US1645558A - Multiplex alternating-current telegraphy - Google Patents

Description

18 1927. Oct J. VOPEL MULTIPLEX ALTERNATING CURRENT TELEGRAPHY Filed Sept. 15. 1924 Patented 18, 1927.

UNITED STATES PATENT- OFFICE.

JOEAINEB VOPEL, OF IBERLIN-HABIENDOBF, GERMANY, ASSIGNOR TO LORENZ AKTIENGESELLSOHAIT, BEBLIN-TEMPELHOF, GERMANY.

KULTI'PLEX ALTIERNA'LING-(JURIREN''1 TELEGRAIPHYZ.

Application filed September 15, 1924, Qerial No. 737,766, and in Germany September 24, 1923.

My invention relates to improvements in multiplex telegraphy in which the synchronous transmission of several messages over one wire is eflected by means of alternating currents of difierent frequencies. The system of multiplex telegraphy referred to acts by transmitting a plurality of alterating currents of different frequencies and each car rying a different message over one transmisslon line. from one terminal telegra h station to another associated station, while commutators are provided at this latter sta tion connected between said transmission line and a plurality of terminal telegraph circuits each one of which corresponds to one of the above mentioned alternating telegraphing currents. The commutators operate in synchronism with each of their respective telegraphing currents in such a manner as to convert the received alternating currents into direct current-telegraph impulses.

The ran e of alternating current freuencies to is used for multiplex telegraphy epends essentially on the quality of the wine used. The number of messages to be transmitted for a certain range of frequenoies depends on the selectivity of the receivin apparatus to be employed and on the to egraphing speed. According to my invention in a system of multiplex telegraphy of the kind referred to there are employed\ two alternating currents of the same fre uen but with a phase difference of 90 g or t e simultaneous transmission of two 85 diflFerent messages, whereby the number of messages to be transmitted for a certain '-range of frequencies may be doubled. Hence for simultaneously transmitting two telegrams two different frequencies are not 40 required as heretofore, but only'two alternating currents of the same frequency but having a phase displacement with respect to one another of 90. If on the transmitting side there is therefore employed an alternator suitably constructed or connected for this pu ose,the. two alternating currents displ by 90 can be separated by two commutators at the receiving station so arranged'as to have a relative phase displace W ment with respect to one another of 90, or by one single commutator having two sets of brushes displaced by 90 with respect to one another.

In multiplex systems of similar type to that previously referred tobut using resonating circuits for separating the different frequencies, telegraphic signs can only be transmitted by switching in or interrupting the alternating current, while according to a further feature of my invention when using synchronously'operated commutators inthe, 7 known manner hereinbefore mentioned separable current can be used, for instance in such a way that at the end of every telegraphic sign the phase of the alternating current is changed by 180, whiclr acts on the relay behind thmcommutato'r'of the receiving-system as a current opposite to the current of the signs, thus enabling a neutral relay to be. employed. This reversal of the current by 180? can be attained by simply changing the polarity of the terminals of the line with the position of the key, or by employing a potentiometer across the terminals of the current generator, one pole of the transmission line being connected to a tapping point in the center of the potentiolneter so that when operating the key either the one or the other terminal of the potentiometer is connected to the other pole of the line, or a repeater having a transformer ratio of 1:1 may be em loyed the primary or secondary of which is alterna- "tively connected to the line according to the position of the key. 1

In order that the invention may be clearly understoodand readily carried into efi'ect i the same will now be described'more fully with reference to the accompanying drawings in which c i Figure 1 illustrates diagrammatically the electrical connections of the system of telegraphy referre'dto, and Figures 2 and 3 are curves representing the transmitted and commutated currents obtained in the various methods of operation according to the present invention. Referring to Figur 1, T T and T are keys each ofwhich is connected to one of three sources of alternating current of dif ferent frequencies and by means of which the first, second and third frequencies F F F respectively can be tapped and transmitted along the line wire L by the common coupling relay A. For separating the car rying frequencies, there are provided rotating commutators K K K coupled to the main line at A in a similar way as the nerators at the transmitting station.

ach commutator is constructed so as to 110 commutate the alternating current of one particular frequency, so that the commutetor K commutates the frequency F but does not ccmmutate the frequencies F and F The relay device R, is therefore actuated only by its own corresponding carrying frequency F The commutators K and K and their respective relay devices R, and R are each operated in a like manner. The receiving commutators K K, and K may be driven by one motor for instance, acting synchronously and in phase with a multiwave alternator of the sending system pro-- during the different signalling frequencies.

Referring to Figure 2 curve a shows the current sent along the wire when the sign is given and curve a the resulting commutated current in the receiving system. Curve 5 shows how during a spacing interval the phase of the alternating current sent along the wire is displaced by 180 as previously stated and curve (1 shows how at the same time the comrhutated current of the receiver changes its direction. Figure 3 illustrates the method of operation employing two currents of the same frequency but displaced with respect one to another by 90; F is the alternating current sent along the wire, f the same current commutated by a commutator in phase, i the current commutated by a commutator displaced in phase by 90. The resulting direct current of every half period being zero, f does not act upon the receiving device.

What'I claim and desire to secure by Letters Patent of the United States is as follows:

1. In a system for simultaneously transmitting several messages over one connecting line by means of two alternating currents of equal frequency and phase displacement of 90 with respect to each other and for separating these currents in the receiving" station, the combination of a mechanical commutating device in the receiving systemfor each signaling current transmitted and means to operate said commutating. devices synchrononslyand in like phase relationship with the transmitter at the sending system generating the respective signaling currents, said commutating devices being so arranged as to commutate only their own particular signaling current.

2. In a system for transmitting simultaneous'ly several messages over one connecting line by means of pairs of alternating cur rents of equal frequency and phase displacement of 90 with respect to each other, each pair being of a difierent frequency, and for separatin these currents in the receiving. system, 1; e combination of a mechanica messes commutating device in the receivingsystem for each signaling current transmitted and means to operate said commutating devices synchronously and in like phase relationship with the transmitter at the sending system generating the respective signaling currents, said commutating devices being so arranged as to commutate only their own particular signaling current.

3. In a system for simultaneously trans-- mitting several messages over one connecting line, the combination of a number of generators at the sending system for producing pairs of signaling alternatin currents, each two currents of each of sai pairs being of equal frequency and displacement by 90 with respect to each other, a trans-.

mission line connecting said sending enerators with a receiving system, mec anical commutators at said receiving System, and I means to operate saidcommutators in synchronism and in like relationship with one of said generators at said sending system, said commutators being arranged to comma tate only their own particular signaling current.

' 4. In a system as claimed in claim 1,, in which in the pauses of si ns alternating current with phase displaced by 180 is sent by the transmitting system over the conduct ing wire and a current opposite to that produced by the signs is generated in the receiving system behind the commutator, twodifi'erent messages being simultaneously transmitted by the employment of two alternating currents of the same frequency, but with a phase difference of the two commutators in the receiving system having a relative phase displacement with respect to one another of 90 so as to separate the-two alternating currents differing in phase by 90 sent out by the transmitter.

5 In a system as claimed in claim 2, in which in the pauses of signs alternating current with phase displaced by 180 is sent by the transmitting system over the conducting wire and a current opposite to that produced by the slgns is generated in the receiving system behind the commutator, two different messages being simultaneously transmitted by the employment of two alternating currents of the same frequency, but with a phase difference of 90, the two commutators in the receiving system having a relative phase displacement with respect to one another of 90 so as to separate the two alternating currents differing in phase by 90 sent out by the transmitter.

In testimony whereby I have affixed my

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