Abstract: An electronic watt and kilowatt hour measuring circuit susceptible of being fabricated for the most part in solid state semiconductor monolithic integrated circuit form is provided. The electronic measuring circuit uses an active load terminated current transformer sensor for sensing alternating load current and a voltage transformer for sensing the alternating current voltage supplied from a source of alternating current electric energy being monitored. The output of the active load terminated current sensor transformer has an inherent DC-offset error voltage added to the alternating voltage which is proportional to the current being measured. This DC-offset error voltage is caused by the operational amplifier employed in the active load terminated current transformer sensor.

Abstract: An improved solid state semiconductor electronic combined watthour and watt meter circuit providing both analog and digital outputs and having automatic error correction comprising first and second input transformers for developing first and second signals proportional respectively to the voltage and current being supplied from a source of electrical energy to a consumer. The first and second signals are supplied to a multiplier circuit for developing pulse-width-modulated and amplitude modulated product output signals representative of instantaneous watts. This product signal is supplied to a summing analog-to-pulse rate circuit for developing an output pulse train wherein each output pulse represents a predetermined quantized amount of energy and which is used to reverse polarity of the multiplier switches to accomplish automatic error correction.

Abstract: A multielement-sensor measuring device having a number of sensor elements is provided with a switching means, a measurement means, a memory data extraction means and an offset and gain compensation means. In adjustment of the device prior to actual measurement, the sensor elements are sequentially switched over to the measurement means which measures their output and produces and forwards to the memory for storage offset and gain values according to the variation in offset and gain among the sensor elements. During operation, the stored offset and gain values are extracted from the memory by the data extraction means and used to control the offset and gain compensation means, whereby the outputs from the sensor elements are compensated so as to be made free from variation in offset and gain.

Abstract: Apparatus which measures loads imposed on load carrying members, and particularly such members in presses, to indicate the peak load reached during a press cycle, has circuits for amplifying the electrical signal from a sensing device such as a strain gage bridge, a peak detector which provides an output representing the peak load, and a digital indicator. Zero setting is achieved by integrating and holding an offset voltage derived by an integrating circuit in negative feedback relationship with the circuit which amplifies the signals from the sensing device. Calibration of the apparatus for press factor is obtained by adjusting the gain of a variable gain stage in the amplifier. The peak detector is reset each press cycle when the load sensed bears a predetermined ratio to rated or full capacity load.

Abstract: A method and apparatus are provided for indicating an operating characteristic of a periodically combusting internal combustion engine, such as a diesel engine, having exhaust gas issuing from one or more combustion chambers in a periodic manner through a duct. The particulate in the exhaust gas stream are electrically charged and of the same polarity, and are grouped in packets associated with the periodic combustion in the respective chambers. An electrically conductive, passive electrode, preferably annular in shape, is disposed such that most or all of the exhaust gas flows therethrough so as to electrostatically sense, principally by induced image charge, the passage of the respective packets of charged particles. The electrode is electrically isolated from the duct.

Abstract: An electronic watthour meter including a pulse width modulation circuit for converting a voltage signal proportional to the load voltage across the power supply lines to a pulse width duty cycle signal and a current-to-voltage converter for converting a current signal proportional to the load current across the power supply lines to a voltage signal. A multiplication circuit issues the product of the voltage signals under the control of the pulse width duty cycle signal as a pulse signal proportional to the instantaneous power consumption of the power supply lines. A filter circuit integrates the pulse signal of the multiplication circuit as an integrated voltage signal. A voltage-to-frequency converter converts the integrated voltage signal to a pulse signal proportional to the consumption power of the power supply lines.

Abstract: Bi-polar electronic signal converters, such as analog-to-digital or digital-to-analog converters, with a single polarity accurate reference source are disclosed. In one polarity direction, the accurate reference source is used in a conventional manner to transform the signal to be converted from one form (e.g., analog) to the other form (e.g., digital). In the other polarity direction, an inaccurate reference source is used in a similar conventional manner to convert the signal from one form to the other form. Periodically, the accurate and the inaccurate reference sources are compared to determine a correction multiplier. The correction multiplier is used during conversions using the inaccurate reference source to compensate for the inaccuracy of the inaccurate reference source.

Abstract: An automatic zero balance circuit for nulling the initial offset signal received from a test transducer. A quadrature oscillator powers a carrier transducer with the phase reference signal. A summing circuit receives the return signal from the transducer and sums it with two other signals. The resultant summation signal is divided into two components, the phase reference component and the quadrature reference component which are fed back into the summing circuit as the two other signals. The component values nullify the return signal thereby cancelling the initial offset signal.

Abstract: Circuit for detecting a fault current in an installation where the load (RL) varies. Total current (IS) is converted into a voltage (VS). During an initialization cycle, means such as counter (9), digital-to-analog converter (10), comparator (5), resistors (R1, R2) generate a voltage (VS) equal to VS at the end of the initialization cycle, and a threshold voltage VS=kVS. During operation, voltage VS is compared with threshold VD in order to provide a fault detection indication which is transmitted to the protection circuit by a logic circuit, that is, AND gate (17) and OR gate (19). During the initialization cycle, protection is obtained by comparing VS with a reference voltage in a comparator (7). This device is used to protect machines having an expandable configuration.

Abstract: For the automatic calibration of an analog-to-digital converter an analog calibration quantity is measured and the digital signal is compared with a digital calibration signal associated with the calibration quantity. A digital difference signal is applied to a register for influencing its counting capacity, while the register contents of pulses counted during the measurement also represents one of the parameters involved in the analog-to-digital conversion. Because of the fully digital character of the calibration, this calibration can be performed very rapidly and accurately.

Abstract: A calibration apparatus for analog-to-digital converter or transient recorder including both analog and digital sections is disclosed. A built-in calibrator automatically calibrates the gain and DC level of the entire system to substantially the same accuracy as that of the digital section, thereby avoiding relatively large errors of the analog section. The amplitude or gain calibration is always performed over the full range of the digitizer used in the digital section.

Abstract: A single slope analog to digital converter uses a DAC to trim the discharge current of a capacitor during calibration thereof. A method of calibrating the analog to digital converter is provided which iterates required steps to obtain a correct current setting within a short period of time. The analog to digital converter discharges a capacitor through a high impedance to obtain a linear discharge. The time to discharge the capacitor appears in a counter and is indicative of the voltage across the capacitor at the beginning of the discharge period once the analog to digital converter has been calibrated.

Abstract: A new microprocessor controlled digital multimeter offers significant advantages to the user. Automatic calibration allows a new reference IC board to be inserted and because of such calibration the multimeter is instantly ready for use.

Abstract: This is an analogue to digital converter channel including an analogue multiplexer, a switched gain amplifier, a mode amplifier, a sample and hold stage, and an analogue to digital converter. Off-set errors can be precalculated and then corrected for by switching the input to the amplifiers to null, and storing the output from the converter, and the amplified output from the gain amplifier respectively at `X` and `Y` and then combining those stored off-set error signals at an adding circuit at the input to the converter during a subsequent analogue to digital conversion.

Abstract: An offset circuit for use in providing an offset signal to an analog-to-digital converter. The analog-to-digital converter has an integrator for performing signal integrate operations and is connected to a digital display. The offset circuit is gated to provide a variable offset current directly to the integrator of the analog-to-digital converter, thereby eliminating adverse loading effects on the high input impedance of the analog-to-digital converter.

Abstract: An electrical measuring apparatus comprising a current domain magnetometer (C.D.M.) (1) and summation means (2) for summing the output pulses from the C.D.M., the sum of the summation means representing the integral of a predetermined function of the voltage and magnetic flux applied to the C.D.M. with respect to time. The predetermined function may be proportional to the product of the voltage and magnetic flux and the apparatus may produce measurements of voltage, magnetic flux, power or phase angle.

Abstract: A method and apparatus for automatically recalibrating a leak detector. A gaseous impurities is detected by means of a corona discharge. This discharge is sampled and a signal that is a function of the corona discharge level is stored. Subsequent corona discharge levels are compared to the stored signal; and an alarm signal is produced when the subsequent discharge levels exceed the stored value by more than a predetermined amount. To recalibrate the circuit a new signal is stored representative of the corona discharge level at that time. Subsequent corona discharge levels are then compared with the newly stored signal.

Abstract: Compensation for errors in an amplitude conversion system caused by inaccuracies in and nonlinearities of system circuit components is realized by employing a self-compensation process in an amplitude measurement system (FIG. 1). In one embodiment first and second reference signals (from 111) are controllably supplied (under control of 105 via A1, A2SW1, SW2, 108, 112, 113 and 103) to a RMS-LOG converter circuit (104) to obtain a measure of the amplitudes of the reference signals (TA, TB) and convert the amplitudes into pulse signals. The pulse signals are supplied to a control circuit (105) for conversion into digital form and storage as reference numbers for future use. A test signal supplied from a remote location over a facility under evaluation is supplied (via T, R, 101, 102, 103) to the RMS-LOG converter (104) where the test signal amplitude (TMEAS) is measured and converted into a pulse signal.

Abstract: A rapid and accurate method for calibrating an instrument for measuring the reflection coefficient and complex permittivity of unknown dielectric materials in a lumped capacitance method for an automatic network analyzer is described. The method includes the discovery that the capacitance of the instrument filled with air can be calculated by measuring only the reflection coefficients of the instrument filled with air and filled with a standard liquid of known permittivity, without the necessity of calculating the capacitance value from the dimensions of the instrument. The complex permittivity of the unknown can then be calculated by measuring the reflection coefficient of the instrument filled with the unknown dielectric. Complex permittivity measurements are useful in, for example, evaluating the time course of dielectric dispersions in biological samples.

Abstract: A self inverting gauging system for such parameters as capacitively sensed distance or inductively sensed resistivity in which the sensor provides an output inversely varying with the dimension of interest. The gauge typically includes a dual slope integrator responsive to a reference value on the up integration and to the sensor output on the down integration. The interval of the down integration necessary to reset the integrator to the original value varies directly, rather than inversely, with the dimension of interest and is typically provided as the digital output indication of a counter. In the application to resistivity gauging, the up integration reference signal is preferably provided by the output of a thickness gauge such that the ultimate counter display represents element resistivity compensated for thickness.

Abstract: A method of and apparatus for calibrating and providing an output from a strain gauge (1) is described. In the method and apparatus there is provided a constant-current source (10). Coupled to the current source (10) is an amplifier (12,13) for providing an output corresponding to the difference between the voltage drop across the strain gauge (1) and a reference voltage from a source (14). The reference voltage is used to adjust the current in the strain gauge (1) from the current source (10). After the current is adjusted, further changes in the voltage drop in the strain gauge (1) relative to the reference voltage is used for providing an output of the voltage difference relative to the reference voltage. The adjusting of the magnitude of the current from the constant-current source (10) is provided by a calibrate-and-zero sample and hold circuit (16) having a sample and hold period sufficient to reduce to negligible levels the effects of the dielectric absorption of an associated capacitive means (20).

Abstract: In a device for continuously monitoring the characteristics of a moving filament, such as the denier of an extended synthetic yarn, by passing the filament through a capacitive sensor to develop an electrical signal representing an absolute measurement of the filament with reference to a prescribed datum, the problem of measurement signal drift arising from contamination of the capacitive sensor is obviated by developing compensating signals to be combined with the filament measurement signal. The compensating signals are digitally formed and stored, thereby eliminating drift in the compensating signals themselves. The compensating signals are developed in an auto-calibration circuit, including an auto-zero circuit and an auto-gain circuit, which receives the measurement signal from the capacitive sensor.

Abstract: A new microprocessor controlled digital multimeter offers significant advantages to the user. Automatic calibration and correction routines ensure long term stability and simplify maintenance; self diagnostics greatly help troubleshooting and even warn of impending failures; software implementation of logic design simplifies hardware, improves reliability and adds capabilities such as fast auto ranging and software I/O control; the ability to process data permits averaging, linearization and normalization of input measurements, minimum/maximum storage and limit detection.

Abstract: A sensor is compensated through the use of a closed loop comprising a digital processor, a digital-to-analog converter and a comparator having inputs coupled to the converter and the sensor and an output fed back to the digital processor. During calibration of the sensor, a signal from the sensor is tracked by the digital processor and at least one of the values characteristic of the sensor signal is stored in the digital processor. The stored value is used as or in the computation of a reference by the digital processor which is compared with the sensor signal during operation of the sensor to appropriately compensate the sensor for gain, offset, drift or degradation in the quality of the sensor signal.

Abstract: An electronic apparatus for automatically zeroing or nulling an analog offset voltage by using multiple bit successive approximation to generate an analog zeroing voltage of equal magnitude and opposite polarity to that of the offset voltage, and then summing the zeroing voltage with the offset voltage.

Abstract: A calibrating device is disclosed for insertion between a control station and its indicators, preferably of the bar graph type, with provisions for establishing accurate reference voltages available at marked jacks for use and specifically for checking the calibration of the indicating elements, and to provide for utilization of one or both indicators as a precision voltmeter for checking the potential of various points in the circuitry. Provisions are also made for bypass plugging in so that the indicators operate in a normal manner as if the calibrator were not present. The normal jacks also provide convenient access to the set-point and variable voltage of the station and facilitate the measuring of these voltages by an external digital voltmeter if desired.

Abstract: A noncontact gauge for edge detecting of semiconductor wafers in a test rig which indexes between circuits in the semiconductor wafer to provide functional tests upon them. The noncontact gauge includes a capacitive probe having an elongated finger that is bent into position a few thousands of an inch above the wafer when positioned for circuit tests in order to detect whether the circuit test system, in indexing from circuit to circuit in the row and column matrix of integrated circuit chips in the wafer, has moved to one edge or the other of the water. The edge detection system operates with conventional wafer test systems which raise and lower the wafer between tests to index from one integrated circuit to the next in the wafer matrix.

Abstract: A tracking generator for a wideband superheterodyne receiver in which a fixed-frequency signal source supplies an IF signal to a mixer for conversion to an RF signal at the frequency to which the receiver is tuned. A second signal is supplied to the mixer from the local oscillator within the receiver. The fixed frequency IF signal may be converted to an RF signal at every frequency that the receiver can accommodate merely by sweeping the local oscillator throughout its frequency range.

Abstract: A calibrating and measuring circuit is disclosed for a capacitive probe-type instrument. The capacitive probe, in contact with a surface to be measured, is connected to an oscillator which generates pulses, the frequency of which is adjustable, the number of pulses generated being a function of the texture of the surface being measured. A digital counter is connected to receive, count and present the resulting summation to a visual numerical display.In order to calibrate the instrument the capacitive probe is placed on a known specimen, the digital magnitude of which is loaded into the counter through a number of thumb switches. The counter first counts down to this number, and then counts up to the number of remaining pulses. The resulting count, called the offset number, is then transferred to a memory.

Abstract: A voltmeter having multiple voltage ranges comprises substantially linear elements such that the transfer functions of the elements can be independently measured and logically combined to derive the transfer function of a given combination of elements configured to obtain a given voltage range.

Abstract: A computerized field meter calibration system which includes an apparatus for testing the calibration of field meters normally utilized for measuring electromagnetic field potential. A reference voltage is applied to the field meter for causing signals to be produced on the output terminals thereof. A bank of relays is provided for selectively connecting output terminals of the field meter to a multiplexer by means of a digital voltmeter and an oscilloscope. A frequency-shift-keyed receiver is also connected to one of the terminals of the field meter for transmitting and converting a frequency shift keyed signal to a digital signal which is, subsequently, applied to the multiplexer. A microprocessor is used for generating coded command signals to the bank of relays and also to the multiplexer for controlling the comparison of the output signals with information stored within the microprocessor to determine if the field meter is properly calibrated.

Abstract: A circuit for performing dual slope integration to provide a digital measurement of an input voltage of either positive or negative polarity employs a single source of reference potential in combination with a switchable resistive network as a source of reference current.

Abstract: A conditioning circuit for a resistance bridge transducer that includes output signal amplification, a voltage regulated DC power source for transducer excitation and a calibration select circuit for selectively inserting a shunt calibration resistor into parallel with one bridge arm. The calibration select circuit comprises a field effect transistor switch that is connected in series with the calibration resistor between two adjacent transducer terminals. The field effect transistor switch is operated by the output of an operational amplifier in response to positive and negative DC control signals. The conditioning circuit is adaptable to miniaturization through the use of integrated and hybrid circuits.

Abstract: A bridge circuit having reference and measurement thermistors in respective adjacent arms is automatically readjusted to off-set any long term drift of the thermistors. The readjustment of the bridge circuit is performed between normal measurement operations using a bridge output error signal produced by the drift of the thermistors. The output signal of the bridge circuit is also applied to a comparator circuit to produce a polarity characterized output signal in response to the relative magnitude between the bridge output signal and a fixed reference signal. This characterized output signal is used to control the counting direction of an up/down counter. A source of fixed frequency pulses is connected to the input of the up/down counter during a sample window time between the measurement operations to change the count stored in the counter in accordance with the direction of counting as determined by the output signal from the comparator.

Abstract: A rapid-response generating voltmeter for measuring a high d-c voltage between a high voltage electrode and ground comprises two sets of stator segments, the segments of each set being electrically interconnected and each set being connected through its own capacitor to ground. Each set of stator segments has a time-varying capacitance with respect to the high voltage electrode, but the sum of these time-varying capacitances is maintained substantially constant with time.First and second circuit means respectively sense the voltages e.sub.1 and e.sub.2 present across said two capacitors and develop first and second intermediate signals e.sub.5 and e.sub.6 substantially proportional to e.sub.1 and e.sub.2, respectively, minus, in each case, an error voltage attributable to discharge of the associated one of said capacitors. Summing means develops an output signal substantially proportional to the instantaneous sum of e.sub.5 and e.sub.

Abstract: A measurement system of the type having a sensor the electrical resistance of which varies as a function of a parameter being measured, and a bridge circuit connected to the sensor, wherein a source of a reference voltage is provided to excite the bridge to produce a bridge output indicative of the parameter being measured when the bridge is balanced, the bridge output being dependent upon the sensor resistance and the reference voltage except that the system includes circuitry for causing the output to be independent of the reference voltage at one end of a range of values of the parameter, and output circuitry is provided for converting the bridge output into a system output in accordance with an output function, featuring, in one aspect, first calibration circuitry connected to the output circuitry to provide a first calibration signal for calibrating the system at one end of the range by controlling the output function; second calibration circuitry connected to the bridge circuit to provide a second calib

Abstract: A moisture measuring apparatus includes a tuned circuit, a moisture sensor, coaxial cable means between the sensor and the tuned circuit wherein the tuned circuit tunes the coaxial cable, and a circuit for ascertaining the loading presented by the sensor to the tuned circuit whereby moisture is measured. The sensor is alternately connected and disconnected to an end of the coaxial cable and the signal drive across the tuned circuit is standardized, when the sensor is disconnected, for zeroing the instrument. Also, the gain of the circuitry is adjusted by periodically providing a standard load to the tuned circuit while adjusting amplification to bring about a standard output. The apparatus is not as sensitive to cable changes as prior apparatus and a plurality of selectable coaxial cables are provided on reels adjacent the sensor console.

Abstract: A digital scaler adjusts the processing of an input signal to a digital fback integrator by a multiplying technique which is implemented by shifting the connections between an analog-to-digital converter and the input to an adder, both forming the input section of a digital feedback integrator, in order to maintain a constant dynamic range of the output signal.

Abstract: An optical oil monitor that measures particle contamination in oil by passing light through an oil sample and picking up the light that is scattered at 90.degree. by the particle contamination and measures chemical breakdown by the attenuation of the light passing substantially straight through the oil with a second sensor. Alternately a sample and a reference are passed between the light responsive sensors for error correction and calibration so that each sensor will have an output signal alternating between a sample signal and a reference signal. A control signal of the same frequency is provided in combination with a plurality of gates to separate the sample and reference signals. The attenuation reference signal is compared to a standard signal to produce an error output for regulating the intensity of the light source to compensate for power source fluctuations, lamp characteristic changes, window soiling and the like.

Abstract: A calibratable heterodyne receiver can be adjusted to a calibration mark or similar entity of an indicating device connected to the output of the receiver during feeding of a calibration alternating current with the help of adjusting means which change the gain of the amplifier. The calibration alternating current frequency is adapted during each calibration to the tuning frequency and is obtained by means of mixing the output voltage of the heterodyne oscillator with an auxiliary voltage which corresponds to the intermediate frequency. The auxiliary voltage is tapped from an intermediate frequency stage of the receiver and is derived by way of a limiting circuit which is constructed and dimensioned in such a way that a calibration voltage amplitude and calibration voltage phase results which causes self oscillation around the circuit.

Abstract: A method and apparatus is provided for compensating for repeatable error signal components which occur with information components. The method provides for detecting the peak amplitude of an error signal and providing a representation thereof, storing the representation, providing a composite electrical signal having the information and error components, detecting the peak amplitude of the composite signal and providing a representation thereof, and combining the stored error signal representation with the composite signal representation to provide an output signal from which the error signal component has been substantially removed.

Abstract: A calibration circuit and method for use with systems of the type displaying values of a measured condition in response to electrical pulses received at the system input in which the repetition rate of the received pulses is representative of the value of the measured condition. Electrical pulses, having a known repetition rate are generated for simulating a value of the measured condition in response to a reference signal of known frequency, the repetition rate of said simulating pulses being determined by the frequency of the reference signal.

Abstract: The integrating fluxmeter disclosed herein employs a second electronic integrator which operates during the intervals between test periods to adjust a compensating bias current, applied to the main integrator, to a value accurately canceling any residual drift. The integrating capacitor employed in this second electronic integrating circuit is of sufficient size so that the value of the compensating current does not vary significantly during a test period.

Abstract: The output of the sensor whose variations are to be compensated is applied to one input of a DC amplifier whose other input is connected to an analog storage. The output of the DC amplifier is applied to a voltage-controlled oscillator whose frequency varies as a function of the voltage applied thereto. A phase detector compares the output of the voltage controlled oscillator to a standard reference frequency and furnishes a DC compensating voltage corresponding to the difference therebetween. Prior to each measurement the DC compensating voltage is applied to the analog storage thereby forming a closed loop circuit and causing the voltage controlled oscillator to oscillate at its standard frequency. At the start of the measurement the connection between the phase detector and the analog storage is broken thereby causing the DC compensating voltage present at the beginning of the measurement to be applied to the DC amplifier throughout the measurement.

Abstract: Baseline drift and noise can produce difficulties in registering signals quantitatively without recourse to frequent rezeroing of the registering instrument. The invention provides a circuit in which the registering instrument only functions when a required signal is to be noted, the instrument at all other times being at a zero reading. The characteristics of a signal to be registered will be known. The circuit includes a differentiator which notes the rate of change of incoming signals and operates a switching device upon detecting a required rate of change to enable the signal to pass to the registering instrument. At all other times the registering instrument is isolated by the switching device.

Abstract: An apparatus for measuring small currents in which the current is applied to an integrator. The integrator output is applied to a slope detecting means, preferably differentiator and the integrator output is reduced at intervals to zero.

Abstract: An automatic calibration system for pH meters includes a digital counter and a digital-to-analog converter which produces an output voltage connected to compensate the zero offset DC voltage of the pH measurement system. During a calibration operation a switch is closed to reset the binary counters and to thereafter supply clock pulses to the counters. As these clock pulses are counted, the digital-to-analog converter produces a staircase output voltage. This is applied to one input of a difference amplifier and the measuring voltage of the pH probe is applied to the other input. A detector stops the application of clock pulses to the counter when the staircase voltage equals the DC offset voltage of the pH measuring probe.