28 May
2010
28 May
'10
6:33 p.m.
fons(a)kokkinizita.net wrote:
On Fri, May 28, 2010 at 08:30:54AM -0700, Niels Mayer
wrote:
AM could be caused by residual ripple from the DC source, but the signal
was clearly separated from any 50 Hz harmonics. So it wasn't LF noise on
the voltage reference?
Audio ADCs and DACs have three important inputs;
the signal input, the voltage reference, and the clock.
Noise and interference on the voltage reference causes
amplitude modulation, and jitter on the clock causes
phase modulation. The resulting modulation products
look very similar in the frequency domain. 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.
You're close. See the extra hint in a previous post.
Ciao,