Abstract: A time-domain baseband measurement method measures modulated microwave signals typically used in communication systems by converting microwave signals to baseband before measurement for improved accuracy compared to direct measurement at the microwave frequency. A downconverting receiver is first characterized using a prior characterization method and then the modulated microwave signal is applied to the downconverting receiver and the response of the downconverting receiver is removed to provide an accurate characterization of the modulated microwave signal. Such an accurate measurement of the modulated microwave signal can be used for communications system performance verification as well as for characterizing communications devices and systems. One particular application is the measurement of input/output characteristics of nonlinear power amplifiers using such modulated microwave signals.

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: The invention relates to a time domain method for obtaining transfer characteristics of a device under test (DUT). The method comprises the steps of applying a sine sweep and a cosine sweep to an input of the DUT, and measuring response signals at an output of the DUT. The sine sweep and cosine sweep together establish a complex input signal, whereby to each instant there is related a particular frequency. Similarly, the respective response signals together establish a complex response signal. The magnitudes and phases of both complex signals are calculated and the transfer characteristics of the DUT then follow from the magnitude ratio and the phase difference of the input signal and the response signal. The invention also relates to an arrangement for testing transfer characteristics of a DUT and to an integrated circuit comprising the necessary elements for testing a subcircuit contained therein.

Abstract: A three-pair measurement method determines the amplitude and phase transmission response of frequency translating devices including a device under test and two test devices using a vector network analyzer and a controller where one of the devices has reciprocal frequency response characteristics. The characterization of single sideband and double sideband devices such as mixers, is preferably performed by combining data from analyzer two-port swept measurements. The measurement method provides a low-pass equivalent transmission response of the devices.

Abstract: The invention relates to a method for determining the transmission characteristics (H(jf)) of an electric line (2) in an ISDN system, in which a test signal (m(t)) is applied to the line (2) at one end, and at the other end of the line (2) the received signal (g(t)) produced owing to the test signal (m(t)) is evaluated.In order to be able to carry out such a method using a test signal having a crest factor of one with relatively little cost, use is made as test signal of a binary, bipolar random number sequence signal (m(t)) having the crest factor of one, and during a time interval corresponding to the period of the test signal (m(t)) the received signal (g(t)) is scanned and subjected to a Fourier transformation to obtain a spectral signal (G(jf)); the latter is complexly multiplied by a reference spectrum Mi(jf) to obtain an output signal (H(jf) which represents a measure of the transmission characteristics of the line (31).

Abstract: The phase response of a network is measured at uniform frequency intervals. A linear regression analysis is performed on samples of the phase response measured at frequencies within an aperture centered on a group delay frequency to obtain an estimate of the group delay of the network at that frequency. The process is repeated for a sequence of group delay frequencies to determine a trace of the group delay of the network across a range of frequencies.

Abstract: A three-pair measurement method determines the amplitude and phase transmission response of frequency translating devices including a device under test and two test devices using a vector network analyzer and a controller where one of the devices has reciprocal frequency response characteristics. The characterization of single sideband and double sideband devices such as mixers, is preferably performed by combining data from analyzer two-port swept measurements. The measurement method provides a low-pass equivalent transmission response of the devices.

Abstract: A three-pair measurement method determines the amplitude and phase transmission response of frequency translating devices including a device under test and two test devices using a vector network analyzer and a controller where one of the devices has reciprocal frequency response characteristics. The characterization of single sideband and double sideband devices such as mixers, is preferably performed by combining data from analyzer two-port swept measurements. The measurement method provides a low-pass equivalent transmission response of the devices.

Abstract: A method for measuring a common mode current (Icm) in an outer conductor of a device comprising also at least one inner conductor which includes the steps of interconnecting the one inner conductor and the outer conductor at a junction point to a power source and supplying a current (Icm) to the junction point draining substantially all common mode current (Icm) from the outer conductor at the opposite side of the device by means of a low impedance drain; and sensing the drained common mode current (Icm) with a current sensor.

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: A non-contact type wave signal observation apparatus measures transfer functions of a distributed constant network. A signal is input from a network analyzer to the network to be measured. Electromagnetic waves radiated from the network are received at each observation point on an observation plane arranged in a manner facing the network. The received signals are input to the network analyzer. The transfer functions between an input terminal of the network and each observation point are measured by the network analyzer. The measured transfer functions are converted by an inverse-Fresnel transformer and are stored in memories. The stored data is specified by a control unit and is displayed on a display unit. The stored data can be converted by an inverse-Fourier transformer and is displayed on the display unit as waveforms.

Abstract: A method and apparatus for fast response and distortion measurement of a signal transfer device. A computer processor generates a multitone test signal of predetermined duration and stores it in a memory. The test signal is read out, converted to analog form, if necessary, and applied to the input of a device under test. The output produced by the device under test in response to the test signal is acquired and digitized, if necessary, and a Fast Fourier Transform is performed on the acquired data to determine its spectral characteristics. Frequency response, harmonic distortion, intermodulation distortion, phase distortion, wow and flutter and other signal transfer characteristics are measured by the CPU by analysis of the output signal. The multitone test signals a unique combination which is extracted at the output for identifying the source, or location, of the test signals.

Abstract: The present invention includes a method of eliminating interference from an undersettled electrical signal, the undersettled electrical signal including a test signal at a known frequency. One embodiment of the present invention includes a method comprising the steps of providing a digitized version of the undersettled electrical signal (at 46); generating a frequency spectrum of the digitized version of the undersettled electrical signal (at 56); spectrally interpolating the frequency spectrum to generate an interference signal frequency spectrum (at 65); and subtracting the interference signal frequency spectrum (at 65) from the undersettled signal frequency spectrum (at 56) generating a settled signal spectrum (at 75).

Abstract: A multistate electronic transfer standard provides electronic conditions to at least one of two ports of a vector network analyzer. One embodiment of the multistate electronic transfer standard includes a plurality of semiconductor interconnected by transmission lines. Each of the semiconductor devices are biased to generate different conditions at each of the two ports. A control computer controls the biasing of devices according to a predetermined procedure and compares impedance values measured for at least one of the two ports of the network analyzer to known values stored by the control computer. The control computer thereby derives calibration coefficients that are used by the network analyzer in performing further measurements.

Abstract: The sweep rate limitations that heretofore have constrained the maximum sweep rates of swept analysis instruments are obviated by optimizing filter circuitry and post-processing the IF signal using various techniques to compensate for errors caused by fast sweeping. Some selective windowing is also used to compensate for distortions due to fast sweep rates.

Abstract: An apparatus and method for measuring the permittivity of a polar solution specimen to enable a determination of the concentration of polar constituents in the specimen. The apparatus (10) employs a band pass filter including containment means (18) formed to contain the polar solution (26) therein and electrically dispose the polar solution (26) as a dielectric element in the band pass filter; conducting means (12); a source of electrical current (56) connected to said band pass filter; frequency variation means (52) electrically connected to the electric voltage source (56) to enable variation of the frequency at which current is applied to the band pass filter; and voltage sensing means (52) electrically connected to sense the peak voltage passed by the band pass filter.

Abstract: A method and apparatus for a system physically realizing a transfer function and having improved accuracy and fast calibration is described, comprising a plurality of stages configured in a serial fashion, each stage having a transfer function realized with fixed and adjustable elements. Control logic for selectively reconfiguring said stages, operable for coupling any one of said stages to a reference signal and for further coupling said one of said stages to the remaining ones of said stages in a serial fashion is added; control logic for selectively causing said stages to transmit at their output responses to an input which enable measurement of individual components within said stages is included; and control logic for updating the adjustable elements within each stage is described.

Abstract: A network analyzer having .means for determining the type and element values of a hypothetical lossless matching circuit for a device under test (DUT) and for computing and displaying S parameters of the DUT in combination with the matching circuit.

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: 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: 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: Device for testing a network of components, in particular an electronic circuit.The respective potential differences between the terminals of the circuit to be tested are acquired during a chosen time interval and stored in a values memory. A memory contains predetermined functional models of electronic components. The processing means, connected to these memories, are capable of effecting a processing comprising the estimation, during said time interval, of physical values, notably of current-expressions, taking account of expressions contained in said acquired models and values, and storing them in the values memory as well as tests on the values contained in the values memory.

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: Aliasing and synchronization difficulties in determining transfer functions in mixed domain (analog and digital) systems are overcome by sampling the analog signal at an integer multiple of the digital signal, and zero filling the set of sampled digital data 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.

Abstract: In an impedance and transfer characteristic measuring apparatus sine-wave and cosine-wave data are produced using data obtained by accumulating a fixed phase value in synchronism with a clock signal and the sine-wave data is provided to a device under test after D-A conversion. Multiplied outputs are obtained by multiplying type D-A converting part which D-A converts the sine-wave data and the cosine-wave data, using two signals related to an item of measurement of the device under test as analog multiply inputs therefor. An intergration control signal of a predetermined level is generated by a signal generating part for the half-cycle period of a sine-wave test signal in synchronism with a measurement start signal. For the period during which the intergration control signal is yielded the multiplied outputs are respectively integrated in an integration circuit part to thereby obtain vector-detected outputs.

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 low cost and portable scalar network analyzer for the simultaneous measurement of forward and reflected scalar scattering parameters of devices under test. Plural UHF oscillators of similar construction are mixed to produce a wideband test instrument having good stability characteristics. A dual-diode biased RF detector with feedback, including an in-loop adjustable gain buffer stage, provides enhanced linearity, over a wide dynamic range, and at low cost. The forward transfer parameter measurement arrangement further includes a selectable attenuation/gain PIN-diode switched stage to accommodate the widely varying gain/attenuation characteristics of devices under test.

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 and apparatus for determining the impedance of the discharge in a plasma reactor system comprising a tuning box having variable capacitors is described. The impedance of the discharge is determined in dependence on a pre-established relationship between the operational positions of the variable capacitors on the one hand and the impedance of the discharge on the other. The ionic current relative to the discharge in the reactor also may be determined by taking into account the high frequency voltage of the reactor.

Abstract: In an arrangement for measuring transfer impedances of coaxial systems (3), a generator (1) is connected via a coaxial, supplying system (2) to a conductor shield (6) of the coaxial system (3) at a first end of the coaxial system (3). A voltage measuring instrument is connected to the first end between the conductor shield (6) and the inner conductor (5) of the coaxial system (3). The electrical contact between the supplying system (2) and the conductor shield (6) is created by a gripping collet (12). The conductor shield (6) and the inner conductor (5) are short-circuited at a second end of the coaxial system (3).