Products > Test Equipment
Siglent SDG1032 high level limited to low ...
<< < (4/6) > >>
rf-loop:

--- Quote from: 2N3055 on May 25, 2024, 05:55:20 am ---
--- Quote from: ebastler on May 25, 2024, 04:42:16 am ---
--- Quote from: 2N3055 on May 24, 2024, 11:02:55 pm ---What is going on here?
 :-DD

--- End quote ---

We are discussing a little design issue of a Siglent product and waiting for a white knight to come to Siglent's defense.  ::)

--- End quote ---

None of it makes sense..
There is no design issue.
Just complete lack of understanding how it works. Even by you.

Newbrain tried to explain...

And only white knight coming to someone's defense is you defending eTobeys right to publicly post his weird questions that make no sense.
And you keep doing it systematically lately...
No matter how wrong the statements of his are.

--- End quote ---

It works as designed. But why there exist lack of understanding how it works.

If the user knew what the designer knew / thought, then he would (probably) understand and master its use and find that it works as designed. Including a couple of small details.

Actually, the confusion boils down to the screen where the amplitude limit is set. It can cause confusion. It lacks essential information that would explain its operation more clearly Of course, it doesn't bother us who know how it works.

Example: I set the limit there (Utility > Output Setup > Amplitude) to, for example, 10,000 Vpp.


(I know that, and many others who know it, that) it means the maximum Vpp voltage of the open BNC output port.
It means the maximum voltage out from output BNC even if load is removed. It limits all other settings for keep this true.

It need clarify even more.
 
It mean limits: Lower limit is -([Amplitude Vpp]/2)  and upper limit is +([Amplitude Vpp]/2) in BNC output without load (aka open).
[Amplitude Vpp] here is value in:  Utility > Output Setup > Amplitude

Including situations where the user has selected HiZ, 50 ohm or some other value between 50 ohm to 100 kohm as the external load value. (Yes it is naturally free adjustable)

Example if user have selected now 50 ohm load impedance and this Amplitude limit is 10.000Vpp. He can now set example max 5Vpp square wave with zero offset. In this case to 50 ohm load square wave bottom is -2.5V and top +2.5V
Now if 50ohm load breaks (open)  now output voltage is bottom -5V and top +5V. (10Vpp)
It is clear that it may be confusing if user do not know how it is designed to work and only information is in meny Utility > Output Setup > Amplitude one Vpp value without any explanation. And now also if then try use Low Level/High level setup or Level and offset it may produce confusion.
Only thing what really deen hard code to user brain is. Instead of Vpp limits it set +V limit and -V limit for Open output (HiZ)
Level values  what can then select in signal paramaters depends what is defined Load and other things what affect signal levels. These values limits are calculated so that if then load goes infinite still levels out from generator do not go over these Amplitude limit. 
it works with dBm values, with RMS values, Voltage levels, with all load values what can define for Load. with al AM modulation levels... sorry if I forget something here...

The user may also choose, for example, AM modulation. This is also important to note due to Siglent SDG's AM modulation level principle (Many other AWG do not use this principle).

With all its available modulation depths, the maximum open gate voltage can therefore be between +5V and -5V. (also note that 120% modulation depth is an option)


If the settings screen read additional information that it specifically sets the hard "open load" limits (in this example +5 V and -5 V), the user might understand it better.
(and User manual)

HiZ is used (and, as example, Amplitude limit set for 10Vpp)
Now I want to output a 0 V to 5 V square wave.   I can now set Amplitude 5 Vpp
Offset 2.5 Vdc. Now there is 0 - 5V square.

But now if want 6Vpp square but so that it is between 1V and 6V, with this setup it is not possible.  Then need to change  Amplitude limit to least 12Vpp
Because then it is -6V and +6V

It is very simply if these limits are told in this Amplitude limit setup screen (and of course also in user manual)
This is because also users do not have clairvoyant skills.

What should be improved is the information on the device's setting screen and the user's manual.


At least after you know that it applies to the open output and all load setting values and, among other things, all modulation depths.

Note: This AM modulation is included here separately because Siglent SDG follows the usual principle of RF generators. The output level is set to the level of the carrier wave. Not sum level. When adjusting the modulation depth, the carrier level does not change but sum level change and max is reached when Max available AM depth 120% is in use. So max signal level is rejected so that if user turn AM depth to 120%, then it do not break maximum Amplitude limit (if there is no output load, aka open BNC).
ebastler:
Thanks for the detailed explanation, @rf-loop. But I think the functionality was understood before -- Fgrir had stated the key principle in reply #2, and I had followed up in #5.

While the internal workings are certainly consistent, I still don't think they are the clearest way to present "output level limiter" functionality to the user. I would consider it much more straightforward, from a user perspective, if the output limit I set is always the one the generator aims to adhere to -- i.e. when I set 50 Ohm outputs, the limiter should internally double its value, such that the voltage fed into 50 Ohms remains the nominal one set in the limiter UI. Also, I still don't see how Siglent's implementation is more fail-safe -- see my reply #7.

Anyway, this probably falls into the category of "don't break existing user habits" -- so it won't be changed even if I could convince you that a change would result in a more logical interface for new users. I rest my case.
nctnico:

--- Quote from: ebastler on May 25, 2024, 04:29:38 pm ---Thanks for the detailed explanation, @rf-loop. But I think the functionality was understood before -- Fgrir had stated the key principle in reply #2, and I had followed up in #5.

While the internal workings are certainly consistent, I still don't think they are the clearest way to present "output level limiter" functionality to the user. I would consider it much more straightforward, from a user perspective, if the output limit I set is always the one the generator aims to adhere to -- i.e. when I set 50 Ohm outputs, the limiter should internally double its value, such that the voltage fed into 50 Ohms remains the nominal one set in the limiter UI. Also, I still don't see how Siglent's implementation is more fail-safe -- see my reply #7.

--- End quote ---
Agreed. More likely it is a bug or oversight in Siglent's firmware. I just tried on my Tektronix AFG31000. The limits scale along with the load setting which is much more consistent as the limits are always 1 on 1 related to the amplitude and offset settings (which are scaled for the configured load impedance). It is up to the user to make sure a load with the correct impedance is connected. As Tektronix is a company with a very long history of designing high end AWGs, I trust they got it right based on decades of experience.
2N3055:
Voltage limits will be applied the same, regardless of load settings.

Because unloaded AWG will always have same output voltage, regardless if you set it to High-Z  and 4V P-P and 50Ω and 2V P-P. It will be 4V P-P, and on 50Ω it will become 2V P-P only after you load it with 50Ω.

So if you are working with Hi impedance load (non 50Ω) or with load that is changing from 100Ω to say 1000Ω impedance, voltage on output will vary, with maximum reaching Hi-Z value unloaded.

And that is how every AWG or signal generator works, unless you are using leveled gen or some special AWG (expensive) that does leveling.
2N3055:

--- Quote from: nctnico on May 25, 2024, 04:41:31 pm ---
--- Quote from: ebastler on May 25, 2024, 04:29:38 pm ---Thanks for the detailed explanation, @rf-loop. But I think the functionality was understood before -- Fgrir had stated the key principle in reply #2, and I had followed up in #5.

While the internal workings are certainly consistent, I still don't think they are the clearest way to present "output level limiter" functionality to the user. I would consider it much more straightforward, from a user perspective, if the output limit I set is always the one the generator aims to adhere to -- i.e. when I set 50 Ohm outputs, the limiter should internally double its value, such that the voltage fed into 50 Ohms remains the nominal one set in the limiter UI. Also, I still don't see how Siglent's implementation is more fail-safe -- see my reply #7.

--- End quote ---
Agreed. More likely it is a bug or oversight in Siglent's firmware. I just tried on my Tektronix AFG31000. The limits scale along with the load setting which is much more consistent as the limits are always 1 on 1 related to the amplitude and offset settings (which are scaled for the configured load impedance). It is up to the user to make sure a load with the correct impedance is connected. As Tektronix is a company with a very long history of designing high end AWGs, I trust they got it right based on decades of experience.

--- End quote ---


You keep forgetting to note to beginners and those that don't know that you are comparing a 300 € AWG to a 19000 € one..
Smooth..
Navigation
Message Index
Next page
Previous page
There was an error while thanking
Thanking...

Go to full version
Powered by SMFPacks Advanced Attachments Uploader Mod