Products > Test Equipment
Oscilloscope Zoom Out Quirk
maginnovision:
I feel like you're saying there is never any advantage ever in your life because siglent scopes can't do it. Like it or not I don't want to have a wide timebase to get a capture, zoom in and then zoom back out to catch all the details I want. We're not talking a game changer here, we're talking a shortcut.
tautech:
--- Quote from: maginnovision on May 09, 2020, 06:47:20 am ---I feel like you're saying there is never any advantage ever in your life because siglent scopes can't do it.
--- End quote ---
Oh FFS, do you actually think I've not used other DSO's ? Really ?
My first DSO had 2.5 Kpts memory/channel so to get the best from it you used it wisely.
Even the other 2 laterTeks I had were similarly pitiful.
What are we actually trying to do here, teach the reader some obscure scope usage method rather than proper well know methods that return universally predictable results from any DSO ?
Someone:
--- Quote from: EEVblog on May 09, 2020, 05:02:26 am ---
--- Quote from: Someone on May 09, 2020, 02:39:01 am ---
--- Quote from: stafil on May 09, 2020, 01:03:03 am ---Doesn't capturing data outside the display window => more time to capture data => less waveform updates per second?
--- End quote ---
Yes, which is why "automatic" memory depth usually defaults to the shortest record that will fill the screen.
--- End quote ---
Not on the Keysight. Try it. Unless you are on a slow timebase like 100ms where all the memory is used to fit the screen and it doesn't have any more to give. On 10us or under (which is where it goes to the max 5GS/s), if you press stop and then zoom out it will give you the extra data outside the display window.
--- End quote ---
Thats a "special" behaviour that is only on a minority of scopes. This has cropped up a few times:
https://www.eevblog.com/forum/testgear/new-keysight-scope-1st-march-2017/msg1125192/#msg1125192
https://www.eevblog.com/forum/testgear/new-tektronix-tbs2000-oscilloscopes/msg1282227/#msg1282227
and more recently:
https://www.eevblog.com/forum/testgear/siglent-sds2000x-plus-coming/msg2895750/#msg2895750
Same old names blowing noise and adding FUD left right and centre.
nctnico:
--- Quote from: maginnovision on May 09, 2020, 06:47:20 am ---I feel like you're saying there is never any advantage ever in your life because siglent scopes can't do it. Like it or not I don't want to have a wide timebase to get a capture, zoom in and then zoom back out to catch all the details I want. We're not talking a game changer here, we're talking a shortcut.
--- End quote ---
Agreed on both points.
Frankly I'm amazed so many people are so opposed to using a clever shortcut which yields results in the real world. :-//
But since we are here I can make a list with oscilloscope brands which support recording beyond the screen (or not):
GW Instek: yes
Keysight: older models: yes, newer models: single mode only
Lecroy: no
MicSig: yes
Rigol: yes
R&S: yes
Siglent: no
Tektronix: yes
Yokogawa: ?
Edit: added R&S
2N3055:
--- Quote from: EEVblog on May 09, 2020, 12:47:14 am ---
--- Quote from: 2N3055 on May 09, 2020, 12:38:10 am ---I agree it's worthy of a video. And if you think about it a bit further, you will see that its one of those "you can do it this way too if planets are aligned..." but not really something to rely on.
--- End quote ---
You do know it's entirely predictable, right? (based on timebase and memory depth) It's not some random quirk.
Even the Keysight has a new Digitizer mode that makes it entirely predictable.
--- End quote ---
Well, I don't have R&S RTM3000 to try but I believe what Nico say that it WILL be predictable. An as long as you keep it on same (max)sampling rate it will stay the same.
On Keysight 3000T not so much. It has much smaller memory, and will drop sampling rate fast. Full mem in full sample rate in RUN mode is 400 us.
Also digitizer mode has some limits. When you set digitizer mode, if you set scope to sample at max 5GS and have max 4MS (1ch), scope won't let you set time base to slower than 40us/div. Basically, it starts sampling at that fixed speed and memory buffer. It's not setting sampling speed anymore to allow you to go slower. It behaves as digitizer not GP scope.
But that helps little, because result is the same as in normal mode, if you pay attention and not go slower than 40 us/div in run mode.
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