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| Measuring jitter with an oscilloscope |
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| boB:
You might try measuring a stable source first that you might be able to pretty much trust. Maybe a nice crystal oscillator, with specs if possible, but if you see that this clock is stable, then you might assume it's OK and the Rigol is OK. As long as your trust in jitter is better by some amount than what you are measuring, then should be able to get a good idea of the DUT. |
| drummerdimitri:
--- Quote from: David Hess on January 01, 2019, 02:08:29 am ---Any oscilloscope can do that but what kind of jitter do you want to measure? --- End quote --- High frequency 20 KHz sine waves. |
| tautech:
--- Quote from: drummerdimitri on January 01, 2019, 01:57:36 pm --- --- Quote from: David Hess on January 01, 2019, 02:08:29 am ---Any oscilloscope can do that but what kind of jitter do you want to measure? --- End quote --- High frequency 20 KHz sine waves. --- End quote --- Increase trigger hold off. |
| David Hess:
Test your Rigol first since they had a serious problem with sampling jitter in the past: https://www.eevblog.com/forum/blog/eevblog-699-rigol-ds1054z-oscilloscope-jitter-fix-testing/ All of my old DSOs have jitter levels commensurate with the crystal oscillators I have tested them against which makes sense because they use crystal oscillators to control the sampling clock. It takes a high bandwidth oscilloscope to make meaningful measurements at low jitter levels like you would find between logic stages or between crystal oscillators; a 500MHz instrument will not cut it for this. Sampling oscilloscopes are good for this. For audio applications it is going to depend on exactly what you want to measure but any 100MHz or even slower instrument will reveal anything which matters. A phase noise measurement using an audio analyser would be more relevant. --- Quote from: drummerdimitri on January 01, 2019, 01:57:36 pm --- --- Quote from: David Hess on January 01, 2019, 02:08:29 am ---Any oscilloscope can do that but what kind of jitter do you want to measure? --- End quote --- High frequency 20 KHz sine waves. --- End quote --- Right, but jitter over small time periods or long time periods? Due to limited resolution, an oscilloscope is more suitable for the later unless it has a really high timing resolution like a sampling oscilloscope. |
| 2N3055:
--- Quote from: Bud on January 01, 2019, 06:01:39 am ---To measure jitter with an oscilloscope you need to know jitter characteristic of the oscilloscope, otherwise you will not know if you observe jitter of the signal or the oscilloscope. Knowing how bad rigol is about their master clock, chances are such measurements will make no sence on a rigol. --- End quote --- Oh my god not that again... They screwed up, you found it,you got your spotlight, they fixed it, old news, it's history... Your 5 minutes of fame passed.. Get used to it... If you want to shit on Rigol, do us a favor and search for real bugs in their new products (there are many, bugs and products) and help people get a better product for a price that is affordable.. I can make a very long list of total screwups big names did but for some reason nobody is allowed to say Keysight is "shit" because they made a PSU that destroys equipment connected to it on power up ... It was silently swept under the rug, and only 6 months after there was magically an A version.... It took too much time to fix that, and it left bitter aftertaste. But Keysight did right by us eventually, and all was forgiven, apparently. And release history for MSOX 3000T is 27 pages long.. some of it new features but mostly bug fixes... Yet it's a fantastic piece of equipment. It is not that simple. And Keysight is not shit for mistakes they make, far from it. And neither is Rigol. Rigol is still a long way from it to be in the same league like Keysight (and questionable if ever) but entry level equipment from Rigol is good equipment in it's category. DS1000Z has no advanced features, it has slow UI, but it performs up to spec. No jitter. If you can prove that jitter is still there, please enlighten us. In which case I would stand corrected, and would publicly apologize. Otherwise, forever stop with crap fear mongering, please.... It really doesn't become you. You seem to be wonderful engineer, with vast knowledge. Help us by sharing that. We would be greatly thankful. And respectful of you and your accomplishments. |
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