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Introduction to the NHMFL Pulsed Field Facility at LANL

Information on the physical set-up of pulsed field measurements

Read about lock-in amplifiers and their role in your measurements

Information about noise and ways to eliminate it from your measurements

How to collect and evaluate your measurement data

Information on optical spectroscopy

Information about time-resolved optics

Information on de Haas van Alphen Effect measurements

Information on Shubinkov de Haas Effect measurements

Information on Absolute Resistivity measurements

Information on Heat Capacity measurements

Information on RF Penetration Depth measurements

Setting Up Digitizers


DIGITIZERS:

Measurement settings chosen for the digitizers can create two potential noise problems: digital noise and aliasing.

Digital noise occurs when the digitizing range is set too high, or when the signal is too low. If the signal is reasonable (about 10-100 mV), but the digitizing range has been set too high, simply set the range lower to increase resolution. This is done using a control on the LabVIEW virtual instrument on the computer screen.

If the signal is too low, try increasing the gain of pre-amplifier. Typical amplifier gain is 100-1000 mV.

Aliasing occurs because of an incorrect sampling rate setting. If the sampling rate is too low, you get what looks like a lower frequency oscillation. This is not a real oscillation. Since there are not enough sampling points, if one were to connect the sampling points of a sine wave, the points would be so greatly spread that they would often miss the peaks and valleys of the sin wave. This would result in a poor reproduction of the sin wave with inaccurate curves, and a low frequency. This effect goes away when the sampling rate is increased.