Author Topic: Rigol DS 2072 noise problem  (Read 34395 times)

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Offline Teneyes

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  • Country: ca
Re: Rigol DS 2072 noise problem
« Reply #50 on: March 01, 2013, 10:12:01 am »
Drieg - Thanks for that picture.  It's looking more and more like I have an unrealistic expectation about the A-D resolution.  This all started when I was looking at a rock-solid 13.5 volt input and the peak voltage readout said 15.1 .  With the features come added responsibility in learning how to interpret them.

Not sure what you were using to measure,  As the DSO has  Vpp, Vtop, Vamp Vavg measuring functions
and also Cursors

Can you Capture the Display and Post

As for Noise the DSO is good and also is Sensitive ( with 500uV )
Below I show a Scope Probe grounded to probe gnd in a Picture and a capture Display
I show how this simple 8cm loop picks up signals and when I put my finger in the Loop  the DSO gets a Larger signal.  The Signal is a 94.9 FM radio station in the area (see cursor readings)

With this scope you need to be aware of EMI signals ( lots of mains power)
IiIiIiIiIi  --  curiosity killed the cat but, satisfaction brought it back

Offline tigerwillow1

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  • Country: us
Re: Rigol DS 2072 noise problem
« Reply #51 on: March 03, 2013, 05:02:20 pm »
Maybe I can learn something here.  These are pictures of what I was originally measuring.  It's a steady DC level with a transient when it's shut off.  The 10 ms. and 500 us. pictures are from the same single sweep, displayed at a different horizontal rate.  I need a large vertical scale to capture the transient.  In the 10 ms. picture the first unexpected item is the horizontal line being so "fat", which I didn't understand at first, and the second item is the max voltage reading of 15.2, when I knew darn well it was 13.5 .  With the display changed to 500 us. the vertical noise starts to be evident.  The 3rd picture, 1 us. sweep rate, is a different capture but shows the noise more obviously.

I was expecting to measure the starting DC level using the peak voltage display.  Average voltage doesn't work because of the level change.  I could combine average voltage with cursors, but in this particular setup, it's a whole lot easier to just use a voltmeter.  I first assumed I was picking up some kind of environmental or power line noise.  When I ran the scope with terminators on the inputs and from a different power source I began to realize that the inaccurate reading is from the scope itself.

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