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| Zooming *IN* [actually: signal reconstruction] |
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| 2N3055:
--- Quote from: Fungus on October 22, 2022, 01:28:37 pm --- --- Quote from: 2N3055 on October 22, 2022, 01:22:41 pm ---Max ZOOM ratio (acquired any way) is ratio of available memory. Scopes with same memory and different sample rate will drop at same sample rate after you just change several timebase positions. Actually we can argue that scope with higher sample rate will see it's higher sample rate only on few fastest timebase positions. --- End quote --- So it's best to start out with as high a sample rate as possible...? Another point in favor of the MSO5000. --- End quote --- Are you making a point not think at all before writing an response? I know you can do better than that.. Max sample rate has no bearing to detail acquired when sampling large amount of data if sample rate had to drop because memory is limit... On high memory length to detail ratios, memory will be the limit. Lets presume you have 2 scopes, both with 1Mpoints of memory, one with 10GS/s and other with only 1GS/s. At 10 GS/s you spend 10X more memory than at 1 GS/s per second. Okkay? So if you have 1 Mpoints of memory, at 10GS/s you use up all memory when sampling 100us worth of data. If you want to sample 1ms worth of data , both of those scopes will have to sample at 1GS/s.. and will be the same. You will have same detail on both. That is why we say that long sampling memory is important, to keep native sample rate as long as possible. And that is why Keysight Megazoom is good "analog emulation" scope but loses even to DS1000Z when you need to sample longer period and zoom in to detail... |
| balnazzar:
At this point i feel obliged to ask: why manufacturers don't release scopes with more mem depth. They seem to be on the verge of generous with other specs (see indeed rigol with sub-1k$ 350 MHz 8 GSa/s), but memory depth is almost always the weak point of accessible scopes.. |
| bdunham7:
--- Quote from: balnazzar on October 22, 2022, 02:39:22 pm ---At this point i feel obliged to ask: why manufacturers don't release scopes with more mem depth. They seem to be on the verge of generous with other specs (see indeed rigol with sub-1k$ 350 MHz 8 GSa/s), but memory depth is almost always the weak point of accessible scopes.. --- End quote --- How much do you want? Current model entry level DSOs have an astounding amount of memory compared to older models, even those from A brands. |
| Bud:
--- Quote from: 2N3055 on October 22, 2022, 01:41:28 pm ---That is why we say that long sampling memory is important, to keep native sample rate as long as possible. And that is why Keysight Megazoom is good "analog emulation" scope but loses even to DS1000Z when you need to sample longer period and zoom in to detail... --- End quote --- Not true for event-based sampling. Keysight with its segmented memory can sample and store only when triggered. With that, you can have information captured for much longer if events are spaced apart in time than a scope with larger conventional memory, which will get filled in a few milliseconds. |
| Fungus:
--- Quote from: balnazzar on October 22, 2022, 02:39:22 pm ---At this point i feel obliged to ask: why manufacturers don't release scopes with more mem depth. They seem to be on the verge of generous with other specs (see indeed rigol with sub-1k$ 350 MHz 8 GSa/s), but memory depth is almost always the weak point of accessible scopes.. --- End quote --- I assume it's because they'd have to up the processing power to match. (...so all the EEVBLOG forum haunters don't spend every waking hour pointing out how slow they are) I think some teardowns have seen much more RAM inside them than actually gets used. Also: Note that they don't have 256Mb or 512Mb of RAM or some "computer" number. It's always a nice round number that the processor can handle. |
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