John Fluke Mfg. Co., Inc.

Fluke Corporation

Other

Henriecus Koeman

Jeffrey Sandsmark Bottman

Benjamin T Brodie

Craig Vincent Johnson

A system for determining FEXT and ELFEXT of generic cabling systems provides accurate measurements of these parameters by determining and removing the effect of the connectors at the respective ends of the link, thereby giving measurement values that correspond to the defined link, rather than including the crosstalk contributions of the connectors, which can be substantial.

Method and apparatus to measure far end crosstalk for the determination of equal level far end crosstalk

A pulse-based local area network (LAN) cable test instrument provides a measurement of the cross-talk characteristic of a LAN patch cord as a function of frequency in order to evaluate its relative performance and workmanship of assembly. A LAN cable test instrument applies a test signal in the form of narrow pulses to a selected transmission line of a LAN patch cord while the cross-talk response induced in another transmission line in the same LAN patch cord is measured and stored as a time record in digital memory. The near-end and far-end pulse responses are separated in the time record, leaving only the near-end pulse response. The LAN cable test instrument analyzes the near-end pulse response by performing a discrete Fourier transform on the time record to provide cross-talk versus frequency information. The same test may then be performed on the far-end end of the patch cord to obtain a complete test of the quality of workmanship at both ends of the patch cable.

Method and apparatus for measuring near-end cross-talk in patch cords

An efficient method for calculating Power Sum cross-talk loss is provided. Cross-talk loss measurements may include near-end cross-talk (NEXT) loss, far-end cross-talk (FEXT) loss, multiple disturber NEXT (MD NEXT) loss, and multiple disturber FEXT (MD FEXT) loss. Pair-to-Pair cross-talk loss responses are collected between a given wire pair and all the other wire pairs of concern, with each pair-to-pair cross-talk loss measurement having a number of frequency data points corresponding to the frequencies of interest. The pair-to-pair cross-talk loss response having the lowest positive value for a particular frequency data point is first selected as the baseline cross-talk loss response. The effects of each of the remaining pair-to-pair cross-talk loss responses on the baseline cross-talk loss response are then accounted for by applying power sum contribution values obtained from a look-up table. In this way, Estimated Power Sum cross-talk loss may be calculated for each of the corresponding frequency data points from each of the pair-to-pair cross-talk loss measurements in an efficient manner.

Method for efficient calculation of power sum cross-talk loss

A modular electronic instrument system having automated calibration capability comprises a system controller and a plurality of calibration instruments for calibrating a target instrument. The instruments, if remotely controllable, may be interconnected by a common interface bus. The calibration instruments have associated therewith a characteristics file including resource capability information, and an instrument to be calibrated has associated therewith a characteristics file including calibration information. The system controller automatically derives calibration requirements from the calibration information and matches the requirements with resource capabilities of the calibration instruments. All of the characteristics files may be provided in a standardized format so that a system may be configured without regard to instrument-specific model numbers or manufacturers.

Modular electronic instrument system having automated calibration

A signal whose RMS value is to be accurately determined is first converted into DC form by a relatively inaccurate RMS converter, such as a thermal RMS converter (15). The result is a first converter signal (Y.sub.1), which is stored for recirculation in a suitable storage device, such as a sample and hold circuit (17). Thereafter, the signal stored in the storage device is recirculated to the converter to create a second converter signal (Y.sub.2). Then, the second converter signal is subtracted from the doubled value of the first converter signal (2Y.sub.1 -Y.sub.2) to produce a corrected RMS signal (X). The difference between the first converter signal (Y.sub.1) and the corrected RMS signal (X) is then determined. This error signal (E) is stored. Next, a decision is made as to whether or not a fast mode of operation is to be followed. If it is not to be followed the corrected RMS signal is displayed. If the fast mode is to be followed, the signal whose RMS value is to be accurately determined is reapplied to the RMS converter. The result is a third converter signal from which the error signal is subtracted to produce a corrected signal that accurately represents the RMS value of the reapplied signal. This corrected signal is then displayed or applied to other downstream subsystems, such as signal analyzers or recorders. The fast mode steps are then repeated.

Recirculating RMS AC conversion method and apparatus with fast mode

A waveform digitizer particularly suitable for use in electronic test systems for analyzing and displaying analog signals is disclosed. A digitally derived reference voltage is compared with the analog signal to be digitized during a series of comparison sequences. Simultaneously with the start of each comparison sequence a digital clock is started. Each time the analog signal rises above, or drops below, the reference voltage a decision change detector produces an enable pulse. Each time an enable pulse occurs, a data word, having a portion related to the value of the digitally derived reference voltage and a portion related to the digital clock value, is stored and/or used to control a display. At the end of the first comparison sequence (determined when the digital clock value reaches a predetermined level) the reference voltage is incremented and a second comparison sequence started. These steps are repeated until the reference voltage reaches a predetermined level. The resulting set of digital words is digitized equivalent of the waveform of the analog signal.

Analog waveform digitizer

A signal whose RMS value is to be accurately determined is first converted into DC form by a relatively inaccurate RMS converter, such as a thermal RMS converter (15). The result is a first converter signal (Y.sub.1), which is stored for recirculation in a suitable device, such as a sample and hold circuit (17). The first converter signal is also doubled (2Y.sub.1) and stored (41). Thereafter the first converter signal stored in the storage device is recirculated to the converter to create a second converter signal (Y.sub.2). Then, the second converter signal is subtracted (43) from the doubled first converter (2Y.sub.1 -Y.sub.2) to produce a highly accurate RMS output signal.

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Edmonds, WA, United States of America

Henriecus Koeman