Digital Jitter Measurements

Is it possible to measure the digital jitter performance of a DAC using the QA403? I would be interested in something similar to the AP J-Test feature but I was wondering want type of hardware is required. I didn’t see any questions similar to this and was wondering if this is something that was considered for the upcoming QA404 or perhaps as an add on.


Hi @speakergeek, if you “play” a J-Test signal (via WAV) into a dac, you should see the j-test spectrum on the QA403. If you “play” a j-test from the DAC on the QA403, you’d probably not see anything because the ADC and DAC are using a shared clock. Any jitter on one would be seen on the other and the net result would appear to be no jitter.