Products > Test Equipment

Pocket-Sized 6 GHz 1 TS/s ET Scope

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joeqsmith:
Looks like the EEVBLOG site is having problems again.  I'll try and get back with you later on in the day.

***
I am using an RF generator to a DC splitter to ch1&2.  3&4 are turned off.  10MHz signal, 0V trigger, 100ps/div, 64pts/div, 500ns holdoff.  Start with around 200mVp-p level.   Center the waveforms at 10mV/div.  Set ch2 to 5mV/div.  Decrease signal level.   See attached.


joeqsmith:

--- Quote ---As to why the vertical division has any effect at all: the displayed vertical region changes the CDF search bounds. This in principle shouldn't affect anything (just gives higher resolution), but gives a starting point if you want to investigate it over serial.
--- End quote ---

Learned something new about the product.  Reading the manual:


--- Quote ---The parameters s0…s7 represent the lower bound (“start voltage”) of the region to sample
for each channel, on a scale from –1.5 V (0) to +1.5 V (65535). This will be the lowest voltage
returned in the corresponding CDF data. The number of parameters required depends on
the model of the oscilloscope, and is equal to the number of channels (regardless of the
bitmask).
• Likewise, the parameters e0…e7 represent the upper bound (“end voltage”) of the region
to sample on each channel, and will be the highest voltage returned in the corresponding
CDF data.
• The parameters s0…s7 and e0…e7 are optional and will retain previously set values if omitted.
Modifying them can be useful for obtaining higher vertical resolution when the samples
per CDF K is low.
The search region (e0 - s0, e1 - s1, etc.) for any channel should not be smaller than 200 units
(∼9 mV). Undefined behavior will occur if this range is too small.
--- End quote ---

There is no mention at all of the boundaries having any effect on the trigger.  But it seems they do.  Adjusting these to a smaller value for channel 1 allows the scope to trigger on some very small signals.   

Showing channel 1&2 attached to the spillter.  -26dBm 2.4GHz signal applied and having no problem with the trigger. 

SJL-Instruments:

--- Quote from: joeqsmith on February 06, 2024, 12:45:46 am ---Thinking about your UI and idea of dragging waveforms.  Set up a waveform to say 400mV.  Now set the scale to 10mV/div.  Now try and drag the waveform into view.  If you release the mouse and try to drag again, it resets back to the original offset.   You can only drag to -125mV.   You have to zoom out to get it back on the screen, take small adjustments and then you can set the offset to keep it on the screen all the way to 10mV/div.

--- End quote ---
Easy enough to allow the marker to be dragged down indefinitely once it hits the bottom of the screen. Will be implemented in next version.


--- Quote from: joeqsmith on February 06, 2024, 01:28:12 pm ---If there truly is a problem with customers entering out of range values, you may want to consider coercing the entry to the boundary conditions.

Looking at the PicoTech software, they appear to set boundary conditions.

--- End quote ---
Thanks for the suggestion - this is already implemented in some places (e.g. the trigger holdoff), and we'll systematically go through each input and check when this makes sense.


--- Quote from: joeqsmith on February 06, 2024, 01:30:09 pm ---I am using an RF generator to a DC splitter to ch1&2.  3&4 are turned off.  10MHz signal, 0V trigger, 100ps/div, 64pts/div, 500ns holdoff.  Start with around 200mVp-p level.   Center the waveforms at 10mV/div.  Set ch2 to 5mV/div.  Decrease signal level.   See attached.

--- End quote ---
Based on the CDFs you've sent, this might be metastability in the trigger circuit. It looks like the CDFs are a mixture between the correctly triggered samples, and samples taken at uncorrelated times throughout the waveform. This can occur if you're working on the very edge of the trigger sensitivity (below the recommended 200 mVpp). We'll look into a way to detect or mitigate this. (For now, we can mention this effect in the manual.)


--- Quote from: joeqsmith on February 06, 2024, 01:30:09 pm ---There is no mention at all of the boundaries having any effect on the trigger.  But it seems they do.  Adjusting these to a smaller value for channel 1 allows the scope to trigger on some very small signals.   

Showing channel 1&2 attached to the spillter.  -26dBm 2.4GHz signal applied and having no problem with the trigger.

--- End quote ---
The exact way in which these interact, and the precise minimum signal level required for a trigger, is subject to process variation. The recommended 200 mVpp is a "safe" guideline. We can briefly mention some of these effects in the documentation (e.g. smaller range leading to increased trigger sensitivity), but can't give exact numbers applicable to every unit.

joeqsmith:
Dang, -42dBm and it will trigger well enough to detect the 2.4GHz just above the noise floor.  I was thinking it would be a problem to trigger some basic logic levels.  Apparently this is not the case, at least with this particular scope.

You've been holding out on us!   :-DD   :-+

***
Now that I have had a small taste,  I want these settings exposed in your software!  Time to add a power user mode and let us push the hardware!   
***

--- Quote ---The recommended 200 mVpp is a "safe" guideline.
--- End quote ---
  I don't want to play it safe!   :-DD

SJL-Instruments:

--- Quote from: joeqsmith on February 07, 2024, 01:18:12 am ---Dang, -42dBm and it will trigger well enough to detect the 2.4GHz just above the noise floor.  I was thinking it would be a problem to trigger some basic logic levels.  Apparently this is not the case, at least with this particular scope.

You've been holding out on us!   :-DD   :-+

--- End quote ---
We generally try to keep all the specs conservative  :). Since it's early in the lifecycle, with relatively low volume and low statistics, it's better to play it on the safe side, in case a 3 sigma event occurs (violating a min/max spec) and we get an angry customer.

Perhaps this is a bad idea from a marketing perspective. But much better to underpromise than overpromise.


--- Quote from: joeqsmith on February 07, 2024, 01:18:12 am ---Now that I have had a small taste,  I want these settings exposed in your software!  Time to add a power user mode and let us push the hardware!   
***

--- Quote ---The recommended 200 mVpp is a "safe" guideline.
--- End quote ---
  I don't want to play it safe!   :-DD

--- End quote ---
Got it - we will add this mode. With all the necessary disclaimers, etc. :D
UI might be less polished than the "standard" mode at first. Always open to feedback on which options should be extended, preferred layout, etc.

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