US2340590A - Telegraphy transmitter - Google Patents

Description

Feb. 1, 1-944. NI 2,340,590

TELEGRAPH! TRANSMITTER v Filed Nov, 15, 1940 mm F lil

y g C qrrenf Padio Means S Fansmiiier as r if B E 5 flzierzmfiny Current Radio Source Wansmizfer INQVEIISITOR FRITZ HE/ N/G ATTORNEY 7 Fil q] Patented Feb. 1, 1944 TELEGRAPHY TRANSMITTER Fritz Hennig, Berlin, Germany; vested in the Alien Property Custodian Application November 15, 1940, Serial No. 365,744 In Germany October 13, 1939 2 Claims.

In keying radio transmitters with telegraph devices check-up reception by radio is not always feasible. This, in the first place, is impossible when no receiver apparatus is available. Moreover, where the transmitter and the receiver are quite close together so that, for instance, they have a joint antenna and ground, or a joint source of current supply, a coupling may arise between the transmitter and the receiver of such a nature that the telegraphic signals are vitiated or obliterated in the receiver. The monitor record will accordingly become unclean or illegible and will not provide an accurate indication of the message being sent out. In all of these instances the check-up of the message must be made locally, in other words, the circuitous way through radio transmitter and receiver is not feasible.

The keying circuit of radio telegraphic transmitters is often designed for direct current and is so operated, for instance, that the keying contact or the telegraphic transmitter opens the closed direct current circuit to key the transmitter. Reception, however, is mostly carried out by use of a keyed tonal-frequency circuit at the receiver.

Now, according to the invention, operation of these different circuits is made feasible in a simple way by causing a single telegraphic keyer to key simultaneously several circuits in which currents of different kind are flowing. One of th keyed currents is used to control the transmitter, the other keyed current being used to operate a receiver or monitor to check up on the message.

In instances as hereinbefore mentioned, the various circuits are preferably connected in parallel in relation to the telegraphic transmitter, while the alternating current of one of the circuits is excluded by suitable stopper circuit means in the other circuit. The direct current is kept out of the alternating current circuit by a condenser included therein.

For the sake of simplication, under certain operating conditions, which shall be explained more fully hereinafter, it is possible also to resort to a pure series arrangement of all circuit elements. The radio transmitter is then blocked ofi by means of a condenser for the tonal-frequency signals, the said condenser being connected in parallel relation to the output terminals.

Figs. 1 and 2 of the appended drawing illustrate exemplified embodiments of the invention which show further details of the scheme.

The keying circuit of the radio transmitter DS starts from battery B and runs through the telegraphic signal transmitter or keying means TS, stopper circuit F to the radio transmitter DS. i'Ihis stopper circuit F may be as shown a parallel circuit parallel resonant to the tonal frequency supplied by source S. The telegraphic device TS may consist, for instance, of a picture point scanner and transmitter drum. The tonalfrequency circuit starts at the source of tone current supply S and runs through condenser C, telegraphic transmitter TS, primary winding I0 of transformer U and back to the said source of supply S. When sending through the telegraphic instrument TS both circuits are keyed. The entrance of direct current into the tonalfrequency circuit is precluded by condenser C, while stopper or rejector circuit F precludes tonal frequency from the direct-current circuit. The telegraphic receiver, used here to check-up on the message, is united with terminals TE.

In the case of the embodiment shown in Fig. 2, the assumption is made that the direct-current resistance of theprimary winding IU of transformer U and of the source of tonal frequency S is very low. In this case, both may be looped in the direct current keying circuit of the radio transmitter without any appreciable drop or loss of direct current being incidentally occasioned. The direct-current impulses in the primary winding ID of transformer U will not affect the monitor record. Condenser C short-circuits the input end of the radio transmitter DS for impulses of tonal frequency from source S. A resistance R is provided for insuring current limitation. Thus, in this circuit arrangement mutual disturbance or interference of the direct-current and tonal-frequency impulses is avoided.

What is claimed is:

1. In a telegraphy system, a transmitter circuit, a receiver circuit, a source of current of varying amplitude, a source of direct current, a single keyer in circuits coupling one of said sources to said transmitter circuit and the other e of said sources to said receiver circuit, means in said circuits for preventing current from said source coupled to said transmitter circuit from reaching said receiver circuit, and means in said circuits for preventing current from said source coupled to said receiving circuit from reaching said transmitter circuit.

2. In a system for producing signalling energy and for monitoring the said signalling energy as produced, a source of direct current, a source of current of varying amplitude, a keyer, a transmitter circuit, a monitor circuit, a direct current circuit, including said keyer and direct current source in series, coupled to said transmitter circuit, a variable amplitude current circuit including said source of current of variable amplitude and said keyer in series, coupled to said monitor circuit, a variable current stopper in said direct current circuit and a direct current stopper in said variable current circuit.

FRITZ HENNIG.

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