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| Oscilloscope Zoom Out Quirk |
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| mawyatt:
--- Quote from: SilverSolder on March 07, 2021, 05:06:18 pm --- Thank you for attempting to keep a positive tone - it is entirely possible to disagree while still being civil about it... it is just so bloody HARD when there are so many idiots in the world who won't see things your way! :D --- End quote --- Someone once said "You can't win an argument with an idiot, they have more ammunition!" ::) Best, |
| Someone:
--- Quote from: Fungus on March 07, 2021, 05:01:55 pm --- --- Quote from: Someone on March 06, 2021, 09:41:00 pm ---Thats a Rigol (the specific brand you asked for) causing aliasing or slow update rates if the user selects an inappropriate memory depth. --- End quote --- Any 'scope can have pathologically slow combinations of memory depth/sample rate. eg. If you tell a Rigol DS1054Z to use 24Mb memory with 25kSamples/sec. sample rate then yes, it takes 10 seconds to refresh the screen. It's math. This isn't what's being discussed here though so let's not pretend that it is. If I tell a Siglent to use all the memory then it should use it. --- End quote --- Read your own words, that I quoted in full, and will do so again with the expanded context 2N3055 very clearly explained: --- Quote from: Fungus on March 06, 2021, 09:22:22 am --- --- Quote from: 2N3055 on March 06, 2021, 09:05:58 am ---LeCroy, Siglent, Picoscope, Rigol (by default AUTO strategy), R&S (by default AUTO strategy), Keysight Infiniivision (Run mode), Micsig (by default AUTO strategy) and all others that have AUTO memory mode use that same method of only grabbing only amount of data that is equivalent to length of screen in current timebase. They all do it to minimize amount of data taken in every trigger to get faster reacting scope and keep sampling rate high to avoid aliasing. It is like analog scope, you see what you see. There is NO data before or after screen, and there is no need to. If you want to see more, you put more time ON the screen. Benefit of digital scope is that you can stop it and then zoom in and still see details. --- End quote --- Are you saying Keysights are slowed down and/or suffer aliasing because of this? My Rigol certainly wasn't. --- End quote --- Two entirely different behaviours of aliasing and update rate, joined together into a barely coherent point. Lets take them all apart since you don't seem to understand the underlying behaviours. Aliasing does occur if you don't leave the memory on auto (and sometimes even if you do), on the Rigol scope. Its extremely hard to get aliasing artefacts to show on the Keysight Infiniivision (mega-zoom) scopes, switching from normal to high-res mode makes it worse but still very minor. You joined a Rigol scope (that does suffer aliasing) in with a scope that effectively doesn't. No differentiation, just trying to say they are the same. They are different there. They are also different that the Keysight mega-zoom scopes don't offer the manual memory settings to create long captures outside the visible window (that reduces update rates). So trying to say they are the same on either of these points is completely untrue. I pointed that out and showed previous examples of the Rigols behaviour. Note that the keysight mega-zoom can't have pathologically slow combinations as they don't offer the controls to set that (and the other scopes that refuse to leave memory outside the visible window). So you're still pushing further misleading information, trying to make a generalisation that all scopes are impacted the same when they aren't. There are a group of scopes which force the user to maximise information reaching the screen, and there are a group of scopes which let the user capture data outside the screen. This entire thread. But you seem to get it disastrously wrong and add yet more noise to whats rapidly becoming a dumpster fire (people don't bother to read the content and keep bringing up the same questions/wrong information over and over, suggesting the correct/accurate information is buried). |
| Fungus:
--- Quote from: Someone on March 07, 2021, 10:44:03 pm ---There are a group of scopes which force the user to maximise information reaching the screen, and there are a group of scopes which let the user capture data outside the screen. This entire thread. --- End quote --- The ONLY point I'm making is that the two aren't exclusive. The argument being made in this entire is that the Siglent doesn't allow zoom out because it would slow down disastrously. That's not true, and that's the point I was trying to make by example. Keysights don't slow down, Rigols don't slow down... not unless you pick a pathological combination of sample rate and buffer size. Both Keysights and Rigols allow zoom out (among others). That's it. That's the total of what I'm trying to say. If this thread is a "dumpster fire" it's because the Siglent people refuse to accept the simple facts and are trying to deflect the plain truth via. hand waving. |
| Someone:
--- Quote from: Fungus on March 07, 2021, 10:59:49 pm --- --- Quote from: Someone on March 07, 2021, 10:44:03 pm ---There are a group of scopes which force the user to maximise information reaching the screen, and there are a group of scopes which let the user capture data outside the screen. This entire thread. --- End quote --- The ONLY point I'm making is that the two aren't exclusive. The argument being made in this entire is that the Siglent doesn't allow zoom out because it would slow down disastrously. That's not true, and that's the point I was trying to make by example. Keysights don't slow down, Rigols don't slow down... not unless you pick a pathological combination of sample rate and buffer size. Both Keysights and Rigols allow zoom out (among others). That's it. That's the total of what I'm trying to say. If this thread is a "dumpster fire" it's because the Siglent people refuse to accept the simple facts and are trying to deflect the plain truth via. hand waving. --- End quote --- Scopes slow their waveform rate if they are capturing data outside the screen. True, proven, tested. It doesn't happen on the Keysight Infiniivision/megazoom models as they don't do it, despite what you think, they aren't capturing the data outside the screen constantly. It does happen on the Rigol: https://www.eevblog.com/forum/testgear/new-tektronix-tbs2000-oscilloscopes/msg1283038/#msg1283038 Adding more memory depth does slow down the Rigol DS1054, regardless of if that adds capture outside the screen or not. Keysight Infiniivision/megazoom scopes do slow down when adding more memory, its well hidden and hard to get the data, but its still true: https://www.eevblog.com/forum/testgear/rigol-mso4000-and-ds4000-tests-bugs-firmware-questions-etc/msg973064/#msg973064 They slow down so much less than other scopes (it appears to be their major design goal and marketing point regardless of the true benefits) that there is no option to reduce the memory depth because it is such a small penalty compared to other competitive products. Selecting more memory on the Rigol is guaranteed to slow it down in almost every single realistic case (waiting for you to do the classic fanboy thing and jump on one of the obscure cases where that was reversed). The list of examples above that 2N3055 collected summed this up really clearly: --- Quote from: 2N3055 on March 06, 2021, 09:05:58 am ---LeCroy, Siglent, Picoscope, Rigol (by default AUTO strategy), R&S (by default AUTO strategy), Keysight Infiniivision (Run mode), Micsig (by default AUTO strategy) and all others that have AUTO memory mode use that same method of only grabbing only amount of data that is equivalent to length of screen in current timebase. They all do it to minimize amount of data taken in every trigger to get faster reacting scope and keep sampling rate high to avoid aliasing. --- End quote --- Thats it, there are some scopes that don't let you set the capture window larger than the window visible on the screen. Its a valid design decision and one I prefer. |
| Martin72:
--- Quote ---If this thread is a "dumpster fire" it's because the Siglent people refuse to accept the simple facts and are trying to deflect the plain truth via. hand waving. --- End quote --- No Sir. |
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