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| Siglent SDS1104X-E vs. Rigol DS1054Z Advice? |
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| Fungus:
It's not "unknown" at all. The Rigol does all calculations, serial decodes, etc., based on the block of 1200 samples that's currently displayed on screen (squished into 600 pixels). You want a better answer? Zoom in on the area of interest (or press 'auto' :popcorn:). PS: Any RMS calculation of non-bandwidth-limited white noise is always a bit 'suspicious' and a very suspect way to demonstrate a 'scopes supposed superiority. The VPP number is the one to focus on. 1.3mV of noise @1GHz with the probe in 1x mode? Turn on the bandwidth limiter, that's what it's for. |
| rf-loop:
--- Quote from: Fungus on August 27, 2018, 05:29:11 pm --- It's not "unknown" at all. The Rigol does all calculations, serial decodes, etc., based on the block of 1200 samples that's currently displayed on screen (squished into 600 pixels). You want a better answer? Zoom in on the area of interest (or press 'auto' :popcorn:). 1) PS: Any RMS calculation of non-bandwidth-limited white noise is always a bit 'suspicious' and a very suspect way to demonstrate a 'scopes supposed superiority. The VPP number is the one to focus on. 2) 1.3mV of noise @1GHz with the probe in 1x mode? Turn on the bandwidth limiter, that's what it's for. --- End quote --- 1) Perhaps Keysight engineers are wrong and you are right? But here is Keysight: --- Quote ---Understanding Noise and How it Should Be Measured: Random noise, sometimes referred to as white noise, is theoretically unbounded and exhibits a Gaussian distribution. Unbounded simply means that because of the random nature of noise, the more data you collect in noise characterization measurements, the higher the peak-to-peak excursions will grow. For this reason, random phenomenon such as vertical noise and random jitter should be measured and specified as an RMS (one standard deviation) value. --- End quote --- 2) 1GHz |O I still believe that Rigol have 100MHz "gaussian like" BW (if you understand how BW affect noise...) and here compared with 200MHz BW Siglent what also can calculate RMS and it do it right. (here used Stdev for remove possible DC offset for get noise RMS) Of course we can also compare with more narrow BW. But if I need 100MHz scope for measurements I need know how it works with 100MHz. If I measure unrepetitive 1Hz square wave what have 4ns risetime I can not reduce BW. I need full 100 MHz BW or better if more. So simple. Of course when want less noise and IF can reduce BW then just reduce BW. Also it is not so important what are these absolute values... but as you can see there is two scope face to face and using enough same setup. They are comparable. You can also see peak to peak just with eyes from screen image if you want and it is big. Of course there is lot of differences. This is only just one. |
| KungFuJosh:
--- Quote from: Fungus on August 27, 2018, 05:29:11 pm ---Turn on the bandwidth limiter, that's what it's for. --- End quote --- Do you think that's good to use in general for audio stuff? Is there any reason I would need to see anything above 20Mhz probing a tube amp? Is that a dumb question? ;) |
| nctnico:
It doesn't matter whether you turn the BW limit on or off because the Rigol 1000Z is noisy like hell. The more recent oscilloscopes from GW Instek, MicSig and Siglent use a very low noise analog front-end and ADC (IIRC they all use the same so their performance when it comes to noise is comparable). |
| KungFuJosh:
--- Quote from: nctnico on August 27, 2018, 10:52:32 pm ---It doesn't matter whether you turn the BW limit on or off because the Rigol 1000Z is noisy like hell. The more recent oscilloscopes from GW Instek, MicSig and Siglent use a very low noise analog front-end and ADC (IIRC they all use the same so their performance when it comes to noise is comparable). --- End quote --- I'm returning the Rigol. I'll have a Siglent on Saturday. So what then? |
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