In Reply to: RE: How do you figure? posted by Dave_K on April 5, 2016 at 05:08:51:
The J-test was designed by its creator to deal with specific artifacts related to SPDIF signal integrity. One might be able to devise specific tests for USB implementations that could do a better job. Or one could just use a collection of high frequency sine waves.
Testing the noise floor for digital black is not a bad idea, but simply looking at the noise floor on a spectrogram may not show some artifacts, because a spectrogram shows only half of the available information. (For example, white wide-band noise and a digital impulse may both show the same amplitude spectra, but the digital impulse will be audible at a might lower level than the wideband noise.)
The interesting activity is probably artifacts that are correlated with the signal, since these are perceived as part of the music rather than as part of the background. Detecting these correlations requires either working in the time domain or doing some kind of synchronous average related to USB bus activity.
Tony Lauck
"Diversity is the law of nature; no two entities in this universe are uniform." - P.R. Sarkar
This post is made possible by the generous support of people like you and our sponsors:
Follow Ups
- RE: How do you figure? - Tony Lauck 04/5/1608:42:36 04/5/16 (0)