Products > Test Equipment
Pocket-Sized 6 GHz 1 TS/s ET Scope
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SJL-Instruments:

--- Quote from: joeqsmith on February 25, 2024, 11:51:19 pm ---Looks like the actual changelog was not updated.   

Nice job with the new release. 

--- End quote ---
It may be cached by your browser. Try a refresh - this goes for the manual as well.
joeqsmith:
Ran the new software a fair amount and did not find any problems.   Looks like you fixed some of the minor problems I saw with the previous versions.   I like you are taking the time to clean it up as well as adding features.   I like the new dialog readout.   The auto setup has been working well for me.  A time saver.  I like that I can tune the time base to get it close and have it auto adjust from there.  It was a good idea.

IMO, the two big ticket items now are programming the FPGA and microcontroller over the USB, if it is even possible.  The other is or course, can it be sped up with a loss of performance.   I make use of the manual resolution settings to hunt down the timing but that only helps so much.  Having a way to sweep faster would be very helpful even suing the setup phase.

While making the review, I though about comparing it with my old LeCroy 7200 while looking at an ignition signal.  The problem is that I am working with trigger rates <500Hz.  The scope is currently just too slow for this application.   It may be a case where it just isn't going to be a good fit for this application.   
SJL-Instruments:

--- Quote from: joeqsmith on February 26, 2024, 02:02:21 pm ---Ran the new software a fair amount and did not find any problems.   Looks like you fixed some of the minor problems I saw with the previous versions.   I like you are taking the time to clean it up as well as adding features.   I like the new dialog readout.   The auto setup has been working well for me.  A time saver.  I like that I can tune the time base to get it close and have it auto adjust from there.  It was a good idea.

--- End quote ---
Thanks for the feedback. Glad to hear that the recent features have been helpful, and that no new bugs have cropped up.


--- Quote from: joeqsmith on February 26, 2024, 02:02:21 pm ---IMO, the two big ticket items now are programming the FPGA and microcontroller over the USB, if it is even possible.  The other is or course, can it be sped up with a loss of performance.   I make use of the manual resolution settings to hunt down the timing but that only helps so much.  Having a way to sweep faster would be very helpful even suing the setup phase.

--- End quote ---
USB-based DFU for the FPGA and microcontroller is possible with the current hardware. It just takes time to implement. Our plan is for the next firmware revision (v14) to be the last one requiring external flashing hardware.

So far we have sped up the firmware by a factor of ~3 compared to v13. Above 500 ktrig/s, we can achieve at least 30x practical speedup based on our accounting of timings. This also just takes time.

Before release, will also need to rerun our glitch/performance/temperature tests for at least a week, as these are substantial firmware changes. It's a bit early to give an ETA, but we're aiming for end of March.


--- Quote from: joeqsmith on February 26, 2024, 02:02:21 pm ---While making the review, I though about comparing it with my old LeCroy 7200 while looking at an ignition signal.  The problem is that I am working with trigger rates <500Hz.  The scope is currently just too slow for this application.   It may be a case where it just isn't going to be a good fit for this application.   

--- End quote ---
The theoretical minimum acquisition time for one point @ 500 Hz trigger rate is 12*2 ms = 24 ms for 12-bit resolution, with 1 trigger per CDF sample. At 4 pts/div, this is ~1 second per sweep. Slow, but usable.

For comparison, we measure ~250 ms required with firmware v13 @ Nmin=5, Nmax=5, K=12 with 500 Hz trigger. We measure ~15 seconds/sweep with these settings @ 500 Hz.
So practically, there's a factor of 10 to be gained at low trigger rates.

Asymptotically, CDF sampling requires about the same number of triggers as an ADC sampler, when the full distribution (noise, eye diagram) is required. (Section 2.1.2, point 3.) This holds in the limit of many points acquired. But for single-valued signals where only 1 sample is needed, CDF sampling requires 12x more triggers for a 12-bit resolution.
joeqsmith:

--- Quote from: SJL-Instruments on February 25, 2024, 05:06:28 pm ---
--- Quote from: joeqsmith on February 25, 2024, 04:32:54 pm ---From the manual:

--- Quote ---When vector trace mode is disabled, the full distribution of the measured signal is displayed with
intensity grading.

--- End quote ---
While you have described how to calculate the voltage for a given time, you do not explain how this full distribution is derived.   Can you provide more details?  Are you still working with the same set of data from the R command?  If so, do you still toss out the same outliers? 

--- End quote ---
The full probability density function (PDF) is obtained by numerically differentiating the CDF data from the R command. You can implement this with a finite difference. Nothing is tossed out.


--- Quote from: joeqsmith on February 25, 2024, 04:32:54 pm ---
--- Quote ---... if the signal is single-valued at each point in time.
--- End quote ---
   
I assume that this full distribution is needed to see the multiple points in time. 


--- Quote ---When vector trace mode is enabled, the channel is drawn with one continuous line that follows
the average of the measured sample distribution. The standard deviation will be shown as a band
around the trace, indicating of the noise level.
--- End quote ---
I assume this standard deviation is also looking at the same full distribution.   

--- End quote ---
Yes, the full distribution is required for multivalued signals such as eye diagrams.
The standard deviation can be calculated from the PDF. The software calculates it directly from the CDF for numerical efficiency (integration by parts), but it gives equivalent results.

--- End quote ---

While it seems simple enough, based on my past history, let's start out making sure I am interpreting your comments correctly.  Shown is the PDF for your example data from 4.3.3.   Assuming this is correct, you just directly plot this data when the vector is disabled?
SJL-Instruments:
You should also take the differences of the voltage array, and perform a division. The PDF is given by dF/dV.
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