Uncertainty evaluation on the absolute phase error of digitizers

Abstract

In many engineering applications the phase angle of a signal is a key parameter. Especially when measuring small angles, the measurement accuracy is of a vital importance. Often, the absolute phase error of a digitizer, which is defined as the phase displacement between the digitized output and the input analog waveform and which represents a systematic measurement error, is neglected. Therefore, in this paper, a new measurement technique for the evaluation of this absolute phase error is discussed, along with a deep theoretical analysis on the uncertainty sources and how to handle them. The measurement technique is validated through a high accuracy experimental setup. Experimental tests demonstrate that even high accuracy digitizers can show non-linear behavior in the absolute phase errors.

Traceability for AC Ripple Over DC Current

“…The DeT ratio and phase frequency response have been determined twice, inverting R AC and R BLK position, in order to compensate for the gain and phase error introduced by shunts and digitizer acquisition channels. This technique has been already discussed in [19], [20], [21], it allows to completely compensate all systematic effects, in the hypotheses of short-time invariance of the involved shunts and digitizer channels, the measured ratio depends only on the DeT transfer function, no type B uncertainty has to be included. For both configuration 31 iteration has been conducted to evaluate repeatability and stability according to [22].…”