US2257917A - Multiple telegraphy and telephony - Google Patents

Description

Oct.7, 1941. PUNGs 2,257,917

MULTIPLE TELEGRAPHY AND TELEPHONY Filed M ay 14, V193e :if-'7 L fr @1A *,j* jl: QA.

Patented Oct. 7, 1941 UNITED STATES PATENT OFFICE Application May 14, 1938, Serial No. 207,921 In Germany May 11, 1937 (Cl. Z50-9) 2 Claims.

As is well known in high frequency transmission a high frequency channel, intended for telegraphy and telephony, may be utilized in multfold fashion by using multiple modulation effected with the aid of intermediate frequencies. With thisy method, however, for each channel merely a part-utilization of the transmitter is possible, since the total of al1 proportions should not exceed the full utilization of the transmitter. In addition, special precautions are necessary in order to avoid cross modulation.

The novel method likewise aiords the possibility of a high frequency connection. By the word connection not a high frequency channel ln a narrower sense is meant here but this expression is intended to cover the transmitting and receiving system, comprising dipoles and collecting and directing means, such as reflectors, etc. Therefore the arrangement described hereafter is of special advantage when employed with connections utilizing ultra-short waves and waves in the decimetre range. In particular, the novel method will be advantageous wherever the cost of the said collecting and directing means is high as compared with that of the transmitter proper.

In accordance with the invention it is proposed to subdivide the transmitter as distinguished from the radiating system in two or more parttransmitters, thus avoiding multiple channel modulation in a single transmitter. Each such part-transmitter is only modulated with an intermediate frequency and the voice frequency. All of the transmitters are arranged to act simultaneously upon a radiating and collecting and directing system common to them, whilst their frequencies are so close together that on the one hand the best possible radiation conditions shall be established while on the other hand the transmitters shall not be disturbed by the high frequency side bands. The attenuation of the radiation system being considerable, pretty great frequency differences of the transmitters will be admissible in general. If greater differences are admitted then in most cases there will be no necessity for neutralizing the systems. If, however, such neutralization prove to be necessary then it may be obtained with the aid of well known means. In order to avoid disturbances caused by the high frequency side bands, the frequencies serving as intermediate frequencies should not be too high.

On the receiving side the high frequency mixture is received by a single collecting and directing system and is rectified and the several channels are separated with the aid of the respective intermediate frequencies. If it is desired to work with sharp feed-back connection the two carrier waves must of course be somewhat closely spaced together. Also, there is another possibility, namely, to use transmitters tuned to the fundamental waves and at the same time to use transmitters tuned to harmonics thereof. In most cases however a system of this kind will not be practicable for reasons that reside in the bundling arrangement.

In the accompanying drawing Figs. 1 and 1A are wiring diagrams of a transmitter and receiver, respectively showing one embodiment of the invention,

Figs. 2 and 2A are schematic representations of a transmitting and receiver antenna, respectively, for use in arrangements of the kind shown in Fig. l.

Two short wave transmitters UI, U2 are adjusted to operate with approximately the same frequencies and are modulated by long wave transmitters HI, H2 which in their turn are modulated by voice frequency sources Ml, M2. The receiving dipole E is connected to a device Gu that serves to rectify the short waves arriving from UI, U2. The separation of the message channels is made by long wave receiving systems LI, L2 from which the Voice frequencies are taken in well known manner after a second rectification has been effected.

The modification shown in Figs. 2 and 2A comprises two dipoles D on the transmitting side, which are disposed in the focus of a reector S and are arranged at right angles with respect to each other while forming angles of 45 with the vertical. The dipoles D are of the same dimensions and are each connected to a transmitter modulated with a respective intermediate frequency,'as described with reference to Fig. l. The transmitters are approximately tuned to the same wavelength. The receiving side has one dipole E, and the transmitted energy is separated here by means of the respective intermediate frequencies.

What is claimed is:

l. A system for simultaneous telegraphy and telephony, comprising a plurality of separate transmitters operating at different related carrier frequencies, each of said transmitters including an intermediate stage which is modulated by signals of lower frequency and a high frequency stage modulated by energy from the intermediate stage, and a common directive radiation system including at least two antenna units, said units being tuned to a frequency related to said carrier frequencies and being adjusted for directive transmission of both said frequencies, whereby eilicient directive transmission of both signals is achieved.

2. A system according to claim l, wherein said different carrier frequencies are harmonically related.

LEO PUNGS.

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