[LAD] A little quiz about audio measurements...

[Ralf Mardorf]

Niels Mayer wrote:
> On Fri, May 28, 2010 at 8:37 AM,  <fons at kokkinizita.net> wrote:
>   
>> On Fri, May 28, 2010 at 08:30:54AM -0700, Niels Mayer wrote:
>>     
>>> [...]
>>>       
>> You're close. See the extra hint in a previous post.
>>     
>
> It the "close" has to do with jitter:
>
> * Something on the USB bus is causing a "periodic jitter" with a cycle of 100Hz?
> * Something is causing a buffer to become empty every 0.01 seconds and
> causing a periodic desync?
>
> If the "close" has to do with induced or actual 50hz hum, perhaps
> frequency-doubled via rectification:
>
> * something in the  USB power supply, as well as how that power supply
> floats w/r/t ground (ground noise) is the source.
>
> Which would agree with the Wolfson experts from
> http://wolfsonmicro.com/uploads/documents/en/Specifying%20Jitter%20Performance.pdf
> stating "One of the authors once spent several days trying to track
> down a low-frequency jitter problem, only to find that it was in fact
> a problem of LF noise on the voltage reference."
>
> Niels
> http://nielsmayer.com
>   

Don't forget to argue for what card. A or X?