US1901043A - Oscillation generator - Google Patents

Description

March 14, 1933. 1.. o. ROOSENSTEIN 1,301,043

OSCILLATION GENERATOR Filed Sept. 4, 1929 /7bediwmbr a l 5 4 1 1 -z 70 Ufff/17477064.

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7+ mao-mmm HANS oT-ro Roossnsrsm zzaaaaxc. BY' 7 MW ATTORNEY Patented Mar. 14, 1933 Unirse STATES Partnr tries HANS OTT() ROOSENSTEIN, 0F BERLIN, GERMANY, A.SSIGNOR TO TELEFUNKEN GESELL- SCHAFT FUR DRAHTLOSE TELEGRAPHIE M. B. H., OF BERLEN, GERMANY, A CORPO- RATION' OF GERMANY OSGILLAT'ION Application led September 4, 1929, Serial No.

For the production of short waves, as is well known from the prior art, crystal-controlled thermionic-tube generators are emf ployed, and these offer the practical advantage that they insure an almost absolutely constant wave-length. Now in practical work, the p-roblem to vary the carrier frequency of a transmitter within certain nar row limits, arises quite frequently; and, a crystal-controlled transmitter does not lend itself readily to such variation.

rShe present invention is concerned with a transmitter arrangement which furnishes a useful frequency, which latter, while being extremely stable, is also adapted to be varied quite readily. According to this invention, the transmitter outfit consists of the combination of a mechanically controlled and preferably crystal controlled thermionic generator and a generator which is not subject to crystal control, that is, most suitably a self?A excited thermionic transmitter or in other words, an electrically controlled generator. The auxiliary generator which produces a substantially lower frequency than the crystal-controlled thermionic transmittenis employed for the modulation of the wave of the crystal controlled transmitter; and, from among the ensuing oscillations, one side band is separated by a filter circuit or equivalent means, and used in the usefulA or load circuit. By changing the frequency of the auxiliary generator, this working or useful frequency can be easily varied within definite limits. For instance, if the frequency of the crystal controlled transmitter is g and the modulating frequency of the auxiliary generator 7L, there result these two frequencies:

g-lz, and gh one of which is utilized.

In the accompanying drawing, Fig. 1 diagrammatically illustrates the invention; Fig. 2 is wiring diagram therefor; and, Fig. 3 is a graph explanatory thereof.

A fundam-ental circuit scheme is shown in Fig. 1 wherein a modulator 3 is influenced by two wave generators, the crystal controlled generator 1 and the vacuum tube regeneratively connected generator 2 and where the desired wave is separated by means of a filter circuit 4;.

GENERATOR 390,369, and in- Germany September 10, 1928.V

It is obvious that the working or useful frequency is extremely stable inasmuch as in the presence of fluctuations of the frequency of the auxiliary generator (the wave length of the crystal controlled transmitter being admissibly considered absolutelyconstant) the percentage variations of the useful frequency are essentially lower than lwhen-the useful frequency were generated without `a stable V crystal generator. For instance, if the stable frequency 7:20000 kilocycles, and the modu` lation frequency variable inside thev range 500-2000 kilocycles, then the usefulY or working frequency is capable ofvariation inside a range between 18000-19500 and 20500- 22000 kilocycles, as explained graphically in Fig. 3 where the abscissae stand for the frequency e and the ordinates for the amplitudes.

@ne specific embodiment of the basic idea of theinvention is shown in Fig. 2 by way of example where thetube arrangement or assembly 1 Vdenotes the crystal controlled transmitter, the tube 2 the auxiliary generator, tube 3 the modulator tube, and 11 is the lter circuit. rlhe arrangement according tothe invention may be employed in transmitter apparatus and in receiving apparatus since, as is well known, in many receiver apparatus the production of an auxiliary wave, for instance, for heterodyning is necessary and silpce also this heterodyn-e wave must be varia le. v

The invention Vis also useful for fading elimination. By wobbling the frequency of generator2, the carrier output is wobbled andmay be used to good advantage for fading elimination.

Then again, by properly choosing the frequency of generator 2, each of the sidebands produced may be used to separately transmit the same or preferably different signals without interference. side bands for use as carriers may be accom-V plished by the use of filters.

I claim:

1. Apparatus for the generation of substantially constant frequency oscillations comprising a mechanically controlled oscillator having a high degree of frequency sta- Separation of the bility, an independent non-mechanically controlled oscillator arranged to generate frequencies Which are relatively loW compared to the frequencies generated by said mechanically controlled oscillator, means for adjusting the frequency of said independent non-mechanically controlled oscillator, and a modulator having input and output circuits for inter-modulating Waves from said oscillators, said input circuit being coupled to both said oscillators, and a selector circuit coupled't'o the output of said modulator for choosing a desired Wave from the output 'of said modulator. Y

2. In a system comprising a high frequency piezo-crystal oscillator and a relatively loW adjustable frequency oscillator, the method of producing a Wave Whose frequency is variable over a range which is small compared to the frequency of said crystal and yet having substantially the same degree of frequency stability as the frequency 0f the Wave produced by said Crystal oscillator, Which consists in intermodulating Waves from said high frequency crystal controlled oscillator With Waves from said relatively` loW adjustable frequency oscillator, thereby producing Waves of side band frequencies, and selecting a Wave 'of a desired side band.

3. In a system comprising a. substantially constant vacuum tube oscillator Whose frequency is controlled by a mechanical resonant device, andan independent adjustable frequency oscillator Whose frequency is 10W `relative to the frequency generated by said vacuum tube oscillator, the method of obtaining ka Wave Whose frequency is variable over a range Which is small compared to the frequency of said vacuum tube oscillator and yet having substantially the same degree of frequency stability as the frequency of the wave produced by said vacuum tube oscillator, Which comprises intermodulating Waves from said high frequency vacuum tube oscillator with Waves from said relatively low adjustable independent oscillator, thereby roducin Waves of side band fre uenc and selecting a Wave from a desired side band. HANS OITO ROOSENSTEIN.

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