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REVIEW - Rigol DS2072 - First Impressions of the DS2000 series from Rigol

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marmad:

--- Quote from: EEVblog on April 17, 2013, 12:03:02 am ---Rigol are supposed to be getting me one of those, looks interesting.
They should most certainly get you one too!

--- End quote ---

I agree on both points! ;D  Seriously though, it does look interesting - a little like a response by them to the educational options offered by the Agilent X2000/3000 (which I always thought were pretty cool).

Hydrawerk:
Not sure if Rigol can be used by students at school 8 hours a day for say 10 years? Rigol is better for hobbyists who want a bang per buck.

grego:

--- Quote from: marmad on April 16, 2013, 09:12:49 pm ---I'm not sure if the DS6000 Demo Board has been mentioned before on EEVBlog or not (a quick search didn't turn up anything), but I found it at Batronix while searching for any possible new UltraVision products - and I hadn't seen it before and thought it was kind of interesting. It lists at €163 / $225 (excl.), and I've attached the user guide below.

"This Demo board is used to illustrate the basic functions of the oscilloscope. It is powered through USB port and can output 25 kinds of signals for the illustration of oscilloscope functions, i.e. sine, video (PAL/NTSC), AM Modulation, Sweeps, many digital signals and lots more. Delivery including Demo Board, USB Cable, CD with manual."



--- End quote ---

It's got the Instek one beat - Instek demo board only does 10 analog and 5 digital/LA functions for $205 list (so probably about $185 discounted).

I might have to get me one of these to play around with.

Galaxyrise:

--- Quote from: marmad on April 16, 2013, 11:18:54 pm ---I just took the sample points image into Photoshop and connected the first few segments. I don't really think you could mistake the difference
--- End quote ---
Obviously not those sample points. I didn't have access to them at first, and even now I have no reason to think they match exactly with the vector capture. The trigger setting is different, and dots/vectors trigger a little differently.

Compare the peak from your interpolated capture with one that has plenty of data and see how much rounder the correct curve is! It wasn't until I tried it that I could see how it didn't work out, but it's really not far off.  I can draw lines that only differ significantly at the very top of the peak.  If I then chop off the pointy bit, I get something very similar to your capture (effectively adding just one more sample per peak.)

So maybe now you can see where I was coming from.  But either way, sorry to ask and I won't take any more of this long thread with what's way off topic.

marmad:

--- Quote from: Galaxyrise on April 17, 2013, 06:20:25 am ---Obviously not those sample points. I didn't have access to them at first, and even now I have no reason to think they match exactly with the vector capture. The trigger setting is different, and dots/vectors trigger a little differently.
--- End quote ---
The trigger setting didn't really matter - here's another image I just captured of the same 100MHz uninterpolated sine wave (sorry - slightly less amplitude due to a loose 50 Ohm terminator) with the trigger set to the previous 180mV level. It's almost the same image as before - with the dots just shifted horizontally.





--- Quote ---Compare the peak from your interpolated capture with one that has plenty of data and see how much rounder the correct curve is!
--- End quote ---
DSOs are imperfect devices - and besides doing the sin(x)/x interpolation, the scope is doing other transformations to the sample data to get it to the display (e.g. the Rigol is mapping 200 bits of vertical ADC resolution to 400 pixels of vertical screen resolution). Perfectly correct curves may or may not be precisely what you see on the display - although with a small number of sample points, the difference between linear and sin(x)/x interpolation is pretty noticeable.

Here are two images from a LeCroy Waverunner LT 224; the first one showing sin(x)/x using 10 samples per div. Can you see what looks like short line segments at the tops and bottoms of some of the sine waves?




This image shows both linear and sin(x)/x interpolation using 5 sample points per div as in my Rigol example (although with longer cycles).





--- Quote ---If I then chop off the pointy bit, I get something very similar to your capture (effectively adding just one more sample per peak.)
--- End quote ---
Well sure, adding sample points in convenient locations can definitely help linear interpolation look more like sin(x)/x.  ;)  But in any case, to me, the difference between your linear interpolation and the 'bad' curve is still noticeable - one looks like straight vectors and the other looks like less-than-perfect curve fitting.


--- Quote ---But either way, sorry to ask and I won't take any more of this long thread with what's way off topic.
--- End quote ---
It wasn't any problem to ask, and I don't think it's off topic since it's about the Rigol's interpolation (and I brought it up in the first place). I was just surprised at the question - and I thought I answered good-naturedly with a bit of ribbing -  while trying to point out that, IMO, it would have been clear if linear interpolation had been used on that waveform with 5 points per div. - even though, as I mentioned in my later post, I understood your point and conceded that it would have been more clear if I had used a lower frequency sine wave in the example.  :)

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