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8vs 12-bit scopes in economy class - couple of questions...

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Phil1977:
Many reasons for 12-Bit:

- All 8-bit scopes I know have visible quantization error on screen, even on the small screens. All 12-bit-scopes I know show super clean lines.
- 12 bit give you much more resolution for doing maths, e.g. calculating the difference between two channels or a reference waveform and the channel
- An ADC works best if its lowest 1-2 bits are noise. So in a 8-bit scope you practically only have a little more than 6 bits real resolution per sample.

Why don't the manufacturers spend more on the display & GPU? I just assume they invest into the ADC and it´s very closely connected RAM. Most of the signal processing magic happens there for very good reasons. And if the pre-processing has been done there, you only need a reasonable but not a very fancy display unit.

Fungus:
Example: The Rigol DS1054Z has 400 vertical pixels in the trace display area and an 8-bit ADC, at least one bit of which is mostly noise so really only 7 bits even on a good day.

Do you see why 12 bits might be better even though the screen resolution doesn't go up much...?

2N3055:

--- Quote from: nctnico on September 08, 2024, 09:25:26 am ---
--- Quote from: Psi on September 08, 2024, 08:11:45 am ---Put simply, you only use a small range of the total voltage range of the scope when looking at a signal.
So your 0 -> 2V signal showing on screen only covers a tiny range of the bits.

Meaning an 8 bit scope with 256 possible levels ends up very marginal once you consider the number of possible levels being used to represent your 0 - 2V signal.

It's why the voltage measurement on scopes is normally terrible and the noise makes it jump up/down by perhaps 0.1V.

That being said, normally you don't need accurate voltage readings on a scope.

--- End quote ---
12 bit doesn't help to make a scope more accurate. If you look at the specs, you'll see the DC gain accuracy is typically between 1% and 2%. 12 bit doesn't improve that. What more bits does help with is showing more details of a signal. But to actually see those details, you'll need a bigger screen.

--- End quote ---

Or if you buy propper brand it can be 0.5% DC accuracy...

Geoff-AU:

--- Quote from: Hella_Wini22 on September 08, 2024, 06:35:10 am ---  4. How much more useful is 12-bit over 8-bit for the most of hobbyistic to prosumer audience ?
--- End quote ---

Not very.  I have an SDS2000X-HD at work and an SDS-2000X-Plus at home.  The Plus is more than adequate for all my needs.


--- Quote ---  5. I guess FFT could be one field where it makes a difference. But even that is limited.
--- End quote ---

The FFT on my HD is just as clunky and horrible to work with as my Plus.  As you said, a real spectrum analyser is much better.  But for dealing with low frequencies, the scope will do.

jasonquin:
Application processor costs. Drive a high-resolution display at high frame rate will put too much burden on the tiny Zynq, which is used in almost every entry level scope.

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