US2857526A - Selective pulse-translating system - Google Patents

Description

E. B. GALTON SELECTIVE PULSE-TRANSLATING SYSTEM Oct. 21, 1958 Oct. 21, 1958 E. B. GALToN SELECTIVE PULSE-TRANSLATING SYSTEM 2 Sheets-Sheet 2 Filed Sept. 22, 1953 United States Patent O SELECTIVE PULSE-TRANSLATING SYSTEM Eugene B. Galton, East Meadow, N. Y., assignor to Hazeltine Research, Inc., Chicago, Ill., a corporation of Illinois Application September 22, 1953, Serial No. 381,580

6 Claims. (Cl. 307-885) GENERAL This invention relates to selective pulse-translating systems and, particularly, to selective pulse-translating systems of the type gated by signals developed by a generator of the transistor type.

Selective pulse-translating systems are useful in, for example, telemetering equipment which transmits and receives a plurality of distinct and unrelated sets of information by means of a single signal carrier. Such circuits are particularly useful in connection with guidedmissile and other applications where it is desired that maximum information be translated by a minimum amount of equipment. Such information, for example, may represent test-measurement data from various testing apparatus aboard the missile.

Telemetering equipment heretofore proposed has employed pulse-time modulation of the transmitter output signal to enable the various sets of information to be transmitted in time multiplex. For this purpose, the transmitting equipment has employed a plurality of gated signal-translating systems in order that the various information sources might individually be effective to control the modulation of the transmitter signal during successive time intervals.

Some selective pulse-translating systems previously proposed employ gated circuits controlled by signals developed lby gate-signal generators. Vacuum tubes have heretofore been employed in these circuits of the telemetering equipment, but vacuum-tube circuits are undesirable where size, weight, and power requirements must be held at a minimum. Another system heretofore proposed utilizes a transistor gate-signal generator for supplying gating signals to a gated circuit but requires a coupling condenser of cumbersome physical size to pass satisfactorily to the gated circuit only the pulsating component of a gating signal of long duration, for example, 2000 microseconds. Another previously proposed type of system utilizes a relatively bulky potentiometer to apply an adjustable direct-current signal to the gated circuit to compensate for undesired directcurrent variations applied thereto as a result of alterations of transistor parameters. Such alterations may be caused, for example, when commercially obtainable transsistors of the same type, which may undesirably have different parameters, are substituted in the gate- Signal generator as replacement parts.

It is an object of the invention, therefore, to provide a new and improved selective pulse-translating system which substantially avoids one or more of the foregoing limitations of such systems heretofore proposed.

lt is another object of the invention to provide a new and improved relatively simple transistor-type selective pulse-translating system of reduced bulk.

It is a further object of the invention to provide a new and improved transistor-type selective pulse-translating system which automatically compensates for -alterations of transistor parameters.

Patented Oct. 2li., 11.558

lCC

In accordance with the invention, a selective pulsetranslating system comprises a bias-'responsive gating device for selectively translating pulses applied thereto and bias-circuit means including a unidirectional-potential source for normally biasing the gating device to a nontranslating condition. The system further includes a gate-signal generator including a transistor having an output electrode directly coupled to the gating device through the bias-circuit means and having a unidirectional-potential level partially determined by the parameters of the transistor for supplying to the gating device recurrent gate signals to condition the gating device for conduction during gating intervals. The system additionally includes potential-variation-attenuating impedance means included in the bias-circuit means and including a potential divider coupled between the unidirectional-potential source and the output electrode and having a tapped portion directly coupled across the gating device for developing and applying to the gating device a bias potential representative of said'unidirectional-potential level but having substantially reduced magnitude variations relative thereto automatically to reduce variations in the duration of the gating intervals caused by alterations of the parameters of the transistor.

For a better understanding of the present invention, together with other and further objects thereof, reference is had to the following description taken in connection with the accompanying drawings, and its scope will be pointed out in the appended claims.

Referring to the drawings:

Fig. l is a circuit diagram, partly schematic, of a complete telemeter transmitter including a selective pulse-translating system in accordance with the present invention, and

Fig. 2 is a graph representing signals developed at various points of the Fig. 1 system and used in explaining the operation thereof.

Description of Fig. 1 telemeter transmitter Referring to Fig. l of the drawings, the telemeter transmitter there represented comprises a source of precisely spaced periodic pulses including, for example, a crystal oscillator 1G, an amplifier-limiter 11, and a triggered pulse generator 12., all of conventional construction and coupled in the order named. The transmitter further includes, for example, three similar time-modulation channels individually including unit groups 13- 18, inclusive, 25-30, inclusive, and 19-24, inclusive, for individually controlling the modulation of the transmitter ouput signal during successive time intervals. Gated signal-translating circuits 13, 25, and 19 of the individual channels, constructed in accordance with the invention in combination with units 14, 26, and 20, respectively, and more fully described hereinafter, are coupled to the triggered pulse generator 12.

In the first channel there are coupled to the gated signaltranslating circuit 13, in cascade, and in the order named, a triggered gate-signal generator 14, a linear sweep-signal generator 15, a comparing circuit 16, and a triggered pulse generator 17 which, except for the combination of units 13 and 14, may all be of conventional construction. Also coupled to the comparing circuit 16 is an information-signal source 1S.

The second channel comprising units 25-39, inclusive, contains units corresponding to those of the rst channel with the triggered gate-signal generator 26 shown in detail. The third channel comprising units 19-24, inclusive, also corresponds to the other channels with the gated signal-translating circuit 19 shown in detail. The output units of the time-modulation channels, namely, the triggered pulse generators 17, 29, and 23 are coupled through a pulse-power amplifier 31 to a radio-frequency oscillator 32 which, in turn, is coupled to an antenna sysytern 33, 34. Units 31 and 32 and the antenna system 33, 34 may also be of conventional construction.

The triggered gate-.signal generator of each tinge-modulation channel is also coupled to the gated signal-.translating circuit of the following channel, for example, the generator 14 of the iirst channel is coupled to the gated signal-translating circuit 2S of the second channel, generator 26 of then second channel is coupled to the gated signal-translating `circuit 19 of the third channel, and the generator 20 of the third channel is coupled to the gated signal-translating circuit 13 of the iirst channel to C0111- plete a ring-type system for selectively translating pulses in the various channels.

While three time-modulation channels have been shown for explanatory purposes, it will be understood'that a telemeter transmitter may contain any number of such channels. Also, as telemeter transmitters are often used in applications where space and size requirements are critical, it may be desirable that miniaturized circuitry including transistors ,and contact diodes be employed throughout the transmitter. The units 1(5-32, inclusive, with the exception of the combinations of gated signaltranslating circuits 13, 25, and 19 and the generators 14, 26, andv 20, respectivelyrmay be of conventional construction and operation so that a detailed description and explanation of the operation thereof are unnecessary herein. rlfhe comparing circuits 16, 22, and 28 may cornprise, for example,y diode comparators of the type shown onV page 3.38 of the text Waveforms by Chance et al., volume 19, Radiation Laboratory Series, McGraw- Hill, 1949.

Operation of Fig. 1v telemeter transmitter Considering briefly the general operation of the abovedescribed teleineter 'transmitter as a Whole, the crystal oscillator generates a sinusoidal signal having a frequency of, for'exarnple, 1400 cycles per second which is supplied to the amplifier-limiter 11 wherein the sinusoidal signal is amplified and shaped to develop a periodic signal of rectangular Wave form of corresponding frequency. This signal is supplied to the triggered pulse generator 12 which, yin synchronism with the individual waves thereof generates periodic pulses of, for example, one-microsecond duration and occurring at a repetition frequency of, for example, 1400 pulses per second. These precisely timed periodic pulses from the generator 12 are applied to the input units of the three time-modulation channels 13-18, 25-30, and 19-24- At any given instant, as, will be more fully explained, hereinafter, the input unit or gated signal-translating circuit 13, 25, or 19, of one ofthe three time-modulation channels is in a translating condition while those of the other channelsl are in a nontranslating condition. The condition of each channel changes with time so that the periodic pulses from the generator 12` are selectively and successively translated yby the gated circuits 13, 25, and 19 of the respective channels. 'ln this mannen considering the pulses in arbitrary groups of' three, every firstk pulse is translated by the gated circuit 13 ofthe first channel, every second pulse is translated by the gated' circuit 25 of the second channel, and'every third pulse is translated by the gated circuit 19 of the third channel.

. Assuming for the present that the gated circuit 13 is maintained in a translating condition by a gate signal supplied thereto from generator 20 while the gated circuits 19 and 25 are in a nontranslating condition, then an iniltial one of the pulses from the generator 12u will be translated by the gated circuit 13 tothe triggered gate-signal generator 14 to cause the generator 14 to generate a gate signal which is supplied to the linear-sweep-signal generator 15. This signaly serves to initiate-the generation in the sweep-signal generator-15. of/alinear-sweep signal of sawtooth Wave form which is supplied to the comparing circuit 16. Also supplied to the comparing circuit 16 is an information signal from the information-signal source 18 representing, for example, information derived from a measuring device, such as a temperaturerneasuring thermocouple, a strain gauge of an electrical type, etc.

The comparing circuit 16 compares the linear sweep signal with the information signal and when the magnitude of the sweep signal equals the magnitude of the information signal, the comparing circuit 16 supplies a time-modulated short-duration pulse to the triggered pulse generatorY 17. This pulse is time-modulated in accordance with the information signal because the time at which it occurs reiative to the initiation of the sweep signal is controlled by the magnitude of the information signal. yIn response to this pulse from the comparing circuit 16, the triggered pulse generator 17 generates a pulse of preferred magnitude and duration, for example one-half microsecond, which is supplied to the pulse-power amplifier 31 wherein it is amplified and supplied to the radio-frequency oscillator 32 for controlling the oscillations thereof. In response thereto, the radio-frequency oscillator 32 supplies a burst of radio-frequency energy to the antenna system 33, 34

Vfromwhich it is radiated.

signal supplied to the sweep generator 1S, the triggered gate-signal generator 14 also generates and supplies to the gated circuit 25 of the second channel another signal suitable for gating that circuit. This gate signal causes the gated circuit 25 to operate in a translating condition during a time interval satisfactory for allowing translation of a second of the crystal-controlled pulses supplied by the generator 12. The gated circuit.13 does not translate this second pulse and is no longer able to translate pulses because the gate signal previously supplied thereto by the p ulse generator 20 of the thirdv channel has. ceased being effective and the circuit has returned to its nontranslating condition.

The second pulse from the crystal-controlled generator 12, which is translated by the gated circuit 25, is supplied to the triggered gate-signal generator 26 wherein it causes generation of a pulse signal which is supplied to the sweepsignal generator 27 and a gate signal which is supplied to the gated circuit 19 of the third channel. The operation of the remainder of the second channel is analogous to that of the rst channel previously explained.

The gate signal from the generator 26 of the second channel enables the gated circuit 19 of the third channel to pass a third pulse from the crystal-controlled pulse generator 12. In the meantime, the gate signal supplied by the generator 14 of the iirst channel, to the gated circuit 25 of the second channel is no longer effective, thereby causing. that circuit to become nontranslating. The action of this third pulse from the crystal-controlled pulse generator 12 in the third time-modulation channel is similar to theoperation of the other two channels, a gate signal generated by the generator 20 being effective subsequently to enable the gated circuit 13l of the iirst channel to pass a fourth pulse from the pulse generator 12.

As explained, the crystal-controlled periodic pulses selectively translated by the various time-modulation channels cause the generation of corresponding pulses which are time-modulated in accordance with desired items of information and are supplied to the radiofrequency oscillator 32 through the pulse-power amplifier 31. The radio-frequency oscillator 32, which is successively controlled by pulses from the first, second, and third time-modulation channels, generates a transmitter signal with three sets of interlaced pulses individually .5 tepresentng the sets of information supplied by the three channels. In order to synchronize a receiver unit, one ofthe channels may have a fixed-magnitude signal supplied to the comparing circuit thereof by the corresponding information-signal source so that one set of pulses of the transmitted signal may be utilized for tirne-reference purposes.

.Description of selective pulse-translating system of Fig. 1

Referring again to Fig. l of the drawings, there is represented in detail a selective pulse-translating system constructed in accordance with the present invention and preferably comprising a gated signal-translating circuit 19 and a triggered gate-signal generator 26. The system comprises a bias-responsive gating device, for example, an electron-discharge contact diode 40 coupled to the crystal-controlled triggered pulse generator 12 by a coupling condenser 41, for selectively translating pulses applied thereto.

The system further includes bias-circuit means for normally biasing the gating device 40 to a nontranslating condition. The bias-circuit means preferably includes a source of unidirectional potential C connected across a potential divider comprising series-connected resistors 43 and 44 of unit 19 and a transistor emitter-base circuit including resistors 56 and 55 of unit 26. A coupling resistor 45 is connected between the junction of resistors 44 and 56 and the cathode of the gating device 40. The bias-circuit means also includes a coupling resistor 46 connected between a tap of the potential divider at the junction of resistors 43 and 44 and the anode of the gating device 4t). A pulsating-signal by-pass condenser 47 is connected across the resistor 43 and the source -C.

The system additionally includes circuit means comprising a coupling condenser 59 and pulse-input resistor 58 of the gate-signal generator 26 for supplying recurrent trigger pulses translated from the crystal-controlled pulse generator 12 by the gated circuit 25.

The gate-signal generator 26 includes a transistor 50 having a first output electrode or emitter 51, a second output electrode or collector 52, and a base electrode 53. The emitter and base serve as trigger-pulse-input electrodes. The generator 26 may comprise, for example, a rnonostable switching circuit having an emitter-current cutoff operating mode. The emitter 51 is directly coupled to the gating device 40 through the previously mentioned bias-circuit means including resistors 43, 44, 55, 56 and has a unidirectional-potential level partially determined by the parameters of the transistor 50 for supplying to the gating device 40 recurrent gate signals of, for example, saw-tooth wave form and negative polarity relative to the unidirectional-potential level to condition the gating device 40 for conduction during gating intervals which ordinarily have a duration dependent on the magnitude of the saw-tooth gate signals. By the expression to condition the gating device lfor conduction it iS meant that the gating device is capable of being conductive upon the application thereto of pulses to be translated. For some applications, the gating device may be rendered conductive by the gate signal alone or it may require the simultaneous application of the gate signal and a pulse to be translated to render the gating device conductive.

The resistor 55 is connected to the base 53 of the transistor 50 and is a preferred form of regenerative feedback impedance means common to both the emitter-base and'collector-base circuits while the resistor 56 is directly connected between the emitter 51 and the base 53 for allowing a small emitter-base current to flow while the transistor 50 is in an emitter-current cutoff condition. Also coupled to the emitter 51 are a condenser 57 which, together with the resistors 55 and 56 and a series-connected pulse-input resistor 58, is primarily determinative of the duration of the emitter-gate signal. The collector 6 52 is coupled to a source of collector potential C through a load resistor 60.

The selective pulse-translating system 19, 26 additionally comprises potential-variation-attenuating irnpedance means included in the bias-circuit means for developing and applying to the gating device 40 a bias potential representative of the unidirectional-potential level at the output electrode 51 but having substantially reduced magnitude variations relative thereto automatically to reduce variations in the duration of the gating intervals caused by alterations of the parameters of the transistor 50. This impedance means preferably includes a potential divider comprising the series-connected resistors 43 and 44 and having a tapped portion comprising resistor 44k directly coupled across the gating device 40 for developing and applying thereto a bias potential representative of the collector current during emitter-current cutoi intervals intervening the gating intervals. The resistor 43 preferably has a value greater than the resistor 44 and ordinarily approximately twice the value thereof.

Operation of selective pulse-translating system of Fig. 1

Considering the operation of the selective pulse-translating system 19, 26 just described, as is well known in Vthe art, gate-signal generators comprising transistors may be .constructed to have one or more stable operating modes and one or more unstable operating modes including a negative-resistance operating mode. These modes are ordinarily referred to in terms of operating potentials and currents of the transistor electrodes. One stable mode constitutes a low-conduction or emitter-current cutoff operating mode while one unstable mode constitutes a high-conduction emitter-current and collectorcurrent saturation operating mode.

The transistor gate-signal generator 26 preferably has a steady-state operating condition, during intervals between trigger pulses from the gated circuit 25, in the cutolf mode because of the negative emitter-base bias developed across the resistor 56. While the generator 26 is in its steady-state operating condition, the potentialsupply source -C causes current to flow through resistors 55 and 56 of the generator circuit 26 and through resistors 43 and 44 of the gated circuit 19. As this current flows through the resistor 44 in the gated circuit 19, it develops a bias-potential component thereacross for maintaining the diode 40 in a normally nontranslating condition. The negative unidirectional-potential reference level at the emitter 51 is represented by curve A of Fig. 2 while the average potential level at the junction of resistors 43 and 44 is represented by curve B of Fig. 2. During the intervals between pulses supplied by the generator 12, the potential represented by curve B is also the potential level at the anode of the gating device 40 and during intervals between gate signals supplied by the generator 26, the potential represented by curve A is also the potential level at the cathode of the gating device 40. The'difference between the potentials represented by curves A and B, therefore, represents the reference operating bias of the diode 40.

At a time to, one of the crystal-controlled pulses from the generator l2 is translated by the gated circuit 25 and applied with positive polarity through the coupling condenser 59 to the emitter-base circuit of the transistor 50 overcoming the negative emitter-base cuto bias. This pulse, therefore, causes increasing emitter-to-base current flow ofthe transistor 50, thereby causing the generator 26 to switch to its unstable negative-resistance operating mode and, by virtue of current amplification within the transistor 50 and regenerative feed-back action afforded by the base resistor 55, both lthe emitter-base current flow and base-collector current ow increase rapidly. This results in an almost instantaneous switch of the generator to the saturation operating mode when the trigger pulse from the generator 12 is supplied. As this occurs, both the emitter 51 and. base 5,3 become more negative,l and the condenser 57 in the emitten circuit begins to charge negatively through the emitter-base circuit including,- resistors 55', 56, and'58;while the. emitter-basecurrent iiow diminishes as the emitter-base bias becomes moreV negative until the emitter-base current value is less than that required to maintain operation in the saturation mode. Atfthis point, the generator re-enters the unstable negative-resistance mode and' almost vinstantaneously switches back to the cut-oti operating mode. Subsequently, as a consequence of the discharge of thecondenser 57 through resistors 55, 6, SSat a rate-greater than the rate at which negative charge is. being supplied thereto through resistors 43, 44 by the potential source -..C, the initialV steadystate operating condition is attained.

During the` operation just, discussed, the emitter potential becomes. more negative. relatively rapidly as a result ofthe charging of thecondenser 57 through the emitter-base circuit of the transistor 50, After the generator 26 returnsl to its cutoffl operating mode, the emitter potential slowly becomes less negative as the condenser 57 discharges through the resistors 55, 56, and 58. There is thus generated at the emitter of the transistor ay potential of saw-tooth wave form which serves as the gate signal for the gated circuit 19. This savvtooth potential is represented by curve C of Fig'Z, commencing at time to and also represents the gate-signal potential variation at the cathode` of the diode 40.

The potential, at theI anode of thediode 40, represented by curve D of Fig. 2, corresponds essentially to the potential level B with the crystal-controlled pulses supplied by the generator 1-2f through the coupling condenser 41 superimposed thereon. The peak magnitude of the crystal-controlled pulses of curve D representsl a potential level as shown` byy curve F` of Fig. 2- which, together with the san/tooth gate signal representedk by curve C, determines thev translating or gating intervals. At a time r1, when the saw-tooth gate signal represented by Curve C becomes more negative than this peak-pulse potential level F, the diode 40 is conditioned for con duction. When this occurs, the gated circuit 19 is able to translate portions of the positive pulses, represented by curve D, applied thereto by thepulse generator 12. This gating interval` during which the saw-tooth gate signal is more negative than the potential level F is of sufficient duration to allow translation of the next; pulse supplied by the crystal-controlled pulse generator 12 which occurs at time t2. At the time f3, the saw-tooth gate signal decreases to a Value equal to the potential level F so that the diode 40 is thereafter returned to a nontranslating condition and the gated circuit 19 no longer translates pulses until the occurrence of the next translating interval beginning at a time t8.

Curve E of Fig. 2 represents the potential at the cathode of the diode 40 which is applied to the output terminals. of the gated' circuit 19,. This potential corresponds to the saw-tooth gate signal represented by curve C and supplied by the generator 26 with the portions oi" the pulses represented by curve D which are more positive than the saw-tooth gate signal during gating intervals superimposed thereon. It will be understood, of course, that the triggered gate-signal generator 20 preferably includes an input resistor-coupling condenser network similar to the resistor- condenser network 58, 59 oi' unit 26 for translating only the short-duration pulses of curve E to the remainder of the generator.

The advantages of the presentl selective pulse-translating system will be apparent when thel eifects of alterations in the parameters of they transistor 50 are considered. Alterations. in the transistor parameters occurring, for example, when lcommercially obtainable transistors are substituted as replacement parts, cause variations in the cutoi mode collectorV current, thus causing variations in the potential developed across the feed-back resistor 55. These potential variations are suppliedy through the resistor 56 to the gate-signal-output or emitter electrode 51,V eausingvariationsinthe unidirectional-potential level, as represented,.byA curvef A thereof. As a result,` the current iiowing throughthe potential-divider resistors 43 and 441 varies and hence', the bias potential of the diode 40 exhibitsa small portion of the-variation therein.

Assume, for example, that a parameter alteration of the transistor 50 causes the cutoff mode-collector current to increase. This in turn causes the potential level at the base 5,3,- andi hencey the unidirectionallpotential reference level aty theernitter 51 to; become more negative. The current. fiowing throughthe potential-divider resistors consequently decreases. This current decrease shifts both the cathode and anode reference-potential levels of the diode 40, representedby, curves, A andB of Fig. 2, ref spectively, to` values, represented by curves4 A and Bf of Fig.v 2 becauseof the decreased average potential drops across resistors ttandV 4,4; Thedierencein levels represented by curves B and B is smaller thanthedif ference iny levels represented by. curvesvA andA because anyy change of,- emitter-potentialv level is attenuated by potentialydividing;resistors;43 and 44. The shift in the emitter-potential level represented by curve A' causes a corresponding shiftin the saw-tooth gate signal, as indicated byv4 cur-ve C of Fig. 2; The shift in the anode reference-potential level of thel diode 40 represented, by curve B` causes a.v corresponding shift in the pulses, as indicated by-curveDf, and hence the lpeak-pulse potential level, as represented bycurveFy of Fig. 2.

The decreased average operatingbias.. potential develv opedacross the potential-divider, resistor 44, represented -by the reduced` diferencetbetween the potential levels,

at. the emittery 51- and the junction, ofthe resistorsl 43 Vand 44, as representedg by.,- curves, A', andy B', causes a slight increase inthe'translating interval of the diode 4.0 asrepresented by the time-,difference t3-,t4 of Fig. 2, the leading edge of; thel gate signalhaving negligible `change in the translating interval associated therewith because of its;Y relatively shortV risetime. The reduction of the bias potential-of the diodel 40 and the correspond ,ing time; difference z3-t4V has been exaggerated in the drawing for'the sake of clarity. With proper-selection ofcircuit` parameters, this. increase in the translating interval is suiiiciently slight to,prevent translation of an undesired pulse.V l'l-heincrease orl change in translating interval-is slight becausethe potential divider 43, 44 :has, in eiiect, attenuated the-potentialvariation supplied to the diode 40 as aresultcf the cutoff mode-collector current alteration, therebyl causing the bias potential to have substantially reduced magnitude variations.

ln selective pulse-translating systemsof a type heretof fore` proposed,` thereference-potential level supplied t0 the anode of the gated bias-responsive pulse-translating diode thereof remains ata predetermined value and does not vary in response to cutoi mode-collectorl current variations. Thus, thetranslating interval of the diode may increase by an interval, corresponding, for example, to the time difference tS--tlV of'Fig. 2,l sufliciently great to allow translation of an undesired pulse, corresponding, for example, to that occurring at time t5 of Fig.l 2.l In a system constructedfiin accordance with the presentinvention, however,` the anode reference-potential level, represented by curve B', as Well as the cathode potential level, represented by A', of the diode 40 becomes more negative in response, to'V the increase in cutoff mode,- collector current, thus. compensating for any variation thereof andthereby automatically reducing variations in the duration ofthe gatingiortranslating intervals caused by alterations of they parameters of the transistor.

While applicant does not intend to limit the invention to any particular designeconstants, the following Values have been found suitable for a selective pulse-translating system Qonstructed inaccordance with the presentV inf venti@ and partsularlvtusefultinz e` telemeter transmitter having eight 'time-modulation channels similar to the three shown in Fig. 1: Y

t 10 partially determined by the parameters of said transistor for supplying to said gating device recurrent gate signals to condition said gating device for conduction during gating intervals; and potential-variation-attenuating impedance means included in said bias-circuit means and including a potential divider coupled between said unidirectionalpotential source and said output electrode and having a tapped .portion directly coupled across said gating device for developing and applying to said gating device a bias potential representative of said unidirectional-potential level but having substantially reduced magnitude variations relative thereto automatically to reduce variations in the duration of said gating interv-als caused by alterations of the parameters of said transistor.

3. A selective pulse-translating system comprising: a

y bias-responsive gating device for selectively translating v From the foregoing description, it will be apparent that v a selective pulse-translating system constructed in accordance with the present invention is a new and improved transistor-type selective pulse-translating system which automatically compensates forA alterations of transistor parameters and avoids use of bulky circuit components, such as potentiometers and large coupling condensers, employed in systems of this type heretofore proposed.

While there has been described what is at present considered to be the preferred embodiment of this invention, it will be obvious to those skilled in the art that various changes and modications may be made therein without departing from the invention,` and it is, therefore, aimed to cover all such changes and modications as fall within the true spirit and scope of the invention.

What is claimed is:

1. A selective pulse-translating system comprising: a bias-responsive gating diode for selectively translating pulses applied thereto; bias-circuit means including a unidirectional potential source for normally biasing said diode to aA nontranslating condition; circuit means for supplying recurrent trigger signals; a monostable switching circuit coupled to said trigger-signal-supply means and including a transistor having an emitter, a base, and a collector and including ernitter-base and collector-base circuits having a common feed-back impedance means directly coupled to said emitter, said transistor having an emitter-current cutoff operating mode and said emitter being directly coupled to one side of said diode through said bias-circuit means and having a unidirectional-potential level partially determined by the parameters of said transistor for supplying to said diode recurrent gate signals of saw-tooth wave form and negative polarity relative to said unidirectional-potential level to condition said diode for conduction during gating intervals of duration dependent on the magnitude of said saw-tooth gate signals; and potential-variation-attenuating impedance means included in said bias-circuit means and including a potential divider coupled between said unidirectional-potential source and said emitter and having a tapped portion directly coupled across said diode for developing and applying thereto a bias potential representative of said collector current during emitter-current cutoff intervals intervening said gating intervals and representative of said unidirectional-potential level but having substantially reduced magnitude variations relative thereto automatically to reduce variations in the duration of said gating intervals caused by alterations of the parameters of said transistor.

2. A selective pulse-translating system comprising: a bias-responsive gating device for selectively translating pulses applied thereto; bias-circuit means including a unidirectional-potential source for normally biasing said gating device to a nontranslating condition; a gate-signal generator including a transistor having an output electrode directly coupled to said gating device through said biascircuit means and having a unidirectional-potential level pulses applied thereto; bias-circuit means including a unidirectional-potential source for normally biasing said gating device to a nontranslating condition; circuit means for supplying recurrent trigger signals; a monostable switching circuit coupled to said trigger-signal-supply means and including a transistor having an output electrode directly coupled'to said gating device through said bias-circuit means and having a unidirectional-potential level partially determined by the parameters of said transistor for supplying to said gating device recurrent gate signals to condition said gating device for conduction during gating intervals; and potential-variation-attenuating impedance means included in said bias-circuit means and including a potential divider coupled between said unidirectionalpotential source and said output electrode and having a tapped portion directly coupled across said gating device for developing and applying to said gating device a bias potential representative of said unidirectional-potential level but having substantially reduced magnitude variations relative thereto automatically to reduce variations in the duration of said gating intervals caused by alterations of the parameters of said transistor.

4. A selective pulse-translating system comprising: a bias-responsive gating device for selectively translating pulses applied thereto; bias-circuit means including a unidirectional-potential source for normally biasing said gating device to a nontranslating condition; a saw-tooth gate- Signal generator including a transistor having an output electrode directly coupled to said gating device through said bias-circuit means and having a unidirectionalpotential level partially determined by the parameters of said transistor for supplying to said gating device recurrent gate signals of saw-tooth wave form and negative polarity relative to said unidirectional-potential level to condition said gating device for conduction during gating intervals of duration dependent on the magnitude of said saw-tooth gate signals; and potential-variation-attenuating impedance means included in said bias-circuit means and including a potential divider coupled between said unidirectional-potential source and said output electrode and having a tapped portion directly coupled across said gating device for developing and applying to said gating device a bias potential representative of said unidirectionalpotential level but having substantially reduced magnitude variations relative thereto automatically to reduce variations in the duration of said gating intervals caused by alterations of the parameters of said transistor.

5. A selective pulse-translating system comprising: a bias-responsive gating diode for selectively translating pulses applied thereto; bias-circuit means including a unidirectional-potential source for normally biasing said diode to a nontranslatory condition; a gate-signal generator including a transistor having an output electrode directly coupled to one electrode of said diode through said bias-circuit means and having a unidirectional-potential level partially determined by the parameters of said transistor for supplying to said diode recurrent gate signals to condition said diode for conduction during gating intervals; and potential-variation-attenuating impedance means www included inA said bias-circuitA means and including apotential. divider coupled between said. unidirectionalpotential-,source and said output electrode andhaving a tapped portion directly coupled across saidy gating' diode for supplying thereto a potential representative ofA said unidirectional-potential level automatically to reduce. variations in the duration of said gating intervals caused by alterations of the parameters of said transistor. v

y6r, A selectivev pulse-translating system comprising: a bias-responsive gating device for selectively translating pulses applied thereto; bias-circuit means including a unidirectionalfpotential source for, normally biasing said gating device` to avnontr'ansl-ating condition; a gate-signal` generator including a transistor having an emitter, a base,;and a collector and including emitter-base andY collector-base circuits having a common feed-back impedance means di.- rectly coupled tor said emitter, said transistor having an emitter-current cutoff operating mode and said emitter being directly coupled to said gating device through said bias-circuit means and having a unidirectional-potential level partially determined by the parameters of said transistorfor supplying to said gating device recurrent gate signals to condition said gating device for conduction dur- References Citedin the ile of this patent UNITED STATES PATENTS B-1iss Jury 4, 195o 2,616,960 Dell et al. Nov. 4, 1952 2,628,310V Wood Feb. 10, 1953 2,665,845 Trent Jan. 1'2, 1954 2,679,594 Fromm May 25, 1'954 2,724,780 Harris Nov. 22, 1955

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