GXD8 Operational Manual
Rev 1.0
Clocks
Genex Research Limited
Page 8
down arrow will also light to indicate a pull-up or pull-down rate respectively (see note below). The
sample rate button is disabled in this case. However, single, dual or quad-wire mode can now be
selected. The indicated rate will change based on the output wire configuration. For example:-
•
A clock rate of 48kHz is connected to the clock input and detected:
In single-wire mode, a sample-rate of 48kHz will be indicated
In dual-wire mode, a sample-rate of 96kHz will be indicated
In quad-wire mode, a sample-rate of 192kHz will be indicated
In this way, the GXD8 always displays the actual
sample
rate rather than the external
clock
rate.
Note that when locked to a clock rate of 88.2kHz or 96kHz only single or dual-wire mode may be
selected.
NOTE:
When either of the pull-up / pull-down LEDs are lit, the GXD8 is using a fast reacting, wide
locking RC Phase Locked Loop instead of its variable crystal oscillators. As a result, the
GXD8 may not notice if you subsequently change the incoming sample rate, particularly if you
change from a ±0.1% modified to the unmodified rate. In this case, to ensure the GXD8 locks
to the new unmodified rate using its variable crystal oscillator (which has far greater jitter
performance and thereby greater audio conversion quality), the unit should be forced to re-
lock (just cycle the unit through to master clock mode and back again).