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| Standardised Way To Test Oscilloscope Screen Update Rate |
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| bdunham7:
--- Quote from: EEVblog on May 01, 2024, 02:28:29 am ---They are not. I'm sure there are scopes that manipulate the data to provide a more "analog like" display. --- End quote --- That gave me the obvious idea to compare an analog scope with a DSO. Here's a slo-mo 960fps of a Tek 2221A (in the .zip file) with the readouts turned off, the same 1kHz 8-step signal with a 301Hz trigger and the brightness cranked up. And then a 60fps video of both side by side. If you just look at them and then go frame-by-frame, the Siglent DSO is actually remarkably comparable with the behavior of the CRO as far as persistence, fadeout and even the random appearance of the vertical transitions, although those are very faint in real life on the CRO. So yeah, I assume they went to considerable trouble to mimic CRT appearance. The photo is a snapshot from the 60fps video, you can see 4-5 lines appearing on each one. |
| teddychn:
Below are some of my guesses and assumptions: When sending a 1MHz signal into the SDS2000X HD, it looks like each trigger cluster has a period of about 16.28ms, suggesting that the screen update rate could be around 61FPS. Trig_Out-1: 1 cluster = 31 - 14.72 = 16.28 (mS) 1 / 16.28ms = 61.43 FPS I know most of us usually think in terms of 60 FPS, but these numbers are just derived from my observations. In another test, 1MHz bursts were sent to see if the trigger signal keeps its tempo. It seems to do so, as the timing is likely to be an integer multiple of 16.28ms. This suggests that the screen might be updating its screen at 61Hz, independent of the signal timing. There's another story for slow signals or processing bottlenecks. Of course, to accurately observe the real delay between the signal and the screen display, a high-speed camera would be needed. Trig_Out-2: (112.6 - 14.72) / 16.28 = 6.01 ≈ 6 Trig_Out-3: (373.8 - 14.72) / 16.28 = 22.06 ≈ 22 Trig_Out-4: (863.5 - 14.72) / 16.28 = 52.14 ≈ 52 In a previous rough test, the SDS2000X Plus was estimated to have a screen update rate of about 30 FPS. |
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