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SDS800X HD Wanted Features

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KAKUL:
Hi Guys
SDS1000X HD
Please add DVM feature.

AndyC_772:

--- Quote from: AndyC_772 on April 19, 2024, 10:38:07 am ---
--- Quote from: 2N3055 on April 19, 2024, 10:20:37 am ---As for cursor behaviour it is not a bug.
Scope's capture ENDS with the end of screen.

--- End quote ---

Try: capture a whole pulse, stop acquisition, then use the magnifier to zoom in on each edge individually to position a cursor accurately. The delta-X interval is reported correctly, regardless of what portion of the trace is on screen.

Then, exit magnifier mode and zoom in on one of the edges by changing the time base and position instead. The delta-X measurement is now clipped to the edge of the display.

The two methods result in different behaviour, and that can't be right. I humbly suggest that the distance from a cursor to the edge of the screen isn't ever useful, could be misleading, and should instead always be the distance between cursors - just as it is if the magnifier is used.

--- End quote ---

I'm bringing this back up again because I've just treated myself to an SDS3034X HD and now really do need a solution to this simple problem.

Having the cursors clip against the edge of the screen is something odd that I just can't see a use case for - and at the very least, I'd like to request an option to have them remain at the exact same position relative to the waveform, even when that position is not currently visible because the waveform is zoomed in. The waveform data is still there, and the cursor position is still known - it reverts back to its correctly assigned position if the waveform is scrolled or zoomed back out to put it within the displayed region again.

Please, feature request: "Cursors clip to edge of display: on / off".

Also, just in case that I'm missing something... what IS the recommended way to measure the time interval between two arbitrary points in a waveform, as accurately as possible?

2N3055:

--- Quote from: AndyC_772 on December 05, 2024, 10:09:50 am ---
--- Quote from: AndyC_772 on April 19, 2024, 10:38:07 am ---
--- Quote from: 2N3055 on April 19, 2024, 10:20:37 am ---As for cursor behaviour it is not a bug.
Scope's capture ENDS with the end of screen.

--- End quote ---

Try: capture a whole pulse, stop acquisition, then use the magnifier to zoom in on each edge individually to position a cursor accurately. The delta-X interval is reported correctly, regardless of what portion of the trace is on screen.

Then, exit magnifier mode and zoom in on one of the edges by changing the time base and position instead. The delta-X measurement is now clipped to the edge of the display.

The two methods result in different behaviour, and that can't be right. I humbly suggest that the distance from a cursor to the edge of the screen isn't ever useful, could be misleading, and should instead always be the distance between cursors - just as it is if the magnifier is used.

--- End quote ---

I'm bringing this back up again because I've just treated myself to an SDS3034X HD and now really do need a solution to this simple problem.

Having the cursors clip against the edge of the screen is something odd that I just can't see a use case for - and at the very least, I'd like to request an option to have them remain at the exact same position relative to the waveform, even when that position is not currently visible because the waveform is zoomed in. The waveform data is still there, and the cursor position is still known - it reverts back to its correctly assigned position if the waveform is scrolled or zoomed back out to put it within the displayed region again.

Please, feature request: "Cursors clip to edge of display: on / off".

Also, just in case that I'm missing something... what IS the recommended way to measure the time interval between two arbitrary points in a waveform, as accurately as possible?

--- End quote ---

It is how this scope works. It is not a bug to be fixed. It is dictated with chosen architecture.
Cursors DO stay in fixed time position as you defined, relative to trigger.
They clip to the edge of the screen when you change timebase because there is nothing outside the screen, as far as scope is concerned.
Main screen extent is what scope processes, what it has to work with.

To do this you need to use zoom, like you already know. Work with the instrument, not against it.
Capture whole event, use zoom to position 1st and 2nd point t make sure it is right there where you want it, and measure.

AndyC_772:

--- Quote from: 2N3055 on December 05, 2024, 10:37:05 am ---They clip to the edge of the screen when you change timebase because there is nothing outside the screen, as far as scope is concerned.
Main screen extent is what scope processes, what it has to work with.

--- End quote ---

I'm sure you've said this before and I still don't understand what you mean by it.

Capture a waveform, then stop acquisition and zoom in. The whole capture is there in memory, you can scroll left and right to view the entire thing in as much detail as you like, which is what the deep memory is for, after all.

This idea that there is "nothing outside the screen" makes no sense whatsoever I'm afraid, unless we're talking about making automated measurements on visible data. This might make good sense, but it's not what I'm trying to do.

I know I can zoom in on each of the regions where I want a cursor to be, and place them. It's quite clumsy and requires a lot of clicks since the scope doesn't automatically swap the cursor between zoomed-in and zoomed-out regions, but that's OK.

What's not OK is that, having positioned the cursors, I can either:

- switch to the zoomed-out view, and get a delta-X measurement that's correct but rounded to just a few significant figures (much less precision than should be possible), or
- switch the zoomed-in view, and get a time measurement that's between whatever cursor is on screen, and the edge of the screen. I cannot for the life of me think why this would be preferred, or indeed, any possible use case for this behaviour.

Performa01:

--- Quote from: AndyC_772 on December 05, 2024, 10:09:50 am ---Also, just in case that I'm missing something... what IS the recommended way to measure the time interval between two arbitrary points in a waveform, as accurately as possible?

--- End quote ---

Cursors are not the tool of choice for accurate measurements – they are largely a thing from the past when DSOs were not powerful enough to do proper waveform analysis but had to resort to tools from the analog scope era instead. Nowadays I would only use them to illustrate measurements, but let the DSO calculate the actual results.

It doesn’t make much sense to demand an accurate time interval measurement on truly arbitrary points – such as different arbitrary positions on a flat region of the waveform. It will rather come down to measuring the interval between two transitions.

If it is about a single trace, then we have the Time measurements, like Period and positive/negative Pulse Width.

If we want to measure the interval between two different traces, there are the Delay measurements (Time 1-4 in upper class instruments with latest firmware), which cover the interval between first/last rising/falling edge in one channel to first/last rising/falling edge in another channel.

If first/last of the whole captured waveform does not cover the relevant interval and changing the timebase doesn’t help, then we can always use the Measurement Gate (or Analysis Gate in case of the SDS3000X HD) to precisely define the measurement.

The big advantage of automated measurements is that we don’t need to zoom in as long as the measurement resolution given by the sample rate is sufficient. With only a single channel active on an SDS800X HD, the sample rate is 2 GSa/s and the time resolution is 500 ps. Measurements can make use of that up to 10 Mpts record length, hence even at a slow timebase of 500 µs/div, we can still measure time intervals with 500 ps tolerance in the main window.

Likewise, with two channels active in half channel-mode on an SDS3000X HD, the sample rate is 4 GSa/s, the time resolution 250 ps and measurements can use up to 40 Mpts. Once again we can go as slow as 1 ms/div and still measure with only 250 ps tolerance.

If we demand even greater resolution, then we either need to restrict ourselves to short time intervals and record lengths below the screen width, such as <50 ns/div on an SDS800X HD and <20 ns/div on the SDS3000X HD in order to force internal interpolation for better time resolution (which will restrict the maximum measurable interval to 200 ns for the SDS800X HD and 100 ns in case of the SDS3000X HD), or we better use the advanced math to create an interpolated copy of the original waveform and measure that instead. This way we can get up to 25 ps resolution for the SDS800X HD and 12.5 ps for SDS3000X HD even for longer intervals.

We should still be aware that the math trace cannot get longer than the maximum analysis length (10 Mpts for SDS800X HD, 40 Mpts for SDS3000X HD), so with the maximum interpolation we can only use 50 µs/div timebase max. This still allows maximal accurate measurements for intervals up to 500 µs.

EDIT: corrected the resolution for the SDS800x HD; originally, the numbers were given for an SDS1004X-E).

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