US2986704A - Function generator - Google Patents

Function generator Download PDF

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US2986704A
US2986704A US594839A US59483956A US2986704A US 2986704 A US2986704 A US 2986704A US 594839 A US594839 A US 594839A US 59483956 A US59483956 A US 59483956A US 2986704 A US2986704 A US 2986704A
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rate
network
pulses
current
function
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Roland M Lichtenstein
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General Electric Co
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General Electric Co
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Priority to US594839A priority patent/US2986704A/en
Priority to FR1187745D priority patent/FR1187745A/fr
Priority to GB20301/57A priority patent/GB844872A/en
Priority to DE19571252800D priority patent/DE1252800B/de
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    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03K—PULSE TECHNIQUE
    • H03K21/00—Details of pulse counters or frequency dividers
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R23/00—Arrangements for measuring frequencies; Arrangements for analysing frequency spectra
    • G01R23/02—Arrangements for measuring frequency, e.g. pulse repetition rate; Arrangements for measuring period of current or voltage
    • G01R23/06—Arrangements for measuring frequency, e.g. pulse repetition rate; Arrangements for measuring period of current or voltage by converting frequency into an amplitude of current or voltage
    • G01R23/09—Arrangements for measuring frequency, e.g. pulse repetition rate; Arrangements for measuring period of current or voltage by converting frequency into an amplitude of current or voltage using analogue integrators, e.g. capacitors establishing a mean value by balance of input signals and defined discharge signals or leakage
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R23/00—Arrangements for measuring frequencies; Arrangements for analysing frequency spectra
    • G01R23/02—Arrangements for measuring frequency, e.g. pulse repetition rate; Arrangements for measuring period of current or voltage
    • G01R23/10—Arrangements for measuring frequency, e.g. pulse repetition rate; Arrangements for measuring period of current or voltage by converting frequency into a train of pulses, which are then counted, i.e. converting the signal into a square wave
    • G—PHYSICS
    • G06—COMPUTING OR CALCULATING; COUNTING
    • G06G—ANALOGUE COMPUTERS
    • G06G7/00—Devices in which the computing operation is performed by varying electric or magnetic quantities
    • G06G7/12—Arrangements for performing computing operations, e.g. operational amplifiers
    • G06G7/26—Arbitrary function generators
    • G06G7/28—Arbitrary function generators for synthesising functions by piecewise approximation
    • G—PHYSICS
    • G06—COMPUTING OR CALCULATING; COUNTING
    • G06G—ANALOGUE COMPUTERS
    • G06G7/00—Devices in which the computing operation is performed by varying electric or magnetic quantities
    • G06G7/48—Analogue computers for specific processes, systems or devices, e.g. simulators
    • G06G7/62—Analogue computers for specific processes, systems or devices, e.g. simulators for electric systems or apparatus
    • G06G7/625—Analogue computers for specific processes, systems or devices, e.g. simulators for electric systems or apparatus for filters; for delay lines
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03K—PULSE TECHNIQUE
    • H03K9/00—Demodulating pulses which have been modulated with a continuously-variable signal
    • H03K9/06—Demodulating pulses which have been modulated with a continuously-variable signal of frequency- or rate-modulated pulses

Definitions

  • This invention relates to a pulse rate measuring apparatus which produces a signal which is a desired function of input pulse rate.
  • this invention relates to a class of function generators utilizing this principle that converts an input current into an output current which is some prescribed function of the input current.
  • time series In many engineering, scientific, and industrial areas, it becomes necessary to measure the characteristic parameters of a time series of events. In practice, many different types of time series may occur. However, the simplest and most important of these are the periodic series and the stationary random series. In the periodic series, the time interval between any two consecutive events has the same fixed duration T. The quantity is called the rate.
  • a random series is characterized by the following property: The probability that an event occurs in the short time interval t-t+dt is rdt, Where r is a characteristic parameter of the series similarly called the rate. If the rate for a random series is a constant, the random series is called stationary.
  • a stationary random series there occur, on the average, rt events during a time interval of duration t, or r events per unit time.
  • the rate r may depend on time, in which case the random series is, technically, no longer stationary.
  • the random series may be regarded as stationary for all practical purposes, as long as the rate does not vary too rapidly with time, i.e., as long as r a! is small as compared to r.
  • random time series appear and are quite significant. That is, the radiation is detected by means of counters, such as pulse chambers, proportional counters, or scintillation counters, which produce individual output pulses in response to the radiation intensity representing the events in the time series.
  • counters such as pulse chambers, proportional counters, or scintillation counters, which produce individual output pulses in response to the radiation intensity representing the events in the time series.
  • the random series is stationary.
  • the random series may be regarded as stationary for all practical purposes if the rate does not vary too rapidly. In practice, this condition is often fulfilled and, as a consequence, the stationary random series is of practical importance in nuclear instrumentation.
  • a further object of this invention is to provide a count ing rate device with a logarithmic output which does not contain any unstable elements. 7
  • Yet another object of this invention is to provides network having a transfer admittance which is a specified function of a complex frequency which represents aura put pulse rate.
  • l 5 Still another object of this invention is to provide a general class of function generators which produce an output current which is a desired function of current.
  • Yet another object of this invention is to provide ail apparatus which provides a pulse output, the repetition rate of which is a desired function of an input current.
  • a net-work is provid which is constructed of simple components such asjgresistors, capacitances, and induotances.
  • the network is so constructed, according to network synthesis, principles, that a current is caused to flow when randominput pulses are applied thereto which is a desired function of the rate of occurrence of the pulses. That is, the transferee; mittance of the network is made a desired function of it complex frequency, in this case representing twice t e pulse rate, so that a current flows which depends on the pulse rate in the same manner as the admittance of the network depends on the complex frequency, rinspecifig, function depends on the design of the network.
  • an output current is produced which a desiredfunction of the'inputpulse rate.
  • an anti-counting rate device By cascading an anti-counting rate device and a counting rate apparatus, it is possible to produce a function generator which converts an input current into an output current which is a given desired function of the input current. That is, the repetition rate of the pulses from an anti-counting rate apparatus may be made a desired function of an input current by controlling the nature of the network within this apparatus. These pulses are then applied to the input of a counting rate apparatus which supplies an output current which is a desired function of this input repetition rate by controlling the type of network within this apparatus. Thus, the output current can be made a desired function of the input current.
  • Fig. '1 is a schematic diagram of a network embodying the principles of this invention and constructed in accordance therewith;
  • FIG. 2 is a schematic circuit diagram of a counting rate apparatus constructed in accordance with the invention and which embodies a network such as is shown in Fig. 1;
  • Figs. 3a and 3b are block diagrams of the showing of Fig. 2 and is utilized to show the underlying theoretica considerations of the circuit of Fig. 2;
  • Figs. 4a, 4b and 4c are a series of graphs of the voltage and current wave forms appearing in different portions of the circuit shown in Fig. 3;
  • Fig. 5 is a showing, partially in block diagram form, of anti-counting rate apparatus constructed in accordance with this invention.
  • Fig. 6 is a showing, also partially in block diagram form, of a function generator constructed in accordance with this invention and utilizing constructions such as shown in Figs. 1 and 2 as portions thereof.
  • a network which is characterized by the fact that it will transform input pulses into an output current which is a function of the rate of occurrence of the input pulses.
  • the relative magnitudes of the network forming components are such that the transfer admittance of the network is a function of the complex frequency which, in the instant case, is the pulse rate of the input pulses.
  • the transfer admittance of a network may be defined m the'following manner: if a two-terminal-pair network has an input voltage applied to one pair of terminals,
  • Fig. 1 shows a network 1 having a pair of input terminals 2 and a pair of output terminals 3.
  • the network consists of n parallel branches, which for the sake of simplicity and for illustrative purposes, have been shown as branches 4, 5, 6, 7, and 8.
  • Each branch consists of a series connected resistance-capacitance combination such as R4C4, R5C5, etc.
  • the network is characterized by a transfer admittance which is a desired function of the complex frequency where the complex frequency represents the rate of occurrence of the input pulses applied between the terminals 2, so that a current flows in the output terminals 3 and through a load circuit which is related to the rate of occurrence of the pulses in the same manner as the transfer admittance.
  • the network 1 may be described by the fact that the time average T of the output current depends on the rate of occurrence of the input pulses. That is,
  • the precise functional relationship of the time average of the output current T and the rate of occurrence r of the pulses may be controlled by controlling the relative magnitude of the resistive and capacitive components of the network.
  • an output current which, for example, is a logarithmic function of the input pulse rate
  • a network is synthesized in which the resistive and capacitive elements of the various branches are related according to the equation:
  • R, T are design parameters, and a is a dimensionless number assumed to be greater than unity. Dimensions of R and T are those of a resistance and time respec tively. The exact manner in which these formulae for the resistance and capacitance elements are derived will be shown in detail later when a rigorous mathematical analysis will be disclosed. However, it must be pointed out that the synthesizing of networks having desired admittance characteristics are techniques well known to those skilled in the art, and reference is made to Symposium on Modern Network Synthesis, Polytechnic Institute of Brooklyn, New York (1952), which provides an excellent review of the techniques and principles of network synthesis.
  • the counting rate apparatus of Fig. 2 comprises a network which is characterized by a transferadmittance which is a desired function of the complex frequency where this complex frequency represents apulse rate, an electronic switch means which is adapted to be switched successively to positive and negative states by successive input pulses representing the events in a random time series, and unidirectional conducting means coupled to the output of the network whereby a current flows which is a desired function of the rate of occurrence of the input pulses.
  • the switch means consists of a bi-stable multivibrator 20 which, as is well known, possesses two conditions of stable equilibrium.
  • the bi-stable device 20 consists of two cross-coupled electron discharge devices 21 and 22.
  • the electron discharge device 21 is a vacuum triode which has its anode connected to a source of energizing voltage with respect to ground B-+ through an anode resistance 23.
  • the cathode is connected to a source of reference potential such as ground through a cathode resistance 25 which is by-passed for AC. by means of a capacitance 26.
  • the electron discharge device 22 has its anode connected to a source of voltage 8+ through an anode resistance 24 while its cathode is connected to a source of reference potential such as ground by means of the same cathode resistance 25.
  • the cathodes of the two electron discharge devices are connected through the common cathode resistance 25 and the bypass capacitance 26 to provide a suitable cathode bias for the grids of the electron discharge devices.
  • the anode of the discharge device 21 is coupled to the control grid of discharge device 22 through a parallel resistance capacitance circuit 29 and to ground through the grid leak resistance 30.
  • the anode of discharge device 22 is coupled to the control grid of the electron discharge device 21 through a parallel resistance capacitance circuit 27 and then to ground through the grid leak resistance 28.
  • Circuits of this type are char- .acterized :by the :fact that they possess two conditions of stable equilibrium. One of these conditions is when the discharge device 21 is conducting and the discharge device 22 is non-conducting; and the other when discharge device 22 is conducting and discharge device 21 is cut off. The circuit remains in one or the other of these two conditions with no change until some action occurs which causes the non-conducting tube to conduct.
  • a double diode 31 mounted in a single envelope provides the means for injecting triggering pulses into the circuit.
  • the diode 31 contains a common cathode member 32 connected to an input terminal 35 to which are applied a series of negative pulses representing the random events in the time series whose rate of counting is to be measured.
  • a pair of diode anode members 33 and 34 are connected respectively to the anodes of the discharge devices 21 and 22.
  • negative pulses appearing at the input terminals 35 are applied through the diodes 31 to the anode of the non-conducting tube, since the anode of the non-conducting tube and that of the diode connected to it is at a high positive potential relative to a cathode 32 of the diode 31, thus permitting conduction of the diode.
  • the negative pulse applied to the anode of the non-conducting tube is applied to the grid of the conducting tube through the capacitance element of one of the parallel resistance-capacitance circuits 27 and 29.
  • the conducting tube is thus cut off, by virtue of the negative pulse applied to its control grid, causing its anode voltage to rise thereby raising the grid voltage of the formerly non-conducting tube, causing to to become conductive.
  • This condition then continues until the next negative-input pulse comes in at which time the equilibrium condition will again be reversed in'a similar fashion.
  • the electron discharge devices 21 and 22 will be switched successively to conducting and non-conducting conditions by successive input pulses.
  • the anode voltage of the electron discharge device 22 will successively be switched to a positive condition when the discharge is not conducting and to a negative state when it is conducting.
  • a network 10 of the type shown in Fig. 1 which consists of a number of parallel branches, 11, 12, -16- n, each of which consists of a series connected resistance capacitance combination. Coupled to the output of the network 10 are a pair of oppositely poled rectifiers 36 and 37 and a meter 38 to provide a measure of the current iiowing through the network 10 and the rectifiers.
  • the network 10, as was pointed out previously, may be constructed to have a transfer admittance which is a 1 I 7 function of the complex frequency which in this instance i represents a pulse rate. Thus, there flows in the output .of the network a current which is a desired .function of the input pulse rate.
  • Fig. 3a and 3b a generalized form of the apparatus of Fig. 2 is shown as Figs. 3a and 3b and will be utilized in establishing the theoretical basis.
  • the circuit of Fig. 3 consists of:
  • a stable linear network 40 active or passive, including two terminal pairs of suitable transfer admittance e
  • Two synchronized single-pole, double-throw switches 41 and 44 both thrown either to the upper or lower position simultaneously. These switches are actuated in such a fashion that they change position whenever an event in time series occurs.
  • the network shall have a transfer admittance Y(s), where s is a complex frequency.
  • Y(s) transfer admittance
  • the position of the switches may be described by a switching function (t), which assumes the value plus one when the switches are in the plus position, and the value minus one when the switches are in the minus position.
  • a switching function (t)
  • Fig. 4c An example of such switching function is illustrated in Fig. 4c.
  • the steps in the switching function of course. coincide with the events of the time series.
  • Equation 13 u t(t) 2 Y(s)e form-)4
  • Equation 17 The integral over '1' that occurs in Equation 17 may be transformed as follows:
  • Equation 26 (T) -(n-Zr) rd VG-27)
  • Equation 27 results in the following form of the equation
  • transforms the equation into Equation 30 is the key formula on which many practical devices may be based. This equation states that the ensemble average of the current in lead B of the deviceshown in. Fig.
  • the meaning of the term large values of the time t is that transients that are caused by the switching on of the generators (not transients that are caused by the switching, since these are essentially to the operation) have had time to die out.
  • a condition for constructing a measuring apparatus having these characteristics is that the input pulses to the network are alternately positive and negative.
  • the transfer admittance of the network is a function of a complex frequency which, in the instant case, represents a pulse rate. Consequently, if the network is constructed to have a transfer admittance which is a desired and specific function of the complex frequency, it will produce an output current which in a similar fashion is functionally related to the input pulse rate.
  • the right hand switch 44 of Fig. 3 may be replaced by a pair of oppositely poled diodes such as are shown in the specific embodiment of Fig. 2.
  • the left hand switch of Fig. 3 may be replaced by an electronic switch, such as a bi-stable multivibrator, which is actuated by pulses coincident with the events in the time series and function to switch the equilibrium condition alternately to a positive and negative state.
  • the generalized apparatus of Fig. 3 may be replaced by simple electronic equipment to produce a counting rate apparatus, such as shown in Fig. 2, embodying the instant invention.
  • Equation 35 a network must be synthesized which has a transfer admittance Y(s) as a function of the complex frequency s as given by the equation Y(s log (1+%') 37
  • This class of functions has the property that g(z) may be expressed in the form where sc 0 and. h(:c) 0 for 2:22; (40) Obviously g(z) must fulfill certain conditions so as to be expressed in the form disclosed in Equation 40.
  • the necessary first step is to find the function h(x). This may be done by means of well-known procedures utilized in the theory of analytical functions (the transfer admittances are analytical functions of the complex frequency). Starting with the Cauchy integral form where the integration contour enclosures, in a counterclockwise direction, the point z but no singularity of an I If the functions g(z) are restricted to a type whose only singularity lies on the negative real axis to the left of some point Z 0, the following integration contour may be used advantageously.
  • Equation 41 assumes the form 1 z 1 3? lbelow Where ()-]above:
  • Equation 48 upon substitution of the proper functions therein, takes the form A (2+ 2) z i l? 1+2 It" is obvious, once the. substitution is made, that Equation 48 devolves into the desirable form exhibiting logarithmic characteristics.
  • the integral of' Equation 50 maybe approximated" by a sum, which thus permits the obtaining of an approximate value Y s) for the transfer admittance.
  • the equation. for; the. approximate: value Y fi) is 2 log a 2 8 T 2a R s T+2+2a 2+2a or, rewriting the above equation, it takes the form
  • This equation. may then be rewritten. in. the following. form then with the terms R andC being defined by the following equations Equation 53 shows that the transfer admittance is the admittance of a circuit with an infinite number of parallel branches, n being the order number of the branches,
  • branch n consisting of a resistor with resistance R
  • counting rate meters with logarithmic outputs may be designed according to a wide range of specification.
  • counting rate devices may be designed having output currents which are a specified function of an input pulse rate.
  • a network was synthesized for use in such a device which provides an output current which is a logarithmic function of the input pulse rate. It must be realized, however, that many other networks having functional relationships other than logarithmic may be synthesized for use in devices of this type.
  • Equation 35 there must be synthesized a network having a transfer admittance defined by the equation
  • This network will also be constituted of a number of parallel branches, each of which comprises series connected resistance-capacitance combination.
  • the function g(z), as defined in relation to Equation 38 takes the form
  • the branch point 2 is now Equation 46 may now be utilized to find the functions g above and below, thus
  • the term Zu may be :determined
  • Equation 67 takes the form sT sT+a Y(s) R T a dn (68)
  • Equation 70 shows that the transfer admittance is the admittance of a circuit with an infinite number ofparallel branches, n being the order number of the branches, with branch n consisting of a resistor with ,a resistance R and a capacitor with a capacitance q connected ,in
  • Equation 71 which defined the magnitude of the resistance and capacitance components is utilized in designing the various components of the network.
  • the parameter a therein is a dimensionless number which is greater than and less than 1, while R is a design parameter.
  • many other types of networks may be synthesized in order to produce a counting rate device which produces an output signal which is a desired function of the input pulse repetition rate.
  • the mathematical analysis principle of this invention has been based on a repetition rate of the input pulse that is random.
  • the apparatus designed by operation with random series may be utilized as well for other time series, such as the periodic.
  • the current produced by the application of a periodic series will exceed that produced by the application of a random series.
  • the excess becomes constant and may, therefore, be cornpensated for by means of calibration techniques. Consequently, for higher counting rates, the apparatus here disclosed may be utilized with periodic time series, as well as with stationary random series.
  • any counting rate apparatus may be converted into an anti-counting rate apparatus. That is, a device that converts a current into a pulse rate having a desired functional relationship to the current.
  • an anti-counting rate device may be constructed by combining a source of variable pulses and a counting rate device.
  • a pulse source 53 having a variable pulse rate may be any one of the many well known types which have a variable pulse repetition rate.
  • One type of pulse source which may be advantageously utilized in this circuit is the random pulse generator of the radiation detector type. That is, a radiation detector of the proportional counter or scintillation type is positioned in a constant magnitude radiation field. The output of the detector is coupled to a discriminating tube, which functions to control the number of pulses per unit time passed to its output circuit.
  • the discriminating circuit includes a grid biased triode, with the magnitude of the grid bias determining the number of pulses per unit time which are passed. By controlling the magnitude of this grid bias in response to a control signal, it is possible, therefore, to vary the number of pulses per unit time produced by this pulse producing circuit.
  • Patent No. 2,662,188 issued to K. C. Crumrine et al. for a typical showing of a circuit of this type.
  • the output from the pulse source 53 is connected to an output terminal 52 and to the input of a pulse rate measuring apparatus 54 of the type illustrated in Fig. 2.
  • the counting rate apparatus 54 includes a network 60 having a transfer admittance which is a desired function of a complex frequency, where this complex frequency represents the input pulse rate. Coupled to the input of the network 60 is an electronic switch means 57, of the bi-stable multi-vibrator type, which provides alternately positive and negative pulses in response to the input pulses from the pulse source 53. Coupled to the output of the network 60 are a pair of oppositely poled diodes 63 and 64.
  • the bi-stable multivibrator 57 consists of two alternately conducting space discharge devices 58 and 59 of the vacuum triode type, which have their anodes and control grids cross-coupled by means of the parallel resistance, capacitance networks 61 and 62. Circuits of this type are characaterized by the fact that they possess two condi tions of stable equilibrium. The multivibrator remains in one of the other of these two conditions until some action occurs which causes the non-conducting tubes to conduct. The tubes then reverse their function and remain in the new condition until another action occurs.
  • the pulses from the pulse source 53 are injected into the circuit by means of the double diode 56.
  • the pulses are applied through the diode 56 to the control grid of the discharge devices 58 and 59.
  • the negative pulses will, as was explained with reference to Fig. 2, cause the conducting tube to be cut off while the nonconducting tube becomes conducting. This condition then continues until the next negative pulse, at which time the equilibrium condition will again be reversed.
  • the electron discharge devices 58 and 59 are successively and alternatively actuated to conducting and non-conducting states by successive input pulses.
  • the anode voltage of the electron discharge divice 59 is successively at a maximum level when the discharge device is non-conducting and at a minimum level when it is conducting, thus effectively applying alternately positive and negative voltages of the type shown in Fig. 46, to the network 60.
  • a comparison means comprising a capacitance C wherein the output current from the measuring apparatus 54 is compared with the input current supplied through terminal 51 to provide a control voltage on capacitance C for varying the repetition rate of the pulse source 53 until the two currents are equal. If the output current from the counting rate apparatus 54 does not equal the input current applied to the terminal 51, there will be produced a voltage on capacitor C which is applied by means of leads 65 to the input of a direct current amplifier 55.
  • a capacitance C has been shown for the sake of simplicity, it will be obvious that many other suitable comparison means may be utilized.
  • a differential amplifier system of the type disclosed in Waveforms, Chance, Hughes, MacNichol, Sayre, and Williams, McGraw-Hill Book Co., New York, 1949, vol. 19, Radiation Laboratory Series, page 642, Fig. 18.13, may be utilized in place of the capacitance C.
  • the output of the direct current amplifier 55 is in turn connected to the pulse source 53 in order to vary its repetition rate until the output current from the counting rate apparatus 54 equals the input current at the terminal 51.
  • the repetition rate of the pulse source appearing at the output terminal 52 is functionally related to the input current in a manner depending on the specific character of the network 60 in the counting rate apparatus 54. For example, if the network 60 is of the type which produces an output current which is a logarithm of the input pulses, the repetition rate of the output pulses at the terminal 52 will be exponential function of the current applied at the input terminal 51.
  • the rate r is an exponential function of the input current I, that is,
  • Fig. 6 illustrates a function generator embodying the principles of the instant invention.
  • 'Ihisfunction generator consists, broadly speaking, of an anti-counting rate apparatus 70 having an output terminal 72 connected to the input of a counting rate apparatus '86 having an output terminal 96.
  • the primary components of the function generator are operationally related in that the anti-counting rate apparatus produces an output pulse rate at its output terminal 72, which is a desired function of a current applied to its input terminal 71.
  • These are ap-. plied to the counting rate apparatus 86 and are converted into an output current appearing at the output terminal 96 which is a specified function of the input pulse rate. Consequently, the output current at the terminal 96 is a function of the input current at 71, the specific function depending on the type of network utilized both in the anti-counting rate apparatus and the counting rate apparatus.
  • the counting rate apparatus 70 includes a pulse source 73 having a variable repetition rate which may be adjusted in response to a control signal.
  • the pulse source 73 may be of any well known type and, specifically, may be a scintillation detector or proportional counter type discussed in detail with reference to Fig. 5.
  • a counting rate device 74 Coupled to the output of the pulse source 73 is a counting rate device 74, comprising bi-stable multivibrator 7-7 and network 100, which, for the sake of clarity in distinguishing it from the counting rate apparatus 86, will be referred to as an internal counting rate apparatus.
  • the internal counting rate apparatus 74 functions to produce an output current which is a desired function of the repetition rate of the pulses from the source 73. This output current is applied to a comparis n means con-,
  • the pulse repetition rate of the pulse source 73 appearing at terminal 72 is functionally related to the input current in a manner depending on the type of network utilized in the internal counting rate meter. That is, iffor example, a network having a logarithmic characteristic is utilized, the repetition rate of the output. pulses, as will .be shown later by a rigorous mathematical analysis, Will be an exponential function of the input current. i
  • the internal counting rate meter 74 comprises a bistable multivibrator 77 which functions to apply alternately positive and negative pulse voltages to a network in response to successiveinput pulses from the pulse source 73.
  • the bi-stable multivibrator consists of two space discharge devices 78 and 79 of the vacuum triode type having their anodes and control grids cross coupled by means of the parallel resistancercapacitance network 80 and 81.
  • the input pulses from the source 73 are applied to the bi-stable multivibrator 77 by means of a double diode 76 having a common cathode and two anodes that are connected respectively to anodesof the triodes 78 and 79.
  • the multivibrator 77 is characterized by two conditions of stable equilibrium.
  • the circuit remains in one or the other until an input pulse arrives from the pulse source 73. Upon the occurrence of such a pulse, the circuit reverses its condition until the occurrence of the next pulse. As a consequence, the anode of the triode 79 is alternately at a maximum level and a minimum 'level depending on whether the tube is nonconducting or conducting.
  • a network of the type disclosed in Fig. 1 which consists of a multiplicity of parallel branches, each of which consists of a series resistance-capacitance combination.
  • Connected to the output of the network 82 are a of oppositely poled diodes 83 and 84.
  • the network 82 may be constructed to have a transfer admittance which is a desired function of the complex frequency and which, this instance, represents a pulse rate.
  • the output terminal 72 provides output pulses which have a repetition frequency which is a specified function of the input current applied to the terminal 71 of the counting rate apparatus 70.
  • the counting rate apparatus 86 Connected to the terminal 72 is a counting rate apparatus 86 which, as explained previously, functions to transform these pulses into an output current which is a specified function of the repetition rate of the pulses.
  • the counting rate apparatus 86 similarly includes a bi-stable multivibrator 88 having coupled to its output a network 87 whose transfer admittance is a desired function of the input pulse rate.
  • the bi-stable multivibrator 88 comprises two space discharge devices 89 and 90 of the vacuum triode type, having their anodes and control grids cross-coupled by means of the parallel resistance-capacitance networks 91 and 92.
  • the input pulses from the terminal 72 are applied to the bi-stable multivibrator 88 by means of a double diode 93 having its anode members connected respectively to the anodes of the triodes 89 and 90.
  • the input pulses function to reverse the equilibrium conditions of the circuit upon the occurrence of each input pulse. Consequently, the vacuum triode 89 is successively placed in a conducting and non-conducting condition by these pulses, and its anode voltage is alternately at maximum and minimum level depending on its conducting or non-conducting conditions.
  • These effectively alternate positive and negative pulse voltages are applied to the network 87 and will cause a current to flow which is a specified function of the pulse rate.
  • Coupled t0 the output of the counting rate apparatus 86 is an adjustableconstant current source 97.
  • This constant current source functions either to add a constant DC. current of a given magnitude or to subtract a constant DC current of a given magnitude.
  • the function of this constant current source will be explained in greater detail when a more rigorous mathematical analysis of the operation of the function generator is given.
  • the constant current source may be any of many well known types. For example, it could constitute a battery, or a constant current pentode, or even a regulated current source.
  • the specific construction of the constant current source is not critical as long as the magnitude of the current produced thereby is both constant and adjustable.
  • the pulse rate r appearing at the output terminal 72' is a function of the input current I applied at the terminal 71.
  • the precise function depends on the design of the network 82 in the internal counting rate apparatus 74, forexample, if. a network is synthesized which provides a logarithmic res sponse, then the relationship between the current and rate of pulses is defined by the equation:
  • the repetition rate of the output pulses is an exponential function of the input current 1.
  • a network is utilized that has a linear scale, so that its output current I follows the equation:
  • a pulse rate measuring apparatus comprising means actuated in response to input pulses having a variable rate of occurrence for furnishing successive positive and negative pulses, network means coupled to said last named means, said network means characterized by an admittance which is a function of a complex frequency representing a pulse rate so that an output signal is produced whichis dependent on the rate of occurrence of said pulses, and unidirectional conducting means coupled to the output of said network.
  • a pulse rate measuring apparatus comprising switch means actuated in response to pulses having a variable rate of occurrence, said switch means adapted to furnish successive positive and negative pulses in response to successive input pulses, network means coupled to said switch means characterized by an admittance which is a function of a complex frequency representing a pulse rate so that an output signal is produced which is dependent on the rate of occurrence of said pulses, and unidirectional conducting means coupled to the output of said network.
  • a pulse rate measuring apparatus comprising switch means actuated in response to random pulses having a variable rate of occurrence, said switch means adapted to furnish successive positive and negative pulses in response to successive input pulses, network means coupled to said switch means for receiving said successive positive and negative pulses, said network being characterized by a transfer admittance which is a logarithmic function of a complex frequency representing a pulse rate so that a current flows which is a logarithmic function of the rate of occurrence of said input pulses, and unidirectional conducting means coupled to the output of said network.
  • a pulse rate measuring apparatus comprising switch means actuated in response to random pulses having a variable rate of occurrence, said switch means adapted to, furnish successive positi e; and negative pulses in, re; sponse to successive input pulses, network meanscoupled, tosaid switch means for receiving said successive positive and; negative pulses, said network being characterized by a transfer-- admittance which is. a fractional power ⁇ 1111C ⁇ tionof a; complex frequency representing a pulse rate sothata; current flows which is a fractional power function, of the rate of-occurrence of said input pulses, and uni directional conducting means coupled to the output of; said; network. 7
  • a pulse ratemeasuring-apparatus comprising switch means actuated in response, to pulses having a; variable rate of occurrence, said switch means adapted to furnish successive positive, and negative pulses in response to successive input pulses, network means, coupled to, said switch means for receiving said successive positive and negative. pulses, said network being characterized by a transfer admittance which is a logarithmic function of a complex frequency representing a pulse rate whereby a current flows which is a logarithmic function of the. rate of occurrence of said pulses, said network comprising a multiplicity ofparallel connected series resistance capacitance branches, and undirectional conducting means coupled to the output of said network.
  • a pulse rate measuring apparatus comprising switch means actuated in response to random pulses having a variable rate of occurrence, said switch means adapted tofurnish successive positive and negative pulses in: response to successive input pulses, network means. coupled to said switch means for receiving said successive positive and negative pulses, said network being characterized by a transfer admittance which is alogarithmic function of a complex frequency representing a pulse rate so that a current flows which is a logarithmicfunction of the rate of occurrence of said pulses, said network comprising n parallel connected series; resistance-capacitance branches, the magnitudes of; the resistive and capacitive elements-being defined by where r is the ratev of occurrence of the input pulses, T is time, and a and R are designed parameters, and unidi rectional conducting means coupled to the output of said network;
  • a pulse. rate measuring apparatus comprising electronic switch means actuated in response to random pulses, having a variable rate of occurrence, said switch meansadapted to furnish successive positive and nega-v tive pulses in response to successive input pulses, network means coupled to said switch means for receiving said positive and negative pulses, said network beingcharacterized by a transfer admittance which is a function of a complex frequency repr enting a pulse rate so that a current flows; which is dependent upon the rate of occurrence of said input pulses, aunidirectional conducting means coupled to the output of said network.
  • a pulse rate measuring apparatus comprising electronic switch means actuated in response to random pulses having a variable rate of occurrence, said switch means adapted to furnish successive positive and negative pulses in response to successive input pulses, network means coupled to said switch means for receiving said PQSitive and negative pulses, said network being characterized by a transfer admittance which is a loga rithmic function of a complex frequency representing a pulse rate. so that a current flows which is a logarithmic 26 nd paral e a con e ed un di a cond c n coupled to the output of said network.
  • a pulse rate measuring apparatus comprising a bias-table multivibrator actuated in response to -succes-; sive input pulses to transfer its conductive states and furnish successive; positive and negative pulses, saidine put pulses having a variable and random rate-ofioccur rence, network means coupled to said multivibrator-for receiving said positive and negative pulses, said network; being characterized by a transfer of admittance which is a logarithmic function of a complex frequency rep-.- resenting a pulse rate so that a current flows which is a logarithmic t'unction of the rate of occurrence of said input pulses, said network comprising a multiplicity of series resistance-capacitance combinations connected in parallel, oppositely poled rectifying means connected to said network.
  • a pulse rate measuring apparatus comprising; a bi-stable multivibratoractuated successively to transfer its conductive states to furnish successive positive and negative pulses in response to successive input pulses, said input pulses having a random and variable rate of occurrence, rectifying means connected to the input of said multiyibrator to'apply said pulses thereto, network means coupled to the output of said multivibrator to receive said positive and negative pulses, said network being characterized by a transfer admittance whichis a logarithmic function of a complex frequency representing a pulse rate so that a current flows which is a logarithmic function of; the rate of occurrence of said input pulses, said network comprising a multiplicity of series resist ⁇ antic-capacitancecombinations connected in parallel, and oppositely poled, diodes connected to said network.
  • pulse repetition rate, comparison means having applied thereto current from saidcountng ate. means, and said input current, and means to vary the repetition rate of said pulse generating means until said currents. are equal whereby the repetition rate, of saidpulse generating means is a function said input current.
  • tion rate is a function of an input current
  • the combina: tion comprising pulse generating means having a variable repetition rate, counting rate means coupled to said pulse generating means for producing a current which is a function of the repetition rate of said pulses including a switch means, actuated in response.
  • said generating means to furnish successive positive and negative: pulses, a network coupled to said switch means for receiving said positive and negative pulses,.said network being characterized .by a transfer admittance that is dependent on the pulse repetition rate for producing an output current which is a function of the pulse repetition rate, comparison means including a storage means having applied thereto the current from said counting rate means and the input current, means to vary the repetition rate of said pulse generating means until said cur-rents are equal whereby the repetition rate of said pulse generating means is a function of said input current.
  • counting rate means coupled to said pulse generating means for producing a current which is a logarithmic function of the repetition rate of said pulses including a switch means actuated in response to pulses from said generating means to furnish successive positive and negative pulses, a network coupled to said switch means for receiving said positive and negative pulses, said network being characterized by a transfer admittance which is a logarithmic function of a complex frequency representing said pulse rate for producing an output current which is a logarithmic function of the pulse repetition rate, comparison means including a capacitance having applied thereto the current from said counting rate means and said input current, means responsive to the output from said comparison means to vary the repetition rate of said pulse generating means until said currents are equal whereby the repetition rate of said pulse generating means is an exponential function of said input current.
  • the combination comprising pulse generating means having a variable repetition rate, counting rate means coupled to said pulse generating means for producing a current which is a logarithmic function of the repetition rate of said pulses, said counting rate means including electronic switch means adapted to furnish successive positive and negative pulses in response to successive input pulses from said generating means, and a network coupled to said switch means having transfer admittance which is a logarithmic function of a complex frequency representing said pulse rate for producing an output current which is a logarithmic function of the pulse repetition rate, comparison means having applied thereto the current from said counting rate means responsive to the output from said comparison means and the input current, means to vary the repetition rate of said pulse generating means until said currents are equal whereby the repetition rate of said pulse generating means is an exponential function of said input current.
  • the cambination comprising pulse generating means having a variable repetition rate, counting rate means coupled to said pulse generating means for producing a current which is a logarithmic function of the repetition rate of said pulses, said counting rate means including electronic switch means adapted to furnish successive positive and negative pulses in response to successive input pulses from said generating means, and a network coupled to said switch means for receiving said positive and negative pulses, said network comprising a multiplicity of parallel connected series resistance-capacitance combinations having a transfer admittance which is a logarithmic function of a complex frequency representing said pulse rate for producing an output current which is a logarithmic function of the pulse repetition rate, comparison means responsive to'the output from said comparison means having applied thereto the current from said counting rate means and said input current, means to vary the repetition rate of said pulse generating means until said currents are equal whereby the repetition rate of said pulse generating means is an exponential function of said input current.
  • said comparison means includes a capacitance.
  • a function generator comprising means to generate pulses havinga repetition rate which is a given function of an input current, means coupled to said pulse generating means to produce an output current which is a function of the repetition rate of said pulses including a switch means actuated in response to pulses from said generating means to furnish successive positive and negative pulses, a network coupled to said switch means for receiving said positive and negative pulses, said network being characterized by a transfer admittance which is a function of a complex frequency representing said pulse'rate so that a current flows which is dependent 28 on the repetition rate of said pulses whereby the output current is a desired function of the input current.
  • a function generator comprising means to generate pulses having a repetition rate which is a given function of an input current including a variable rate pulse source, a counting rate means to produce a current which is a function of the pulse rate, means to vary the repetition rate of said pulses until the current from said counting rate means equals said input current whereby the repetition rate is a function of the input current, means coupled to said pulse generating means to produce an output current which is a function of the repetition rate of said pulses including a switch means actuated in response to pulses from said generating means to furnish successive positive and negative pulses, a network coupled to said switch means for receiving said postive and negative pulses, said network being characterized by a transfer admittance which is a function of a complex frequency representing said pulse rate so that a current flows which is dependent on the rate of occurrence of said pulses whereby the output current is a desired function of the input current.
  • a frmction generator comprising means to generate pulses having a repetition rate which is an exponential function of an input current, including a pulse source having a variable repetition rate, a switch means actuated in response to said generating means to furnish successive positive and negative pulses, a network coupled to said switch means for receiving said positive and negative pulses, said network being characterized by a transfer admittance which is a logarithmic function of a complex frequency representing the pulse rate and causes a current flow which is a logarithmic function of the pulse repetition rate, means coupled to said pulse generating means to produce an output current which is a linear function of the repetition rate of said pulses whereby the output current is an exponential function of the input current.
  • a function generator comprising means to generate pulses having a repetition rate which is a linear function of an input current including a pulse source having a variable repetition rate, a switch means actuated in response to pulses from said pulse source to furnish successive positive and negative pulses, a network coupled to said switch means for receiving said positive and negative pulses, said network being characterized by a transfer admittance which is a linear function of a complex frequency representing said pulse rate whereby a current flows which is a linear function of the pulse repetition rate, means coupled to said pulse generating means to produce an output current which is a logarithmic function of the repetition rate of said pulses whereby the output current is a logarithmic function of the input current.
  • a function generator comprising means to generate pulses having a repetition rate which is the given function of an input current including a pulse source having a variable repetition rate, and counting rate means to produce a current which is a function of the repetition rate including a switch means actuated in response to pulses from said generating means to furnish successive positive and negative pulses, a network coupled to said switch means for receiving said positive and negative pulses, said network being characterized by a transfer admittance which is a predetermined function of a complex frequency representing the pulse rate whereby a current flows which is a predetermined function of the input pulse repetition rate, means to compare the current from said counting rate means and the input current, means responsive to the output from said comparison means to vary the repetition rate of said pulses until the current from said counting rate means equals the input current whereby the repetition rate is a function of the input current, means coupled to said pulse generatingmeans to produce an output current which is 29 a function of the repetition rate of said pulses including a network characterized by :a transfer admittance
  • said counting rate means includes a network characterized by a transfer admittance which is a function of the repetition rate of the pulses produced by said pulse source.

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US594839A 1956-06-29 1956-06-29 Function generator Expired - Lifetime US2986704A (en)

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NL218516D NL218516A (is") 1956-06-29
US594839A US2986704A (en) 1956-06-29 1956-06-29 Function generator
FR1187745D FR1187745A (fr) 1956-06-29 1957-06-25 Compteur d'impulsions
GB20301/57A GB844872A (en) 1956-06-29 1957-06-27 Improvements in "function generator"
DE19571252800D DE1252800B (is") 1956-06-29 1957-06-28

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Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3120647A (en) * 1961-07-26 1964-02-04 Houston Instr Corp Logarithmic frequency discriminator circuits
US3210558A (en) * 1959-11-25 1965-10-05 Ibm Periodic waveform generator
US3569989A (en) * 1966-12-20 1971-03-09 Rank Organisation Ltd Afterglow correcting circuit arrangements

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2549065A (en) * 1948-11-02 1951-04-17 Bell Telephone Labor Inc Frequency discriminative electric transducer
US2556200A (en) * 1948-02-26 1951-06-12 Int Standard Electric Corp Electrical translation system
US2658189A (en) * 1948-01-09 1953-11-03 Bell Telephone Labor Inc Signaling system based on orthogonal functions
US2730679A (en) * 1951-05-18 1956-01-10 George A Philbrick Delayed-recovery electric filter network
US2842733A (en) * 1954-11-01 1958-07-08 Itt Function generator

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2658189A (en) * 1948-01-09 1953-11-03 Bell Telephone Labor Inc Signaling system based on orthogonal functions
US2556200A (en) * 1948-02-26 1951-06-12 Int Standard Electric Corp Electrical translation system
US2549065A (en) * 1948-11-02 1951-04-17 Bell Telephone Labor Inc Frequency discriminative electric transducer
US2730679A (en) * 1951-05-18 1956-01-10 George A Philbrick Delayed-recovery electric filter network
US2842733A (en) * 1954-11-01 1958-07-08 Itt Function generator

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3210558A (en) * 1959-11-25 1965-10-05 Ibm Periodic waveform generator
US3120647A (en) * 1961-07-26 1964-02-04 Houston Instr Corp Logarithmic frequency discriminator circuits
US3569989A (en) * 1966-12-20 1971-03-09 Rank Organisation Ltd Afterglow correcting circuit arrangements

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NL218516A (is")
GB844872A (en) 1960-08-17
FR1187745A (fr) 1959-09-15

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