Hey all, I’ve seen this topic come up before and I’ve run into several situations in production testing where I needed to measure the phase of of the DUT. Tractor never had this test, so I made my own.
You can select the reference channel to be the QA401 output, or the Input of the opposite channel. When using the output as reference, the measurement is just the same as what is shown in the QA401 software.
Just a note that this test is only for the QA401. I haven’t needed to use the QA403 for production testing yet. Also there are a few other tweaks to this version of Tractor like relative paths for photos and masks, actually being able to disable tests by unchecking them, and another serial test we use for controlling a switching interface.
Thought I’d share it here if anyone else is interested. May be useful to someone else, maybe not.
Hey @restorer-john, I was able to take a look at making a phase test for the QA403 today.
The compute phase REST API was not returning anything so I implemented my own cross-correlation from the time data to calculate the phase. I had to do some calibration for the propagation delay when using the output as reference but I tested it with 3 different QA403’s and it was consistent when testing with a loopback up until about a test frequency of about 6kHz, and then it starts to break up accuracy a bit.
In the screenshots, the Left channel is going through a device and using the right input loopback as reference and Right channel is just referencing the output and using the calibration offset.
Seems the most accurate at 1kHz test frequency. Could maybe use a bit more work, but its working and getting decent enough results. I might revisit this another time, but hopefully it helps you and others out a bit.
