Abstract: A system for testing a motherboard performance includes a control device, a voltage processing circuit, a voltage regulating circuit and a voltage feedback circuit. The control device stores a plurality of predetermined voltage values and outputs control signals according to the plurality of predetermined voltage values. The voltage processing circuit receives the control signal and outputs a plurality of PWM signals according to the control signal. The voltage regulating circuit receives the plurality of PWM signal and outputs a plurality of DC voltage to a plurality of voltage input terminals of the motherboard. The voltage feedback circuit collects voltage signals at the plurality of voltage input terminals of the motherboard.

Abstract: An adapter is used in conjunction with a testing device to test pacing thresholds of an implanted lead. A main body of the adapter includes a plurality of adapter contacts that are configured to electrically couple to the plurality of connector contacts. A connector module includes a first port configured to couple to a first testing device connector and a second port configured to couple to a second testing device connector. A switch assembly includes a plurality of actuatable elements each associated with one of the adapter contacts. The actuatable elements are each selectably actuatable between a first state that electrically couples the associated adapter contact to the first port, a second state that electrically couples the associated adapter contact to the second port, and a third state that electrically decouples the associated adapter contact from the first and second ports.

Abstract: A method for testing a noise immunity of an integrated circuit; the method includes: determining a value of a power supply noise regardless of a relationship between the power supply noise value and a phase sensitive signal edge position resulting from an introduction of the power supply noise; receiving, by the integrated circuit, a phase sensitive signal; introducing jitter to the phase sensitive signal by a circuit adapted to generate a substantially continuous range of power supply noise such as to alter edges position of the phase sensitive signal; providing the jittered phase sensitive signal to at least one tested component of the integrated circuit; and evaluating at least one output signal generated by the at least tested component to determine the noise immunity of the integrated circuit.

Abstract: Method and device for monitoring the status of a sheath voltage arrester of a cable system, a verification signal being supplied to a measuring loop which comprises the sheath voltage arrester and a measurement signal which is subsequently produced in accordance with the frequency-dependent impedance of the sheath voltage arrester being measured at the measuring loop in order to establish the status of the sheath voltage arrester by evaluating the measurement signal.

Abstract: Application of open and short structures may result in improved accuracy in determination of ABCD parameters of a substantially symmetric THRU for purposes of bisect de-embedding. Either one or both of the open and/or short techniques may be used to improve results of an ABCD optimization algorithm. Bisect de-embedding may then be performed to determine the ABCD parameters of a device under test based on the ABCD parameters of the substantially symmetric THRU and measured s-parameters of the substantially symmetric THRU and the embedded device under test.

Abstract: Techniques for calibrating non-linearities of ADCs are described, which can be applied whether or not the non-linearities change with frequency. When the non-linearities do not change (are static), the frequency of a calibrating signal is first estimated coarsely in a calibration mode, then a fine estimate is determined using the coarse estimate. These estimates are then used to predict the sinusoidal signal using a linear predictor. A Look Up Table (LUT) containing corrections to the ADC is derived from this result. The LUT is then used in a normal operating mode to correct the output of the ADC. In a case where the characteristics of the non-linearities of the input signal are dynamic and thus change with frequency, a frequency spectrum of interest is broken into several regions. In each of these regions, a frequency is identified and used as a calibrating signal to generate the corresponding LUT.

Abstract: A system for online relative phase calibration is provided. The system includes at least one excitation source configured to generate multiple excitation signals. The system also includes at least two sensors coupled to respective ones of the at least one excitation source via a transmission line, wherein the two sensors are configured to receive respective ones of the excitation signals. The system further includes at least two phase detectors configured to receive at least two reflected signals from the two sensors via the transmission line, wherein each of the two phase detectors are configured to output a respective voltage representing a phase difference between respective ones of the reflected signals and respective ones of the excitation signals. The system also includes a switch coupled to the sensors and the phase detectors, the switch configured to switch the phase detectors between the sensors at a pre-determined switching interval.

Abstract: Measurement arrangement and method for active load pull measurements of a device under test (1). A wideband analog-to-digital conversion block (3) is provided for obtaining measurement data. First and second injection signal generators (7, 8) are connected to a source side and a load side of the device under test (1). This set up allows to create predetermined reflection coefficients at reference planes of the device under test (1). Injection signal parameters as determined are converted into the injection signals at the source and load side by digital-to-analog conversion. The wideband analog-to-digital conversion block (3) is further arranged for analog-to-digital conversion of the intermediate frequency signals to obtain the actual measured reflection coefficient versus frequency functions with a first frequency resolution. The first frequency resolution applied in the analog-to-digital conversion is equal to or better than a second frequency resolution applied in the digital-to-analog conversion.

Abstract: The invention concerns in general measurement of the transfer function of linear time invariant systems, more particular the calibration of such systems based on a measured transfer function. According to a first aspect the present invention an arrangement for measuring the transfer function of a linear time-invariant system is disclosed. According to a second aspect of the present invention the arrangement is implemented into a linear time-invariant circuitry having a transfer function representing the amplitude and phase characteristic of the circuitry, where by means of the arrangement for measuring the transfer function the transfer function can be optimized in accordance with certain criteria on-the-fly, i.e. in or before operation of the circuit. Finally, an effective and simple method for measuring of the transfer function of a linear time-invariant system together with the use or application of the method is shown.

Abstract: Provided is a test apparatus for testing the jitter tolerance of a device under test which receives a data signal and a strobe signal indicating the timing at which the data signal should be received, and acquires the data signal at the timing indicated by the strobe signal, including a signal generating section which generates the data signal and the strobe signal to be supplied to the device under test, a jitter applying section which applies a combinational jitter obtained by combining a data jitter which should be tolerated for the data signal and a strobe jitter which should be tolerated for the strobe signal to the data signal or the strobe signal, and a signal supplying section which supplies the data signal and the strobe signal, to one of which the combinational jitter has been applied, to the device under test.

Abstract: A sensor for sensing a measurand is described, the sensor comprising a coplanar waveguide with a first surface and a second surface opposite to the first surface; a first structure with a first periodically varying dielectric characteristic, the first structure being arranged on the first surface of the coplanar waveguide; and a second structure with a second periodically varying dielectric characteristic, the second structure being arranged on the second surface of the coplanar waveguide, wherein a unit-cell of the structures with periodically varying dielectric characteristics is dimensioned such that the sensor has a frequency dependent transfer behavior with at least one transfer minimum, and wherein the sensor is implemented such that the measurand influences the first periodically varying dielectric characteristic of the first structure or the second periodically varying dielectric characteristic of the second structure or a relation between such first structure and second structure.

Abstract: A signal processing system according to various aspects of the present invention includes an excursion signal generator, a scaling system and a filter system. The excursion signal generator identifies a peak portion of a signal that exceeds a threshold and generates a corresponding excursion signal. The scaling system applies a real scale factor to contiguous sets of excursion samples in order to optimize peak-reduction performance. The filter system filters the excursion signal to remove unwanted frequency components from the excursion signal. The filtered excursion signal may then be subtracted from a delayed version of the original signal to reduce the peak. The signal processing system may also control power consumption by adjusting the threshold. The signal processing system may additionally adjust the scale of the excursion signal and/or individual channel signals, such as to meet constraints on channel noise and output spectrum, or to optimize peak reduction.

Abstract: A method for manufacturing an equalizer used to compensate a digital signal passed by a transmission line, in which the digital signal can be presented as a frequency-domain function. The method includes measuring a the transmission line scattering-parameter; performing an integration and a differentiation about the transmission line scattering-parameter, the frequency-domain function, the ideal gain, and an equalizer scattering-parameter to get the component impedances of the equalizer; and manufacturing the equalizer circuit with the derived component impedances.

Abstract: Techniques for bisecting a symmetric, substantially transmissive two-port network (a THRU structure) through an optimization solution of the relevant equations defined by transmission matrix mathematics are described. Bisect de-embedding may be performed using a single substantially symmetric THRU structure, a first half of a first substantially symmetric THRU structure and a second half of a second substantially symmetric THRU structure, and by combining bisect de-embedding with conventionally known de-embedding techniques.

Abstract: One embodiment of the present invention provides a system that facilitates high-sensitivity detection of an anomaly in telemetry data from an electronic system using a telemetric impulsional response fingerprint of the telemetry data. During operation, the system applies a sudden impulse step change to one or more operational parameters of the electronic system during operation. Next, the system generates a three-dimensional (3D) telemetric impulsional response fingerprint (TIRF) surface from a dynamic response in the telemetry data to the sudden impulse step change. The system then determines from the 3D TIRF surface whether the telemetry data contains an anomaly.

Abstract: A measurement and correction method provides for a complete full correction of a true-mode system using only the single ended error matrix developed for 4 port correction of single ended measurements. The degree of misalignment of the balanced sources may be determined from these measurements.

Abstract: A measuring apparatus that measures a characteristic of a device under measurement is provided. The measuring apparatus includes: a signal generating section that outputs a forward signal to the device under measurement through a device side terminal; a directional coupler that outputs a backward split signal obtained by splitting a part of a backward signal inputted from the device under measurement through the device side terminal; a backward mixer that outputs a backward detection signal obtained by multiplying a local signal having a predetermined frequency by the backward split signal; and an analysis section that analyzes a characteristic of the device under measurement based on the backward detection signal. The directional coupler is included in a multilayer substrate, and the backward mixer is included in a chip provided on a surface of the multilayer substrate.

Abstract: A method for inspecting a semiconductor device includes establishing a first circuit state in which electrical conduction through at least one of branch transmission line portions is established and electrical conduction through at least one other branch transmission line portion is prevented. Then, electrical signal reflection characteristics of the transmission line are measured. The method also includes establishing a second circuit state in which electrical conduction through the at least one of the branch transmission line portions is prevented and electrical conduction through the at least one other branch transmission line portions is established. Then, the electrical signal reflection characteristics of the transmission line are measured. The second circuit state is a mirror image of the first circuit state with respect to the primary transmission line. The measured values are compared.

Abstract: A method for measuring and characterizing the nonlinearities of a display device by adaptive bisection using human perception for measurement. This method makes no assumptions about a display device's characteristics and can characterize any type of display device with any arbitrarily complex monotonic display transfer function. Unlike other display measurement solutions, this process is completely software based and has no hardware measurement device requirements that would raise costs and limit portability. As a result, this process can be distributed and applied commercially at a very low cost.

Abstract: Selectable attenuators are used in the reference and test paths of a VNA, with attenuation automatically inserted or deleted when the Device Under Test (DUT) attenuation reaches predetermined thresholds. Attenuation in the reference channel is removed when the signal in the test channel is sufficient to overcome the leakage of the reference channel. Additionally, attenuation is removed from the test channel when the reference channel has a high attenuation inserted to further increase the difference between the leakage reference signal and the reduced test channel signal thus allowing lower isolation requirements on the two (or more) receiving channels.

Abstract: A method and apparatus is provided for measuring alternating current (AC) and direct current (DC) characteristics of a plurality of semiconductor devices. A ring oscillator generates pulses to drive the plurality of semiconductor devices under test. Current/Voltage (IV) and transfer characteristics of the plurality of semiconductor devices are measured using only DC input/output.

Abstract: A method and a measurement system determine a transmission response of a device under test (DUT). The method includes measuring a reflection response from a first port of the DUT while a known reflective termination is on a second port of the DUT, and time gating the measured reflection response to produce a gated reflection response that is the transmission response of the DUT. The measurement system includes a vector network analyzer, a controller, a memory and a computer program. The computer program includes instructions that implement measuring the reflection response from the first port of the DUT, and further implement time gating the measured reflection response. The time gating isolates reflection data associated with the known reflective termination from the measured reflection response.

Abstract: A method and apparatus for measuring alternating current (AC) and direct current (DC) characteristics of a plurality of semiconductor devices. A ring oscillator generates pulses to drive the plurality of semiconductor devices under test. Current/Voltage (IV) and transfer characteristics of the plurality of semiconductor devices are measured using only DC input/output.

Abstract: A system and method of characterizing a device under test wherein a signal is injected into the device under test, the response to the injected signal is measured to determine the impedance of the device under test in the frequency domain, the impedance is converted to the time domain, and the voltage noise of the device under test is calculated based on the impedance of the device under test in the time domain.

Abstract: A method, system and program product to measure performance of a device dedicated to a phase locked loop (PLL). A resistor-inductor-capacitor (RLC) model is produced to simulate the PLL. The RLC model and the device to be measured are mapped together into a test circuit and the characteristics of the test circuit is analyzed to determine whether the device, if attached to the PLL represented by the RLC model, can meet the required standard of performance. This invention can be used to measure the performance of all kinds of devices attached to all kinds of PLLs.

Abstract: A first test signal from a test signal source is provided to a spectrum analyzer to produce first measurement data. The test signal source is expressed by a first transfer function G(w) and the spectrum analyzer is expressed by second transfer function F(w). A second test signal is provided to the spectrum analyzer to produce second measurement data where the second test signal is derived from the first test signal by shifting the frequency by a known increment. From the first and second measurement data, the components are the same on G(w) but different on F(w). The G(w) components are cancelled by calculation using the first and second measurement data and then the second transfer function F(w) is evaluated independently of G(w).

Abstract: One embodiment of the invention provides a system that characterizes cells within an integrated circuit. During operation, the system obtains a number of input noise signals to be applied to the cell. The system then simulates responses of the cell to each of the input noise signals, and stores a representation of the responses. This allows a subsequent analysis operation to access the stored representation to determine a response of the cell instead of having to perform a time-consuming simulation operation.

Abstract: The invention concerns a method and a device for phase calculation from attenuation values using a Hilbert transform for reflectometric measurements in the frequency domain. The invention is characterized in that the measuring system comprises a signal source for a measurement signal, a coupling element connected to the signal source, and an object to be measured connected to the coupling element. The part of the measurement signal reflected by the object to be measured is uncoupled via the coupling element and measured at a collector. The invention is further characterized in that an attenuator is mounted in the signal path, between the coupling element and the object to be measured. The attenuator can also be comprised in the coupling element.

Abstract: A method comprises generating first and second current levels and measuring the first and second current levels. The method further comprises alternately generating the first and second current levels repeatedly to generate a periodic current waveform, and measuring the voltage at at least one port in a system a plurality of times to obtain a plurality of sets of voltage measurements. The plurality of sets of voltage measurements are averaged. The method further comprises alternately generating the first and second current levels repeatedly at a predetermined number of different clock frequencies, determining a Fourier component of the averaged voltage measurements to determine clock frequency-dependent noises, removing the clock frequency-dependent noises to generate a filtered average voltage, and determining an impedance by dividing a Fourier component of the filtered average voltage by a Fourier component of the periodic current waveform having alternating first and second current levels.

Abstract: According to one embodiment of the invention, a computerized method for tuning a wire to have a particular electrical length is provided. The method includes providing a reference wire and the wire to be tuned. The method also includes transmitting a reference signal and a test signal over the reference wire and the wire, respectively, to a destination. The method also includes determining the time difference between arrival of the respective signals at the destination. The method also includes providing, based on the time difference, an indication of the location along the length of the wire where the wire has an electrical length approximately equal to the electrical length of the reference wire.

Abstract: A system for the detection of narrowband signals in wideband noise that combines information across two frequency channels that straddle the frequency of the target signal. Two band pass filters having center frequencies that straddle the frequency of the target signal and that have phase transfer functions that differ by 180 degrees relative to each other at the frequency of the target signal. The presence of the target signal is detected by performing a running cross-correlation of the outputs of saturating, non-linearities that follow from the filters, and determining when the output of the running cross-correlator drops below a predetermined threshold due to the phase shift between the two filter responses caused by the presence of the target signal.

Abstract: A method and apparatus for characterizing a device under test (“DUT”) calibrates a multiport test set and measures S-parameters [S] of the DUT. The method and apparatus further involves determining elements of a scalar orthogonal matrix [M] corresponding to terminals of the DUT and DUT modes of operation. The scalar orthogonal matrix [M] comprises a row of elements representing a single-ended terminal of the DUT, and four rows of elements representing a balanced terminal of the DUT. The S-parameters of the DUT are then transformed into mixed-mode S-parameters [Smm] according to Smm=MSM−1. A method of and apparatus for characterizing a DUT involves calibrating a multiport test set, coupling the DUT to the multiport test set, and measuring S-parameters of the DUT. The S-parameters are converted to a time domain representation and at least one of the S-parameters is convolved with a simulated input signal to generate an output response.

Abstract: In a spectroscopic process a sample for producing a test spectral line or spectrum of at least one component contained in the sample is stimulated and the transmitted and/or emitted electromagnetic rays are used to create the test spectral line or spectrum. In order to improve such a spectroscopic process to such an extent that variations of certain parameters, which alter the shape and/or occurrence of a spectral line, are compensated, a comparison spectral line or spectrum of a known comparison material is produced under substantially the same parameters as the sample. The comparison spectral line or spectrum is compared with an ideal comparison spectral line or spectrum in order to calculate a transfer function, and the transfer function is applied to the test spectral line or spectrum in order to calculate a corrected test spectral line or spectrum.

Abstract: A system for determining a response characteristic of an nth order linear system, such as a phase locked loop, is disclosed. An input signal is supplied to the linear system, and the system measures an output signal produced by the linear system. A variance record is constructed for a measurable quantity, such as jitter, extracted from the output signal. The response characteristic of the linear system is then obtained from the variance record. The response characteristic, such as the transfer function, noise processes, and/or power spectral density (PSD), may be found through a numerical or analytical solution to a mathematical relationship between a response function of the nth order linear system and the variance record.

Abstract: Analysis of a linear time-invariant system's sampled output data can identify the unknown continuous-time transfer function of the system. The method excites the system with two orthogonal sinusoids and constructs a linear complex equation that relates the sampled output points to the unknown values of the transfer function. This method can identify the continuous-time dynamics of a hard disk drive system in which the number of servo bursts and the spinning speed of the disk fix the sampling frequency of the output. In the hard disk case the input excitation signal is passed through a specially designed pre-filter and the sampled output data are modified to account for the control input and external disturbances. The method can also be used to reconstruct the output of the system even in the presence of aliasing provided the input excitation can be approximated by a sum of sinusoids with known frequencies.

Abstract: With a view to determining the complex transfer function of a measuring instrument, a line spectrum is fed in from a pulse generator which, for example, is constituted by a step-recovery diode, and the digitized output signal arising at the output of the measuring instrument is evaluated in a computer.

Abstract: An inversion in-phase component and a non-inversion in-phase component of a modulation signal inputted from a quadrature modulation section of a sample machine captured in a pair of signal lines, and an inversion quadrature component and a non-inversion quadrature component of the modulation signal, are computed by a pair of computers, respectively. In addition, these components are analog/digital converted at a pair of analog/digital converting sections, and then, are stored in a waveform storage memory. A modulation characteristics analyzing section performs predetermined computation processing of the storage data, thereby analyzing modulation characteristics of the modulation signal. A balance/imbalance switching section is provided at each one of the pair of signal lines, and the signal lines are grounded, whereby a state for transmitting a modulation signal of a balance transmission format is switched to a state for transmitting a modulation signal of an imbalance transmission format.

Abstract: A circuit that provides the root-mean-square (RMS) value of an input signal and that detects and independently recovers from an output fault condition is provided. The circuit includes reconfigurable circuitry that changes from normal operating mode to fault recovery mode when an output fault is detected. During fault recovery mode, the circuit provides a modified output signal that allows independent recovery from an output fault condition. Once recovery is complete, the circuit returns to normal operating mode and provides a DC output signal proportional to the RMS value of an AC input signal.

Abstract: A method is provided for quickly determining low threshold voltages and high threshold voltages of a test circuit. Specifically, a transformed voltage transfer curve for the test circuit is generated. The maximum and minimum points of the transfer circuit are determined to calculate transformed voltage threshold values. The transformed voltage threshold are transformed to find the desired threshold voltages.

Abstract: Absolute delay of a FTD is characterized by applying a stimulus signal to a first port of the FTD. A second port of the FTD is coupled to a delay element having a known delay and a reflective termination. A drive signal is applied to a third port of the FTD. A time domain reflection response to the stimulus signal is obtained and a signal peak within the response that corresponds to a return signal from the reflective termination is identified. Absolute delay of the frequency translation device is then extracted based on the known delay of the delay element and a time that corresponds to the occurrence of the identified signal peak. Delay versus frequency is characterized by isolating a segment of the obtained time domain reflection response that corresponds to a return signal from the reflective termination. Inverse frequency transforming the isolated segment of the time domain reflection response provides delay characteristics of the FTD versus frequency.

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 filters have different characteristic shapes for the voltage/frequency curve, and processing is applied to the measured results in a computer 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-section 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 sampling function generator capable of providing continuous output corresponding to a sampling function. The sampling function generator 1 comprises a B spline function generation circuit 10, delay circuits 12 and 14, inverting amplifiers 16 and 18, and adding circuits 20 and 22. The B-spline function generation circuit 10 continuously produces signal waveforms according to a third order B spline function. After delayed by predetermined time or attenuated to 1/4 amplitude and inverted, the signal waveforms are combined in the adding circuits 20 and 22 to form a signal waveforms of a sampling function that is differentiable once over the range and has values of local support.

Abstract: Absolute delay of a FTD is characterized by applying a stimulus signal to a first port of the FTD. A second port of the FTD is coupled to a delay element having a known delay and a reflective termination. A drive signal is applied to a third port of the FTD. A time domain reflection response to the stimulus signal is obtained and a signal peak within the response that corresponds to a return signal from the reflective termination is identified. Absolute delay of the frequency translation device is then extracted based on the known delay of the delay element and a time that corresponds to the occurrence of the identified signal peak. Delay versus frequency is characterized by isolating a segment of the obtained time domain reflection response that corresponds to a return signal from the reflective termination. Inverse frequency transforming the isolated segment of the time domain reflection response provides delay characteristics of the FTD versus frequency.

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 T-section low pass 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: 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 method for determining the harmonic phase response ∠POx of a device under test (DUT) is performed on a vector network analyzer (VNA). The phase ∠GN1 of the transfer response GN1 of the DUT at the fundamental frequency is determined from VNA measurements after appropriate normalization. The corrected phase ∠GHxC of the harmonic transfer response of the DUT is determined from VNA measurements after appropriate normalization. The corrected phase ∠GHxC of the harmonic transfer coefficient GHx is subtracted from a predetermined phase reference ∠refx to obtain a difference ∠refx−∠GHxC, and the phase ∠GN1 of the transfer coefficient GN1 at the fundamental frequency is added to the difference ∠refx−∠GHxC to obtain the harmonic phase offset ∠POx. For the second and third harmonics using a clipping waveform, the phase reference ∠refx is 180°.

Abstract: An apparatus and method for determining a transducers principle operating parameters which utilizes two transfer functions; 1) the transfer function from the pressure response (50) to the voltage drop across the transducer (60); and 2) the transfer function from the pressure response (50) to the current flow through the transducer(70). The parameters of simple filter equations are fitted to these measured response curves. The transducers operating parameters are then calculated directly from the fitted parameters of the filter equations. Several methods for measuring the pressure and determining the appropriate filter equations are shown.

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 C-section low pass 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: For determination of the transmission function of a measurement apparatus, in particular of a spectrum analyzer, a calibration signal, modulated with a modulation signed such that a line spectrum arises within the frequency band of interest is provided in the measurement apparatus. In a computer, the modulation signal is calculated from the digitized output signal of the measurement apparatus. The desired transmission function is then calculated therefrom according to magnitude and phase.

Abstract: An improved fuel control in which the transfer function of a wide-range exhaust gas oxygen sensor is automatically and periodically learned or re-learned in the course of vehicle operation. The oxygen sensor is calibrated at two different operating conditions: at a stoichiometric air/fuel ratio, and at a fuel cut-off or free-air ratio. The first operating condition occurs during steady state operation when a switching sensor disposed in the exhaust gas stream downstream of the catalytic converter indicates that the engine is being fueled at the stoichiometric air/fuel ratio. The second operating condition occurs when engine fuel is shut off, either during vehicle deceleration, or when the engine is turned off. Once both calibration points have been determined, the transfer function of the wide range sensor is adjusted to match the stored voltages, and engine fueling is thereafter based on the adjusted transfer function.