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| Bode Plot Computational Time for various DSOs |
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| Martin72:
First of all I really don´t have a problem with it, but.... It´s remarkable how short others can perform it while the siglents take their time.... In this case minutes against seconds... On the siglent you got the feeling, they´re switching completely in a different mode, the whole scope becomes a FRA.. - When bode menu is only activated (not starting), you can´t do anything else on the scope until you leave the bode mode. And leaving the bode mode takes also time.... Won´t believe it´s somekind of performance lack. |
| Someone:
--- Quote from: Martin72 on November 07, 2022, 10:08:58 pm ---It´s remarkable how short others can perform it while the siglents take their time.... In this case minutes against seconds... On the siglent you got the feeling, they´re switching completely in a different mode, the whole scope becomes a FRA.. - When bode menu is only activated (not starting), you can´t do anything else on the scope until you leave the bode mode. And leaving the bode mode takes also time.... Won´t believe it´s somekind of performance lack. --- End quote --- The widely variable time is somewhat related to performance and the design tradeoffs that the manufacturer has chosen: https://www.eevblog.com/forum/testgear/faster-fra-from-scope-by-external-control-over-visa/ As an example for this thread, that Keysight DSOX1102G takes 42 seconds for the above requested 100-100k, 20pts/decade measurement. But 4 seconds of that is the autoscaling of the input attenuators. Swap to a script running on a (slow) computer and you can have a similar quality answer in 14 seconds, but now with the user being able to choose how much averaging to apply at each frequency step. Want to go faster? A chirp excitation should be able to do this in a few seconds. |
| 2N3055:
--- Quote from: colorado.rob on November 07, 2022, 07:47:25 pm ---What accounts for the 2 orders of magnitude time difference to acquire a Bode plot between Siglent and R&S scopes? --- End quote --- Taking 5 averages at every frequency. Biggest impact is at low frequencies. It takes time to gather enough samples of a signal that has period of 10 ms. Benefit is that it works with noisy signal (like switchers) and gets few dB better dynamic range.. MSOX3104T did it in 35sec with simple DUT (few resistors and capacitors). It would have been a bit slower if DUT was exercising autoranging. But it gave up when pushed to small signals..... Siglent's implementation at this moment doesn't win speed competition. But is very accurate, has best dynamic range, has capability to do multichannel Bode plot (one input and 3 outputs in 4 ch scope) has automatic measurements, best frequency range, works with outside AWG (interesting things can be done there with large signal and channel locking) and has very good accuracy... |
| gf:
--- Quote from: Martin72 on November 07, 2022, 10:08:58 pm ---It´s remarkable how short others can perform it while the siglents take their time.... --- End quote --- There is always a trade-off between measurement duration and dynamic range (noise floor). Comparing the duration is IMO rather meaningless if the achieved dynamic range is not compared as well. On the other hand, if the dynamic range of the DUT happens to be much lower in the frequency span of interest, then aiming for a too large dynamic range can result in wasted time. |
| nctnico:
--- Quote from: gf on November 07, 2022, 11:12:46 pm --- --- Quote from: Martin72 on November 07, 2022, 10:08:58 pm ---It´s remarkable how short others can perform it while the siglents take their time.... --- End quote --- There is always a trade-off between measurement duration and dynamic range (noise floor). Comparing the duration is IMO rather meaningless if the achieved dynamic range is not compared as well. On the other hand, if the dynamic range of the DUT happens to be much lower in the frequency span of interest, then aiming for a too large dynamic range can result in wasted time. --- End quote --- I agree. I have the feeling the engineers at Siglent geeked out on getting the lowest noise floor while losing sight of what is also important: speed. |
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