Products > Test Equipment
DSOX1204G 200Mhz vs Used MSO3014A (Calibrated in 2018)
Someone:
--- Quote from: 2N3055 on October 28, 2021, 11:51:48 am ---
--- Quote from: Someone on October 28, 2021, 11:24:44 am ---
--- Quote from: kcbrown on October 28, 2021, 10:21:16 am ---
--- Quote from: 2N3055 on October 28, 2021, 09:19:31 am ---Memory is not the problem.
Problem is that you have 4GS/s that is not 4GS anymore as soon as you use any timebase longer than 50us/div. And then drops rapidly. If you set timebase for 2ms/div (to look at somethin 20 ms long) it takes nosedive to 40MS/s.. At that timebase, if you have anything higher than 20 MHz in signal it will alias and show weird artefacts in signal that aren't there.
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Well, seeing how the actual sample rate ultimately determines the maximum frequency you can reconstruct anyway, wouldn't they use a low-pass filter with a variable upper frequency on the input in order to eliminate the aliasing you're talking about? I mean, this is an issue you'd have even on the SDS2000X series. Once you make the timebase long enough you can't maintain the native sample rate. The additional memory helps, of course, but doesn't eliminate the issue.
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Some users who are more familiar with other brands of scopes fear aliasing as its pretty easy to produce. But... its very hard to get the Keysight/Agilent meagzoom scopes to show aliasing artefacts as their front end filtering and decimation "just work" (invisibly and without any controls, prioritising maximum sample rate possible at all times).
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You are correct, Keysight uses all kinds of neat tricks, and it kinda deals with some aliasing artefacts. For instance it will silently use Peak detect to extract outside envelope of AM modulated signal that should alias. But that will be only screen display, if you press zoom, zoom will show nonsense. But, still, better than others.
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Depends which acquisition mode the scope is set in, as whats on the screen and whats in the waveform acquisition memory are often completely different!
Acquisition ModePlotter (screen)Memory (decimated)NormalFull BandwidthRandomPeak DetectFull BandwidthMin/MaxHigh ResolutionAnti-aliasedAnti-aliasedNone of those modes "alias", you're probably recalling zooming in on a signal outside the memory sample rate bandwidth in normal mode where the random decimation makes it look like noise. But the realtime/screen display always shows an accurate picture. The point of the phosphor emulation is to show the full path of the incoming waveform, so of course that includes the min/max points, but its not throwing away all the other points and showing solid blocks (as in the peak detect memory acquisition), it shows the relative likelihood of the waveform in the much desirable (and expensive to produce) 2D histogram.
You're simplifying it down way too much, and trying to minimise the effects with sideways statements like "kinda deals with some aliasing artefacts", perhaps some examples? I've never(!) seen aliasing on those scopes, ever, even when trying to provoke it, so more like "always eliminates aliasing".
Whats important to remember is that the acquisition waveform and screen display are decoupled and not produced from each other.
And if you want to have the screen and/or acquisition antialiased, turn on the high resolution. Nothing silent or hidden or sneaky, all the users choice.
samsh:
Sorry to revive this thread, but I am in almost the exact same boat here. DSOX-1204g vs used DSOX3014A vs RTB2004 but now with the Tek 2 series thrown into the mix. My main concern with the DSOX3000A is the lack of bode plot functionality, I might be better served by spending the extra for a used DSOX30014T.
Pricing is a bit munted, the RTB2004 is actually only worth buying as the most expensive option fully bundled with 300 MHz bandwidth, DSOX1204g is cheapest obviously, and while the used DSOX3000 is reasonably cheap I do count a lack of probes and warranty as serious issues. I am worried I will feel disappointed with the UI on the Tek and RTB, having been first educated/used to Keysight models (I have used the Tek 2 and RTB before, the RTB was OK and the Tek was fine but did chug when doing heavy math across most of its memory).
I already have a Saleae logic analyser, but the Tek and RTB both comes with MSO capabilities. Tek being upgradable to 500 MHz is cool, but I don't think I would ever actually spend that much and 200 MHz is my highest needed bandwidth (with me having access to multi GHz scopes for short bursts). Also form factor matters somewhat, which is a boon to the Tek, but frankly I think the DSOX-1204g is the cutest looking piece of test equipment I have ever seen.
I would welcome any advice (and a looking back perspective from @erwets ).
Someone:
--- Quote from: samsh on November 21, 2024, 06:34:58 am ---My main concern with the DSOX3000A is the lack of bode plot functionality, I might be better served by spending the extra for a used DSOX30014T.
--- End quote ---
The DSOX3PWR option includes "Power Supply Rejection Ratio (PSRR)" measurement, which is a bode magnitude plotter. But like the on bode analysis on later Keysight scopes (and most/all scopes of other brands) it is nothing spectacular and you're almost always better off using an external computer to complete the task:
https://www.eevblog.com/forum/testgear/faster-fra-from-scope-by-external-control-over-visa/msg2282465/#msg2282465
Even dedicate a raspberry pi or similar running Jupyter notebooks (https://en.wikipedia.org/wiki/Project_Jupyter) for such automation tasks and keep it on the back of the scope.
2N3055:
Look into what Siglent offers in that price range..
samsh:
External computer probably a fine solution, I have done it this way in the past (although not with a scope) but seeing the Bode plot as a feature on the DSOX1204g as a 'standard' (while not on the 3000A series) was a bit jarring (they seem to have streamlined the 'options' on it also). The interface did look clunky (1000 points or 1000 points per decade? can only start on 10^n steps, exe) on what little videos I saw of it. Integral math is the other thing I would miss with the DSOX1204g, but I do wonder how good an implementation on a scope could be (the Tek manual is well documented: its not even trapezoidal integration but that shouldn't really matter if your sample rate is fast enough).
Well aware of offerings from Siglent/Rigol. The SDS2000+ is a bit cheaper than the Keysight but the SDS2104X HD is spitting distance from the R&S cost wise (and thats the loaded R&S vs base model Siglent, although I can only assume it is hackable).
I would like to know if anyone has an 'updated' perspective on the Tek 2 series, now that the dust has settled a but regarding software updates exe.
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