Патент USA US2107425код для вставки
FIPBIOZ' xp 2,107,425 Feb. 8, 1938. SEARCH RGON ?Uba KtrLKtNbl: 2,107,425 C. PROTZE MONITOR Filed Aug. 20, 1936 KEYED WAVE FROM TRANSMITTER LC Sp FA’OM OUTPUT 0F TELEGRAPH REEE/I/EI? ‘ INVENTOR CURT PROTZE BY ATTO R N EY Patented Feb. 8, 1938 2,107,425 UNITED STATES PATENT OFFICE 2,107,425 MONITOR Curt Protze, Berlin, Germany, assignor to Tele funken Gesellschaft fiir Drahtlose Telegraphic m. b. H., Berlin, Germany, a corporation of Germany Application August 20, 1936, Serial No. 96,980 In Germany July 13, 1935 3 Claims. In the wireless communication it is often de sirable for the telegraph operator to be able to hear his own telegraph signals as produced in the transmitter in order to be able to control the 6 working of his transmitter. For this supervision it is necessary to be sure that the high frequency power is actually being sent out. It should be kept in mind that this could not be readily ascer tained where the control arrangement or moni 10 toring means is placed directly in the keying cir cuit, since it is possible that failure may take place within the individual stages of the transmitter and not be noticeable to the operator. , Where a supervisory control for the entire 15 transmitter is required there exists the disadvan tage that the controlling volume, i. e., the moni toring signals ?uctuate to a high degree unless means to counteract this ?uctuation are provided. In many cases the transmitter is not always op 20 erated with the same power, since at resumption of communication a high power is used for send ing to permit the transmitter easily to assume its proper operating state. Thereafter the power is reduced to a point just su?icient to retain the 25 volume necessary for communication. Not only is the ?uctuation in the volume of the transmitter of great inconvenience to the telegraph operator, but eventually if the volume becomes too large it will endanger the hearing of 30 the operator, and it will also not be possible for the latter to hear the softer signals of the oppo (01. 250-17) addition it should be borne in mind that for com mercial communication, tubes having different over-all dimensions are used whereas modern multiple electrode tubes as used in receivers, are not as yet manufactured in the commercial trans mission form. It would obviously be possible to avoid such special tubes and not to avail one self of the advantages thereof, but the circuits hitherto known have the disadvantage that the control arrangements are sensitive to variations 10 in the operating voltages, and that even the tubes of the same type diifer as to their characteristics, so that therefore the position of the lower bend of the characteristic is not established with su?l cient accuracy. 15 In accordance with the present invention, the constant volume in an audible control device for transmitted telegraph signals is attained in that the high frequency derived from the transmitter and then detected is applied to the grid of a tube 20 serving as control organ or element for the re ceiving indicator, whereby the grid potential of said tube is prevented from becoming more posi tive under the in?uence of a counter potential de spite an increase in the detected positive potential, - 25 said counter potential being produced by the grid current at an ohmic resistor placed in the grid lead. Thepinvention may be put into practice by connecting the tube serving as control organ in the plate circuit of a low frequency generator,v 30 and negatively biasing the grid of said control site station with su?icient clarity directly after his ' tube to such a degree that it will be blocked when hearing has been jeopardized on account of too large a volume. For this reason an automatic 35 volume control is greatly desirable. The arrangement heretofore used was such that the detected high frequency fails, thereby,-stop ping the generator owing to a cutting off of the plate potential. . . This arrangement will now be elucidated with the high frequency obtained from the transmitter reference to the single ?gure in the drawing has been detected, and the direct potential so ob tained has been utilized as plate potential of a 40 tube arranged as tone frequency generator. How wherein I have illustrated one embodiment of my monitoring circuit. The keyed high fre ever, in this case a sufficiently constant volume was quency is supplied from the transmitter across condenser C to the detector tube I , whereby said not attainable since the plate potential of the tone frequency generator and hence the ampli high frequency may be derived from the antenna tude of the tone produced varies with the energy 45 of the transmitter to be controlled. An automatic volume control such as known for instance in broadcast reception could be used. However, this involves di?iculties since for com mercial communication several other require 50 ments must be ful?lled. It is not advisable to use special control tubes such as hexodes in tele graphy systems for instance, since owing to the desire of reducing the number of spare tubes to a minimum, the number of different types of tubes 55 in a receiver should be as small as possible. In iii-o ,; or from an intermediate circuit for instance, al though as is obvious, it may also be inductively transmitted to coil Sp. The high frequency po 45 tential appearing at the ends of coil Sp will be detected in tube l, which by the way, may be a single grid tube to avoid increasing the number of types of tubes, the grid of said tube being con 50 nected to the cathode or anode. There appears at the terminals of resistor W a direct-current potential of the rhythm of the keyed signals, the value of which depends upon the power to which the transmitter is adjusted to send out. The time constant of the circuit con 55 2 2,107,425 sisting of resistor W and condenser C1 is suffi ciently short to avoid distortion of the signals at the highest telegraph speeds. The produced di rect potential is applied to the grid of tube 2 in such-manner that it opposes the negative bias of battery V. During the pauses of the operator's own transmitter no voltage exists at resistor W so that only the biasing potential V is e?ective, and which is just sumcient to block the tube 2. Con 10 sequently owing to the then existing high direct current resistance of tube 2, the plate potential applied between -—A and +A will be substantially distributed over the impedance of tube 2, thus pre venting the tube 3 from oscillating owing to in 15 su?icient plate potential so that no tone can be heard in the head piece T. But the receiver can then be heard across the conductors shown. If operator’s own transmitter is being keyed, a direct potential appears at W imparting to the 20 grid of tube 2 a more positive bias thereby re ducing its direct current resistance. Then tube 3 receives plate potential and oscillates. Up to this point the arrangement does not offer any ad vantage in reduction of loud signals in the moni tors’ phones in the presence of high amplitude telegraphy, since for higher direct potential at W, the plate potential on 3 likewise increases. This is avoided however, in the present invention by utilizing the condition that the grid current ?ow 30 ing in tube 2 produces in resistor R placed in the grid circuit a negative, and hence opposing po tential. This opposing potential as is obvious, is also produced at W, but in view of the afore mentioned short time constant W is but a low 35 ohm resistor, whereas the value of R is approxi mately equal to 500,000 ohms. 0n the other hand, it will not be possible to maintain a short time constant by decreasing 01 while providing a large value for W, since C1 40 is to represent a su?icient short circuit as re gards high frequency. If, therefore, the potential appearing at W exceeds the biasing potential V so that a positive bias exists at tube 2 producing a grid current, this increasing positive potential 45 at W owing to the opposing potential at R causes a but very slightly higher positive potential at the grid of tube 2. Moreover, in view of this fact the direct current resistance of tube 2 and hence the plate potential at tube 3 will be constant, and 50 therefore also the volume will have the same value despite varying high frequency intensity. The advantage of the arrangement resides in that with few auxiliary means it is possible to obtain a constant volume throughout a very wide 55 signal amplitude range, and that changing the controlling tube 2 owing to the relatively constant grid current development, does not cause a change in the operating condition. As already pointed out, the range of constant 60 volume begins only when grid current ?ow be gins, i. e., when the negative biasing potential V is overcome. However, this is no disadvantage since for instance at a fluctuation of the trans mitter power at the ratio of for instance 1:1000 (for instance between 20 w. and 20 kw.) and at a corresponding fluctuation of the voltage am plitude at the ratio of 1:33, the audible control device can be coupled to the transmitter in such 70 a way that at the lowest power of 20 w. which appears, grid current starts already. Furthermore the feedback of tube 3 can be so dimensioned that it still remains in the non-oscil lating state at low plate potentials. Finally, by 75 causing the tube 3 to oscillate at excessive poten tial, the constancy of the volume can be still further enhanced. I claim: 1. In a device for producing monitoring sig nals indicative of the operativeness of a trans mitter and for controlling the intensity of the sig nals produced, an oscillator including an electron discharge tube having electrodes connected in os cillation producing‘circuits, one of which circuits includes a source of potential su?icient to produce 10 oscillations in said tube and circuit, a second elec tron discharge device having its impedance con nected with said one of said circuits and source of potential to control the value of the potential applied by said circuit to one 01’ said electrodes, 15 said discharge device having a control grid and a circuit therefor including means for normally biasing said device to a point at which said sec ond device impedance is high and oscillations are cut off in said ?rst tube-and circuit, a resistance 20 connected with said control grid, rectifying means connected with said resistance for producing a potential therein opposing the normal potential applied to said control grid whereby oscillations may be produced in said oscillation generator tube 25 and circuits, means for impressing Wave energy to be monitored on said recti?er, and additional means for producing an additional potential drop which opposes said potential drop produced in said resistance when direct current ?ows in to the grid of said second named device. 2. In a system for producing indications of the presence of wave energy in the output of a trans mitter and maintaining said indications of sub stantially constant amplitude, an oscillator com prising an electron discharge device having its electrodes connected in oscillation producing cir cuits, tube impedance means and a source of po tential connected in one of said circuits of said device for charging an electrode of said device to a potential relative to its cathode at which said device is substantially cut off, and oscillations are not produced in said tube and circuits, recti?er means energized by and responsive to wave energy to produce a. controlling potential, means con necting said recti?er to said tube impedance means to control the impedance thereof, in the presence of said produced potential to increase said potential to which said electrode is charged relative to said cathode to cause said device and circuits to produce oscillations, additional means for producing a potential which opposes said ?rst named controlling potential in the presence of oscillations of substantial amplitude in said device and circuits, and an indicator coupled to said. device. 3. In a device for indicating the presence of 30 35 40 50 55 the wave energy sent out from a transmitter and for producing indications thereof of substantially constant amplitude in an indicator, an electron» 60 discharge device having an anode, a cathode, and a control grid connected in oscillation producing circuits, one of which includes a source of po tential, a second electron discharge device hav ing an anode and a cathode connected in said last. 65 named circuit, said second device having a con trol grid, a source of potential for normally bias ing said control grid negative relative to said cathode to increase the impedance of said second device to lower the potential on the electrodes of 70 said ?rst named device to prevent the production of oscillations in said ?rst named device and cir cuits, a recti?er having input electrodes excited by wave energy from the transmitter and having output electrodes connected with a resistance in 75 2,107,425 which a. potential drop of a value characteristic of the intensity of the wave energy of the trans mitter is produced, means for connecting said resistance to the control grid and cathode of said second named device in a sense to overcome said normal negative bias whereby oscillatory energy is produced in said ?rst named device and re sistive means in the control grid and cathode La 3 circuit of said second named device for produc— ing a potential in the presence of grid current therein which opposes the potential produced in the resistance connected with the output of said recti?er and an indicator coupled with said ?rst 5 device. CURT PRO'I'ZE.