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Siglent SDS2000 new V2 Firmware
nctnico:
--- Quote from: Performa01 on January 09, 2016, 08:42:59 pm ---
--- Quote from: nctnico on January 09, 2016, 05:14:39 pm ---The trigger system in any DSO works by detecting whether a threshold has been crossed. The values of the samples where the threshold crossing occured are stored and used to calculate (interpolate) the exact trigger point and required shift to adjust the time reference of the samples so subsequent acquisitions overlap eachother perfectly and the signal is properly aligned with the trigger point.
--- End quote ---
What you describe is the traditional analog trigger architecture.
We are talking about the SDS2000, which incorporates a fully digital trigger system.
--- End quote ---
Calculate doesn't happen in the analog domain! But please explain how a digital trigger system should work...
Performa01:
--- Quote from: nctnico on January 09, 2016, 08:57:49 pm ---
--- Quote from: Performa01 on January 09, 2016, 08:42:59 pm ---
--- Quote from: nctnico on January 09, 2016, 05:14:39 pm ---The trigger system in any DSO works by detecting whether a threshold has been crossed. The values of the samples where the threshold crossing occured are stored and used to calculate (interpolate) the exact trigger point and required shift to adjust the time reference of the samples so subsequent acquisitions overlap eachother perfectly and the signal is properly aligned with the trigger point.
--- End quote ---
What you describe is the traditional analog trigger architecture.
We are talking about the SDS2000, which incorporates a fully digital trigger system.
--- End quote ---
Calculate doesn't happen in the analog domain! But please explain how a digital trigger system should work...
--- End quote ---
Here is an excellent application note on this topic:
https://cdn.rohde-schwarz.com/pws/dl_downloads/dl_application/00aps_undefined/Benefits_of_RTO_digital_trigger_system_2.pdf
Pico technology have introduced the digital trigger in 1991, using the same arguments as R&S (much later obviously).
Performa01:
To solve the puzzle: what does a 500MHz signal look like, when acquired with 1GSa/s ?
Fist let’s have a look at the signal sampled at 2GSa/s, sin(x)/x reconstruction and vector display (500MHz_2GSa_vectors_fast_sinx)
Well, the waveform looks pretty unexciting, basically the same as 250MHz would look like at 1GSa/s. But we see that despite the low trigger level of 8mV, the trigger frequency display is not even close to the true value, whereas the automatic period measurement is spot on. The automatic measurements also indicate rise and fall times of 600ps, which is almost exactly the expected value and it is quite surprising to see this so accurately measured on a scope with a specified rise time of <1.2ns.
What if we lower the sample rate to 1GSa/s?
In this case, the signal frequency would be equal to the Nyquist frequency of the sampling system. Look what we get (500MHz_1GSa_vectors_fast_sinx)
It’s a nice amplitude modulated waveform, with a 500MHz carrier and a modulation frequency that is the difference between signal frequency and half the sample rate. This is unknown of course, but most probably less than 10kHz. The trigger frequency display is the same amount off as before, and even the automatic measurements for the transition times haven’t changed significantly.
If we use dots display, now having no interpolation whatsoever, we can see the true sampled data. It’s just 14 dots per trigger event, at random amplitude. At the exact nyquist frequency we would get steady amplitude, which in turn depends on the phase relationship between signal and sample clock (500MHz_1GSa_dots_fast_sinx)
Consequently, with vector display again, but this time sin(x)/x reconstruction turned off, we get another nice picture (500MHz_1GSa_vectors_fast_x)
Note that trigger frequency is off as always, but automatic measurements for period and transition times are spot on.
Performa01:
--- Quote from: tautech on January 09, 2016, 08:52:02 pm ---Will you examine the Power Analysis option?
--- End quote ---
Probably not. I have purchased my scope with all available options from Batronix, who is my nearest distributor here in the EU, but Power Analysis hasn’t been available back then and still isn’t today.
Of course, I actually don’t really need that option, but still would have included it with my purchase, if it had been available at a reasonable price. Not sure if I would purchase it separately if it ever becomes available… ;)
tautech:
--- Quote from: Performa01 on January 09, 2016, 10:14:59 pm ---
--- Quote from: tautech on January 09, 2016, 08:52:02 pm ---Will you examine the Power Analysis option?
--- End quote ---
Probably not. I have purchased my scope with all available options from Batronix, who is my nearest distributor here in the EU, but Power Analysis hasn’t been available back then and still isn’t today.
Of course, I actually don’t really need that option, but still would have included it with my purchase, if it had been available at a reasonable price. Not sure if I would purchase it separately if it ever becomes available… ;)
--- End quote ---
Power Analysis is already installed in all new SDS2000 series units and is freely available for 30 trial uses.
It's in the Utilities menu on P2 and unless you've enabled it more than 30 times you should have some Trial cycles of the Power Analysis option remaining. :-//
On P3 of Utilities/Options/ Information will display remaining free trial cycles. :popcorn:
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