Products > Test Equipment
Show us your square wave
tautech:
--- Quote from: TunerSandwich on January 28, 2015, 07:46:29 pm ---My guess is running the built-in gen on the a-s at it's "limit" is producing useless data (in terms of analyzing the cabling and acquisition tool.
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Yep. This is normally the case, dedicated FG's are superior.
Working on my main PC ATM, I'll post some waveforms later of what the inbuilt AWG can do in the SDS2304.
And as the have been a temp graded ones I'll do some of those too.
TunerSandwich:
--- Quote from: Wuerstchenhund on January 28, 2015, 07:57:32 pm ---
No, and what I've seen from Rigol so far nowadays I probably wouldn't touch another of their products with a bargepole. Admittedly some Rigol devices aren't as bad as say, Siglent, but after the DG1062z I've decided to stay with the big names.
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As a "general purpose" "hobby" type scope the ds2000A is not too bad. I actually really like it for some very specific things, but the math operations (especially FFT) is/are utterly useless.....I don't see any purpose in their "higher end" products though.....they just don't stack up, and you can get used examples of "big name" kit for roughly the same prices or less.....I imagine they don't sell many $5000 scopes or analyzers, and the company floats on the "hobby grade" stuff....
Electro Fan:
--- Quote from: Pjotr on January 28, 2015, 04:05:35 pm ---
Well, there is at least one turtle that benefits from a near perfect square wave source: Adjusting your high impedance HF probes as good as it gets :D
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Ok, we have a nominee for a reason to care about a "strong" square wave :-+ :)
Electro Fan:
--- Quote from: Wuerstchenhund on January 28, 2015, 12:46:07 pm ---
The picture is a 3D color persistence screen, which is essentially a more advanced variant of the common 2D persistence function many scopes have today.
Most scopes have a monochrome persistence function (i.e. intensity grading) where individual waveforms overlap each other on a single "depth" layer (the screen plane) and where the brightness represents the amount of times a waveform has passed through a particular spot on the screen. This can be used (in limits) to see jitter or other signal anomalies. More advanced scopes use color grading,
i.e. the color shows how often a waveform has passed through a particular spot, where red ('hot') shows places of high occurrence, yellow for medium occurrence and blue for low occurrence.
In a 3D persistence screen each waveform is 'stacked' on top of the other, which shows much better how the waveforms change over time. Again, the colors indicate the occurrence of a waveform passing through a certain spot in the horizontal (x/y) plane.
It's a great tool but for this specific exercise I don't think it adds any value, and since the scope was running in RIS (ETS) mode I'm not sure the waveform that is displayed has much to do with the input signal. The picture shows noticeable variations in the waveform, which means RIS is unsuitable here.
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Thanks for the color legend and the overall explanation
joeqsmith:
--- Quote from: Jay_Diddy_B on January 28, 2015, 12:27:38 pm ---Hi,
I had a look at this picture:
The FFT shows spectral lines that are 5 GHz apart. This is sampling frequency of the scope 5G samples per second. The Lecroy scope is using RIS acquisition.
Regards,
Jay_Diddy_B
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I agree.
--- Quote from: TunerSandwich on January 28, 2015, 04:00:31 pm ---
It is amazing how different the results are, between the two devices.....no doubt about that....I would argue that you have the superior scope for this kind of test.....?
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I really was not interested in comparing the two setups for the 15MHz squarewave shape. When I saw your original post with those spurs, it was not at all what I was expecting and I was thinking there was a software problem. I checked my old LeCroy 7200 and did not see the spurs at the sample rate. So I attempted to replicate it with my Wavemaster that has the latest version of X Stream loaded on it. I tried various FFT settings to attempt to replicate those spurs and could not.
I would have thought they would handle the FFT the same between the two DSOs but it appears they don't. I assume you were using a boxcar. What happens if you use a Hamming window? Some other setting?
Not useful but I thought it was strange.
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