Abstract: Electrical filter circuits are tested by connecting to the filter inputs without the need to connect to the filter outputs or to disconnect the outputs from a load. A signal generator of known source resistance applies a.c. signals successively over a range of frequencies to the filter inputs, and a voltmeter monitors the voltage across the filter inputs. Different types of filter have different characteristic shapes for the voltage/frequency curve, and processing is applied to the measured results in a compute to determine the location of inflections in the curve and other characteristics of the curve. Methods are disclosed for determining the values of the individual sub-components of the filter. Where the filter is an L-C filter, an interactive process is applied to successively improve the accuracy of the component value determinations. Using the techniques described enables the insertion loss of the filter also to be readily calculated by the computer.

Abstract: A parameter extraction technique for an electrical structure is based on a definition of network parameters that isolates pure mode responses of the electrical structure, and that makes mode conversion responses of the electrical structure negligible. A set of network parameters is obtained that represents pure mode responses for the electrical structure (410). These network parameters are processed to obtain model parameters that characterize each pure mode response (422, 424, 426, 428, 432, 434, 436, 438). Preferably, the mode specific parameters to combined to obtain mode independent parameters, such as coupling factor, propagation constant, and characteristic impedance values (440, 450).

Abstract: An apparatus (310) for characterizing a multiport circuit (390) includes a signal generator (320) and a circuit interface apparatus (330, 340, 350). The signal generator (320) has an output (329) selectable from among a set of composite signals that are linearly independent. The circuit interface apparatus (330, 340, 350) is coupled to the signal generator (320) and has an output (319) of a set of circuit stimulus signals derived from the set of composite signals, which set of circuit stimulus signals are linearly independent, and which together form a complete basis for describing any response for the multiport circuit (390). The circuit interface apparatus (330, 340, 350) has measurement circuitry for measuring circuit response of the multiport circuit (390). Preferably, the circuit interface apparatus (330, 340, 350) is formed from multiple two-port test sets.

Abstract: Apparatus and method for low cost monitoring the level of signal at a test point in a system for susceptibility to electromagnetic fields. A probe, including a detector diode, and a non-metallic, electrically overdamped conductor, which is transparent to the electromagnetic field, is used to monitor the signal level at a test point as an amplitude modulated radio frequency carrier. The carrier is transmitted to a monitor outside of the range of the electromagnetic field using a transmission link, such as an optical waveguide transmitter, that is transparent to the electromagnetic field when the system under test fails. The probe may include a plurality of detector diodes mounted on a printed circuit board in a shielded structure that is directly connected to the test wire of the circuit to be monitored.

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: Apparatus and method for low cost monitoring the level of signal at a test point in a system for susceptibility to electromagnetic fields. A probe, including a detector diode, and a non-metallic, electrically overdamped conductor, which is transparent to the electromagnetic field, is used to monitor the signal level at a test point as an amplitude modulated radio frequency carrier. The carrier is transmitted to a monitor outside of the range of the electromagnetic field using a transmission link, such as an optical waveguide transmitter, that is transparent to the electromagnetic field when the system under test fails. The system under test can then be removed from the electromagnetic field and, for each frequency at which the system failed, a voltage can be injected, using a voltage injection probe, into the system at another point to recreate the detected level of signal at the test point that was coupled into the system from the electromagnetic field.

Abstract: Apparatus and method for low cost monitoring the level of signal at a test point in a system for susceptibility to electromagnetic fields. A probe, including a detector diode, and a non-metallic, electrically overdamped conductor, which is transparent to the electromagnetic field, is used to monitor the signal level at a test point as an amplitude modulated radio frequency carrier. The carrier is transmitted to a monitor outside of the range of the electromagnetic field using a transmission link, such as an optical waveguide transmitter, that is transparent to the electromagnetic field when the system under test fails. The system under test can then be removed from the electromagnetic field and, for each frequency at which the system failed, a voltage can be injected, using a voltage injection probe, into the system at another point to recreate the detected level of signal at the test point that was coupled into the system from the electromagnetic field.

Abstract: The present invention provides a method and an apparatus for controlling and measuring the phase window of a data separator that is suitable for implementation in an automatic test equipment (ATE) system. The test circuit comprising cross-coupled flip-flops uses the pump up (PU) and pump down (PD) signals produced by a phase detector of a phase-locked loop (PLL) to digitally monitor the phase window. The PLL captures a fixed frequency data pattern provided to the data separator and tracks its frequency. The clock inputs of the cross-coupled flip-flops are driven by the pump up and pump down signals output by the phase detector. Once the PLL has captured the fixed frequency data pattern and settled, a single data bit is shifted from its initial position in the center of the phase window. The single data bit is shifted so that its phase leads or lags its initial position. When the single data bit is shifted in the data pattern, the phase detector correspondingly sets PU high, PD high, or both PU and PD high.

Abstract: A method to verify that a test and measurement system continues to operate within a predetermined acceptable range with respect to a given calibrated state previously defined for that system without the need for conventional external reference components. In accordance with one embodiment, performance verification of a network analyzer used to perform electrical measurements is achieved by storing RF "thru" measurement data (an RF thru measurement trace of the system) at the time of calibration at the factory or later repair and/or recalibration at a field service site. In accordance with another embodiment, performance verification of a lightwave component analyzer, used to perform electrical, electro-optical, opto-electrical, and optical measurements, is achieved by storing RF and optical thru measurement data (both an RF thru measurement trace of the system and an optical thru measurement trace of the system) at the time of calibration at the factory or later repair and/or recalibration.

Abstract: A system for evaluating the performance of an electrical filter installed on an electrical power supply network passing through the screening of a Faraday enclosure, includes a transmit device for transmitting an inlet electrical pulse to the inlet of the filter. A receive and processing unit receives and processes the response electrical signal at the outlet of the filter corresponding to the pulse. A display displays the results obtained by processing the signal. The inlet electrical pulse is coupled to the power supply network and is conveyed thereby through the filter. The response is obtained from the outlet of the filter by decoupling.

Abstract: Methods and apparatus are described for automatically determining correction factors for an electrical device to compensate for variations in the device as a result of mechanical and/or environmental influences, using a "three cable" method. A primary cable is used to conduct signals between electrical devices, for example a probe antenna and an antenna under test ("AUT") in an antenna test range. The primary cable is subjected to mechanical and/or environmental influences such as cable flexing and temperature changes. A first secondary cable and a second secondary cable are provided alongside the primary cable, and are subjected to similar environmental influences. A switching network connects the primary cable, the first secondary cable, and the second secondary cable in combinations to form three cable pairs during a calibration mode. A computing system determines insertion factors associated with the primary cable at a first time and a second time, using transfer functions associated with the cable pairs.

Abstract: A device for measuring and isolating noise-creating imbalances in a paired telecommunications line has an internal circuit which includes a pair of substantially balanced ac current outlet pathways and a pair of high voltage bias pathways in parallel. An oscillator in the circuit generates a low voltage longitudinal ac signal that is transmitted across the balanced pathways and a dc power source simultaneously generates a high voltage dc signal that is transmitted across the high voltage bias pathways. Both signals are further transmitted to the paired line where it is the function of the high voltage dc signal to punch through any concealed faults in the line. In contrast, the low voltage ac signal travels the length of each conductor in the line and returns to the circuit as a metallic voltage signal. If there is any imbalance between the two conductors, the metallic voltage signals for the two conductors will be different.

Abstract: A Moire measurement system uses spectral analysis to characterize the moire effect on a television signal introduced by a particular device. A known television signal is processed by the particular device, such as a video tape recorder, and the output is input to a spectral analyzer, such a windowed fast Fourier transform. The spectral analyzer includes input gating to select a portion of the known television signal from the particular device. The frequency of the desired component of the known television signal, together with the rms values of all the other components introduced by the Moire effect, give the X- and Y-coordinates of a point on an output display. The window is moved across the test signal, giving a family of X- and Y-coordinates that characterize the Moire effect as a function of amplitude, frequency or video pedestal. The Moire characteristics of the particular device then may be used to correct the output of the particular device.

Abstract: A generator provides a repetitive pattern which is applied to the input of a DUT and to the input of a timing generator. The output of the DUT follows the pattern at the input, switching the voltage between two levels. The High Frequency Voltage Sampler measures instantaneous voltage levels on the output waveform of the DUT. The timing generator uses the input signal to generate enable signals for the High Frequency Voltage Sampler which are synchronized to the test waveform and which can be time-delayed in precise intervals and with good repeatability. By placing this signal at a desired point anywhere along the test waveform the voltage at this point can be measured by the High Frequency Voltage Sampler. The High Frequency Voltage Sampler uses the leading edge of the enable signal to start the measurement of the instantaneous voltage level and it uses the trailing edge to store this level.

Abstract: A device for measuring and isolating noise-creating imbalances in a paired telecommunications line has an internal circuit which includes a pair of substantially balanced ac current outlet pathways in parallel, a differential amplifier connected to a pair of voltage inlet pathways, and an oscillator to supply longitudinal alternating current to the paired line across the balanced pathways. A longitudinal alternating current signal is sent from the oscillator to each conductor of the line across the outlet pathways, travels the length of each conductor and returns to the inlet pathways as a metallic voltage signal. If there is any imbalance between the two conductors, the metallic voltage signals for the two conductors will be different. Accordingly, the differential amplifier measures this difference and it is displayed in units of noise or balance.

Abstract: A frequency conversion section sweeps an object signal within a desired measurement frequency range, thereby frequency-converting the object signal. A peak detector detects a peak of an output from the frequency converting section. A measurement detector measures and detects the output from the frequency conversion section simultaneously with the peak detection by the peak detector. The measurement detector has an output characteristic lower than an output characteristic of the peak detector. A display displays an output from the peak detector and an output from the measurement detector on a single display screen, in synchronism with the sweeping by the frequency conversion section, with these outputs of the peak detector and the measurement detector being plotted along an axis representative of frequencies. In another mode of the invention, an alarm device indicates the fact that an output from the peak detector has exceeded a predetermined allowable limit level.

Abstract: A vector network analyzer for performing swept frequency measurements on non-linear RF devices, using either an internal or external signal source. This simplifies and speeds linear and non-linear amplifier and mixer measurements, such as impedance, amplifier gain, and mixer conversion loss, on the one hand, and measurement of harmonics, on the other hand.

Abstract: A one port tuner having a source port for connection to a device under test so that, in combination with a noise meter, the noise performance of such device can be evaluated. Preferably the one port tuner includes a plurality of predetermined admittances, a switching device having an output port for selectively connecting one of the admittances to the output port, and a two port device having a selectable response and interconnected between the output port of the switching device and the source port of the one port tuner. Desirably, the two port device includes a multiple-state attenuator where the signal passing through the attenuator is selectable in degree. Alternatively, or in combination, the two port device includes a phase shifter where the phase of the signals passing through the phase shifter are selectively shiftable.

Abstract: An arrangement for monitoring a transducer, or detector, which produces an analogue or digital output signal corresponding to a state sensed by the transducer. The invention is characterized in that the transducer includes activatable and deactivatable elements (RB 3, 23) which are intended to influence the transducer in a manner to cause the transducer to produce a signal which deviates from the actual state detected by the transducer, and in that there is provided a control circuit (10) which is intended to activate and/or deactivate the elements in a predetermined sequence, in response to the signal produced by the transducer. The arrangement also includes a control device for detecting the transducer output signal and comparing changes in the output signal in dependence on the activation and/or deactivation of the elements (RB 3, 23). The control device is constructed to detect whether or not the function of the transducer is correct, on the basis of this comparison.

Abstract: A fast, nondestructive, and low cost method for measuring the integrity of semiconductor multi-layer conducting structures uses a voltage spectral density technique. The method compares the magnitude and frequency of generally non-periodic low frequency voltages induced by direct current flow in test structures to the same parameters of a defect free structure.

Abstract: Method and apparatus for simultaneously measuring noise power of a two-port device under test (DUT) using a one-port tuner, a low-noise amplifier, a power divider with a plurality of outputs, and a plurality of noise meters. The noise meters are configured to measure available noise power in different frequency ranges which are closely spaced around a selected central frequency, thereby yielding the noise parameters of the DUT at the central frequency.

Abstract: A circuit for determining frequency response includes a voltage controlled oscillator (VCO) which generates a signal for application to a system under test and a counter which either counts quartz-stabilized pulses during a VCO period or which counts, during a quartz-stabilized counting interval, the VCO output itself. The counts represent with quartz accuracy the test frequency, which corresponds to the mean value within the counting interval, and are associated with respective measurement of signal level returned from the unit under test to thereby establish frequency response. Counts, together with corresponding levels developed by the system under test, are applied to a suitable display.