Патент USA US2131443код для вставки
Sept. 27, 1938. ' ' w. KUMMERER ET AL 2,131,443 SIGNALING Filed May 16, 1954 2 Sheets-Sheet 1 ~F7l29 I i 114 5/6/1/415 / + 15 MODULA?/VG PO5TE/VWAL 10 1%? 4 INVENTOR 01/00 era-w W/U/ELM mam/m5? . - m ATTORNEY Sept. 27, 1938. w, KUMMERER ET AL 2,131,443 SIGNALING Filed May 16, 1934 2 Sheets-Sheet 2 CARR/67? W4l/E ‘SOURCE . 16 O/RECT CURRENT SOURCE F1945 14 #LT gm INVENTOR ' Mil/ELM lfl/MME/Pf/P ATTORNEY Patented Sept. 27, 1938 ‘ 2,131,443: UNITED STATES PATENT OFFICE 2,131,443 SIGNALING Wilhelm Kummerer and Rudolf Giirtler, Berlin, Germany, assignors to Telefunken Gesellschaft' fiir Drahtlcse Telegraphic m. b. H., Berlin, Ger many, a corporation of Germany Application May 16, 1934, Serial No. 725,846 In Germany May 18, 1933 10 Claims. This invention relates to an arrangement to change grid biasing voltage in tube circuits as a function of the signal strength. In a great number of electric circuits compris 5 ing tubes it is desirable that the static value of the voltage of a tube stage should adjust itself in a de?nite way as a function of the signal strength or an electrical quantity controlled or governed thereby. (01. 179-171) is controlled by controlling the static voltage on the grid of the modulator in accordance with energy characteristic of the modulating poten: tial amplitudes; while ' Figs. 4 and 5 are modi?cations of a portion of the controlling circuits of Figs. 1, 2. and 3. ~ The signal amplitude or else a voltage which is a function thereof, is impressed upon the ter The general requirement in minals I, 2, of the arrangement shown in Fig 10 cases like these is that in the presence of signal ure 1. By means of the recti?er 4 there is pro amplitudes falling below a certain minimum limit or level, the static value of the voltage of a tube, say, the grid biasing voltage, should have a selected constant, while being also constant 15 and of higher value in the presence of ampli tudes above a de?nite upper limit. For signal amplitudes located midway between the said two duced across the terminals of capacity 6 a'direct limiting values, the said biasing voltage is to adjust itself as a function of the signal ampli 20 tude. Now, according to this invention, control of the static voltage value to be acted upon is in sured by utilizing the fall of potential in a re sistance caused by the plate direct current of an 2 Ch auxiliary tube, there being provided in the grid circuit of the said auxiliary tube an additional resistance in series with a recti?er which is given a negative biasing voltage, across which addi tional resistance current of the recti?er con 3 O trolled by the signal currents produces a poten tial which is a function of the signal amplitude. The novel features of the invention have been pointed out in the claims attached hereto as required by law. ' \ The nature of my invention and the operation \thereof will be better understood from the fol lowing detailed description thereof and there - from. when read in connection with the attached 4 drawings in which; Figures 1 to 5 inclusive are circuit diagrams of embodiments of the invention. Fig. 1 illustrates a system wherein the static voltage applied to the grid of a thermionic tube is controlled in accordance with the amplitude 10 current voltage which isnegative with respect to the grid of the tube 9-, the said direct current voltage acting, through its control of the grid potential, upon the plate current of the tube 9 15 ?owing through the resistance Ill, thereby in ?uencing the fall of voltage across the resistance NJ, to which generally a condenser II is con nected in parallel, and consequently across the terminals I4, 15. The potential drop across I4, 20 I5, is caused to act in the grid circuitof the particular stage whose grid biasing voltage is to be a function of‘the signal strength in a way as has hereinbefore been indicated. As a general rule, the grid circuit also contains in series with 25 l4, l5, a direct current source IS. The static value of anode current of the tube 9, apart from the direct current caused by the voltage of source l2, and the plate resistance I0, is further a func tion of the size of the biasing voltage of source 8. If desired, the source of biasing potential 8 may be dispensed with. In the case of all voltages across I, 2, whose amplitude falls below a predetermined critical negative biasing potential of the recti?er 4 as 35 adjusted at the source of direct current potential 5, the said recti?er will be blocked so that no direct current voltage will arise across the con denser 6. The grid bias is now supplied wholly by source 8. The consequence is that the work ing point of the tube will not be shifted by sig nals of amplitude below said critical value, and 40 Fig. 2 illustrates a practical arrangement wherein the static bias on the control grid of a carrier wave modulator of the grid modulation .thus the voltage across [0 remains constant. It is only in the presence of signal amplitudes which exceed the said lower critical value that the 45 source 5 is overcome so that the recti?er 4 be comes conductive; and there arises across the type is controlled in accordance with the ampli tude or percentage of modulation of the modu lated energy derived from an ampli?er energized capacity 6 a potential which, according to its size, diminishes the plate current of tube 9 and thereby the fall of potential acrossthe resistance 50 by the controlled modulator; I0. In the presence of the selected critical maximum signal strength the direct current voltage arising at vt is so high that. the tube 9 is out off or is blocked, no current ?ows-through Sand the of signal potentials; ' Fig. 3 is a modi?cation of the arrangement, of Fig. 2. In the arrangement of Fig. 3, the con trolling potentials are derived from the modu 55 , lating potentials and the carrier wave amplitude potential drop across to will be -of.zero value. 55v 2 2,131,443 Signals which exceed the said upper limit will, to be sure, cause a higher direct current voltage across the terminals of 6; but since the tube 9 is already blocked and the voltage at I4, I5 is zero, it follows that the grid biasing voltage of the above mentioned tube connected to I4, I5 will not be altered by these signal potentials. One practical application of the invention is illustrated in Figure 2. In this case the arrange-_ 10 ment hereinbefore described serves the purpose to lessen the distortions occasioned by the curved portions of the modulation characteristic in a transmitter. The plate direct current of tube I8 is conducted by way of the resistance I3. The 15 resistance I9 which is traversed by the plate cur rent of the auxiliary tube 9 is connected in series with the source of voltage I6 and- the modulation transformer I‘! in the grid circuit of the tube I9. The source I6 and/or resistance I I) shifts the 20 working point of the tube I9 into thelower por tion of its characteristic curve so that the tube is working in the region of and above the lower knee. In lieu of the voltage sources 5 and 8 of Figure 1, the biasing voltage 5a is provided in the circuit scheme of Figure 2. The resistance ‘Ia as a general rule is high compared with the re sistance I3 and the internal resistance of the valve 4. By the plate current of the tube 9 an additional biasing voltage for the tube I9 is 30 occasioned across the external resistance II]. In asmuch as the plate direct current of the tube I8 grows with the amplitude of the alternating cur rent amplitude or the percentage of modulation, it will be seen that also the potential across the 35 resistance I3 will increase. If then, in the course of operation of the modulator circuit the admis sible modulation percentage is extended or in creased, so that the wave amplitudes grow to such degree that they extend as far as the lower knee 40 of the characteristic curve. of tube I8, there is produced a growth of the plate current of the tube I8 and also due to the said recti?cation in tube I8 the same is negatively biased to a corre sponding degree. Due to increase in plate cur 45 rent in I8 the fall of potential across the resist ance I3 in the plate-to-cathode circuit of I8 also grows. Past a certain point, the potential drop across resistance I3 will exceed the electromotive force produced by source 5a and the recti?er 4 50 will become conductive. This permits the nega tive biasing voltage produced across resistance I3 to reach the grid of tube 9. Consequently, the plate current through 9 and the ‘voltage pro duced by the potential drop across the resistance 55 I0 are both diminished. The resultant biasing voltage of the tube I9 becomes less negative and the working point of tube I9 climbs up along the characteristic curve. A working point located above the lower bend at closer proximity to the middle of the characteristic curve results in 'a greater freedom from distortion. My novel cir cuit insures operation of the tube I9 at such working point. The arrangement is so dimen sioned in this instance that the valve 4 remains 65 blocked as long as the operation takes place somewhere above the lower bend of the charac teristic curve upon the rectilinear part of the modulation characteristic. And for the same length of time, also the grid biasing voltage will 70 remain constant in the tube I9. In other words this modulation percentage is exceeded with the result that operation takes place in the curved portion of the modulation characteristic,,then the fall of potential across I3 will go beyond and exceed the biasing‘ voltage 5a, the valve 4 becomes conducting and the higher voltage from I3 will reach and become active at the grid of tube 9, with the result that the plate current decreases and therewith the fall of potential across Ill and thus the biasing voltage of the tube I9. As a re sult the latter will be modulated to a higher de gree or percentage, as the alternating current amplitude grows, and the modulation character istic of the tube I9 becomes straighter. In other words, inside certain limits a correction of the 10 distortion is brought about. By choosing dimen sions appropriately, conditions may be so made that in the presence of 100% modulation the tube 9 will just be blocked. In that case the fall of voltage across I0 becomes zero, .and the biasing voltage of the tube I9 can not be changed any further. When the plate current in I8 assumes larger values, this will cause no additional e?ect upon the tube I 9 because the lower negative bias ing voltage of I9 is limited by the source I6. Another exempli?ed embodiment of the basic idea of the invention is illustrated in Figure 3. This is the fundamental scheme of the modula~ tion stage of a transmitter of the thermionic tube type whose carrier is controlled or modu lated in proportion to the signal strength. For the purpose of insuring carrier control recourse is had fundamentally to a scheme of the kind shown in Figure 1 which in the present instance is somewhat expanded and developed for the sake of example. The signal voltage is impressed upon the terminals I and 2, and on the transformer I'I. When the amplitude of the signal voltage is at a low critical value, or below, recti?er 4 is blocked by the source 5 and the bias potential on the grid of 9 is due substantially solely to the voltage of Ba as modi?ed by resistors 20, etc., and 9 is conductive. Plate current ?owing through 9 and through resistance I9 produces a potential drop in ID. The potential drop in II] adds to the voltage of source I6, as in Figure l, and the plate current through I9 falls. Now, if the modulat ing voltage amplitude equals a critical value, or more, the recti?er valve 4 becomes conductive and current flows in the resistance ‘I producing a voltage drop which modi?es the potential sup plied from 8a to bias the grid of 9 more negative, 25 30 35 40 45 thereby lowering 9’s conductivity and reducing the flow of current through ID. This makes the control grid of I9 less negative and increases the 50 ?ow of plate current in I9. In this manner we produce across the resistance II] a fall of poten tial which is a function of the signal strength. The size of the capacities 6 and II and of the resistances ‘I and I0 govern the particular rate of speed» at which the direct current voltage across I4, I 5, will increase and diminish. Contradistinct to known circuit schemes used for the control of the carrier wave, it is possible in the present in vention to adjust to a large extent the speed of carrier growth regardless and independently of the rate of speed of the reduction of the carrier. If the ripples of the direct current voltage across I 4, I5 can not be sui?ciently suppressed or smoothed by the capacities 6 and II seeing that 65 the values of the latter can not be raised ad libitum because of the resultant time-constants, it would be recommendable to use ?lter circuits of the kind as shown, for instance, in Figure 3 where instead of 6 the ?lter circuit 6, 2|, 22 is 70 connected. . Figure 3 shows a further development of the arrangement residing in the provision of the re sistance 29 which is traversed by the plate cur rent of tube 9 and which is included in the grid 3., 2,131,443 circuit of the tube 9, said resistance serving the purpose of compensating the curvature of the characteristic of the tube 9. The said resistance device having a controlling electrode and a cath ode, a circuit applying carrier wave energy to said controlling electrode, a source of modulating po will have to be used whenever the desideratum is tentials, an impedance and a source of direct cur to insure as linear as feasible an interrelationship rent potential connecting said source of modulat between the signal amplitude across I and 2, and the biasing voltage across M and I5. ing potentials between the controlling electrode and cathode of said ?rst named device, a recti her having input electrodes energized by said Cases may arise in which the voltage across the resistance I0 is not desired to bear a linear 10 dependence upon the signal amplitude. In that instance, at the point marked 9 one or more tubes possessing suitable characteristics are provided. Also the frequency curve of the transformer 3 may be so chosen that between the signal ampli 15 tude across I, 2, and the voltage across l4, it, the desired non-linear relationship will be ful?lled. The lower and the upper limit or levels depend upon the choice of the recti?er bias, in Figures 1 and 3, and the turn-ratio of the transformer 3 or 20 the adjustment of the potentiometer l3, in Fig ure 3. Hence, what is essential is that the volt age at 5 and in some suitable manner also the ratio of transformation of the applied voltage and the one transferred to the recti?er should be 25 adjustable. modulating potentials, an additionaltube hav ing an anode, a cathode, and a controlling elec trode, a second impedance, a ?lter circuit con necting the output electrodes of said recti?er with said second impedance, a connection between said second named impedance and the controlling electrode and cathode of said additional tube, and a connection between the anode and cathode of said additional tube and said ?rst named impedance. 7 3. In a modulation system, an electron dis charge modulating device having electrodes in- ' eluding input electrodes on which wave energy to be modulated is impressed, a source of modulat ing potentials connected with an electrode in said device and means to regulate the static value of the operating ‘voltages of said device as a func— If an extensive suppression of the voltage rip ples is desired, then as illustrated in Figure 4, two tubes 9, 9a, are connected push-pull fashion in the grid, while their plates are connected in 30 parallel. The recti?er 4 works upon the capacity 6 and the resistance 1 in the grid circuit of the tube 9 and upon the capacity 60. and the resist ance ‘la. in the grid circuit of the tube 9a. The voltage ripples across to are of opposite phase 35 compared with the voltage ripples across 5 so that tion of the strength of said modulating poten tials comprising, an auxiliary'tube having an The condenser l I may be chosen so small that it will practically exercise no effect upon the time— constant under certain circumstances it may be dispensed with. So far as the dimensioning of the condensers 6 and 6a and of the resistances 7, ‘la, are concerned there is a good deal of latitude in the case of this circuit scheme. current potential in series connected with the control grid and cathode of said auxiliary tube, said source of potential being of such avalue and, they will largely be neutralized at the plate end. 40 When using tubes having their grids connected 45 push-pull fashion the recti?er 4 may be dispensed with, while the grid biasing Voltage of the tubes 50 9, 9a, which is to be a function of thesignal may be obtained by means of grid recti?cation. One exempli?ed embodiment of such an arrangement is schematically shown in Figure 5. By selection of the biasing potential 5 and adjustment of the anode, a cathode and a control grid, at resist ance connected between the anode and cathode of said auxiliary tube, a capacity connected in 30 parallel with said resistance, said capacity being suitable to the frequency of said modulating po tentials, means for coupling said resistance to an electrode in said discharge device, the voltage applied to which is to be regulated, a second re sistance and a recti?er and a source of direct so connected as to normally block said recti?er, 40 means for biasing the control grid of said auxil iary tube relative to its cathode by a potential such that current normally flows in said auxiliary tube and ?rst resistance, and a circuit for ap-' plying energy characteristic of the modulating 45 potentials to the input electrodes of said recti?er for overcoming said blocking potential when the amplitude of the modulating potentials exceeds a selected value. ' 4. A system as recited in claim 3 in which said potentiometer E3, the upper and the lower con second resistance connected with the control grid and cathode of said auxiliary tube is connected trol limits or levels are ?xed. with said recti?er by way of a ?ltering circuit Having thus described my invention and the 55 operation thereof, what I claim is: 1. A signaling system comprising, a thermionic tube having a control grid and a cathode, a cir cuit for applying carrier waves to said control grid, a source of modulating potentials, a trans 60 former having its primary winding connected to said source of modulating potentials, a resistance and a source of potential connecting the second ary winding of said transformer between the con trol grid and cathode of said ?rst named tube, a comprising capacity. 65 recti?er having its input electrodes energized by sistance connected between the anodes and cath odes of said auxiliary tubes, a capacity con nected in parallel with said resistance, said ca said modulating potentials, an additional tube having an anode, a cathode and a control grid, a second resistance, a ?lter circuit connecting the output electrodes of said recti?er in parallel with 70 said second resistance, a connection between said second resistance and the control grid and cath ' 5. In a modulation system, an electron dis 55 charge modulating device having electrodes in cluding input electrodes on which wave energy to be modulated is impressed, a source of modu lating potentials connected with an electrode in said device and means to regulate the static value 60 of the operating voltages of said device as a func tion of the strength of said modulating potentials comprising, a pair of auxiliary tubes each having an anode, a cathode and a control grid, a re 65 pacity being suitable to the frequency of said modulating potentials, means for coupling said resistance to an electrode in said discharge device, the voltage applied to which is to be regulated, a recti?er and a source of direct current potential ode of said additional tube, and a connection be tween the anode and cathode of said additional in series connected with the control grid and .cathode of each of said auxiliary tubes, said tube and said ?rst named resistance. source of direct current potential being of such a 75 2. In a signaling system, an electron discharge 75 4 2,131,443 value and so connected as to normally block said recti?er, means for biasing said auxiliary tubes by potentials such that current normally flows in said auxiliary tubes and ?rst resistance, and a circuit for applying energy characteristic of the modulating potentials to the input electrodes of ,said recti?er for overcoming said blocking po tential when the amplitude of the'modulating po tentials exceeds a selected value. 6. In a modulating system an electron dis charge modulating device having electrodes in cluding input electrodes on which wave energy to be modulated is impressed, a source of modulating potentials connected with an electrode in said device and means to regulate the static value of the operating voltage applied to an electrode of said device as a function of the strength of the modulating potentials comprising a pair of auxiliary thermionic tubes each having an anode, 20 a cathode and a control grid, a resistance con necting the anodes and cathodes of said auxil iary tubes in parallel relation, a circuit for cou pling said resistance to an electrode in said modulating device, a circuit connected between the control grids of said auxiliary tubes, means for coupling said circuit to said source of modu lating potentials, a recti?er connecting a point on said circuit between the control grids of said auxiliary tubes to the cathodes of said auxiliary 30 tubes, and means connected with said recti?er for normally blocking said recti?er. '7. An arrangement as recited in claim 6 in which the control grid and cathode of each of said auxiliary tubes is shunted by a resistance and 35 by a condenser and in which direct current po such that current flows in said tube and re sistance to produce in said resistance a potential drop, a source of potential coupling said re sistance to the control grid and cathode of said modulator tube to apply therebetween said po tential drop and potential from said source of potential, a recti?er having its anode circuit con nected to the control grid of said auxiliary tube, said recti?er being normally biased to cut off, and means for applying moduated wave energy from said ?rst tube to the input electrodes of said recti?er to control the conductivity thereof. 9.,In a modulating system, an electron dis charge modulator device having a control elec trode and a cathode and an output electrode from which modulated energy is derived, a source of wave energy coupled to said control electrode, a source of signal voltage coupled to an electrode in said device, and means to regulate the static value of the operating voltage applied to the con trol electrode of said electron discharge device as a function of the amplitude of the signal voltage to be impressed on an electrode of said device and to limit said regulating action between upper and lower voltage amplitudes comprising a source of 25 biasing potential and an impedance for applying to said control electrode relative to said cathode of said device a selected biasing potential, means for changing said biasing potential when the amplitude of said signal voltage exceeds a se 30 lected critical lower value commensurate with said selected biasing potential, said last named means comprising an additional discharge device hav ing output electrodes connected to said impedance and having input electrodes, a recti?er having an tentials are applied to the anodes of said auxiliary output connected to the input electrodes of said tubes to charge the said anodes relative to the additional discharge device and an input excited cathodes by potentials such that said auxiliary tubes are conductive in the absence of signals to by voltages characteristic of said signal voltages, and means for normally biasing said recti?er to out off in the presence of signal voltages equal to 40 be ampli?ed. ‘ 8. In a modulation system a thermionic modu lator tube having electrodes including a control grid and cathode, a source of wave energy to be modulated and a source of modulating potentials’ 45 coupled to said control grid and cathode and means to regulate the static value of the biasing potential applied to the control grid of said thermionic modulator tube as a function of the strength of the modulating potentials comprising, an auxiliary tube having an anode, a cathode and a control grid, a resistance connected between the anode and cathode of said auxiliary tube, means for biasing said control grid of said auxil iary tube relative to its cathode by a potential or lower than said selected critical value. 10. A system as recited in claim 9 including means for rendering said means for changing said selected biasing potential inoperative when said voltages characteristic of signal voltages ex ceed a predetermined upper amplitude value 45 whereby the biasing potential on said control elec trode of said ?rst discharge device is controlled in accordance with the amplitude of said voltages characteristic of signals between said upper and 50 lower limits. WILHELM KUMMIERER. RUDOLF GI'JRTLER.