Abstract: A return-loss detector for a serial digital signal source uses a return-loss bridge circuit to exploit the broadband spectral characteristics of a serial digital signal from the signal source to monitor the termination conditions of a system being driven. A differential pair of serial digital signals from the source are input to the bridge circuit having a reference termination in one leg and the system termination in the other. A broadband detector is used at the output of the bridge circuit to generate an error signal, which is measured by a detector or metering circuit. The measured signal may be displayed as a value in dB or may be input to a comparator to provide an alarm or warning signal to an operator.

Abstract: A dynamic range tester which simultaneously generates two signals, each of hich is composed of a clean signal plus an excess quantity of independent and isolated random noise is disclosed for use in producing real world signals which can be used to provide a simulated operating environment within which to evaluate the dynamic range or evaluate the processing gain of an electronic or acousto-optic system. The power level of the signal and power level of the noise in each of the two outputs of the dynamic range tester can be independently varied such that a range of signal-to-noise ratios may be set-up in each output.

Abstract: Equivalent circuit parameters of a piezoelectric resonator are measured in order to precisely control the amplitude and/or frequency of oscillation of an oscillator including the resonator, or to compensate for variations in the amplitude and/or frequency of oscillation. Significant variations are caused by shunt capacitance, and to a lesser degree, series resistance. The equivalent circuit parameters are measured by exciting the resonator at a plurality of frequencies, measuring responses of the resonator at the frequencies, including a complex response at one of the frequencies, and determining a value of the shunt capacitance from the responses. Preferably, the resonator is simultaneously and continuously excited at three different frequencies, one of which is approximately the resonant frequency of the resonator.

Abstract: A test system for measuring the characteristics of an active circuit employs a pulsed bias technique for periodically biasing the input control port of the active circuit into the active region of operation. Biasing is achieved with a bias voltage that is periodically pulsed ON and OFF. An RF source is pulse modulated ON and OFF synchronously with the pulsed bias voltage and applied to the input control port of the active circuit. The pulsed RF occupies a portion of the time interval encompassed by the pulsed bias voltage. These voltages are combined and applied to the input port of the active circuit which operates only during the presence of the pulsed bias voltage and which is OFF during the absence of the pulsed bias voltage. A DC supply is utilized to bias the output port. The amplified RF power is then measured at the output port of the circuit, after the RF power has been separated from the DC bias by a non-reciprocal device.

Abstract: The assembly comprises an electrically insulated linear array of a plurality of active plates working in conjunction with common return plate means to provide a line of capacitors. The electrically insulated active plate array and common return plate means extend through a column of multi-phase fluid. A discrete oscillator circuit is positioned adjacent to and is permanently connected to each active plate for charging and discharging it. Means are provided for sequentially enabling the oscillator circuits to produce signals which are each indicative of the dielectric constant of the thin horizontal slice of fluid extending between the active plate and the return plate means. The signals are collected by a microprocessor which analyzes them to provide a dielectric constant profile of the fluid column. Interfaces of phases can be located from the profile and the composition of the fluid phases can be determined.

Abstract: Device for estimating, at high temperature, the electromagnetic properties of a material, including:an oven (1, 19, 20);a waveguide (3) disposed at least in part in said oven, a housing for a specimen piece of uniform thickness made of said material, this specimen piece being such that, when it is disposed in said housing, its outer periphery matches the inner surface of the waveguide;means (4, 5, 6) for applying an incident very high frequency electromagnetic wave to the waveguide (3); andmeans (4, 5, 6) for collecting the electromagnetic wave reflected by said specimen piece.A vertically disposed waveguide has (3) said housing provided at the open lower end (3B ).

Abstract: A device under test is placed in a metallic reverberation chamber and test are run for various characteristics. An antenna positioned in the chamber radiates microwave energy into the chamber. There is disclosed a method of frequency stirring which uses band limited White Gaussian noise (WGN) up-converted by performing double sideband, suppressed carrier modulation with a microwave signal from a synthesized sweeper. The output is then amplified with a TWT amplifier to meet the higher power level requirements. The synthesized sweeper is used to generate the monochromatic signal which determines the center frequency of the output while the WGN source and low pass filters provide the frequency agility.

Abstract: An inverse scattering processing method with enhanced noise immunity and resolution capabilities for use in modeling multi-layer acoustic, electromagnetic or other propagating media. A time bounded filtering step is incorporated within a peeling method for use in processing TDR characteristic waveforms of the propagating media.

Abstract: Aliasing and synchronization difficulties in determining transfer functions in mixed domain (analog and digital) systems are overcome by sampling the analog signal at a higher sampling frequency that the digital signal, and zero filling the set of sampled digital data (if necessary) so that the sampled digital data corresponds to the more densely sampled analog data. By so doing, a single fixed frequency anti-alias filter in the analog channel can be used to avoid aliasing problems in mixed domain measurements over any span of frequencies, up to the entire passband of the filter. The invention is particularly illustrated with reference to measurements both across digital-to-analog boundaries and across analog-to-digital boundaries.

Abstract: A method of alternating current potential drop measurement is provided in which the flow of the current in the specimen is laterally confined by passing the applied current externally over and in the immediate proximity to the surface of the specimen. To this end, a voltage probe is provided having a longitudinally extending isolated conductor which is connected to one current contact of a pair of current contacts. In use, this is arranged to provide an external flow path for current applied to the specimen. The isolated conductor is arranged to lie adjacent to the voltage probe contacts. For convenience of mounting, the conductor may be implemented as a conductive track on a printed circuit board. The track may also be bifurcated in order to accommodate one or more short lengths of conductor which can be used to form one or more compensating inductive loops which latter may be wired to afford cancellation of picked-up induced emf.

Abstract: An automatic, multi-use device for measuring the transfer function of any nonlinear continuous network or network component. Transfer functions (also known as input/output reactions) are the main characteristics of all communication and information processing systems. Their evaluation, in the general case, is an elaborate problem. The conventional evaluation procedure had been to linearize the problem, but this procedure was inaccurate in principle and time-consuming. The method of the invention includes the steps of measuring a set of harmonics resulting from application of one (or two) single-frequency sinusoidal signal(s) to the network of interest, and then processing the measured data. The measurement operation is extremely simple. For most networks, only a small number of harmonics of the network's response to a single sinusoidal input signal need be measured.

Abstract: An apparatus and a method for determining the error due to inherent PM and M noise in a noise measurement device. The apparatus is a calibration standard having a high frequency carrier source and a Gaussian noise source. The outputs of both sources are linearly combined by a power summer so that AM and PM noise components are equal at the output terminals of the calibration standard. To carry out the process of calibrating the calibration standard then determining inherent noise in a noise measuring device under test, the calibration standard includes means for switching to output a signal indicative of either the noise floor or a high frequency signal linearly combined with the output of a Gaussian noise source.

Abstract: Automatic device for measuring the noise level of electronic components. This device comprises selection means (20) to which are connected the components and which are able to select one of these components, measuring means (28) able to determine the noise of the selected component, said measuring means incorporating means (32,34) for biasing the selected component and for processing signals supplied by the thus biased selected component and also incorporating analysis means (36) determining the noise from signals supplied by the processing means, as well as means (10) for controlling the selection means (20) and measuring means (28), said control means (10) being electrically decoupled from the selection means (20) and the biasing and processing means (32,24). Application to the sorting of electronic components following their manufacture.

Abstract: The present invention relates to a method of calibrating levels of a waveform analyzing apparatus. An analog switch produces a square wave signal of a low frequency by switching ON and OFF a preset level of DC voltage from a DC voltage setting circuit at a frequency of a control signal from a frequency setting circuit. The square wave signal is applied to the waveform analyzing apparatus and the low frequency output level is calibrated by a theoretical level of a frequency spectrum of the square wave signal. A diode detecting circuit is calibrated at the low frequency using the calibrated waveform analyzing apparatus, which in turn is calibrated at a high frequency using the calibrated diode detecting circuit.

Abstract: In an analyzer for measuring the frequency characteristics of quadripoles, comprising an indicator circuit in which the output of the quadripole to be measured is converted to an intermediate frequency by a mixer and a frequency-variable local oscillator, and comprising a variable-frequency second local oscillator whose output frequency is mixed with another mixer and with the frequency of the local oscillator to be converted to an input signal for the quadripole to be measured, the output frequency of the variable frequency second local oscillator is adjusted to be offset by at least .+-.5 MHz relative to the intermediate frequency value of the indicator circuit.

Abstract: A variable transient simulator employs a source of pulsating DC voltage for charging a first capacitance bank to a desired potential difference. After a device under test (DUT) is connected to a second capacitance bank, the charged-up first capacitance band is isolated from the DC voltage source and allowed to discharge into the second capacitance bank and, together, both capacitance banks provide discharging current into the DUT which simulates a desired loop during transient response. The simulator can provide repetitive as well as variable positive and negative transients.

Abstract: An emitter assembly of low-power electromagnetic signals with random or pseudo-random frequency variation is located inside an electromagnetic shield to be monitored. These signals are detected by at least one synchronous detection receiver located outside the shield, a second transmission channel, preferably constituted by an optic fiber, connecting the emitter and receiver assemblies to enable synchronous detection of signals transmitted via an electromagnetic channel through the shield. The amplitude of the electromagnetic signals received by the detector is significant of the quality of the shielding.

Abstract: An arrangement of digital circuitry is disclosed for testing a cable communication system to determine its performance when subjected to near-end cable crosstalk. The circuitry digitally generates a crosstalk signal indicative of the combined effect of one or more interfering sources and the near-end crosstalk coupling path linking the interfering sources with the system-under-test. The circuitry includes a pseudo-noise sequence generator for producing a stream of bits that are normally distributed and a digital filter, responsive to the sequence generator, for implementing a frequency characteristic corresponding to the spectral content of the interfering source as weighted by the near-end crosstalk path.

Abstract: A vector network analyzer comprising a circuit for measuring the real and imaginary components of the central spectral line in an RF pulse from a device-under-test is provided. The circuit comprises a modulator in response to a profiling pulse for modulating the amplitude of the RF pulse, mixers for down-converting the frequency of the amplitude modulated RF pulse, a narrow band filter for filtering the RF pulse having a bandwidth of 500 Hz and a synchronous detector responsive to the output of the crystal filter for providing a pair of dc outputs, which correspond to the real and imaginary components of the output of the device under test as the profiling pulse is shifted in time relative to the RF pulse.

Abstract: A method for measurement of transmission characteristics consists of supplying a test pulse to an object under test and measuring the pulse at the output of the object under test with the assistance of Fourier analysis. The test pulse is made up of a plurality of components which are equally spaced apart in frequency, and the initial phase values of each of the components are chosen so as to reduce loading of the object under test to an acceptable level both at the input of the test object and its output. Evaluation of the test pulse at the output of the object under test yields attentuation and phase shift characteristics for each component frequency. Initial phase angles for the components of the test pulse are determined by taking into consideration the likely distortion in the test object in such a manner that a minimum crest factor is attained both in the tranmitted pulse and in the pulse received at the output of the test object.

Abstract: Method for determining qualities and/or frequencies of electrical tuned circuits. The method includes the steps of exciting the turned circuit with a switching pulse which has a short rise and fall time as compared with a period corresponding to the resonant frequency of the circuit, and evaluating the oscillation dying out after the switching impulse.

Abstract: An apparatus for measuring the resistance of a test specimen includes an insulated-gate-bipolar-transistor (IGBT transistor) which is provided for applying a test current to the test specimen. A voltage measuring unit is provided including a serial connection of a voltage measuring device and an MOS transistor. A current measuring device is provided for measuring the test flowing through the test specimen. The voltage measured by the voltage measuring unit is used to compensate for the voltage drop across the IGBT transistor when calculating the resistance of the test specimen.

Abstract: The invention relates to a method and apparatus for testing the response of a stress wave sensor to confirm that the transducer and amplifier are functioning satisfactorily.A pulser is connected to the stress wave sensor at a point between the transducer and the amplifier. The pulser supplies a first and a second electrical pulse in series to the stress wave sensor. The first electrical pulse has a large amplitude such that it causes an operative transducer to oscillate and produce an additional electrical pulse. The first electrical pulse and the additional electrical pulse are supplied to the amplifier. An operative amplifier amplifies the first electrical pulse and any additional pulse to give an output signal, the output signal indicates if either the transducer or amplifier are not operating satisfactorily, the lack of an output signal indicates the amplifier is inoperative.

Abstract: A circuit is described for applying a potential to an electrode of a biosensing test cell, which electrode, when properly inserted in a female connector, is contacted by a pair spaced apart contacts. The circuit includes a source of excitation potential and an operational amplifier having one input connected to the source of excitation potential. A switching circuit is coupled between the operational amplifier and a first one of the spaced apart contacts, with the switch means exhibiting an impedance. A feedback circuit is connected between the second of the spaced-apart contacts and another input to the operational amplifier, to feed back a potential appearing at the second contact. The feedback is for the purpose of maintaining the output of the operational amplifier at a level which compensates for impedance losses in the swtiching circuit.

Abstract: An apparatus for determining the electromagnetic compatibility of a system, including a wide-band frequency source 2, optionally subject to frequency and amplitude modulation, and coupled to a cable 9 of the system. Accuracy may be improved by the addition of a current measuring arrangement 11, 12. The two coupling devices may be split and assembled into hinged frames to facilitate use.

Abstract: A digital sine-wave generator, which includes at least one sine waveform memory, is read out by the output of a phase accumulator to generate a first digital sine wave, a second digital sine wave and a digital cosine wave. The first digital sine wave is converted by a D-A converter into an analog signal and then supplied to a measuring object. The output of the measuring object and the second digital sine wave are multiplied in a first multiplying type D-A converter, and the output of the measuring object and the digital cosine wave are multiplied in a second multiplying type D-A converter. The outputs of the first and second multiplying type D-A converters are respectively integrated by first and second integrators for a period which is an integral multiple of the sine wave period.