Indeed, at 5.8GHz the required level is different than 1GHz. Is the sensitivity vs frequency defined somewhere? I assume that we can bias that 200mV anywhere as long as we stay within the common mode range (+/-950mV).
0.2 X 20 (probe attenuation) or 4V swing which is CMOS. Even if you work reliably at 100mvp-p, or a 2V swing, that rules out most logic? Are you expecting it to work with say LVDS and a 20X resistive probe? The manual doesn't offer any suggestions or guidelines when it comes to probing.
QuoteThe THD will display as invalid if there isn't enough resolution to get an accurate measurement. You should have five full periods (ideally 10) to get a meaningful result. We'll clarify this in the manual.Is the THD in your software calculated differently than the calibration certification? If the settings are critical as far as replicating what you call out, you may want to define them.
Interesting idea about including probes. 5X is getting down there. I try to keep loading under 10% error and use 10X (500ohms) in many cases. 100 ohm differential termination with another 200 to ground on each leg .... maybe... I guess as long as people understand the limits of the trigger it's fine. Leave it up to them to sort out if it can be used or not. Consider you may be using a delay line with the 5X probe, knocking another 6dB off. A lot to consider. As you said, it's down to price point.
After starting the software, set all offsets to 0. Entering 50 for scale on channel 1 will randomly select 50 V/div or 50 mV/div. I would expect it to be predictable and was surprised that 50V would be valid. Seems easy enough to reproduce.
...
It's a real pain to hunt down your waveforms with manually setting the offset and scale. Typing in the scales rather than the drop down selection do allow me to set it to what ever I want, but now its a bigger time waste entering all that data.
I have had the software appear to hang. Basically it was displaying wait, but appeared not to be updating the plots as nothing was being displayed on the graph for all 4 channels. Nothing, meaning a blank screen. I changed the scale to 500mV/div, and it remained blank. Offsets all set to 0. I increased the input voltage to 500mVp-p with no triggers. 10MHz. All I did was exit the software and restart, everything was working as expected. I have not been able to replicate this but I have seen the software hang like this before with an earlier revision.
It's the same with dragging the waveform to change the offset, the min/max doesn't track it. It's a constant close waveforms and recreate. Or if I change the vert scale for channel 1, the scale for the min/max don't track it.
Having that start of acquisition time moving all over based on the Base is a pain. I am constantly dragging waveforms.
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I would like to see this thing have some sort of intelligent mode where is autoscales the vertical, locks the start of acquisition to the left[...]
Point being, software for these is IMO, is every bit as important as the hardware. If it drives different than every product out there, it may not get a lot of acceptance. Again, MO.
After starting the software, set all offsets to 0. Entering 50 for scale on channel 1 will randomly select 50 V/div or 50 mV/div. I would expect it to be predictable and was surprised that 50V would be valid. Seems easy enough to reproduce.
...
It's a real pain to hunt down your waveforms with manually setting the offset and scale. Typing in the scales rather than the drop down selection do allow me to set it to what ever I want, but now its a bigger time waste entering all that data.Entering "50" will give 50V/div, and entering "50m" will give 50 mV/div. We'll change this back to a dropdown in the next update, with an option to change it to a textbox if you need arbitrary scales. This change was made primarily for compatibility with high-voltage probes.
I have had the software appear to hang. Basically it was displaying wait, but appeared not to be updating the plots as nothing was being displayed on the graph for all 4 channels. ...That's odd - nothing, as in the axis labels were gone also? Or only the traces?
Shortly after v2.5.7 released, we noticed that de-embedding did not work at 128 pts/div (screen would blank), and re-uploaded a patched version. This may or may not be the issue.
To clarify: the software currently references the "timebase position" to the center of the screen. Changing the base (or zooming in with the scroll wheel) will zoom in keeping the center of the screen fixed. This lets you put the event of interest in the center of the screen, and zoom in.
It was implemented this way by customer request.
Are you proposing that changing the timebase scale should instead keep the left side of the screen fixed? Or the T=0 marker fixed? It's easy enough to make this an option.
Point being, software for these is IMO, is every bit as important as the hardware. If it drives different than every product out there, it may not get a lot of acceptance. Again, MO.We agree with this - your feedback so far has been immensely helpful. We want to be as responsive as possible to customer feedback, to push the software in the right direction.
Is the THD in your software calculated differently than the calibration certification? If the settings are critical as far as replicating what you call out, you may want to define them.The THD in the calibration certificate is obtained via a time-domain regression, not an FFT. With only a few periods, the THD calculated from the FFT will depend on the windowing method used and the timebase range. The time-domain method is immune to these considerations (and gives statistical uncertainties on the extracted parameters).
We will mention this, as well as the exact timebase settings used, in the manual.
I guess I wasn't clear. Entering "50" does not always give 50V/div. It will sometimes give 50mV/div. Try setting channel 1 using 50m. You should see 50 mV/div. Now set it to 50. Does it stay at 50 mV/div or does it change to 50 V? Try it a few times. It's not repeatable every time. Appears random.
Sorry I did not take a screen capture. It was showing wait. Signal input was more than enough to trigger device. Trigger level set to 0. It was like the internal trigger was not working and it wasn't able to detect a valid trigger. Restart of the software cleared it.
Exactly. I want to lock the timebase position to the left, center or right. Adjusting anything else in the timebase would not effect its location.
I would also like to be able to set the acquisition length rather than the samples per division. I want to start at T0, or 11ns, record for 2ns with a resolution of 1ps. Today, it's not that flexible.
Is there a reason why you do not implement the same method in your software as what was used to derive the calibration cert?
This was intentional,
Really? Personally, I'm not a fan of software that tries to outguess me. If it units are volts and I enter 50, it should give me 50, not m,u,n... It should always do the same thing. But that's just MO.
Showing screen capture of PicoTech's 9400 software. This is the first time I have ever looked at their software and it seems fairly intuitive. Note the time base settings. Trigger would need to take on a new meaning with your product. I like their quick button press for most settings returns them to center.
Really? Personally, I'm not a fan of software that tries to outguess me. If it units are volts and I enter 50, it should give me 50, not m,u,n... It should always do the same thing. But that's just MO.We had it implemented as you stated, and changed it after receiving complaints that e.g. typing 50 into the offset box would set it to 50V instead of 50mV.
Interesting. The idea of using the previously set value to determine how to interpret the entry isn't user intuitive IMO. I can't believe someone would want it work this way.
I'm sure as sales grow, you will receive lots of opinions and I wouldn't be surprised if some of those are not how things typically work. If I get 20 people to suggest you should scan right to left with the earliest time always on the right side, will you do it? Just remember it's your product.
Really? Personally, I'm not a fan of software that tries to outguess me. If it units are volts and I enter 50, it should give me 50, not m,u,n... It should always do the same thing. But that's just MO.We had it implemented as you stated, and changed it after receiving complaints that e.g. typing 50 into the offset box would set it to 50V instead of 50mV.
10MHz, voltage set just above where the scope will trigger. Lots of back and forth to center the waveform at 10mV/div. Now set it to 5mV/div. Now change it back to 10mV/div. What is the cause of it going unstable? It's channel 2, so nothing to do with the trigger. Easy to repeat.
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.
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.
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.
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.
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.
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.
The recommended 200 mVpp is a "safe" guideline.
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!
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!
***QuoteThe recommended 200 mVpp is a "safe" guideline.I don't want to play it safe!
We generally try to keep all the specs conservative . ...
Perhaps this is a bad idea from a marketing perspective. But much better to underpromise than overpromise.
... this might be metastability in the trigger circuit.
... this might be metastability in the trigger circuit.
Is it possible this could have been the cause of my locking up the sweeps? If so, is there actually a way the restarting the software can somehow shake it loose? I could believe when it hung both times, I was working with very low trigger levels.
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!
***QuoteThe recommended 200 mVpp is a "safe" guideline.I don't want to play it safe!
Do you remember if the software hung for more than 10 seconds?
Along these lines, you can push the timebase down to 8 or 9 ns if you need it. There will be more distortion on Channel 1, but the other channels should be ok.