Metrology Publications dealing with NI Hardware

[Henrik_Volkers]

Hi,

wasn't shure in which board it would fit best, so I start here ...

While hunting for the next digit I came across two recent IEEE puplications dealing with NI hardware.

Would be nice if NI had a place on their web to collect such informations... meanwhile maybe this thread could be a start.

Characterization of Metrological Grade Analog-to-Digital Converters Using a Programmable Josephson Voltage Standard

Abstract

A test bench has been developed for systematic characterization of high-resolution analog-to-digital converters. The reference signal is generated by a programable Josephson voltage standard. Three 24-bit digitizers have been characterized. Noise performance has been measured at direct current using the Allan deviation, whereas integral nonlinearity has been measured with quasi-dynamic stepwise triangular waveforms at frequencies between 0.5 Hz and 1 kHz. None of the digitizers outperforms all others for each tested characteristics. Therefore, such a systematic characterization provides the overview needed to identify the most suitable digitizer for a given application.

a poster of some results can be found here

and in the same issue:

Characterization of a Wideband Digitizer for Power Measurements up to 1 MHz

Abstract

A two-channel high-speed digitizer has been extensively characterized in the frequency range of 50 Hz-1 MHz. Measurements involved alternating-current (ac) flatness, phase, linearity, input impedance, and the effects of direct-current offsets, temperature, and an internal self-calibration routine. A digital antialiasing filter inside the digitizer negatively affects ac flatness in the low-frequency region. An inverse compensation filter has been designed and applied, which improves frequency response with a factor of 25-60 and makes it flat within 25 μV/V up to 100 kHz and within 100 μV/V up to 1 MHz. The phase difference between the two channels can be modeled by a constant time delay between the two channels, which for the 2- V_pp range equals (250 ± 30) ps. The overall results of the characterization indicate that the digitizer can be applied in wideband power measurements under practical circumstances with (k = 1) uncertainty contributions of not more than 70 and 400 μW/VA at 10 kHz and 1 MHz, respectively. This uncertainty excludes loading effects, which are significant at frequencies above 100 kHz. At low frequencies, up to three times lower uncertainty are achieved when the digitizer is calibrated at the signal level and temperature at which it is subsequently used.

poster see here

Both papers appears in: Instrumentation and Measurement, IEEE Transactions on
Issue Date: July 2011
Volume: 60 Issue: 7
ISSN: 0018-9456

Both deal with the 5922, the first also with the 4461, (to bad the calibrators workhorse HP3458 wasn't included)

[johnsold]

Henrik,

Thanks for posting this.  I am behind in my reading and had not seen those yet.

Metrology is often overlooked, yet is the basis for every measurement made.  I sometimes wish every scientist and engineer was required to take at least an introduction to the subject.

Lynn

[Henrik_Volkers]

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@johnsold wrote:

Metrology is often overlooked, yet is the basis for every measurement made.  I sometimes wish every scientist and engineer was required to take at least an introduction to the subject.

Lynn

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Full ACK.

[jwdz]

Good idea！