| Products > Test Equipment |
| How much noise floor and other things matter in oscilloscope usability |
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| tautech:
--- Quote from: Fungus on December 24, 2021, 09:47:49 pm --- --- Quote from: tautech on December 24, 2021, 09:42:27 pm ---Don't, it's an abomination --- End quote --- Tautech says something made by Siglent is an abomination? Avoid like the plague. :scared: (I haven't actually used one, I sorta assumed it would work for 300 Euros given that the rest of the 'scope is OK) --- End quote --- It works fine but it becomes another box on the bench instead of being inbuilt which would be difficult with the very compact SDS****X-E series. --- Quote from: Fungus on December 24, 2021, 09:47:49 pm --- --- Quote from: tautech on December 24, 2021, 09:42:27 pm ---get the SDS2104X+ and SPL2016 instead. Totally different and better class of MSO probe. --- End quote --- And ... totally blows the budget. That's the tautech we know and love. :) Edir: I'm only kidding, OP did mention "2000 Euros" somewhere and it's not quite 2000... --- End quote --- SPL2016 with a new scope are on special ATM until at least years end for the unbeatable price of $219 with MSO and FG licensing. That's one hell of a deal unless you want to DIY one with the info from that thread. Christmas midday dinner calls....... |
| Fiorenzo:
--- Quote from: bdunham7 on December 24, 2021, 09:17:11 pm --- --- Quote from: Fiorenzo on December 24, 2021, 08:20:51 pm ---Here I am, I did the test you asked for, please let me know whath do you think about It. Thank you very kind! --- End quote --- So just as a quick apples-to-apples comparison with your first example, I set up an SDS1104X-E with the same no-probe, 20MHz BW, 5us/div and 1mv/div. Then I connected a 1mVrms 100kHz signal so you can see the suitability of the scope for viewing such a signal. The noise makes it a bit jumpy and jittery because it affects the trigger point. I have some low-frequency noise that isn't from the scope but is from other stuff that I have around that I can't turn off right now, so I did both a live snapshot and a stopped picture, which is effectively a single-shot. As you can see, the scope is perfectly usable on 1mV signals and your Rigol, which is over 3X as noisy, might have a tough time with the same signal. I also took a snapshot with the input set to GND, which shows you the ADC noise, or so I think. The LSB at this setting is 40uV, so the peak-to-peak noise is 1 bit. I can't tell you what scope works best for you, but if you work at all with small signals, the front-ends of the entry level Siglents is definitely the best for the buck. Features like the ERES acquisition mode and the 10-bit mode of the SDS2000X+ series do make them better, but you shouldn't generally count on multi-capture averaging even though it can look very good, as this can lead to errors. --- End quote --- What circuits works with such a low intensity signals? Sensors for example? I could think about maybe a shunt, they gives very low output when measuring currents, i use many times shunts in my circuits.... Speaking instead about a signal amplifier, as suggested by some one in this thread, It was told that they are a better way to check low intensity signals than giving faith on a low noise front end. Is this true all times? |
| Fungus:
--- Quote from: Fungus on December 24, 2021, 10:34:17 pm ---AC will center the ripple waveform around zero so you measure RMS, etc. --- End quote --- ...which is of course the wrong way to do it, and was the big error in the now-infamous "Rigol vs. Siglent noise" video. Using AC mode to calculate RMS assumes the 'scope is perfectly calibrated, ie. with zero offset voltage. The correct way to measure RMS is with "Std.Dev", which removes the offset voltage mathematically in both AC and DC modes. You should still use AC mode though because it centers the signal and allows you to crank up the vertical scale without going off screen. |
| Fungus:
--- Quote from: Fiorenzo on December 24, 2021, 10:24:16 pm --- --- Quote from: Fungus on December 24, 2021, 10:16:52 pm ---Have you tried averaging mode yet? --- End quote --- Yes many times, and also hi-res mode. I didn't used It in the photos because i wanted to show the real front end noise. --- End quote --- Averaging mode isn't cheating! It's there for a reason... :-+ (And even Siglents have it) |
| Fiorenzo:
Watch this photo attached. If i don't ground the probe tip the oscilloscope shows a 50hz sinewave. I have also tried turning off every appliance connected near the scope and also the lights but the sine wave remain unchanged. |
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