I have noticed a pretty serious bug which can go unnoticed if you don’t listen to the signal.
Basically sometimes the software is set to produce 1kHz but in reality is it producing 500Hz. It is still plotting it at 1kHz, so you have no way of telling this is happening unless you are listening to the signal! (e.g. have a speaker plugged in)
A similar thing happens with the input scale setting where the actual input scale on the device is different from what the software tells you it is. You can tell visually, if you know the exact gain of your DUT and are paying close attention. It is dangerous none the less. Because the interface may tell you the signal level is lower than what it actually is. That could lead you to increase the signal level to dangerous level and blow something up.
I think the bug arise from QA403 and the software not being in sync. I haven’t root caused it carefully, but I think this happens when the computer goes to sleep and wakes up while the software is running and you are on a different sampling rate than 48kHz. But I’m not sure if that’s the only time this happens. I think I have seen it get into this out of sync state without going to sleep.
Software version: 1.215
Firmware: 60
OS: Windows 10
Hi @siarez , there was a bug fixed in 1.209 where the sample rate wasn’t reverting to 48 kHz correctly when File→New was issued.
The next time you see this happen, stop the acquisition, select 48k sample rate and see if it fixes it. What you note–that the HW and SW are out of sync– was what was happening prior to that 1.209 fix. If you are seeing 500 Hz when 1 kHz was expected, then what is likely happening is the hardware is at 96k and the software thinks it’s at 48k.
Based on your description, I tried this:
Set to 192k sample rate and 1k tone and verify 1 kHz output on scope.
Go to sleep. While in sleep, unplug the QA403 and plug it back in. This resets the hardware and the software isn’t aware of this reset.
Wake the machine up from sleep. It still thinks its at 192k sample rate.
Run, and verify 250 Hz on scope.
Now, the software has no notion of going to sleep or waking. But a guard against this would be to re-write the sample rate to the hardware on every start of acquisition. I’ll think on this more. But please see if the above (power cycling QA403 while asleep) might explain what you are seeing.
I’ve been using the “new settings” as a “reset” sanity check, then loading my default.settings file which I’ve set up to have my usual dashboard tiles layout. I also made the default.settings file a read-only file so the QA40x SW cannot update it on shutdown. That way, the SW always starts up with my preferred layout no matter what I had open/displayed at shutdown.
I don’t think I’ve experienced the wake-up from sleep SR issue as the USB port cuts off the power when it goes to sleep on my (older) PCs/laptops and the QA403 gets a power cycle reboot.
Hi @siarez, I think the sample rate bug you identified has been fixed in 1.221. The relays re-writes will need another release to get fixed. But please see if this is fixing the sample rate bug you identified. And thanks very much for reporting this!