US2415874A - Stabilized oscillatory system - Google Patents

Description

Feb 18 .1947- l |.t E. GoLDsTlNE 4155874 v STABILIZED OSCILLATORY SYSTEM filed March 27, 1944 /LL A Tal IN1/mmmI H. E. 6'04@ .sr/Ne Patented Feb. 18, 1947 IUNITED STATES PATENT orrica STABILIZED OSCILLATORY SYSTEM Hanan E. Goldsune, Rocky Point, N. Y., assigner to Radio Corporation of America, a corporation ol' Delaware Application March 27, 1944, Serial No. 528,204

4 claims. (ci. 25o-as) modulation or transmission takes place the phase may be modulated in an' undesired manner by non-linearity in the system. For example, such undesired phase modulation might very well result from non-linear operation of electron dis-` charge devices in conjunction with circuit reactances .in frequency multiplier or amplifier stages.

A primary object of my invention is reduction of undesired phase or frequency modulation of currents used in signalling and similar systems wherein it is desired that the currents be of substantially constant phase.

Briey, this object is attained in accordance with my invention by taking energy, of say the crystal frequency Fu, from the system at a point following the point at which the undesired phase or frequency modulations Ko are produced, say after the current of frequency Fo and undesired deviation K has been multiplied N times and supplying the same to a mixer or converter, also supplied with oscillatory energy Fo (taken more directly over a separate path) from the crystal which energy is multiplied by a factor N+ 1. The difference frequency equal to Fo-NK (where represents the undesiredphase modulation) is.

taken from the converter and added (algebrai cally) to the crystal'output of frequency Fo fed to the multipliers in a stage preceding the multipliers and in proper phase relation to reduce the undesired phase or frequency deviation.

In the figure, 2 is a source of oscillations of substantially constant frequency, for example, a crystal oscillator. 4 designates in generalan amplifier or repeater arrangement feeding oscillatory energy from the crystal to the frequency multiplier stages at 8. The amplier or repeater 4 will be described in greater detail hereinafter. The frequency multiplied oscillations from 8 are supplied to an amplifier i and then used. In the ampliiier lll, the oscillatory energy of multiplied frequency may be modulated by signals as desired. shown an amplitude modulator I2 coupled to the amplifier il?.

Some of the carrier current, say for example, the carrier current of multiplied -frequency, is taken from a stage following the frequency multipliers, as for example, by lines from i 0 or picked up by an aerial system I6 and supplied to a converter 20. If we say the crystal oscillator frequency is Fo and the undesired phase deviation takes place at vthis frequency, then we may consider that the aerial I6 picks up and supplies f to the limiter and if desired frequency multiplier I8 and to converter 20, current of a frequency N (Fo+K), where N is the factor of frequency multiplication and Kqi represents the undesired phase deviation of the current of frequency Fc The crystal oscillator also supplies by line 24 oscillations of the fundamentalfrequency Fo to a frequency multiplier 30 and from the frequency multiplier 30 to the converter 20. In the example given, the frequency multipliers in 30 should preferably have a multiplication factor of- N+1, so

that this multiplier 30 supplies to the converter 20 current of a frequency (N+1) Fo.

Other objects and the manner in which the same are attained will appear from the detailed description which follows. reference will be made to the attached drawing, wherein the single figure is a circuit diagram showing the essential features of a signalling system arranged in accordance with my invention In this description In order to compress or reduce the undesired phase or frequency deviations the difference frequency is taken at the output of 20 and in the example given, this .difference frequency is equal to Fo-KN. This difference frequency is then supplied by way of lines orother means described in detail hereinafter to the amplifier 4, wherein it is combined with the original crystal oscillator energy and fed to the frequencys'nultipliers in 8.

I'he amplifier in 4, as stated'above, may take many forms, the essential feature beingthat the R. F. output is a function of the R. F. grid excitation. In other words, the R. F, output is to be proportional to the R. F. input. In the embodiment illustrated, the amplier 4 comprises a 'pair of pentodes 3 and 3'. Pentode tubes are used asian example because the screen grids therein insures that there is little reaction of the 5| plate circuit on the control grids. The anodes For purposes of illustration, I have and 5' 4of these two tubes are tied together and coupled to the frequency multiplier 8.

The control grid 1 of tube l is coupled to the crystal oscillator 2. The control grid 1' of tube 3' is coupled by way of a phase adiuster to the converter 2li. The electrodes of these tubes are supplied with operating potentials by the means shown schematically and a description of the same is believed unnecessary. The essential requirement of these amplifiers has been given above, and it is noted that amplifiers operating Class C are-satisfactory. y

The combining of the output of 2 and the output of the converter in the amplier I is not a mixing or converting action. The two currents are combined in the proper phase so that they produce a resultant substantially of the frequency Fo and of a phase and .frequency which tend to compensate or wipe out the undesired phase or frequency modulation produced in the circuits following the amplifier I.

In a practical arrangement the proper phasev of the current fed to tube 3 as a consequence of the resultant supplied to the multiplier 8 may be Vobtained by lines of adjustable length coupling the converter 20 to the control grid I of tube-3'. Reactance networks or an R. and Cnetwork may be used here. For purposes of illustration. I have shown the converter 20 as feeding a phase adjuster of a conventional type. The lines L may also serve as'phase shifters and are considered in adjusting the tap on the inductance 21. 'Ihe phase or frequency reduction or correction depends in part on the phase relation of the currents combined in the outputs of tubes 3 and 3'.

' The amount of phase correction also depends in part on the relative amplitude of the currents supplied to tubes 3 and 3' of the amplifier 4.

A means for adjusting the amplitude of the current from 20 is a potentiometer 29, a point of which is connected to the grid 1'.

Relatively changing the phases or the amplitudes of the voltages or currents from converter 2o and source 2 in'the amplifier 3 Vchanges the phase of the voltage or current in the multipliers 8 and following stages. Increasing the amplitude of the current out of converter 20 causes the phase of the resultant current to swing toward the phase of the current supplied from the converter 20 through the phase shifter to tube 3.

Thus by adjustment of the phase and the amplitude or one thereof of the voltage or current `supplied by the feedback connection, compensation, asdescribed in detail above, is made in such a manner that undesired phase swings of the current supplied to multipliers 8 and following stages are reduced as much as'necessary.

Adjustment of the relative amplitudes of the currents selected out ofthe source 2 and the converter 20 provides a means for adjusting the amount of undesired phase or frequency compensation which takes place. 'I'he amplitude of the current out of 20 is arh'usted bythe potentiometer 2.9. Similar means may be used in unit 2 to adjust the amplitude of the current supplied from this source. current amplitudes may be made also byad jllStlng the gains 0f the tllbES 3 and 3'. AS the feedback R. F. is reduced the phase correction is reduced. l y

In practice the output of the system is put on a phase modulation or frequency modulation receiver and the adjustments described above or one` thereof at the transmitter is used to derive Adjustment of the a 4 zero or minimum deviation as indicated by the receiver output.

The source of oscillations of constant frequency at 2 may be a crystal oscillator or an oscillator stantlally fixed frequency. .The unit 2 may also include frequency multipliers.

The frequency multipliers at 8, I8 and 30 may be of any conventional approved type and since frequency multipliers are so well known in the art no description of the operation of thesame will be given here. The same may be said of the limiter in I8.

`The converter at 2|! likewise may be of any conventional approved type. Since the arrangement and operation of converters is very well known in the art, a detailed description thereof will not be given herein.

The amplifier and amplitude modulator like- 20 wise may be conventional circuit arrangements.

, Moreover, as stated above, other types of modulation and various types of signals may be used here.

I claim:

1. The method of producing oscillatory energy of substantially fixed phase and frequency and of carrier wave frequency which includes these steps, generating oscillatory energy of substantia1ly`xed frequency, multiplying the frequency of said generated oscillatory energy to obtain oscillator energy of carrier wave frequency the phase of which may vary in an undesired manby one, mixing the last mentioned frequency multiplied oscillatory energy with said selected portion of the frequency multiplied oscillatory energy to derive oscillatory energy of the difference frequency wherein any phase variations are also multiplied, adding the derived oscillatory energy and the generated oscillatory energy algebraically, and adjusting the phase of the derived'oscillatory energy to a value such that it neutralizes and cancels phase variations in said rst mentioned frequency multiplied oscillatory energy.

2. In a carrier frequency Wave energy generating and wave energy frequency stabilizing system. a source of wave energy of substantially fixed frequency, -an output circuit, an amplifier stageY having input electrodes excited by said wave energy and having output electrodes, a frequency multiplier coupling the output electrodes of said amplifier to said output circuit to supply wave energy of multiplied frequency to said out- 50 put circuit which wave energy may vary in" phase in an undesired manner, a converter stage excited by the output of said frequency multiplier, a second'frequency multiplier having a multiplication factor differing from the multiplication 66 factor of said rst frequency multiplier by one,

coupling said source of wave energy to said converter, and an amplitude adjuster and phase shifter coupling said converter to said first, mentioned frequency multiplier. 70 3; In a carrier frequency waveenergy generating and wave energy frequency stabilizing system, a source of wave energy of substantially fixed frequency, an output circuit, a first tube amplifier having input electrodes excited by said wave energy and having output electrodes.,l a frequency of any type which provides oscillations of sublsecond amplier tube having input electrodes and having output electrodes coupled in ,parallel with the output electrodes of. said first tube amplier, and a phase shifter coupling said converter tothe input electrodes of said second amplifier tube.

4. A system as recited in claim 3, wherein a l potentiometer is included in the coupling between the phase shifter and the input electrodes of the second amplier tube.

HAILANE. GOLDSTDIE.

REFERENCES ci'ran The following references are of record in the le of this patent: K

UNITED STATES PATENTS Number Name Date p Roosenstein Oct. 30, 1934 l

Images