MSO5000 Bode Plot Capability: Is it Good Enough? [Many tips about a 1st scope]

[mawyatt]

Regarding the Bode plotting capability within various DSOs.

Here's one that honestly we did not think possible, or ever attempted. This is the injection locking of an oscillator which requires the Bode function to correctly surmise the correct response in the presence of the oscillator signal, which is close to the measurement frequency!! We've added a snip from Razvi which is referenced in the thread, and note the Bode response curves from the measurements!!

https://www.eevblog.com/forum/projects/injection-locked-peltz-oscillator-with-bode-analysis/msg4424434/#msg4424434

If you are in to non-linear dynamics, the injection locking phenomenon is fascinating, and having an instrument capable of displaying such is something we did not expect and required no post processing, this is right from the DSO:-+

Best

[2N3055]

And they've added a hires mode that will reduce noise to within spitting distance of a Siglent in a pinch thanks to the beast's massive sample rate.

(but not on all channels simultaneously)

Stop repeating things that are not true. It doesn't work like that. And even more difference in Bode plot calculations, because of, physics..
It is not Siglent marketing but true. Fun fact is that even Rigol is not even pretending that what are you saying is true.. This is your own misunderstanding.....

What you require, really depends on the application and test envioronment.
What are you planning to Bode plot ?

Things such as frequency range, noise floor and dynamic range are pretty obvious, and many measuring instruments these days have some excellent features. If you are studying just analog type circuits, amplifiers, filters, servo systems etc... that is all pretty straightforward.

These days switching power supplies are a significant area of interest, and Bode plots are just about a must have, if you wish to maintain your sanity.
Switching supplies are are very Bode plotter unfriendly by being significant producers of wideband noise by the power components.

Trying to resolve a sine wave of a couple of millivolts submerged in hundreds of millivolts of spikes and ripple is something very simple equipment is just not capable of doing.  Its all very well the software being able to plot a nice smooth gain curve over 100db dynamic range, but unless millivolt or microvolt level signals can be resolved beneath huge levels of noise, the pretty plot on the screen is just not going to happen.

Many if not all low end Bode plot systems just use direct analog to digital conversion and some clever number crunching. That works fine for demo purposes by the plotter salesman, but not when trying to make real world measurements on switching power supplies or in really noisy applications.

The only way to do it is with a couple of very narrow band swept filters, similar in concept to a spectrum analyser.  That can be done either with hardware or very sophisticated software to reject everything but the exact test frequency being run through the equipment under test.
All very clever, but it does not come cheap unfortunately.

So a simple low end Bode plotter may be all you need, or it may not work for you at all, depending on the test environment.

While in general what you say is true, you seem to not know how it is implemented..
Very narrow band swept filters with sophisticated software and processing synchronized with generator and vari-level sampling and vary-level stimulus is exactly how it IS implemented in Siglent.
And it works very well..

[nctnico]

No. But depending on your location, a GW Instek GDS1054B could be a good alternative to buy a decent 4 channel oscilloscope (options can be enabled for free using a key generator available on this forum). For example: https://eleshop.eu/gw-instek-gds-1054b.html

Interesting. Mh. How does it compare to the Siglent? Snappier UI?

The screen looks smaller than Siglent's, but it's still 7". Probably it's the scope body that's larger.. I'm seeing that people on this forum adapted a 8" screen, but it's far from being straightforward.

Tell me, is that Eleshop a reliable vendor? Thanks!

IMHO Eleshop is a reliable vendor. I have bought some test equipment from them (and returned one as well because it didn't meet my expectations). The firmware for the GDS1054B is mature. If you do run into a problem, the service department from GW Instek is responsive and they will fix bugs (if you happen to find one). Personally I find GW Instek's UI easier to use compared to Keysight. The key difference is that GW Instek has a horizontal and vertical row of buttons which makes navigating through the menus much easier. The seperate 'select' button prevents you from turning the rotary encoder while pressing it and selecting a different menu item than the one you wanted to select (which typically happens to me when the rotary encoder and select button are integrated in one).

Little GW Instek 1000 has bode plotting?

No, but it leaves enough room in the budget to buy an analog discovery to do bode plotting with. It could be a more powerfull combo compared to buying a single, more expensive unit.

[mawyatt]

The only way to do it is with a couple of very narrow band swept filters, similar in concept to a spectrum analyser.  That can be done either with hardware or very sophisticated software to reject everything but the exact test frequency being run through the equipment under test.
All very clever, but it does not come cheap unfortunately.

Don't think a traditional SA actually "Sweeps" the analog filter, but "Sweeps" the LO of a Mixer to produce a result that fits within a fixed frequency high quality analog filter. Swept analog filters are very difficult to implement, and high quality swept filters like YIG types are large and expensive.

So don't think Siglent is doing this but implementing an effective swept filter by means of a digital implementation of something similar to the Synchronous Sampling Technique. For this to work well the DR of the overall ADC conversion needs to be very good as well as the noise floor. With the dynamic scaling of the Ch1 and Ch2 input amplifiers and their low inherent noise this allows Siglent to do a very respectable implementation of the Bode Function, which our own experience confirms!!

Best,

[2N3055]

No. But depending on your location, a GW Instek GDS1054B could be a good alternative to buy a decent 4 channel oscilloscope (options can be enabled for free using a key generator available on this forum). For example: https://eleshop.eu/gw-instek-gds-1054b.html

Interesting. Mh. How does it compare to the Siglent? Snappier UI?

The screen looks smaller than Siglent's, but it's still 7". Probably it's the scope body that's larger.. I'm seeing that people on this forum adapted a 8" screen, but it's far from being straightforward.

Tell me, is that Eleshop a reliable vendor? Thanks!

IMHO Eleshop is a reliable vendor. I have bought some test equipment from them (and returned one as well because it didn't meet my expectations). The firmware for the GDS1054B is mature. If you do run into a problem, the service department from GW Instek is responsive and they will fix bugs (if you happen to find one). Personally I find GW Instek's UI easier to use compared to Keysight. The key difference is that GW Instek has a horizontal and vertical row of buttons which makes navigating through the menus much easier. The seperate 'select' button prevents you from turning the rotary encoder while pressing it and selecting a different menu item than the one you wanted to select (which typically happens to me when the rotary encoder and select button are integrated in one).

Little GW Instek 1000 has bode plotting?

No, but it leaves enough room in the budget to buy an analog discovery to do bode plotting with. It could be a more powerfull combo compared to buying a single, more expensive unit.

Analog Discovery II is 400€....

[balnazzar]

No. But depending on your location, a GW Instek GDS1054B could be a good alternative to buy a decent 4 channel oscilloscope (options can be enabled for free using a key generator available on this forum). For example: https://eleshop.eu/gw-instek-gds-1054b.html

Interesting. Mh. How does it compare to the Siglent? Snappier UI?

The screen looks smaller than Siglent's, but it's still 7". Probably it's the scope body that's larger.. I'm seeing that people on this forum adapted a 8" screen, but it's far from being straightforward.

Tell me, is that Eleshop a reliable vendor? Thanks!

IMHO Eleshop is a reliable vendor. I have bought some test equipment from them (and returned one as well because it didn't meet my expectations). The firmware for the GDS1054B is mature. If you do run into a problem, the service department from GW Instek is responsive and they will fix bugs (if you happen to find one). Personally I find GW Instek's UI easier to use compared to Keysight. The key difference is that GW Instek has a horizontal and vertical row of buttons which makes navigating through the menus much easier. The seperate 'select' button prevents you from turning the rotary encoder while pressing it and selecting a different menu item than the one you wanted to select (which typically happens to me when the rotary encoder and select button are integrated in one).

Thanks, that was very useful.
I'm buying that GW-Instek from Eleshop within the next 24 hours, and the AD2 from Amazon (AFAIU the gds1054B doesn't do Bodes..). If I keep lingering I'll never buy anything...

[balnazzar]

No. But depending on your location, a GW Instek GDS1054B could be a good alternative to buy a decent 4 channel oscilloscope (options can be enabled for free using a key generator available on this forum). For example: https://eleshop.eu/gw-instek-gds-1054b.html

Interesting. Mh. How does it compare to the Siglent? Snappier UI?

The screen looks smaller than Siglent's, but it's still 7". Probably it's the scope body that's larger.. I'm seeing that people on this forum adapted a 8" screen, but it's far from being straightforward.

Tell me, is that Eleshop a reliable vendor? Thanks!

IMHO Eleshop is a reliable vendor. I have bought some test equipment from them (and returned one as well because it didn't meet my expectations). The firmware for the GDS1054B is mature. If you do run into a problem, the service department from GW Instek is responsive and they will fix bugs (if you happen to find one). Personally I find GW Instek's UI easier to use compared to Keysight. The key difference is that GW Instek has a horizontal and vertical row of buttons which makes navigating through the menus much easier. The seperate 'select' button prevents you from turning the rotary encoder while pressing it and selecting a different menu item than the one you wanted to select (which typically happens to me when the rotary encoder and select button are integrated in one).

Little GW Instek 1000 has bode plotting?

No, but it leaves enough room in the budget to buy an analog discovery to do bode plotting with. It could be a more powerfull combo compared to buying a single, more expensive unit.

Analog Discovery II is 400€....

Indeed. Considering that the Instek is ~500 eur, and that AD2 is ~400, I should be within my budget. The alternative would be the MSO5074.
But, as far as I understood:

- The MSO5K is noisier than Instek, and has a worse front end.
- It has a buggy firmware, while Instek's is mature enough
- Two instruments are better than one, in case the first goes kablooey, you have the second.
- Differential probing is possible with the AD2 (although up to 9 MHz).
- You can work on digital stuff with the AD2 (while the logic probe for the MSO5K costs a fortune, relatively speaking).

On the cons side:

- 7" inches screen VS. 9" is a big minus
- The fan grid on the Instek appears to be tiny. Tiny fan = more noise. Probably more than the MSO5K.

All in all, I think I'll be better served with the AD2 + Instek, for the same price.

[balnazzar]

Mh, one thing I didn't notice is that the Instek has no external trigger input. That's not a good thing.

[nctnico]

Mh, one thing I didn't notice is that the Instek has no external trigger input. That's not a good thing.

That is lacking on many lower end 4 channel oscilloscopes.

[tautech]

You should also be aware SDS2kX Plus has an inbuilt 50 MHz AWG and therefore already has a stimulus source for Bode plot use whereas with X-E models a stimulus source for Bode plot use is an additional expenditure.

Is it inbuilt? I thought one had to buy the little black boxy thing in order to enable the WG...

Yes and class leading at 50 MHz.

All Siglent DSO's capable of Bode plot can drive the USB powered SAG1021I that is now an isolated channel version however like any internal or USB powered AWG, stimulus levels are very limited, regardless of the brand.

If you need a wide dynamic range and and good stimulus levels from an AWG, a standalone 2ch unit and Bode plot capable DSO is the only way to go and offer far more options as skill and needs develop.

Think of this as upselling if you like but why at this level of investment do you need to your limit capabilities in your future as one day you might think doing this is very valuable:
https://www.eevblog.com/forum/testgear/fooln-around-with-dso-awg/

[balnazzar]

That is lacking on many lower end 4 channel oscilloscopes.

Very bad. I initially thought that one of the two BNCs on the back was for external trig, but it's not so..
The Siglent also lacks it..
I can think of N situations where it would come handy.
What is the cheapest 4chs with external triggering? I'm afraid it's precisely the MSO5000...

[balnazzar]

Yes and class leading at 50 MHz.

All Siglent DSO's capable of Bode plot can drive the USB powered SAG1021I that is now an insulated channel version however like any internal or USB powered AWG, stimulus levels are very limited, regardless of the brand.

If you need a wide dynamic range and and good stimulus levels from an AWG, a standalone 2ch unit and Bode plot capable DSO is the only way to go and offer far more options as skill and needs develop.

Think of this as upselling if you like but why at this level of investment do you need to your limit capabilities in your future as one day you might think doing this is very valuable:
https://www.eevblog.com/forum/testgear/fooln-around-with-dso-awg/

Ok, correct me if I'm making mistakes.

The SDS2000 Plus has an inbuilt WG (how many volts?), it's available with no license (or hackable) and it can be used for bode plotting. OR, the inbuilt WG cannot be used for bode plotting and one needs to purchase the SAG external generator?

[balnazzar]

All Siglent DSO's capable of Bode plot

Apart from the bode plots, if you had to make a case for the Siglent scope vs. the Instek, what would you say to a prospective customer?
What does your scope have that the Instek lacks?

[tautech]

Yes and class leading at 50 MHz.

All Siglent DSO's capable of Bode plot can drive the USB powered SAG1021I that is now an insulated channel version however like any internal or USB powered AWG, stimulus levels are very limited, regardless of the brand.

If you need a wide dynamic range and and good stimulus levels from an AWG, a standalone 2ch unit and Bode plot capable DSO is the only way to go and offer far more options as skill and needs develop.

Think of this as upselling if you like but why at this level of investment do you need to your limit capabilities in your future as one day you might think doing this is very valuable:
https://www.eevblog.com/forum/testgear/fooln-around-with-dso-awg/

Ok, correct me if I'm making mistakes.

The SDS2000 Plus has an inbuilt WG (how many volts?), it's available with no license (or hackable) and it can be used for bode plotting. OR, the inbuilt WG cannot be used for bode plotting and one needs to purchase the SAG external generator?

All Siglent DSO's can use any of their AWG stimulus sources for Bode plots without any licensing restrictions.

However for general FG/AWG use licensing need be purchased for inbuilt or SAG1021I usage whereas for standalone with their much higher stimulus/amplitude levels no licensing is needed although they cannot be controlled from within the DSO's UI like the inbuilt and USB units can.

OTOH for Bode plot usage the DSO takes charge of external AWG stimulus while the Bode plot feature is running via the USB control connection or with the standalone units you can also have the scope control the AWG over LAN.

For Siglent scopes all optional functionality has 30 free trial uses before without licensing these options cease to work. The spectrum analyzer ranges are different and they offer free use of all options until 120hrs of runtime is reached.

[tautech]

All Siglent DSO's capable of Bode plot

Apart from the bode plots, if you had to make a case for the Siglent scope vs. the Instek, what would you say to a prospective customer?
What does your scope have that the Instek lacks?

We sure can compare models with just manuals and datasheets but we need know the model class first.
We inform to help with the best decision for current needs and future use but in the end it is not our money to spend.

[balnazzar]

We sure can compare models with just manuals and datasheets but we need know the model class first.
We inform to help with the best decision for current needs and future use but in the end it is not our money to spend.

I was making reference to the sds1104x-e, which has almost exactly the same price of the Instek 1054B.

I understand that the 2000+ is a much better machine, but it costs a fortune (relatively to typical hobbist/student wallets). Lowering the prince to 1 grand, even without the free perks & options of the MSO5000, would make you sell a lot more of them...

[tautech]

We sure can compare models with just manuals and datasheets but we need know the model class first.
We inform to help with the best decision for current needs and future use but in the end it is not our money to spend.

I was making reference to the sds1104x-e, which has almost exactly the same price of the Instek 1054B.

One could argue the Instek is overpriced being only 50 MHz rated.

Best you spend a good deal more time studying datasheets and manuals to discover the real capabilities and feature set of each model.
Do I need link you the datasheets or can you find them ?

[balnazzar]

One could argue the Instek is overpriced being only 50 MHz rated.

Best you spend a good deal more time studying datasheets and manuals to discover the real capabilities and feature set of each model.
Do I need link you the datasheets or can you find them ?

Come on, it's made to be hacked.

No, I don't need the datasheets. A few things that one doesn't find on the datasheets, if you had occasion to test the Instek: sluggishness of the OS (or lack thereof) and quality of the UI.

[tautech]

One could argue the Instek is overpriced being only 50 MHz rated.

Best you spend a good deal more time studying datasheets and manuals to discover the real capabilities and feature set of each model.
Do I need link you the datasheets or can you find them ?

Come on, it's made to be hacked.

No, I don't need the datasheets.

Seems you can't read datasheets then, maybe it's time to learn.
1 GSa/s times 1 or 2 for the 4ch Instek ? Answer is 1 as they don't make a 4ch 200 MHz 1000 series whereas the SDS1104X-E is a 200 MHz design using two 1 GSa/a ADC's so to maintain sufficient sampling rate with all channels active at max frequency to ensure it meets Nyquist.

Do we need investigate feature sets next or can I leave that with you ?

[Fungus]

A few things that one doesn't find on the datasheets, if you had occasion to test the Instek: sluggishness of the OS (or lack thereof) and quality of the UI.

The Instek has one of the most responsive UIs of any 'scope. It also has separate channel controls and a proper button for menu selections, no error-prone pushing of a twisty knob.

It's a very nice little 'scope, I don't believe the bandwidth can be hacked very high though.

[Martin72]

Lowering the prince to 1 grand, even without the free perks & options of the MSO5000, would make you sell a lot more of them...

Or lowering to 800, much more would buy it.
Life could be so easy. 

[balnazzar]

Seems you can't read datasheets then, maybe it's time to learn.
1 GSa/s times 1 or 2 for the 4ch Instek ? Answer is 1 as they don't make a 4ch 200 MHz 1000 series whereas the SDS1104X-E is a 200 MHz design using two 1 GSa/a ADC's so to maintain sufficient sampling rate with all channels active at max frequency to ensure it meets Nyquist.

Do we need investigate feature sets next or can I leave that with you ?

It's always time to learn, of course, but I didn't manage to be understood in this specific context. Here is what I meant, articulated a bit better:

I can read the specs, but I won't find some things in the specs (or in the manuals). For example:

1. If the OS is fast and responsive, compared to Instek's.
2. If the user interface is intuitive to use (again, compared to the Instek's).

Another interesting thing to know is if the Instek can 'zoom out' (AFAIK, Siglent and Rigol can't).

[balnazzar]

The Instek has one of the most responsive UIs of any 'scope. It also has separate channel controls and a proper button for menu selections, no error-prone pushing of a twisty knob.

It's a very nice little 'scope, I don't believe the bandwidth can be hacked very high though.

Mh, good to know. I mean, both aspects.
I dunno. I was leaning toward the Instek due to responsiveness (there are threads in which owners report that also). Using a sluggish scope is an experience I already made, and it's incredibly frustrating.
But the Siglent seems to be a better machine, at least on paper. And owners seems to be generally happy.
I have to say, however, that the SDS5000s  I used at the university are not sluggish, but they are not astonishingly fast either (considering the price). I briefly used the Keysight dsox1204 for ten minutes at a fair, and it seemed snappier.

Choosing a scope is proving to be a difficult thing.

[Martin72]

Hi,

1. If the OS is fast and responsive, compared to Instek's.
2. If the user interface is intuitive to use (again, compared to the Instek's).

Both can be answered by someone who works with all of the mentioned scopes - And then it´s his own impression.
In my case, I got following "scope owning history":

- Rigol DS1000Z
- Rigol DS2000
- Siglent SDS1104X-E
- Rigol MSO5000
- Siglent SDS2000Xplus
- Siglent SDS2000X HD (actual scope)

GW Instek never came into my mind, maybe they making good scopes and nearly nobody knows about, or they knowing about it and this may explain their place by the hobbyists. 

[tautech]

The Instek has one of the most responsive UIs of any 'scope. It also has separate channel controls and a proper button for menu selections, no error-prone pushing of a twisty knob.

It's a very nice little 'scope, I don't believe the bandwidth can be hacked very high though.

Mh, good to know. I mean, both aspects.
I dunno. I was leaning toward the Instek due to responsiveness (there are threads in which owners report that also). Using a sluggish scope is an experience I already made, and it's incredibly frustrating.
But the Siglent seems to be a better machine, at least on paper. And owners seems to be generally happy.
I have to say, however, that the SDS5000s  I used at the university are not sluggish, but they are not astonishingly fast either (considering the price). I briefly used the Keysight dsox1204 for ten minutes at a fair, and it seemed snappier.

Choosing a scope is proving to be a difficult thing.

It can be unless you take a step back to consider all guidance/advice as to its relevance and importance.

Considered thoughtful and deliberate use sees no need for blindingly fast responsiveness except to satisfy some misguided belief that faster must be better. 

Feature set and specs determine what one can do with any instrument not how fast it can do it.