How to Measure Oscilloscope ADC Dynamic Range

How to Measure Oscilloscope ADC Dynamic Range, using the 12bit Rigol HDO4000 as an example.
This is important to be able to analyse and measure the noise floor, ENOB, and power spectral density of an oscilloscope.
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[@gerardoromano3436]

Hi Dave, I´d call it headroom but i´m an audio guy so don´t take my word on this.

[@anthon5504]

Hi, can you demonstrate the fft on the scope? it should be quite useful white 12 bits

[@عمرمطر-غ5ب]

Can i just measure the clipped signal with cursor after clipping?🤔🤔🤔

[@EEVblog2]

Same as other comment response:
The cursors on screen don't work zoomed in which means you get the same accuracy. The automated measurement does not work in this instance. You also have potential accuracy issues due to visual alignment and/or cursor resolution. But otherwise, yes you can get a reasonable quick reading this way, just not as accurate. Maybe on some scope it's different, but not on this Rigol.

[@johnyang799]

@@EEVblog2 Manually measure it with cursor while zoomed in?

[@gianlucalocri]

I'm pretty sure this is a limitation for this particular scope....

[@johnyang799]

Why not just measure the peak voltage with the clipped waveform?

[@johnyang799]

Or feed 1khz sine with FFT on, mark the voltage before harmonics spike up.

[@EEVblog2]

Because you have to use the cursors on screen which means you can't zoom in the get accuracy. The automated measurement does not work in this instance. You also have potential accuracy issues due to visual alignment and/or cursor resolution.
But otherwise, yes you can get a reasonable quick reading this way.

[@johnyang799]

@@EEVblog2 Hmm. As long the ADC data is the same we can stop the waveform and zoom in on it right? There shouldn't be any screen/display dickery. Usually with 8bit adc the operation is not recommended because of the ADC accuracy but in this case we are measuring the ADC capability here right?
Why can't I use curser while zooming in?

[@smity2255]

Thank you Dave for the video ,i am just asking, can you use the fft algo to see dynamic Range at clip waveform, in case 12 bit resolution it must be 72 db range at peak and noise floor, btw i using RTA4000, using high res mode i get roughly 96dB (its fit what the datasheet says, 16bit at high res mode). i am so sorry for my bad english

[@egonotto4172]

Hi You can use deepl for translation

[@smity2255]

@@egonotto4172 thank you very much I just tried it

[@jim9930]

What is the SFDR of your R&S? Probably no better than -60dBc...??

[@smity2255]

@@jim9930 No info in datasheet, but i ever measure 1 khz sinewave from Siglent SDG1032X, can measure THD from siglent wavegen around -60dBc, (siglent datasheet is 0.075%/ -62dBc)

[@bartomiej368]

If you want to be sure to the last bit then better solution is to connect to pc and get raw adc data.

[@ernestb.2377]

For your calculation of resolution in mV you use the whole (stated) 12-bits, but how do we know if that is the case in the reality? Maybe I am missing something in the actual measuring technique..

[@jim9930]

Two signals slightly offset in freq mixed externally with resistors; that's as 'real world' as it gets with FFT.

[@byronwatkins2565]

I believe that Tektronix' range is 2.56 = 2^8 / 100 times larger than the screen height. An even easier to program option would be 4 x (= 2 bits) the screen height.

[@stevenspmd]

Wouldn't there be a 8.75v reference somewhere? or would it be burried deep in the secret squirrel chip set?

[@pixiepaws99]

Automate this on almost any modern scope with simple SCPI commands!

[@Nik930714]

HDO1000 videos are gonna come, right?

[@cmuller1441]

3:45 Or just read the peak to peak measure given by the oscilloscope...
Now I realize that it just displays **** if it reach the screen border 😕.
I wonder if all scopes do the same.

[@gianlucalocri]

You can always use cursors...

[@armandine2]

I wonder, how many ... if you showed this video to 100 EE students and asked them to describe or demonstrate how to measure the ADC dynamic range of their oscilloscope --- would be right? For me it needed someone to say slow down - what are you doing?

[@jim9930]

Of the hundred plus videos I've watched on ytube - nobody gets it right with modern scope FFT and a modern dual DDS. Better than a DSA, better/cheaper than distortion analyzers.... Go look up 'distortion magnifier' or null measurement techniques (old school)

[@za_ozero]

id call that a product placement vid

[@fouazhdib6813]

good information