As I am learning about all of the features of my Agilent DSOX 2022A oscilloscope, I thought I would check its measurement of a linear power supply against my ExTech branded DMM with a Radio Shack model number (22-816). I don't know what the claimed accuracy of the meter is, but I thought it would beinteresting to see how it compared to the scope.
The ExTech shows 13.48 VDC. So far so good... The scope, however, shows anywhere from 13.4 to 13.7 VDC depending on where on the screen it is.
When I set the scope to 2 V/Div and move the trace so that it and the ground reference are both on the screen, I get 13.5 VDC which agrees with the DMM.
When I set the scope to 10 V/Div and move the trace to the top, I get 13.4 VDC. Moving the trace to the bottom of the screen (keeping the gnd ref on screen) I get 13.7 VDC.
The DMM function of the scope matches the measurement function.
So is this just a case of using as much of the dynamic range of the scope as possible for the most accurate results? Why would the location on the screen cause different results?
I also was wondering about DC RMS - like, what is it? I understand the concept of Root Mean Square of an AC signal, but what does it even mean to have an RMS measurement of a DC value? Then there is DC RMS full screen and DC RMS N Cycles. Is all of this RMS for DC about a non-stable or varying DC signal?
Home
Help
Search
Login
Register
