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Oscilloscope recommendation DS1054Z / SDS1104X-E / GDS-1104B / etc?
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Performa01:

--- Quote from: 2N3055 on June 19, 2023, 11:22:48 am ---As for FRA, Keysight unveiled it in december of 2017 of their "low cost" 1000X series and to 3000T. Previous models did not have any.
Siglent unveiled their BODE analysis 2 months later. Meaning it was already fully developed and tested to production and was awaiting FW release scheduling... It was not reaction to Keysight...

--- End quote ---
Exactly. The idea of a Bode Plot application has been accepted by Siglent management back in September 2016, when there was only Vellemann with some cheap USB oscilloscope (and I don't know about the quality of their implementation) and Keysight had indeed one as part of their expensive PA-package, of course not available in any entry level scope.

The specification for Siglents first version of the FRA was written back in February 2017 and already specified a frequency selective detector, but this was something not yet implemented in the first version.
nctnico:

--- Quote from: mawyatt on June 19, 2023, 02:53:15 pm ---We've used the Siglent Bode function often, and have also reported it's slow, real slow (we are not a fanboy)!! With this in mind it does give superb results as mentioned by 2N3055, slow yes, but accurate with a very wide dynamic range if utilized properly by someone that understands how the Bode function operates within the DSO.

If getting the correct, accurate answers is important, one can often overlook the speed!!

--- End quote ---
Now you make it sound like slow = accurate but that simply isn't true. The results from R&S's implementation (the one I have experience with but I don't see why others should be different) are just as accurate. So they deliver the same answer in less time. I have repeated several of the measurements you have shown using my R&S oscilloscope and got to the same results.
2N3055:

--- Quote from: nctnico on June 20, 2023, 08:23:18 am ---
--- Quote from: mawyatt on June 19, 2023, 02:53:15 pm ---We've used the Siglent Bode function often, and have also reported it's slow, real slow (we are not a fanboy)!! With this in mind it does give superb results as mentioned by 2N3055, slow yes, but accurate with a very wide dynamic range if utilized properly by someone that understands how the Bode function operates within the DSO.

If getting the correct, accurate answers is important, one can often overlook the speed!!

--- End quote ---
Now you make it sound like slow = accurate but that simply isn't true. The results from R&S's implementation (the one I have experience with but I don't see why others should be different) are just as accurate. So they deliver the same answer in less time. I have repeated several of the measurements you have shown using my R&S oscilloscope and got to the same results.

--- End quote ---

He never said slow was accurate.. He said (same as I did) it is dead accurate but somewhat slower then R&S and Keysight... And it is not seconds to hours difference...

And it is debatable if you got exactly the same result. You don't have a Siglent scope to really set it up the same... It looks OK though, and we said that.

Again, against what sub 1000 USD scope you are comparing Siglent SDS1104X-E bode plot feature/speed/accuracy set?
How many scopes (at any price range) can perform bode plot analysis of a 3-way active xover (low, mid, hi) at the same time on the same screen.
How long does it take to do that on Keysight or R&S..

I did check against the Keysight 3000T and got better dynamic range with Siglents I have..
Is that because I'm comparing a 500uV/div 12 bit scope against 8 bit scope with 4mV/div with more noise ??
That could be the case.... But the both SDS6000 and SDS2000X HD had better dynamic range than MSOX3104T...

For general use both will be good enough to gather -3dB point frequency, general shape of curves, etc..

There is also one more thing that were discussing. It is much easier to measure filters (passive and active) in quiet environment, than loop response of switching PSU with aggressor signals being orders or magnitude larger.
With switching PSU, ability of BODE plotter (whatever it is) to extract phase/gain of stimulus is very much a question of extracting very small signal from switcher natural output ripple.
In which case frequency selective detector and averagning helps a lot.. In which case slower is better....

So yeah, it is MUCH more complicated than: SLOW!!!! BAD!!!!!
nctnico:
R&S is also using frequency selective detector. I did those tests as well. Anyway, Siglent could speed up their FRA a whole lot without compromising much so it would make sense for Siglent to implement fast (low dynamic range) and slow (high dynamic range) modes. That would be the proverbial cherry on top.
2N3055:

--- Quote from: nctnico on June 20, 2023, 11:31:23 am ---R&S is also using frequency selective detector. I did those tests as well.

--- End quote ---

I defer to you for this. I have no way to verify it and no reason to doubt you.


--- Quote from: nctnico on June 20, 2023, 11:31:23 am --- Anyway, Siglent could speed up their FRA a whole lot without compromising much so it would make sense for Siglent to implement fast (low dynamic range) and slow (high dynamic range) modes. That would be the proverbial cherry on top.

--- End quote ---

That is what I said. If they can, that would be another win for Siglent. But if not, still OK.. I personally find it mildly annoying, not a dealbreaker..
If other scopes could do 2 sweeps per second than I would be also annoyed. But they cannot. I need to get a 5000 USD FRA to get order of magnitude faster sweeps.
This way, 45 seconds or 90 seconds, for both cases I take that as as moment to get up, stretch my back and go get some water or something.. By the time I'm back, result is there...

If I would do FRA every day, all day long, I would then go for BODE100 device, because not a single scope (even 20000USD+ ones) are as fast, accurate or have as good dynamic range for that purpose.

But, for occasional use, speed is not primary..  And again, Siglent has that capability, and better features than other manufacturers, for a very low entry price, available to hobby users and small business that cannot afford to pay 15X times more for 30 seconds less...
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