Rigol DS1054Z Triggering Question

[Fungus]

Horizontal zoom would do it, where is it?

Push the horizontal scale knob.

[alsetalokin4017]

Or select it from the Horizontal Menu, where it is called "Delayed".

No, on the DS1054z you cannot get "pretty much any timebase value you want" like you can on most analog scopes. You are limited to the same set of timebase values offered by the normal Horizontal Scale knob, and 5 ns/div is the fastest timebase available whether in "zoom" or not. And you may not even be able to zoom that far, depending on how the normal Horizontal Scale is set and what Memory Depth you are using in Acquire. For example if you are set at 1 ms/div, the fastest zoom value that is available is 10 ns/div. And at 10 ms/div the fastest zoom available is 100 ns/div. If you are using 1 channel, 12k Mem Depth and a basic timebase setting of 10 ms/div you can only zoom down to 50 microseconds per division.

[Wuerstchenhund]

No, on the DS1054z you cannot get "pretty much any timebase value you want" like you can on most analog scopes. You are limited to the same set of timebase values offered by the normal Horizontal Scale knob, and 5 ns/div is the fastest timebase available whether in "zoom" or not. And you may not even be able to zoom that far, depending on how the normal Horizontal Scale is set and what Memory Depth you are using in Acquire.

I see. That's indeed quite poor.

My statement was in regards to DSOs in general and not specifically to the DS1054z. I should have made that clearer.

[Fungus]

No, on the DS1054z you cannot get "pretty much any timebase value you want" like you can on most analog scopes. You are limited to the same set of timebase values offered by the normal Horizontal Scale knob, and 5 ns/div is the fastest timebase available whether in "zoom" or not. And you may not even be able to zoom that far, depending on how the normal Horizontal Scale is set and what Memory Depth you are using in Acquire.

I see. That's indeed quite poor.

Why?

You only have 1GS/s sample rate so there's not much point in zooming further than 5ns/div. It already has more than one horizontal pixel per sample.

Sure, you could always zoom further but it doesn't seem worth bashing the 'scope over that tiny limitation.

[alsetalokin4017]

That's right. The thread is about the DS1054z and the horizontal time/div settings are what they are. Sure, it might be nice to be able to set arbitrary time/div values like you can on the Tek 2445B... and I've certainly used this feature on analog scopes in order to make certain measurements easier using the graticule along with an external frequency standard... but frankly it seems to be very rare to actually need this feature and I don't miss it on the Rigol.

[David Hess]

You only have 1GS/s sample rate so there's not much point in zooming further than 5ns/div. It already has more than one horizontal pixel per sample.

It is more of a practical limitation do to bandwidth.  My 100 MHz 2232 which is old enough to drink is also limited to 5ns/div despite a 2 GS/s maximum sample rate.  My 100 MHz analog oscilloscopes also only go to 5ns/div.

[Wuerstchenhund]

No, on the DS1054z you cannot get "pretty much any timebase value you want" like you can on most analog scopes. You are limited to the same set of timebase values offered by the normal Horizontal Scale knob, and 5 ns/div is the fastest timebase available whether in "zoom" or not. And you may not even be able to zoom that far, depending on how the normal Horizontal Scale is set and what Memory Depth you are using in Acquire.

I see. That's indeed quite poor.

Why?

You only have 1GS/s sample rate so there's not much point in zooming further than 5ns/div. It already has more than one horizontal pixel per sample.

It's not poor because of the 5ns/div limitation, I think it's poor that the zoom factors are stepped.

Sure, you could always zoom further but it doesn't seem worth bashing the 'scope over that tiny limitation.

No need to freak out, no-one bashes the scope you so clearly feel fond of. It's just somthing that could have been implemented a bit better. I doubt it's a deal breaker for a $400 scope.

[Fungus]

No need to freak out, no-one bashes the scope you so clearly feel fond of. It's just somthing that could have been implemented a bit better. I doubt it's a deal breaker for a $400 scope.

You still talk like it's a Rigol-specific problem though, which isn't true. Plenty of much-more-expensive 'scopes can't do it either.

It might even be true that the majority of DSOs can't do it, that's you'd have trouble finding one that does. There's simply not much need for it in a DSO and it could complicate the hardware a lot (you'd need to resample the data in real time - not fun!)

[Wuerstchenhund]

No need to freak out, no-one bashes the scope you so clearly feel fond of. It's just somthing that could have been implemented a bit better. I doubt it's a deal breaker for a $400 scope.

You still talk like it's a Rigol-specific problem though,

No, I don't. I actually never never said that it's Rigol-specific, this is just you being hyper-sensitive again.

which isn't true. Plenty of much-more-expensive 'scopes can't do it either.

And plenty more of much-more expensive scopes can, so what?

It might even be true that the majority of DSOs can't do it, that's you'd have trouble finding one that does.

No, not really. There are plenty around that can zoom in into a waveform outside the fixed timebase spacing, like the Agilent/Keysight Infiniium 8000A/9000A/80000A/90000A Series, or the Infiniium S/X/V/Z Series (not sure if the DSOX can do that). Or the LeCroy 9300/LC/WR LT/WR2LT/WP900/WR 6k(A)/WP 7k(A)/WM 8k(A)/WS400/WSXs(-B)/WRXi(-A)/WP7zi(-A)/WR6zi/WM8zi(-A)/WR8k/LM9zi/LM10zi/WS3k.

There's simply not much need for it in a DSO and it could complicate the hardware a lot (you'd need to resample the data in real time - not fun!)

No, it wouldn't. There's no need to resample (which some of the scopes above can do easily). Zoom doesn't generate new data, it simply takes a segment of the sample data to create a closer look.

And there is clearly some need for variable zooming, which is why most of the more advanced scopes have it.

There's little reason why even cost-cutting hardware like the DS1054z could implement a fully variable zoom instead of the stepped approach. I guess the reason it's done is because people coming from analog scopes might find the concept of a 'delayed timebase' with fixed steps easier.

Anyways, my original comment was aimed at David Hess and his suggestion that variable timebase is not available on a DSO.

[2N3055]

No, not really. There are plenty around that can zoom in into a waveform outside the fixed timebase spacing, like the Agilent/Keysight Infiniium 8000A/9000A/80000A/90000A Series, or the Infiniium S/X/V/Z Series (not sure if the DSOX can do that). Or the LeCroy 9300/LC/WR LT/WR2LT/WP900/WR 6k(A)/WP 7k(A)/WM 8k(A)/WS400/WSXs(-B)/WRXi(-A)/WP7zi(-A)/WR6zi/WM8zi(-A)/WR8k/LM9zi/LM10zi/WS3k.

Hate to state the obvious, but I don't see the point in stating that 20000$ and up list price scopes have more bandwidth, nicer and bigger screens, more and more sophisticated features, beautiful and responsive GUI .. etc. etc. etc.. than equipment that costs 10-20 times less...

They better do for that price!!

I personally like that my screen graticule has calibrated meaning (that is why variable vertical sensitivity and variable time base on those analogue scopes was marked "UNCAL", once you use it what you see on the screen is no more quantifiable but  just visible) so I personally don't need linear zoom... I appreciate that it could be useful and nice to have, but not necessary, at least not for me.

On the other hand,  trigger delay limited by sampling rate and buffer size can be a problem. But that is something that comes with the how digital triggering concept is usually implemented..
I agree it could be implemented by postponing buffer acquisition by any arbitrary amount, and probably not even very hard to do, but I guess it was not important enough..
Luckily, so far I could get by by using deep memory, but agree that it could be a problem..

Right now I checked, on 500us/DIV I can zoom in to 5ns, so factor of 100000. That is  a sweet spot, if you go faster or slower, you either get a limit by sample time or memory depth...

So separate hardware based trigger delay would be nice...

But as I said, didn't have a problem with it so far...

Best regards,
Sinisa
 

[David Hess]

On the other hand,  trigger delay limited by sampling rate and buffer size can be a problem. But that is something that comes with the how digital triggering concept is usually implemented..
I agree it could be implemented by postponing buffer acquisition by any arbitrary amount, and probably not even very hard to do, but I guess it was not important enough..
Luckily, so far I could get by by using deep memory, but agree that it could be a problem..

It comes about because despite what the manual implies, the 1000Z series does not implement delayed sweep/acquisition.  Rigol calls it that but it is just a horizontal zoom.  Marketing trumps engineering.

There is *nothing* about digital triggering which prevents delayed sweep/acquisition.  Detect the trigger in real time as usual, acquire as usual, and then continue to acquire overwriting the beginning of the acquisition record.  If that later part seems like an obstacle, consider that the DSO *already* does that to support a pretrigger record.

When I became aware of this issue with the 1000Z, I checked to see which budget DSOs support delayed sweep/acquisition but it is not always easy to tell from the user manuals; you certainly cannot tell from the deceptive Rigol 1000Z manual.  DSOs with short record lengths support it because they have no other choice.  DSOs which support B triggering also support it but as it ends up, there are many DSOs which do not support B triggering that still support delayed sweep/acquisition so unfortunately that is not a definitive test.

[2N3055]

On the other hand,  trigger delay limited by sampling rate and buffer size can be a problem. But that is something that comes with the how digital triggering concept is usually implemented..
I agree it could be implemented by postponing buffer acquisition by any arbitrary amount, and probably not even very hard to do, but I guess it was not important enough..
Luckily, so far I could get by by using deep memory, but agree that it could be a problem..

It comes about because despite what the manual implies, the 1000Z series does not implement delayed sweep/acquisition.  They call it that but it is just a horizontal zoom.  Marketing trumps engineering.

There is *nothing* about digital triggering which prevents delayed sweep/acquisition.  Detect the trigger in real time as usual, acquire as usual, and then continue to acquire overwriting the beginning of the acquisition record.

Thinking about it you are right, it doesn't have delayed triggering at all, but by using zoom you can simulate it to the some extent...  And as I said delayed trigger could be easily implemented... But since you can use zoom for a "sort of delay trigger" I guess they figured they don't need the real one...

Marketing decided it was good enough ..

Cheers!!

[David Hess]

Thinking about it you are right, it doesn't have delayed triggering at all, but by using zoom you can simulate it to the some extent...  And as I said delayed trigger could be easily implemented... But since you can use zoom for a "sort of delay trigger" I guess they figured they don't need the real one...

Marketing decided it was good enough ..

Zoom and delayed sweep/acquisition by themselves do not replace delayed triggering.  Try using the Rigol 1000Z to look at a delayed waveform which has lots of jitter to find out why.

What allows them to get away with it is the large record length which hides this lack of capability but it makes sense for a budget DSO; increasing digital integration follows Moore's Law makes adding additional memory cheap.  It also makes programmable logic resources cheap so adding the logic to support true delayed sweep/acquisition and even delayed triggering is cheap.  What it does not do however is make design time cheap and marketing is cheaper than design.  To put it in terms Dilbert and Stef (userfriendly.org) would understand, if you are not marketing, then you are overhead.

I have pointed out this connection with Moore's Law and increasing integration before.  The reason these oscilloscopes do not have analog triggering and equivalent time sampling has nothing to do with performance; it is because digital triggering is cheaper.

[rstofer]

I have pointed out this connection with Moore's Law and increasing integration before.  The reason these oscilloscopes do not have analog triggering and equivalent time sampling has nothing to do with performance; it is because digital triggering is cheaper.

Or maybe somebody realized that equivalent time sampling makes assumptions about the nature of the signal.  If you get one shot at the signal, ET sampling doesn't buy much.

http://www.tek.com/document/application-note/real-time-versus-equivalent-time-sampling

Much of the justification for the DSO is the 'S' part - storing a single shot waveform.

[Wuerstchenhund]

Hate to state the obvious, but I don't see the point in stating that 20000$ and up list price scopes have more bandwidth, nicer and bigger screens, more and more sophisticated features, beautiful and responsive GUI .. etc. etc. etc.. than equipment that costs 10-20 times less...

Instead of "stating the obvious" you could have just read properly what Fungus and I wrote (including the part you didn't quote), which was:

No need to freak out, no-one bashes the scope you so clearly feel fond of. It's just somthing that could have been implemented a bit better. I doubt it's a deal breaker for a $400 scope.

You still talk like it's a Rigol-specific problem though,

No, I don't. I actually never never said that it's Rigol-specific, this is just you being hyper-sensitive again.

which isn't true. Plenty of much-more-expensive 'scopes can't do it either.[/qb]

And plenty more of much-more expensive scopes can, so what?

It might even be true that the majority of DSOs can't do it, that's you'd have trouble finding one that does.

No, not really. There are plenty around that can zoom in into a waveform outside the fixed timebase spacing, like the Agilent/Keysight Infiniium 8000A/9000A/80000A/90000A Series, or the Infiniium S/X/V/Z Series (not sure if the DSOX can do that). Or the LeCroy 9300/LC/WR LT/WR2LT/WP900/WR 6k(A)/WP 7k(A)/WM 8k(A)/WS400/WSXs(-B)/WRXi(-A)/WP7zi(-A)/WR6zi/WM8zi(-A)/WR8k/LM9zi/LM10zi/WS3k.

There's simply not much need for it in a DSO and it could complicate the hardware a lot (you'd need to resample the data in real time - not fun!)

No, it wouldn't. There's no need to resample (which some of the scopes above can do easily). Zoom doesn't generate new data, it simply takes a segment of the sample data to create a closer look.

And there is clearly some need for variable zooming, which is why most of the more advanced scopes have it.

There's little reason why even cost-cutting hardware like the DS1054z could implement a fully variable zoom instead of the stepped approach.

I guess the reason it's done is because people coming from analog scopes might find the concept of a 'delayed timebase' with fixed steps easier.

Anyways, my original comment was aimed at David Hess and his suggestion that variable timebase is not available on a DSO.

Emphasis mine.

It shouldn't take a reading genius to figure out that I listed much more expensive scopes because the particular argument included much more expensive scopes, so it's a bit silly to complain that I listed much more expensive scopes

Besides, a few of the scopes I listed are pretty old (some are from the early '90s). These days they're hardly "much more expensive", but still in many areas they're still much more capable. But it shows that variable zoom isn't exactly a novelty.

They better do for that price!!

Variable zoom isn't something spectacular, as I said it's been around for a while, and who knows there might even be some entry-level scopes that can do it. I just don't know because that's not exactly the type of scope I use regularly.

[alsetalokin4017]

For the DS1054z, look in the Trigger menu for some delayed trigger options.
Trigger Menu>Type>Delay, then set up your options as required.

Also you can scroll horizontally through the memory so that you can look at sections of the waveform that are far distant in time from the trigger point.

[2N3055]

Instead of "stating the obvious" you could have just read properly what Fungus and I wrote (including the part you didn't quote), which was:
.......
It shouldn't take a reading genius to figure out that I listed much more expensive scopes because the particular argument included much more expensive scopes, so it's a bit silly to complain that I listed much more expensive scopes

OK my English comprehension is not so good, I missed a few valid points.. You are correct...
I'm very sorry that I upset you with my comment...

Have a good one!!

[David Hess]

Or maybe somebody realized that equivalent time sampling makes assumptions about the nature of the signal.  If you get one shot at the signal, ET sampling doesn't buy much.

And what happens when you get one shot at the signal and your digital trigger is subject to aliasing?

For the DS1054z, look in the Trigger menu for some delayed trigger options.
Trigger Menu>Type>Delay, then set up your options as required.

From the manual:

In delay trigger, you need to set signal source A and signal source B. The oscilloscope
triggers when the time difference (?T) between the specified edges of source A
(Edge A) and source B (Edge B) meets the preset time limit, as shown in the figure
below.   
Note: Edge A and Edge B must be neighbouring edges.

That is *not* a delayed trigger in the sense being discussed.

Also you can scroll horizontally through the memory so that you can look at sections of the waveform that are far distant in time from the trigger point.

But you can only do this within the acquisition record and you cannot make a new acquisition presumably at a higher sample rate.  Rigol conflates the common usage for delayed sweep with horizontal magnification.  The former can be used to achieve the later but the later is not a substitute for the former.

I have used many DSOs which have both and go to some effort to separate them avoiding confusion.  The current trend with large acquisition records appears to be to combine these functions leading to the problem of limiting the sample rate in a predictable but obscure way.