US2591749A - Amplitude modulation system - Google Patents

Description

April 8, 1952 J. M. VILLEMAGNE AMPLITUDE MODULATION SYSTEM Filed May 8, 1950 INVENTOR JEAN M. VILLEMAGNE Q BY ATTORNEY Patented Apr. 8, 1952 AMPLITUDE MODULATION SYSTEM Jean Marie Villemagne, Paris, France, assignor to International Standard Electric Corporation, New York, N. Y., a corporation of Delaware Application May 8, 1950, Serial No. 160,755

In France June 3, 1949 3 Claims. (01. 332-44) The present invention relates to very wide frequency band amplitude modulation devices, particularly those providing carrier suppression.

In known modulating devices, there is obtained generally in the output besides modulation products; currents comprising either the carrier current or the modulating current or combinations of these currents and of their harmonics. When it is necessary to obtain pure modulation products, filters have been employed, in the output of the modulating device which introduce undesirable effects, such as different phase shifting at different operating frequencies, etc.

One of the objects of the present invention is to provide an amplitude modulation device with a very wide frequency band which delivers in its output only modulation products, without the need for the use of filters.

Another object of the present invention is to provide a multiplier device in which the two voltages to be multiplied play effectively the same role in order to obtain an output voltage which is effectively proportional to the two input voltages.

7 According to a feature of the invention, there is provided a translation system comprising two pairs of rectifiers, a first means for applying a sinusoidal voltage in push-pull to each pair of rectifiers, a second means for applying a sinusoidal voltage in push-pull to each pair of rectifiers in the same sense as the first means with respect to one pair of rectifiers but in the opposite sense with respect to the other pair of rectifiers, and a pair of output terminals each terminal connected to the output of one pair of rectifiers.

The above-mentioned and other features and objects of this invention and the manner of attaining them will become more apparent and the invention itself will be best understood, by reference to the following description of an embodiment of the invention taken in conjunction with the accompanying drawings, wherein the single figure is a schematic diagram of a system for combining signals which may be used either as a modulator or as a frequency enerator.

In the drawing there is shown four vacuum tubes of the pentode type i, 2, 3 and 4 and adjustable resistances 5, 6, l and 8 and a fixed resistance 9 used for adjusting the working conditions of the said tubes.

The mid-point I2 of the secondary winding of transformer II is connected to a biasing battery l3. lThe terminal l4 of the secondary winding 10 of transformer II is connected by means of a resistance [5, on the one hand to the control grid I6 of pentode 4 and on the other hand to the control grid ll of pentode 2; the terminal I8 of the secondary winding l0 of transformer H is connected by means of resistance 19 on the one hand to the grid 20 of pentode l and on the other hand to the grid 2| of pentode 3. The mid-point 22 of the secondary winding 23 of transformer 24 is connected through a resistance 25 to the positive terminal of a high tension battery 26. The terminal 21 of secondary winding 23 of the transformer 24 is connected on the one hand to the grid 28 of pentode 3 and on the other hand to the grid 29 of pentode 4. The terminal 30 of the secondary winding 23 of transformer 24 is connected on the one hand to the grid 3| of pentode 2 and on the other hand to the grid 32 of pentode l. The anodes 33 and 34 of pentodes l and 4 are connected to the terminal 35 of the primary winding 36 of transformer 31. The anodes 38 and 39 are connected to the terminal 40 of the primary winding 36 of transformer 31. The midpoint 4| of the primary winding 36 of transformer 31 is connected to the positive terminal of the high tension battery 26.

The arrangement having been described, its operation is as follows: if a sinusoidal voltage is applied to the primary winding 42 of transformer I I it will be seen on the drawing that the pentodes l and 2, 3 and 4 act as the vacuum tubes of two push-pull sets or pairs placed in opposition and no current is then obtained in the secondary winding 43 of transformer 37. The same result is obtained when the primary winding of transformer 24 is fed with a sinusoidal current. On the contrary if two sinusoidal voltages, such as a carrier wave and a modulating wave, are respectively applied to the terminals 44 and 45 of the primary winding 42 of transformer II and to the terminals 46 and 41 of the primary winding 48 of transformer 24, it follows from the fact these voltages are applied by means of the circuits described above, to different grids of each one of the pentodes I, 2, 3 and 4 that there is obtained in the output of transformer 31 a modulated current comprising only the side bands, the carrier frequency and the modulation frequency having been eliminated by the operation of the circuits placed in opposition.

If there is applied to the primary windings 42 and 48 of the two transformers H and 24 the same sinusoidal voltage, there is obtained in the secondary winding 43 of transformer 31 the second harmonic of the input current to the device which in this case operates as a multiplier.

It is obvious that the transformers II and 24 may be replaced by outphasing tubes as well known in the art.

While I have described above the principles of my invention in connection with specific apparatus, it is to be clearly understood that this a ment of each tube, a second means for applying a sinusoidal voltage balanced with respect. to. ground in push-pull to each pair of tubes. in the; same sense as the first means with respect to one pair of tubes but in the. opposite sensewith re-- spect to the other pair oi tubes, said second means including connections. to. another control element of each tube, said firstand. second means: including connections to ground, andapair: of output terminals, each terminal connected: to the output of onepair'of tubes.

2; A- translation system according: to claim 1 further including a plurality of adjustable resistant elements, at least one of said resistant elements being inserted in series in the connections from each of said cathodes to ground.

3. A frequency multiplier comprising two pairs of rectifiers, a first means for applying a sinusoidal: voltage. inpush-pull' to each; pain of rectifiers, a=second means for applying the-same-sinusoidal voltage in push-pull to each pair of rectifiers in the same sense as the first means with respect to one pair of rectifiers but in the opposite sense with respect to the other pair of rectifiers, and a pair oi'output. terminals each terminal connected to; the. outputrn". one pair of rectifiers.

JEAN MARIE VI-LLEMAGNE.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES- PATENTS Number Name Date.

2,239,376 Brunrr Apr..29, 1941 2,275,020 Purington Mar..3,,1942 2,484,107 Maron: Oct. 11, 1949

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