RME Audio ADI-8 PRO, Руководство пользователя

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User's Guide
ADI-8 PRO © RME
11
6.5 Word Clock Input and Output
Input
The
ADI-8 PRO
's word clock input is active, when EXT is chosen in the clock section (see
chapter 7, Clock Section). As soon as a valid signal is detected, the EXT LED is constantly lit,
otherwise it is flashing slowly.
Thanks to RME's
Signal Adaptation Circuit , the word clock input still works correctly even with
heavily mis-shaped, dc-prone, too small or overshoot-prone signals. Thanks to automatic signal
centering, 300 mV (0.3V) input level are sufficient in principle. An additional hysteresis reduces
sensitivity to 1.0 V, so that over- and undershoots and high frequency disturbances don't cause
a wrong trigger.
The
ADI-8 PRO
's word clock input is shipped as
high impedance type (not terminated). A push switch
allows to activate internal termination (75 Ohms).
The switch is found on the back next to the BNC jack.
Use a small pencil or similar and carefully push the
blue switch so that it snaps into its lock position.
Another push will release it again and de-activate the
termination.
Output
The word clock output is constantly active and basically delivers the sample rate of the AD-
converter. As long as it is working with internal clock, the output word clock is extremely stable
and jitter-free (< 1 ns). The device can even be used as a central word clock generator (except
for the limitation of having only one output). In slave mode (EXT/INPUT), the amount of jitter is
depending on the input signal.
A word clock signal fed to the
ADI-8 PRO
can even be passed through via the word clock
output, because the output signal is phase locked to the input signal (0°). Thus the usual T-
adaptor at the input is not needed, and the
ADI-8 PRO
can be used as a signal refresher.
This application is even more interesting, because the exceptional input of the
ADI-8 PRO
(1 Vss sensitivity instead of the usual 2.5 Vss, dc cut, Signal Adaptation Circuit) guarantees a
secure function also with critical word clock signals.
Thanks to a low impedance, but short circuit proof output, the
ADI-8 PRO
delivers 4 Vss to
75 Ohms. For wrong termination with 2 x 75 Ohms (37.5 Ohms), there are still 3.3 Vss at the
output.