex signaling systems heretofore used employing a plurality of carrier currents of various frequencies, it has been customary to insert in the transmitting and the receivin branches of the terminal circuit atransfiting device individual to each of the said branches. It is the primary object of the present invention to adapt the terminal circuit arrangement so that the process of modulation, demodulation and amplification of the. various currents in both the transmitting and receiving branches of the terminal circuit may be performed by a single translating circuit. Although the preferable form of translating device is a single thermionic vacuum tube or a pluralit of such tubes in combination adapted to 110- tion as a single unit with respect to the two branches of the terminal circuit, any well known ty e of translating device, such as, for exampqe, the mechanical repeater, may be used.

Another object of this invention is to provide a circuit arrangement whereby low frequency telegraph signals or signaling impulses received over one line circuit may modulate high frequency oscillations from a source connected with the translating circuit, and the modulated high frequency oscillations may be impressed upon the transmission line circuit; and to provide for the demodulation of the high frequency signals received over the said transmission line a and impressed upon the same translating circuit. This invention also provides in rangement shown in Fig. 1. and Fig. 2 shows a type of feedback oscillator adapted to be used with the general circuit shown in Fig ure 1.

Figure 1 shows a means for a plying this invention to the transmission 0 telegraphic signals over wires and Fig. 1" shows means for transmission by radio signalin system. In the figure, L represents a me over which low frequency telegraphic signals may be transmitted to the terminal circuit. This line is connected with the windings of a balanced relay lit having associated therewith a network N adapted to balance the line L The armature of the relay 1 is adapted to impress impulses of opposite polarity upon. the input circuit 2; which is ridged across a condenser connected into the common conductor of the input side of a duplex translating device. Connected also with the same common conductor, either directly or inductively as shown inthe drawing, is as'oui'ce of oscillations of carrier frequency G. Across the input side of the said translating device is a transformer '1 for impressing hi h frequency received oscillations upon t 1e said device. Con- 'nect-ed with the common terminal of the output side of the device MD .is the output circuit 3, by means of which the modulated oscillations may be im ressed by the triple winding transformer upon the transmission line or antenna. A network N is associated with the said transformer to balance either the transmission line ML or the antenna of Fig.1. Bridged across the out at side of the translating device MD is a iffere-n'tial relay R, the armature of which is adapted t'\ respond to the received impulses and ope; and close the low frequency circuit L The relay R, is so designed that if the network N balances the line L,, the impulses transmitted over the line L by the operation of the armature 4 will cause no disturbance of the armature 1 1n the output side of the relay.

In the operation of this circuit low frequency telegraphic signals transmitted o er the line L, will cause the operation of the armature 1 and will apply impulses to the circuit 2 which is bridged across the terminals of the condenser K Simultaneous with the impression of the low frequency signaling impulses on the condenser K, high frequency carrier oscillatlons from the source G will likewise be impressed across the input side of the modulating and demodulating circuit MD,. The high frequency carrier oscillations will be modulated by the impulses impressed upon the condenser K and the modulated oscillations which ap ear in the output side of the modulatlon an d demodulation circuit will be impressed by the transformer T, upon the output circuit 3 from which they will pass to the transmission line ML. Since the low frequency impulses and the high frequency carrier oscillations are impressed upon the common conductor of the balanced modulation and demodulation circuit, the currents resulting therefrom will flow in opposite directions through each half of the winding of the relay R in the out ut side of the circuit and will cause no e ect upon the said relay. When high frequency oscillations modulated by telegraphic impulses are received over the transmission line ML, they will be impressed by the transformer T upon the receiving circuit 5 and will pass to the circuit 6 tuned to reception frequency. These modulated high frequency oscillations which are impressed across the input side of'the modulation and demodulation circuit will be demodulated y means of carrier frequency oscillations impressed upon the same circuit by the source G. The resultant impulses arising from demodulation will operatet-he relay R and accordingly corresponding signals will be impressed upon the low frequency signaling circuit L Since the modulated high frequency oscillations arriving through the circuit 5 are impressed across the input side of the modulation and demodulation circuit, the impulses resulting from detection will produce no effect upon the circuit 3 which is coupled by means of the transformer T with the common-conductor in the output side of the modulation and demodulation circuit.

Figure 2 shows a novel form of generator of high frequency oscillations which is adaptedto be used with the general circuit shown. in Figure 1. In the arrangement shown in- Figure 2 high frequenc oscillatrons arriving over circuit 5 wi be impressed upon the circuit 6 tuned to recaption frequency b the transformer T,. This circuit is tuned y means of the inductance of one of the windings of the transformer T and by the capacity of the condenser P1,. The inductance is divided between the grid and the plate circuitsso as to form the feed back connection necessary in an oscillation circuit. The hi h frequency oscillations set up by the oscilation generator Gr will be impressed upon the input side of the modulation and demodulation circuit as were the oscillations set up by the generator G shown in Figure 1. By means of the oscillation generator shown in Figure 2 substantial identity of he uency is obtained which insures good qua ity in the modulation and the detection of signals.

Although this invention has been described as being embodied in specific form and arrangement of parts, it is to be under-- stood that it is capable of embodiment in other and different forms Without departing from the spirit and the scope of the patent claims.

What is claimed is:

1. In a signaling system, the combination with a signaling circuit of a transmission circuit, networks individual to and adapted to balance the said circuits, a four-wire connecting circuit, a balanced relay adapted to respond to telegraphic impulses transmitted over the said signalin circuit, a translating circuit common to tie transmitting and receiving paths of the said fourwire circuit having means to impress thereon impulses from the said relay, a source of high frequency carrier oscillations and means to modulate the high frequency carrier oscillations in accordance with the telegraphic impulses.

2. In a signaling system, the combination with a low frequency signaling circuit of a high frequency signaling circuit, a fourwire connecting circuit, a balanced relay responsive to low frequency signals from said first mentionedsignaling circuit and adapted to impress them upon the said four-wire circuit, a source of carrier frequency oscillations also connected with the said four-wire circuit, means for modulating the said carrier oscillations by the said telegraph signaling impulses, and means for impressing the modulated high frequency oscillations up n the said high frequency signaling circuit.

V 3. In a signaling system, the combination. with a low frequency signaling circuit of a high frequency transmission circuit,ra fourwire connecting circuit, means responsive to telegraph currents transmitted by the said low frequency circuit to impress correspondmg impulses upon the-said four-wire circuit, a source of carrier-current, means to impress high frequency modulated oscillations upon the said four-wire circuit, and means to modulate the carrier current in accordance with the telegraph currents and de modulate the modulated high frequency uscillations by the carrier current, and to trans modulated output currents upon said high frequency transmission circuit, and means for impressing the received high frequency oscillations upon the said input side of said translating circuit, means for heating said received oscillations and said carrier oscillations, and for impressing the impulses re- Suiting from beating upon signaling appare- 5 tus connected with said low frequency nalin circuit.

5. n a signaling system comprising two line circuits connected by a four-wire circuit characterized by u, circuit common to the transmitting and receiving paths of the said founwire circuit and leaving a source of carrier current connected therewith, the

method of transmitting and receivi 7 halo graph signals which consists in se ecting teiegrraph impulses. selecting modulated high frequency osciliutions, modulating the carrier rurrent h the said telegraph impulses, deinodnleting [he said modulated high fre qneney oscillations by means of the carrier cur-rem, transmitting the resultant currents from modulation and demodulation and preventing singing over the transmitting and receiving paths of the four-Wire circuit.

tiw in ii translating circuit having e trans luring device associated therewith, the combination with means for impressing low frequency currents and modulated carrier freuency currents upon the said inputside of t 1e said translating circuit of a thermionic osciilntor hsi'ing its in hit side connected. with the input side of t 1e said translating circuit and resonant to carrier frequency and a inodulating-demodulsting device connected with the output side of the said oscil lator and :1 iso connected with the input side of the said translating circuit whereby osciiisiions of carrier frequency may be supplied thereto to be modulated by the low frequency currents and to demodulate the modulated high frequency currents.

in testimony whereof, I have signed my name to this specification this th day of Aprih 1921,

LLOYD ESPENSCHIED.

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