US2287296A - Disturbance supperssion in radio receivers - Google Patents

Description

June 23, 1942. G DALLOS 2,287,296

DISTURBANCHSUPPRESSION IN ,RADIO RECEIVERS Filed Aug. 23, 1938 6 Sheets-Sheet 1 hrenfor:

June 23, 1942. DALLQS 2,287,296

DISTURBANCE SUPPRESSION IN RADIO RECEIVERS Filed Aug. 23, 1938 ,6 Sheets-Sheet 2 June 23, 1942. G, DALLOS 2 ,287,296

DISTURBANGE SUPPRESSION IN RADIO RECEIVERS Filed Aug. 23, 1938 6 Sheets-Sheet 3 June 23, 1942. DALLQS 2,287,296

DISTURBANCE SUPPRESSION IN ,RADIO RECEIVERS Filed Aug.- 23, 1938 6 Sheets-Sheet 4 Fig.5.

June 23, 1942. G. DALLOS 2,287,296

DISTURBANCE SUPPRESSION IN RADIO RECEIVERS Filed Aug. 23, 1958 6 Sheets-Sheet 5 June 23, 1942. G. DALLOS 2,287,296

DISTURBANCE SUPPRESSION IN RADIO RECEIVERS Filed Aug. 25; 1938 6 Sheets-Sheet 6 I I I I IJI I I'I'I bra/2hr:

Patented .Yune 23, 1942 UNITED STATE DISTURBANCE SUPPRESSION 1N EADIO RECEIVE George Dallas, Ujpest, Hungary, assignor to United Incandescent Lamp & Electrical Company, Limited, Uipest, Hungary Application August 23, 1938, Serial No. 226,232 In Hungary April 9, 1938 5 Claims. (01. 250-20) This invention relates to wireless signal transmission and more especially to means for suppressing disturbances and producing other useful effects in radio transmission and receiving apparatus.

In the suppression of disturbances in radio receiving sets hitherto various methods have been applied according to which the disturbance is rebased on the following principles and involve the following dimculties:

In order to block the receiver, there is impressed on the control member of an electron valve in the receiver a biasing potential such .that during undisturbed reception no current will flow in the valve. However, if a disturbance arises and the control member is now supplied with a greater potential than the biasing potential mentioned above, current will flow through the load resistance, the voltage of which can be utilized for blocking the receiver. The principle of operation of the systems operating with blockage may be illustrated by the diagramof Fig. 1 of the drawings forming part of this specification, in which the grid potentialanode currentcharacteristic (EB-J8) or an electron tube is shown. On this tube is impressed a biasing potential e; of a value such that during undisturbed reception no current fiows in the tube, 1. e. the starting of current flow is suppressed until the amplitude of the modulated high frequency carrier wave m fed to the control grid exceeds a predetermined limit, which corresponds for instance to a 100 per cent modulation, thus amounting to the double of the carrier wave amplitude. As soon, however, as disturbances having peaks a1 and z: arise, the anode current starts flowing, the amplitude of which is marked 2'1, in the case of a peak 21, and 2's, in the case of a peak 2:2. These current impulses may be used directly, or after rectification (amplification) to block any stage of the receiver. As results further from Fig. 1, a corresponding y great preliminary amplification is required to remove the disagreeable eflect of the lower bend of the char.- acteristic, the effect of the so-called cutting on. This disadvantageous phenomenon consists in that the variation of the slope at the bend. i. e. around the working range, is small, so that only disturbances having a materially greater amplitude than the range adjusted by the biasing potential furnish a sufliciently high voltage for rendering the receiver inoperative. In view of this a preliminary amplification of the disturbances is required in order to bring about a corresponding eflect, but this is connected with higher cost and may lead to the disadvantageous consequence that the blocking potential with regard to the disturbances arising in the receiving channel might be retarded owing to the transition phenomena arising during amplification of the disturbances.

The principle of amplitude limitation is illus-' trated by the diagram of Fig. 2, which shows the saturation characteristic of an electron tube. The working point P of the tube is so adjusted on principle that the peak values of the disturbances having an amplitude which exceeds a predetermined limit, exceeding for instance the amplitude corresponding to a per cent modulation, are cut oil. In practical operation however only an amplitude of the modulated high frequency 111, may be impressed onto the grid such that even with a 100 per cent modulation the bends of the characteristic do not bring about any distortions. If this requirement is complied with, the tube, as shown by Fig. 2, can also allow the peak values arising beyond the 100 per cent modulation, for instance 2a, 24 to pass through (see za, z'4) so that no altogether undisturbed reception is guaranteed. It is true that with the aid of complicated circuits this drawback can partly be avoided, but a reliable cutting off at the desired limit cannot be secured in this manner either.

Experiments have now proven that a particularly favorable mode of suppressing disturbances is obtained, if the two methods discussed above, the amplitude limitation and the blockage, are used together while the disturbance lasts. To

this end, however, a great number of tubes and 2 menace ing to the suggestions the cathode ray is controlled by an electron tube fed with a biasing potential equallingthe limiting value of the operating potential. I! the grid of this tube was supplied with a high frequency exceeding that limit, the cathode ray was deflected, by means of the anode current started, either electrically or magnetically onto an electrode with a resistance connected thereto, the blocking potential being furnished by the current flowing through this resistance. Thus in this case the cathode ray tube only acted as a kind of relay switch. My invention likewise utilizes the system of ray .deflection, however, th arrangement according to this invention constitutes an important development of the system which leads to a number of surprising effects.

The invention consists more especially in an arrangement which produces various electrical effects corresponding to the amplitude of the os- "-cillations received and quite especially suppresses "disturbances, this being effected by means of an electron ray tube comprising means for deflect- "ing theelectron ray. According to this invention the electron ray tube is inserted right into the signal receiving channel and is fitted with a plurality of collecting electrodes to which are "conected circuits or networks which bring about or assist in the production of the various desired electrical effects. The extent of deflection of the electron ray is influenced, by means of deflectingmembers, .by the amplitude of the oscillations received and the electron ray, impinging on one or a plurality of the collecting electrodes, according to the extent of deflection, actuates the circuits or networks connected to them.

In a particularly advantageous form of the invention there is impressed onto the deflecting members the modulated high frequency carrier wave received, while to some collecting electrodes is connected one or to each electrode a separate amplifier or demodulating device, to other collecting electrodes, however, one, or to each a separate device for producing a direct voltage serving for instance as blocking voltage. By means of this arrangement there can be secured amplification or demodulation up to a predetermined limit, and beyond this amplitude limitation in the'manner to be described here below and at the same time blockage of the receiver while the disturbance lasts. Consequently this arrangement is universal; it combines the advantages offered by the known arrangements mentioned above and serving a single purpose, while at the same time avoiding the drawbacks inherent in them. It ofiers the further advantage'that, owing to the high inner resistance of the circuit elements employed, it does not exert any appreciable damping effect and secures the linearity up to the adjusted limit.

In the arrangement according to this invention the cross section of the electron ray may have any geometrical configuration whatever, being for instance a rectangle, a circle etc. which can be obtained by any known kind of electronoptical ray controlling means. The electron ray may preferably be focussed onto the collecting electrodes and in this case also the intensity of I as; deflecting members.

Figures 1 and 2, as previously indicated, show curves illustrating principles of operation of certain apparatus,

In the Figs. 3-10 of the drawings several arrangements embodying my invention are illustrated diagrammatically by way of example. Of these figures Fig. 3 shows an arrangement comprising a cathode ray tube. product in electron ray of rectangular cross section,

Fig. 4 illustrating a detail of this arrangement, partly in perspective view,

Fig. 5 showsa modified form of the arrangement, in which a cathode ray tube is used, which produces a focussed electron ray,

Fig. 6 is a perspective view of a third modification,

Fig. 7 shows a fourth modification,

Fig. 8 illustrates a special arrangement of the collecting electrodes,

Fig. 9 being a cross section on the line A-A in Fig. 8,

Fig. 10 being a perspective view ,of another special arrangement of the collecting electrodes.

In the several figures similar elements are marked with similar reference numerals.

Referring to the drawings and first to Fig. 3, I is a part of the wall of a cathode ray tube, while the source of electrons and the electronoptical means for deflecting the electrons are omitted. In the tube I the deflecting electrodes 2, 3 and the collecting electrode plates 4, 5, 6, I, I are arranged symmetrically relative to the longitudinal axis of the tube. The electrodes 4 and 5 on the one hand and the electrodes 6, I, 8 on the other hand are arranged in parallel planes, the plane of the electrodes 4, 5viewed from the source of electrons (not shown)extending in front of the plane of the electrodes 6, I, 8 and the electrodes 4, 5 overlapping the electrodes 6, I, 8 located behind them. Obviously the collecting electrodes might also be arranged in such manner that the plane of the electrodes 4, 5 extends to the rear of the plane of the electrodes 6, 1, 8.

The middle electrode 5 is connected to earth. To the electrodes 4, 5 is connected an oscillatory circuit consisting of a condenser II and an inductance with grounded tapping point, and to this circuit are connected through condensers l3, II the amplifier tubes l5, I5, connected in push pull fashion. and having biasing potential resistances l4, I4. In the common anode circuit of the tubes l5, I5 is inserted an oscillatory circuit I5, from which the high frequency can be taken off and passed on. To the electrode I is connected a grounded resistance 9 shunted by a condenser Ill, to the electrode 8 a similar resistance 9' shunted by a condenser Hi.

If the tube I is operated without supplying a potential to the deflecting plates 2, 3, the greater part of the electron my 20 will impinge on the electrode 5 and the electrons will flow towards the earth potential. A small part of the electron ray will strike also the electrodes 4, 5. If now the electron ray 20 is deflected, by means of a high frequency alternating voltage applied to the plates 2, 3, so far that the greater part of it alternately strikes the electrodes 4 and 5, current will flow from the electrodes 4, 5 into the oscillatory circuit ll, l2, according to the extent to which the ray is deflected. This current is amplified by the amplifier system I5, [5, and the amplified current can now be taken off from the oscillatory circuit I6 and used for any desired purpose. The current flowing from the electrodes 4, will reach its maximum when the extent of deflection is such that the fully deflected electron ray strikes these electrodes. If with an increase of the high frequency amplitude fed to the plates 2, 3 the electron ray is deflected still further, it will also impinge on the electrodes 1, 8, a voltage being formed along the resistances 9, 9', which may be utilized for any desired purpose, for instance for blocking the receiver.

If" a modiilated high frequency carrier wave is applied to the deflecting plates, the electron ray will be deflected according to the modulation. The carrier wave is advantageously fed to the deflecting plates with an amplitude such that the electron ray begins passing over from the electrodes 4, 5 to the electrodes 1, 8 only with a 100 per cent modulation. I'thereby obtain that up to the 100 per cent modulation of the carrier wave there appears in the oscillatory circuit l6 a correspondingly modulated high frequency which can be fed to the further stages of the receiver. At the same time, however, I achieve that a potential, the amplitude of which exceeds the limit corresponding to a 100 per cent modulation (determined by the edges of the plates 4, 5) cannot appear in the oscillatory circuit l5, so that the amplitude limitation spoken of in the introduction to the specification is secured. If now the amplitude of the high frequency fed to the deflecting plates 2, 3 rises of a sudden due to a disturbance, the electron ray will change over for its greater part to the electrodes I, 8, and a potential will arise cross the resistance 9, 9', which can be utilized for blocking one or a plurality of stages of the receiver, whereby the receiver is also blocked while the disturbance lasts.

Obviously the electrodes 4, 5 may not only be supplied with the modulated high frequency carrier wave, but also with some other alternating voltage of fluctuating amplitude, by means of which, according to its amplitude, various electric effects shall be produced. For the sake of simplicity hereinafter always a modulated high frequency carrier wave will be mentioned, but I wish it to be understood that this wave may in each individual case be replaced by some other alternating potential of fluctuating amplitude.

In the circuit illustrated in Fig. 3 the current to be amplified can obviously be taken off from the electrode 4 or from the electrode 5 or from both electrodes separately and in this case an ordinary (as opposed to push-pull) amplifica-' tion may be effected. Furthermore a demodulating circuit may be connected to the electrodes 4, 5 so that these electrodes can eifect a full wave rectification.

This is illustrated in Fig. 4, where the electrode system according to Fig. 3 is shown perspectively in order to facilitate understanding, always under the assumption that to the deflecting electrodes 2, 3 is supplied a modulated carrier frequency.

In Fig. 4 there is connected to the electrodes 4, 5 a grounded load resistance 2| which is shunted with a condenser 22 for deriving the high frequency. The sound frequency arising through the resistance 2| is fed through a condenser 23 to an amplifier tube 25 with grid leak resistance 24. If dimensioned correspondingly, the electrodes 4, 5 are able to furnish a current of an intensity such that the voltage at the terminals of the resistance 2| may suflice to control a power stage tube.

In the arrangement according to Figs. 3 or 4 the different electrode voltages can be tapped from the potentiometers 30, 3| shown in Fig. 3 and this in such manner that the total voltage of the source of current B is supplied to the terminals 32, '33 of these two potentiometers. To the point 34 of the potentiometer 30- is connected the usual Wehnelt cylinder, to the point 35.be-

tween the two potentiometers the cathode K,

to the points 36, 31, 39 the various auxiliary anodes and to the point 39 through earth the collecting electrodes of the tube I. 39 is the earth point of the amplifier I5, I5 or of the radio receiver. This mode of earthing may be dispensed with, if the potential arising at the resistanc'es 9, 9 is not required to be a negative potential with regard to the earth potential. In this case the cathode point 35 is grounded, whereby the total anode potential becomes smaller. The anodepotential of the tubes l5, I5 is derived from the point B of the source of cur- In Fig. 5 this embodiment is illustrated. Here the tube contains the cathode 42 with heater 4|, an electrode 43 serving to control the intensity, electrodes 44, 45 serving for electronoptical purposes, the deflecting plates 2, 3 mentioned above, other deflecting plates 2, 3 arranged normally to the former and the collecting electrodes 4, 5, 6, I, 8, also mentioned above, to which latter are connected the circuits or networks described with reference to Figs. 3 and 4. The potential for the different electrodes is supplied by a potentiometer 48'connected to the terminals of a battery 49. In order to control the intensity of the ray, the high frequency carrier wave is impressed to the electrode 43 between the points 46 and 41 of the feed line. In other respects the mode of action of this circuit agrees with that of the arrangements shown in Figs. 3 and 4.

The deflecting plates 2', 3' serve for deflecting the ray in the absence of a high frequency signal from the lower level of the electrodes 48, whereby a mute or noiseless tuning between reception and transmitting stations can be attained. It is also possible to feed back the blocking potential of the resistances 9, 9 to the deflecting plates 2, 3, whereby the effect of disturbance suppression is increased.

Fig. 6 illustrated in a perspective view an embodiment of my invention serving to obtain a noiseless tuning. Underneath the collecting electrodes 4-8 is arranged an electrode 50. In the absence of a high frequency signal a direct voltage is applied to the deflecting plates 2', 3,

whereby the ray 2!! is deflected downwardly,

current coating adapted to emit secondary electrons.

This is shown by way of example in Fig. 7, which in other respects greatly resembles Fig. 5. Here This control is required with regard the collecting electrodes 4, 5,1, 8 are formed with a coating for secondary emission and the multiplied currents are collected for the uses mentioned above from the wide-meshed grids 4', 5', I, I arranged in front of these electrodes. In this case the collecting electrodes themselves are connected with each other by their earthed leads and their common connecting line is connected to the point d of the potentiometer II. In the leads of the collecting electrodes may be inserted the resistances I", 5", l", 8". The collecting electrodes provided with a secondary emission coating may also form the first stage of a multistage electron multiplier. In order that the arrangements shown in Figs. 3-7 operate correctly, it is important to provide for the most perfect automatic volumecontrol. In the arrangement, shown in Figs. 8-9, of the collecting electrodes this requirement may also be dispensed with, for in this arrangement the electrodes 54, 55 and 51, 58, which correspond to the electrodes marked 4, 5 and I, 8, respectively, in the former figures, are not rectangular, but their overlapping marginal portions 54', 58? and 55', 51', respectively,

. slope in oblique direction. In this arrangement of the collecting electrodes the high frequency carrier wave is supplied to the electrodes deflecting in the direction which were hitherto designated 2', 3', so that the ray is deflected in the direction a-b proportionally to the amplitude of the carrier. If now the electrodes 54, 55 are so dimensioned or their edges 54', 55. are so inclined that the electron ray which impinges upon the electrodes 54, 55 at some point, begins to pass over from these electrodes to the electrodes 51, 58 only after a 100 per cent modulation (under the influence of the deflecting plates 2, 3) a very flnemethod of cutting off is obtained, which automatically adapts: itself to the carrier wave amplitude present in each individual case. Thus, when receiving weaker stations, the electron ray will shift to the narrower parts of the plates 54, 55, when receiving more powerful stations, towards the wider parts.

Fig. 10 is a perspective view of an arrangement similarly to that shown in Figs. 8 and 9. As a whole the arrangement according to Fig. 10 agrees with that shown in Fig. 5, however with the difference that here the electrodes 4, 5 are replaced by the trapezoidal electrode 60, the electrodes I, 8 by an electrode 5| cut out at 62, which is located to the rear of the electrode 60. The form of opening 62 corresponds to the configuration of the electrode 50, being however somewhat smaller than the electrode. By the deflecting electrodes 2, 3 the focussed electron ray 20, the intensity of which is controlled, is deflected in the direction X and by the electrodes 2', 3 in the direction Y. The mode of action of this arrangement is obvious in view of the explanations given with reference to Figs. 5 and 9. If

the intensity of the electron ray is controlled in enemas the edges 53, H adapts itself to the carrier amplitude, i. e. to the power of the received transmitting station. The charges fed to the collecta voltage fluctuating in the rhythm of the sound frequency. If now a potential proportionate to the enveloping characteristic of the audio frequency alternating voltage is impressed on the plates 2, 3, the cathode ray will shift in the direction X, proportionally to the amplitude, existing in each case, of this alternating voltage. and

7 therefore the limiting level in the function of will be deflected proportionally to the deflecting amplitude in the direction Y and, in the presence of a disturbance, on leaving the electrode, will impinge upon the electrode 5 I. By means of the electrodes 2, 3 the electron ray is deflected proportionally to the carrier amplitude in the direction X in order that the cutting off effected by the audio frequency amplitude can be accurately adjusted in an automatic manner. In this case the sound frequency is first rectified and the voltage thus obtained, after having been filtered correspondingly, is fed to the plates 2, 3 as deflecting voltage.

The invention is by no means limited to the use of a so-called cathode ray tube of axial construction, but 'I may also use in the arrangements according to this invention an electron ray tube of central construction.

,As resorts from the many examples described above, the arrangements according to this invention and the discharge tube to be used in connection with them can be provided in a great variety of ways. The problem according to this invention, which consists in producing various electrical effects in accordance with the amplitude of the oscillations received, can obviously be solved also by many other modifications lying within the scope of this invention. Additional effects may further be obtained if for instance in the tubes used in these arrangements the electrode systems of various kinds are combined with one or more discharge devices, each having two or more electrodes.

Various changes may be made in the details disclosed in the foregoing specification without departing from the invention or sacrificing the advantages thereof.

I claim:

1. An arrangement for suppressing disturbances in radio receiving sets, comprising in combination, a signal receiving channel, an electron ray tube arranged in said channel, means for deflecting the electron beam in said tube, a plurality of collector electrodes adapted to receive said beam in accordance with the degree of deflection, means for blocking the receiver connected to some of said collector electrodes, means for focusing the beam on the collector electrodes, and means for controlling the intensity of the beam in dependency upon the rhythm of the signal.

2. An arrangement for suppressing disturbances in radio receiving sets, comprising in combination, a signal receiving channel, an electron ray tube arranged in said channel, means for deflecting the electron beam in said tube, means for controlling said deflecting means in dependency upon the amplitude of the signal, a plurality of collector electrodes adapted to receive said beam in accordance with the degree of deflection, means for blocking the receiver connected to some of said collector electrodes, means for focusing the beam on the collector electrodes, and means for controlling the intensity of the beam in dependency upon the rhythm of the signal. 4

8. An arrangement for suppressing disturbances in radio receiving sets, comprising in combination, a signal receiving channel, an electron ray tube arranged :1 said channel, means for deflecting the electron beam in said tube in one direction, means for controlling said deflecting means in dependency upon the amplitude 01 the signal. other means for deflecting the electron beam in a direction substantially perpendicular to said first named direction, means for controlling said other deflecting means in dependency upon the mean amplitude of thecarrier, a plurality of collector electrodes adapted to receive said beam in accordance with the degree 01' deflection, means for blocking the receiver connected to some or said collector electrodes, means for focusing the beam on the collector electrodes,

and means for controlling the intensity or the beam in dependency upon the rhythm of the signal. 1

4. An arrangement according to claim 2. wherein the means, connected to some or the collector electrodesdor blocking the receiver comprise at least one device tor producing a direct voltage, and including at least one amplifier connected with some other of said collector electrodes.

5. An arrangement according to claim 2. wherein the means, connected to some 0! the collector electrodes, for blocking the receiver comprise at least one device for producing a direct voltage, and including at least one demodulating device connected with some other of said collector electrodes.

GEORGE DALLOS.

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