US1356222A - Multiple telephony - Google Patents

Description

' E. RUHMER.

MULTIPLE TELEPHONY.

APPLICATION FILED APR.4. 19H. RENEWED FEB. 4.19:9.

Patented Oct. 19, 1920.

Q N N% 5% 3% ai g 53 M- INVENTOR 4W M M ATTORNEYS WITNESSES g/ %z UNITED STATES PATENT OFFICE.

ERNST BUHMEB,

0F BERLIN, GERMANY.

MULTIPLE TELEPHONY.

Application filed April 4, 1911, Serial No.

To all whom it may concern:

Be it known that I, ERNST Romans, engineer, a subject of the German Emperor, residing at Berlin, 248 Friedrichstrasse, in the Empire of Germany, have invented new and useful Improvements in or Relating to Multiple Telephon for which application has been made in rance April 5, 1910.

This invention relates to a method by means of which it is possible to transmit simultaneously several telephonic messages by one and the same wire.

For transmitting conversations, as in wireless telephony by means of electric waves, alternating currents of high frequency and of different frequency are used which are superposed on the line and are separated only at the receiving station where they act on different oscillatory circuits tuned with corresponding oscillatory transmission circuits communicating with the receiving apparatus.

In this method a comparatively loose coupling is used for connecting the transmission line to the different receiving circuits, as well as the latter to each other, for the urpose of obtaining a perfect separation of the difl'erent conversations and thus for avoiding any possibility of hearing unintentionally even the strongest of the latter,

which, more particularly in a case of a large number of simultaneous transmissions, mi ht have a very awkward effect.

everal arrangements according to this invention are illustrated by way of example in the accompanying drawings.

In the drawing,

Figure 1 is a diagrammatic view representing the transmitting and receiving stations with independent sources of high frequency currents at each transmitting station.

Fig. 2 represents diagrammatically a modified form of my improved system.

Fig. 3 shows a combined sending and receiving station embodying my invention.

In Fig. 1, A B C A B C are respectively the corresponding transmitting an receivin stations.

In or or to produce high frequency currents, a known high frequency generator is used here, for instance, a generator of electric waves comprising an electric are 9 with an oscillating circuit 0 I placed in parallel.

The different oscillatory circuits are adspeciflcation of Letters Patent.

618,871. Renewed. February 4, 1919. Serial No.

Patented Oct. 19, 1920.

'usted to different numbers of oscillations lay a suitable choice of the capacity a and of the self-induction Z.

The intensity ,of the rents produced inthese circuits is influence by talking microphones m, which in some cases are in series with batteries b, b',, b',, b or b respectively. Either the supply current, or the high frequency current of the oscillatory circuit can be affected at will.

A changefin the coupling between the emission circuit and the line, is equivalent to a change of intensity of thehigh frequency current passing through the cirhigh frequency curcuits.

Generally speaking, any methods can be used, provided that the microphone of a certain emitting station cannot affect the alternating currents passing into the common line and emitted by other stations. There are receiving installations corresponding to the emission stations thus arranged.

In the drawing A B are oscillatory circuits tuned to the periods of the oscillatory circuits of'the corresponding emission stations A 13. They act on the different receiving telephones t owing to the insertion of a detector d, as in wireless tele hony with electric waves. At C the trans ormation is effected direct, without a detector, by means of a telephone to with Foucault currents.

The transmission" of different talking currents is effected by the common line which can have a comparatively tight coupling to the transmitting oscillatory circuits, but on the contrary, as already stated, must be coupled comparatively loosely to the receiving circuits.

Fig. 2 shows a simplified installation which does not require special apparatus for producing high frequency current.

By talking into the microphone we, there is produced in the oscillatory circuit constituted by the ca acity c and the self-inductanoe l, trains o damped waves correspondd ing to the sound waves acting on the micro hone.

All that has been said with reference to Fig. 1, is also applicable in this case.

Fig. 3 shows a further improvement. It relates to an arrangement by means of which it is possible to use the same oscillatory circuit at one time as a transmitter,

and another time as a receiver, so that it is possible alternately to talk and to listen with one and the same apparatus. This result is obtained owing to a commutator or switch a which switches into the oscillatory circuit, either the microphone m and the battery, or the detector d and the telephone b.

This switch can be designed so as to allow at the same time of a change of coupling of the self-induction coil Z with the line 7, so that when talking, there is produced a tighter coupling, and when listening, a looser coupling. This is effected by connecting switch 8 by means of rod 7" with one arm of bell crank or bent lever g, and connecting the other arm of g by means of rod 1 with pivoted arm a, to which is attached coil 1.

Having now particularly described and ascertained the nature of my said invention and in what manner the same is to be performed, I declare that What I claim is:

1. In a s stem of multiplex telephony, a plurality 0% stations having both transmitting and receiving apparatus, a common line circuit, means coupled to said line circuit for impressing electric oscillations of difl'erent frequencies upon said line circuit, means for modifying said electric oscill tions by sound waves, local circuits at each station tuned to a particular frequencyof said electric oscillations and means for lacing either the transmitting or the receiving apparatus in operative connection with the common line circuit and for simultaneously changing the coupling between said local circuits and the common line circuit.

2. The combination with a conductor, of transmission means coupled thereto for impressing electric oscillations thereon, receiving means associated with said transmission means, and shifting means operative to place either said transmission means or said receivin means into operative relation to said con uctor and to simultaneously modify the coupling between said conductor and said transmission means.

3. The combination with a conductor provided with a coil, of a coil inductively related to and movable with respect to said first mentioned coil, transmission means for impressing electric oscillations on said secon mentloned coil, receiving means for receiving electric oscillations from said sec- 0nd mentioned coil and means operative to connect either said transmission means or said receiving means operatively to said second mentioned coil and to vary the disstance between said coils as a result of such connection.

4. The combination with a conductor provided with a coil, of a coil inductively related to and movable with respect to said first mentioned coil, transmission means including a microphone for impressing electric oscillations on said second mentioned coil, receiving means including a telephone anda detector for receiving electric oscillations from said second mentioned coil, and means operative to connect either said transmission means or said receiving means operatively to said second mentioned coil and to vary the distance between said coils as a result of such connection.

5. The combination with a conductor, of means spaced from but inductively connected to said conductor, transmission means for impressing electric oscillations on said first mentioned means, receiving means for receiving electric oscillations from said first mentioned means, and means operative to connect either said transmission means or said sreceiving means operatively to said first mentioned means and to simultaneously and automatically vary the distance between said conductor and said first mentioned means.

6. The combination with a conductor, of means spaced from but inductively connected to said conductor, transmission means for impressing electric oscillations on said first mentioned means, receiving means for receiving electric oscillations from said first mentioned means, and switching means operative to connect either said transmission means or said receiving means operativel to said first mentioned means and to simu taneously and automatically va'rg' the dis-' stance between said conductor an aid first mentioned means.

In testimon whereof I aflix my signature in presence 0 two witnesses.

ERNST RUHMER. Witnesses:

WALDEMAR Ham, HENRY HAsrnn.

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