Skip to content

Release 1.176

Pre-release
Pre-release
Compare
Choose a tag to compare
@QuantAsylum QuantAsylum released this 11 May 20:56
· 1 commit to main since this release
1.176
d205b58
This commit was created on GitHub.com and signed with GitHub’s verified signature. The key has expired.
GPG key ID: 4AEE18F83AFDEB23
Expired
Learn about vigilant mode.

Release 1.176 (May 2023)

  • Fixed some display bugs where the RTHZ tracking axis that was added in 1.175 wasn't always showing up.
  • Add a new feature to dramatically reduce DC offsets in acquired ADC data. The issue at hand here is that ADC offsets can normally be 2mV or so. The ADC inputs are AC coupled. However, the source of the offsets occurs after the input capacitors--the input buffers, the gain stages and the ADC. This doesn't really impact AC measurements, but the offsets are bothersome when looking at very small signals in the time domain because the signals aren't exactly where you think they will be.

The way the feature works is as follows:

  1. Bring the analyzer up to operating temperature. This will probably take 15-20 minutes or so. The offsets are dependent on the operating temperature.
  2. Short the 4 inputs (L+ and L-, and R+ and R-). These can be direct shorts to ground, or 50 or 75 ohms.
  3. With the analyzer stopped, go to File->Generate ADC DC Offset File. This will result in the prompt:

image

  1. Click yes. Measurements will be made for each full scale input setting, as the voltage offset present is different for each. This process will take several minutes.

  2. When completed, a new file will be written in the MyDocs/QuantAsylum/QA40x/CalibrationData folder. This file will have the name '1234.dcOffsets'. But instead of '1234' it will be the serial number of your Analyzer.

  3. Inside the file you will see the measured offset for each input range:

image

  1. After the measurements are made and the file is written, you'll be asked if you'd like to apply the offsets to measurements.

  2. You can also elect to apply the corrections in the Edit->Settings dialog.

image

  1. Check the time domain to see if the compensation is working as expected. Here's a Analyzer without DC offsets applied. In the plot below, we can see the left channel (blue) has about 2.8mV of offset, and the right channel (red) has bout 1.2mV off offset. This is 0 dBV full scale input.

image

  1. Now, we go into the settings, tick the "Apply DC Offset to Acquisitions" and run the time-domain trace again. This time we see the "DC Offsets" annunciator in the upper left. We can also see the offsets are now about 120uV for the left, and 40uV for the right.

image

  1. Note that since the offset file is different for each Analyzer you might connect the PC, you can create an offset file for each QA40x analyzer, and the correct offset one will be applied when plug the Analyzer in.
Assets 3
Loading