A little follow-up on DC Voltage Measurement Accuracy: fact check Shabaz' graph . The DMM6500 has functions to improve DC Volt measurements.
- nplc or number of power line cycles: you can set the sample time in function of the main utility line frequency. This is one of the big causes of noise. By measuring over a high number of cycles (Keithley advices 100), this effect can be "integrated away" at the cost of measurement speed.
- using an average filter: take multiple measurements and use the average
- autozero: let the measurement validate itself by sampling a known internal reference
image source: Keithley Test Script Builder documentation for the Measuring DC voltage with high accuracy example
Measuring a 2.5 and 2.048 V reference
In the previous blog I measured voltage with one of the preconfigured DC Voltage presets: Autozero, 5 nplc, 20 moving average filter. Now I'm doing that with the settings from the example.
First measurement, on a 2.5V LM4128-2.5 reference , I configured the meter via the touch screen:
The second measurement, on a REF5020 2.048 V reference, was done by running the Measuring DC voltage with high accuracy example from the Test Script Builder:
As you can see on the 121GW, the measurements were made under tropical conditions. Comments and feedback welcome below.
