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recent experience shopping for hobby scope in today's market. tek, rigol, ...

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nctnico:

--- Quote from: David Hess on February 27, 2023, 07:29:49 pm ---
--- Quote from: bdunham7 on February 27, 2023, 07:16:06 pm ---I don't have the TBS1000C, but I have a similar-era Tek with a similar (one generation earlier?) ASIC and I'm not clear on the 'dual delayed sweep' statement.  Mine will do a fixed delay after trigger, but it doesn't display both the A and B sweep like earlier scopes, nor do I see how it could since it doesn't have the memory available to do so.  Is the TBS1000C like this or have they done something else?
--- End quote ---

Not all dual delayed sweep oscilloscopes display both the A and B sweep simultaneously.  If they do, then it is referred to as "alternate dual delayed sweep", which was a later innovation that DSOs tended not to copy.

The TBS1000C operates exactly like a dual delayed sweep oscilloscope in runs-after mode.  So the first sweep starts after the trigger, there is an adjustable delay, and then the second sweep starts and acquires 20k sample points.  Both sweeps are completely independent like a dual sweep oscilloscope, but only one of them is displayed at a time.  On the TBS1000C, it means that a 1 GS/s aquisition can be make way after the trigger point beyond the point where these other DSOs could do it.

--- End quote ---
This is something you can do with any DSO. Just move the screen with the horizontal position control (which equals trigger pre/post delay). This is exactly how setting the trigger delay is described in the TBS1000C user manual BTW. On some DSOs (like the modern ones from R&S) you can specify the horizontal position by entering a number. However, there is a difference between various brands. On Lecroy and Siglent you are limited to a couple of thousand horizontal divisions, on other DSOs the maximum value is typically little over 1 second. The latter makes it possible to visualise jitter on 1 PPS signals from which the edges are far apart.

2N3055:

--- Quote from: David Hess on February 27, 2023, 07:32:52 pm ---
--- Quote from: tautech on February 27, 2023, 07:13:32 pm ---Yet for the vast majority of work 14 Mpts SDS1000X-E has would swamp the capabilities of a similar Tek.
--- End quote ---

Unless you wanted to capture and display a 1 GS/s acquisition beyond 6 milliseconds, and the TBS1000C is still has modern features despite its short record length.

--- End quote ---

With due all respect, no it does not.
It is utterly outdated.  Even Tek themselves didn't dare to even compare it to Rigol DS1000Z, but to an very old and very outdated DS1000E.
All comparisons are against scope designs older than 10 years.

TBS1000C has 4 operations waveform math, no statistics on measurements, no segmented capture, no decodes, no active probe interface, only 2 ch....  And yes that very short memory is significant flaw.

It is literally worth 200 USD in comparison to other scopes you can have. You can buy SDS1104X-E or MSO5000 that make it look like a cheap chinese Finrsi.

bdunham7:

--- Quote from: nctnico on February 27, 2023, 09:05:06 pm ---On Lecroy and Siglent you are limited to a couple of thousand horizontal divisions, on other DSOs the maximum value is typically little over 1 second. The latter makes it possible to visualise jitter on 1 PPS signals from which the edges are far apart.

--- End quote ---

So of course I had to try this on the SDS2104X+.  On a 1pps signal I can delay the trigger by 1 second on a timebase up to 100µs/div, so 10k divisions or 1000 screens worth, all at a full 2GSa/s (which means that it is not, in fact, limited by record length, which surprised me a bit).  However, I can stack that with the zoom feature and dial in down to any available timebase, even 1ns/div if I like.  That would be a hundred million screens worth.  The screenshot is at 5ns/div, so 200 million divisions, with the actual delay finely adjusted as shown in about the middle of the screen.  Obviously the accuracy is limited by the clock, an external clock is a big help here on those scopes up the food chain that have it.

I don't know what the upper limit is, but I was able to set the scope up for a delay of a full hour (displayed as 3.6ksec) with a reduced sampling rate and a maxium of 10 seconds to get the full 2GSa/s, zoomable to 1ns/div.  So it appears that 10 billion divisions of delay is the limit.

tautech:
Yup, that's what deep memory is all about.  :-+
Simple ain't it.

nctnico:
Problem is that 100us/div or even 5ns/div is not very interesting for checking a 1PPS signal (which should be rather obvious...). Things get interesting for me at 200ps/div (or less). The Lecroy Wavepro 7k which I have is pretty difficult to use for these kind of measurements though (max. delay 2us; the Siglent scopes suffer from the same limitation) while the Agilent Infiniium 54845A I used to have was much better at it because it allowed over 1 second of delay. So even though the 54845A only has 64k points per channel and far less capabilities compared to 48Mpts and analysis feature of the Wavepro 7k, the first is better suited for certain measurements. I kind of regret selling it. Bottom line is: you can't go around saying an instrument with more options is alway better. The one feature you need might be missing. Quality over quantity.

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