Abstract: A longitudinal balance measuring bridge circuit includes a common mode signal injection circuit in the form of a center tapped, 4:1 balanced matching transformer. The signal injection circuit is coupleable to an item under test (IUT) and to a source of common mode signal, and provides the common mode signal to the IUT. The common mode signal injection circuit includes balanced outputs. A common mode filter is coupled to the balanced outputs of the common mode signal injection circuit and attenuates the common mode signal. The common mode filter also includes balanced outputs on which are provided a transverse signal resulting from the common mode signal provided to the IUT. A signal output balun is coupled to the balanced outputs of the common mode filter and converts the transverse signal to an unbalanced signal.

Abstract: Time-resolved emission can be used to measure loop-synchronous, small-signal voltage perturbation in integrated circuits. In this technique the measurements are completely non-invasive and so reflect the true device behavior. The time-dependant propagation delay caused by Vdd modulation also shows the expected qualitative signature. This technique should find applications in circuits with relatively fast clock-like circuits where loop-synchronous voltage pickup is limiting circuit behavior.

Abstract: A spectrum analyzer includes an array of frequency-selective bulk acoustic wave (BAW) resonators each tuned to a predetermined different resonant frequency. The spectrum analyzer further includes a broadband BAW resonator that generates acoustic energy when connected to a signal source. An acoustic coupling transmits the acoustic energy generated by the broadband BAW resonator to the frequency-selective BAW resonators so that one of the frequency-selective BAW resonators will generate an electrical output signal if the acoustic energy transmitted from the broadband BAW resonator contains spectral components at its predetermined resonant frequency.

Abstract: A handheld portable battery powered digital antenna and/or network analyzer which derives complex impedance values at a given frequency includes an internal direct digital synthesis generator and provides software-defined multiple operating modes and real time graphic scalar and polar displays of results in a multiplicity of user-selectable visual formats.

Abstract: A method and apparatus for synchronizing presentation of multi-domain measurements using actual or quasi 3-D representation. The synchronization between data streams acquired in different measurement domains is performed by using timestamps, a common trigger event, or a common clock, or a combination of any or all of them. In this way, for example, a transient anomaly in the RF spectrum of a communications signal may be correlated with, and displayed with, a related corrupted data communications packet.

Abstract: An integrated spectrum analyzer for performing on-chip power spectrum measurements, includes a digital autocorrelator that includes an analog input for inputting analog signal samples from a chip, an analog-to-digital converter for converting the analog signal samples into digital signal samples, a storage register for storing a first converted digital signal sample for a period of time, a digital multiplier for multiplying the first stored digital signal after the period of time with a second undelayed digital signal sample to produce a product of multiplication, and an accumulator for accumulating a plurality of products of multiplication for each new period of time. The digital autocorrelator computes an autocorrelation function based on the analog signal samples and is integrally formed on the chip for performing power spectrum measurements on the analog signal samples to compute the autocorrelation function.

Abstract: A spectrum analyzer includes a resonator board that in turn has a substrate and a plurality of resonators. Each resonator may include a first segment that includes a first segment discontinuity and that may also define a boundary and a second segment that has a second segment discontinuity. The second segment may be spaced from the first segment and wherein the second segment is disposed within the boundary defined by the first segment. The resonator board may also include a plurality of wires each of which may be generally parallel to each other and each having a resonator interposed therebetween.

Abstract: A system and method for monitoring and controlling the properties of fluids is disclosed. The inventive concept employs impedance spectroscopy (IS) measurements, and is suitable for real-time, in situ, monitoring and quality control operations, such as quality control during the manufacture of blended lubricants. IS data are obtained for three or more frequencies, where the lowest frequency is less than 1 Hz and the highest frequency is greater than 1 Hz. These data may be interpreted according to statistical techniques such as Principal Component Regression, analytical techniques such as equivalent circuit modeling, or by a combination thereof. The data analysis provides characteristics, or IS signatures, relating to the properties of the fluid. IS signatures for a test fluid are compared to IS signatures for calibration fluids to determine whether the properties of the test fluid fall within specified limits.

Abstract: A spectrum analyzer with a compensation circuitry for prevention of measurement accuracy deterioration due to local oscillators phase noise.

Abstract: A scheme to provide a spectral view of the signals present at the customer premises equipment by the network operator and includes a digital signal processor (DSP) or other signal processing apparatus integrated into a customer premises equipment (CPE) tuner in which the DSP or other signal processing apparatus is operational to perform a spectral analysis.

Abstract: In testing a distributed feedback semiconductor laser with a grating having a phase shift part, a spectrum of the distributed feedback semiconductor laser is measured. A difference between an intensity of a side mode at a high-frequency-wave side of a main mode and an intensity of a side mode at a low-frequency-wave side of the main mode is calculated. The distributed feedback semiconductor laser is judged non-defective when the difference is more than a certain value.

Abstract: A spectrum analyzer includes a resonator board that in turn has a substrate and a plurality of resonators. Each resonator may include a first segment that includes a first segment discontinuity and that may also define a boundary and a second segment that has a second segment discontinuity. The second segment may be spaced from the first segment and wherein the second segment is disposed within the boundary defined by the first segment. The resonator board may also include a plurality of wires each of which may be generally parallel to each other and each having a resonator interposed therebetween.

Abstract: A system and method for monitoring and controlling the properties of fluids is disclosed. The inventive concept employs impedance spectroscopy (IS) measurements, and is suitable for real-time, in situ, monitoring and quality control operations, such as quality control during the manufacture of blended lubricants. IS data are obtained for three or more frequencies, where the lowest frequency is less than 1 Hz and the highest frequency is greater than 1 Hz. These data may be interpreted according to statistical techniques such as Principal Component Regression, analytical techniques such as equivalent circuit modeling, or by a combination thereof. The data analysis provides characteristics, or IS signatures, relating to the properties of the fluid. IS signatures for a test fluid are compared to IS signatures for calibration fluids to determine whether the properties of the test fluid fall within specified limits.

Abstract: A method and apparatus compensates for phase noise added by a spectrum analyzer from phase noise measurements of a signal under test (SUT) taken by the spectrum analyzer. The method comprises the steps of measuring the phase noise of the SUT, determining the added phase noise of the spectrum analyzer, and applying a mathematical correction to the measured phase noise. A spectrum analyzer apparatus that compensates for added phase noise comprises a controller portion, a memory portion, a signal conversion and detection portion, and a compensation algorithm stored in the memory portion. A system that compensates for added phase noise comprises a controller having a control algorithm and a spectrum analyzer. The compensation and control algorithms are computer programs that implement the method of the present invention.

Abstract: In one embodiment, a method of calibrating a multi-port vector network analyzer (VNA) includes (i) performing two-port calibrations on pairs of ports to determine forward and reverse systematic error terms associated with each pair of ports, wherein the pairs of ports are selected such that each port's systematic error terms (directivity, source match, reflection tracking, and load match) are determined, (ii) generating a switch error correction matrix using data from the two-port calibrations, and (iii) performing unknown thru calibration for at least one pair of ports that was not utilized in step (i), wherein the unknown thru calibration comprises applying the switch error correction matrix to measurement data and determining transmission tracking error terms using the corrected measurement data.

Abstract: In one embodiment, a method comprises applying a stimulus signal to a reference frequency translation device (FTD) by a vector network analyzer during a calibration mode, wherein the reference FTD possesses equal conversion efficiency in forward and reverse directions and the reference FTD possesses unknown input and output reflection characteristics; measuring a response of the reference FTD; and determining forward and reverse transmission tracking error terms using data from the measured response and single-port error calibration terms.

Abstract: An impedance spectroscopy technique and system for detecting in real time engine coolant contamination in lubricant. A probe is disposed in the lubricant and the probe excited with an a.c. voltage frequency sweep over a selected frequency range. The current and current phase angle are measured at selected frequency intervals and the reactance and resistance computed and plotted at each frequency internal as Nyquist plots. The Nyquist minimum is determined at various lubricant temperatures and a database compiled. The probe is then excited in-situ and current measurements taken for a selected frequency lower than the Nyquist minimum to insure measurement of electrode surfaces characteristics. The reactance and resistance are then computed and the angle ? of change (slope) of reactance with respect to resistance computed. The value of ? is then compared with values of contamination concentration ? versus ? in a database, and the value of ? determined by interpolation.

Abstract: A database is compiled of values of the frequency fNM corresponding to the minimum reactance Z?MIN (Nyquist minimum) versus temperature TL over a selected range of temperatures for a probe immersed in a sample of the fluid to be monitored and excited by an a.c. voltage and the frequency swept over a range to cover both bulk fluid and electrode interface impedance characteristics. The probe is then excited in situ and the temperature measured. The Nyquist minimum is then determined from the database and the current measured on the low frequency (interfacial) side of the Nyquist minimum. The angle ? of the rate of change of resistance Z? with respect to resistance Z? and magnitude of the impedance ZS is then determined from the current measurement; and, the fluid condition ? determined from a previously compiled database of values of ?, ZS and ?.

Abstract: A system and method compensate for phase noise of a spectrum analyzer based on an established model of the phase noise that accommodates a variety of operating states of the spectrum analyzer. The model is used to form an array that is applied to extract an output signal from measurement traces that are acquired by the spectrum analyzer.

Abstract: A method for measuring the EIRP (Effective Isotropic Radiated Power) of a satellite downlink carrier signal is performed by or under the control of a processor located, for example, at a technical operations center of a satellite communications company. The processor operates in accordance with a computer program which automatically identifies a carrier frequency corresponding to a customer, measures a level and bandwidth of the downlink signal at the customer carrier frequency, determines a level of a reference carrier signal, compares the level of the downlink signal to the level of the reference carrier signal, and determines EIRP power of the downlink signal based on the comparing step. The measured EIRP value is then compared to an EIRP value contractually assigned to the customer, and the difference determines the manner in which the measured EIRP value deviates from the assigned power.

Abstract: The present invention is directed to a centrifugal pump wherein voltage and current data are detected from voltage and current sensors in the motor controller of a pump motor. A power signal is then generated from the voltage and current data and spectrally analyzed to determine the presence of unwanted harmonics which are indicative of mechanical disturbances in the pump. As such, anomalies resulting from mechanical interference may be detected and a warning flag provided without additional transducers and other instruments on the motor or pump.

Abstract: A test apparatus and method of measuring pulling of the frequency of an oscillator. The apparatus includes a bias tee, a power supply, a spectrum analyzer, a second power supply, a symmetrical resistive power splitter, a power meter and a synthesized signal generator. The method includes sweeping the synthesized signal generator frequency from the nominal frequency down to a first frequency. The first frequency is recorded when the oscillator goes out of frequency lock as a first pulling frequency. The synthesized signal generator frequency is then sweet from the nominal frequency up to a second frequency and the second pulling frequency is recorded when the oscillator goes out of frequency lock. The difference between the first and second pulling frequencies is the peak to peak pulling value.

Abstract: A spectrum analyzer is combined with the VNA in a housing measuring approximately 4 pounds with the spectrum analyzer portion operating from slightly above DC to above 3.0 GHz. The components for the spectrum analyzer are provided on a separate printed circuit board from the two printed circuit boards for the display and VNA components in the housing. The design of components for the printed circuit board enable a significant reduction of size from a typical spectrum analyzer which weighs 40 pounds or more and measures on the order of 2 feet by 3 feet by 0.5 feet.

Abstract: Sampling is performed. A strobe signal is generated from a first signal. Multiple sampled signals are sampled using the strobe signal. Each of the multiple sampled signals is synchronous with its own clock reference and each of clock references are asynchronous with respect to each other. Analog-to-digital conversion is performed on each sampled value of each of the multiple sampled signals. For each of the clock references that is not synchronous with the first signal, a phase comparison is performed between the clock reference and the first signal to produce a difference value. The difference value indicates a phase difference between the clock reference and the first signal. Analog-to-digital conversion of the difference value is performed at a frequency determined by the strobe signal.

Abstract: An analog filter in an integrated circuit is tested by placing the filter in a feedback loop. The filter is tested by determining whether the analog filter, while in the feedback loop, provides a signal that oscillates within a predetermined tolerance of an expected frequency.

Abstract: Trigger jitter in an internally triggered real time digital oscilloscope can be reduced through correcting the horizontal position value obtained from a conventional trigger interpolation mechanism by an error or substitute amount learned from an inspection of the acquisition record that notes where in the acquisition record the signal actually crossed the trigger threshold. The display (and measurement) sub-systems that utilize the selection by panning and zooming of a portion of the acquisition record for viewing (and measurement) are supplied with the acquisition record portion of interest, and with an associated horizontal position value that originates with trigger interpolation and that may be subsequently modified by panning.

Abstract: An analog signal is digitized by an analog-to-digital (A/D) converter clocked by a periodically jittery clock signal. Elements of the digital data sequence (vector) output of the A/D converter are sorted into a set of smaller vectors according to clock signal jitter phase and each of the smaller vectors is then separately subjected to Fourier transform and time shift functions. The resulting vectors are then processed to produce an output vector representing the frequency spectrum of the analog signal.

Abstract: A method of measuring the response of an electronic device to a high frequency input signal is performed with an analyzer (1).

Abstract: The present invention provides an RF spectrum measurement analyzer and method and more particularly to a GSM output RF spectrum measurement analyzer and corresponding method. One preferred embodiment of the present invention is applicable to GSM applications. However, other embodiments could be applicable to the general class of Time Division Multiple Access (TDMA) signals of which GSM, PDC (Pacific Digital Cellular), NADC and the like are a part. According to one preferred embodiment of the present invention, the method includes the steps of acquiring an RF carrier signal; converting the acquired RF carrier signal to an IF signal; converting the IF signal to a digital signal of relatively wide bandwidth; FFT filtering the digital signal to measure multiple offset frequencies within the IF bandwidth; and mathematically applying a resolution bandwidth filter at each offset.

Abstract: A direct current machine monitoring system includes a current sensor for monitoring load current of the machine; and a computer for obtaining a power spectrum in a range including a machine trait-passing frequency, determining a magnitude of a maximum peak in the power spectrum in a range including the trait-passing frequency plus or minus an uncertainty frequency, and evaluating the magnitude of the maximum peak to assess a condition of the machine. The computer may additionally or alternatively be used for obtaining a low frequency power spectrum of the load current, obtaining at least one magnitude of a component of the power spectrum at a respective predicted frequency, and evaluating the at least one magnitude of the component to assess the condition of the machine.

Abstract: The present invention is directed to systems and methods for analyzing and characterizing a time-limited waveform to avoid significant delays and miscalculations due to the presence of spurious transitions. In an example implementation, a processor is adapted to sense the signal and interpret various parameters of the waveform using a correlation method. In one application, the correlation method includes providing an autocorrelation function of a segment of the waveform that includes at least one period, and approximating a period of the waveform using peaks in the autocorrelation function. Other aspects of the invention involve approximating the period of the waveform by identifying a segment of the waveform having a steep slope magnitude that exceeds a certain threshold, and determining a polarity associated with the waveform.

Abstract: A method and apparatus for controlling the level of molten metal in a mold for continuous casting by using a molten metal level control system incorporating a molten metal level controller in the control loop thereof, which comprises damping selectively the predetermined frequency of frequencies of periodical molten metal level fluctuations through a notch filter installed in the control loop. The control loop preferably includes the phase compensation calculation part for compensating the phase delay of the stopper opening position control signal for adjusting the amount of the molten metal to be fed to the mold. The control apparatus in the control loop comprises a molten metal level senser, an FFT analyzer, an automatic tuning device for dealing with the results of the FFT analysis, a molten metal level controller and a notch filter.

Abstract: A method and circuitry for implementing a built-in self test (BIST) for determining the frequency characteristics of filter circuits in mixed-signal integrated circuits (ICs). The method comprises inserting a Circuit Under Test (CUT) into a feedback loop that looks like a sigma delta modulation loop and adjust the feedback loop so that it oscillates at the cut-off frequency of the filter. The frequency of oscillation can then easily be measured using either on on-chip counter or digital automated testing equipment. The feedback loop preferably comprises a comparator, a phase-delay component, such as a delay-line, and a one-bit DAC (digital-to-analog converter), wherein the comparator is connected to the output of the CUT, and the output of the one-bit DAC is connected to the input of the CUT. The phase delay of the feedback loop can be tuned through adjustment of the delay-line (e.g., an n-length shift register) until an oscillation frequency is obtained.

Abstract: A method and apparatus for spectral analysis of a sampled signal are provided. According to the method, a first time interval &Dgr;T is determined which represents a sample set over which the signal can be averaged for purpose of decomposing the signal into instantaneous mean and random components. From random component of the signal, the optimal time-dependent time interval AW over which the random component should be averaged to obtain the instantaneous frequency spectrum (IFS) is then calculated based upon the instantaneous signal memory. Signal memory specifies the extent in time beyond which the signal “forgets” its past behavior and thus is a measure of its degree-of-randomness. Defining AW in this way reduces the likelihood that short-lived events are lost (or masked) due to uncharacteristically short (or long) averaging intervals. Importantly, both time intervals &Dgr;T and AW are dynamic and vary randomly with time.

Abstract: Acoustic emission samples for a chemical mechanical polishing process are acquired and analyzed using a Fourier transform to detect wafer vibrations characteristic of scratching. When excess noise levels are detected at frequencies or within frequency bands being monitored, the polishing process is halted and an alarm is generated for the operator. Such in-situ detection minimizes damage to the wafer being polished and limits the damage to a single wafer rather than a run of wafers. Polish endpoint detection may be integrated within the scratch detection mechanism.

Abstract: A spectrum analyser that includes means (8) for converting, at each of a series of frequency settings, a received radio frequency signal into an intermediate frequency signal, each intermediate frequency signal being derivable from more than one nominal received radio frequency signal. The spectrum analyser carries out a frequency analysis (14) of each intermediate frequency signal to produce a power spectrum thereof and constructs a composite received radio frequency signal power spectrum corresponding to each intermediate frequency signal power spectrum. The composite radio frequency signal power spectrums are then operated on by the spectrum analyser to provide the actual power spectrum of the received radio frequency signal.

Abstract: A mode selection method for signal analyzers having alternative swept and Fast Fourier Transform (FFT) modes of operation enables tradeoffs between measurement speed and dynamic range to be optimized in selecting between the alternative operating modes. The method includes setting the signal analyzer to either a manual state or an automatic state according to a first input to a user interface. When the manual state is set, the analyzer is operated in either the swept operating mode or the FFT operating mode according to a second input to the user interface. When the automatic measurement state is set, a third input to the user interface determines whether measurement speed or dynamic range is optimized. Measurement speed is optimized according to a first optimization scheme and dynamic range is optimized according to a second optimization scheme.

Abstract: The present invention relates to an electro-optic sampling oscilloscope. This electro-optic sampling oscilloscope carries out measurement of measured signal by using an optical pulse generated based on a timing signal generated from a timing generation circuit synchronous with a trigger signal, providing: a timing generation circuit comprising a fast ramp circuit that outputs a ramp waveform using said trigger signal as a trigger, a slow ramp circuit that increases stepwise and sequentially the output value according to said timing signal; a comparator circuit that compares the output of said fast ramp circuit and the output of said slow ramp circuit and outputs the results of this comparison; and a gate circuit that limits the output of said comparator circuit by closing a gate only when the output of said comparator circuit is unstable based on the input trigger signal and timing signal.

Abstract: An exemplary embodiment of the present invention is an apparatus for receiving sweep testing signals and generating frequency response values therefrom. The apparatus includes a test input, a controller, a receiver circuit and a measurement circuit. The test input has a first connection arrangement for connecting to a test output of the sweep transmitter and also has a second connection arrangement for connecting to a terminal of the communication system to be tested. The controller is operable to generate a sweep control signal responsive to a sweep plan. The receiver circuit has a control input connected to receive the sweep control signal from the controller, and is operable to tune to a plurality of frequencies responsive to the sweep control signal. The measurement circuit is coupled to the receiver circuit and is operable to generate measurement signals corresponding to the plurality of frequencies.