RME Audio Hammerfall Digiface, Руководство пользователя

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User's Guide HDSP System Digiface
© RME
37
RME’s exclusive SyncCheck
technology (first implemented
in the Hammerfall) enables an
easy to use check and display
of the current clock status. The
‘SyncCheck’ field indicates
whether no signal (‘No Lock’),
a valid signal (‘Lock’) or a
valid
and synchronous signal
(‘Sync’) is present at each of
the digital clock source inputs.
The
AutoSync Reference dis-
play shows the current sync
source and the measured fre-
quency.
In practice, SyncCheck pro-
vides the user with an easy
way of checking whether all
digital devices connected to
the system are properly configured. With SyncCheck, finally anyone can master this common
source of error, previously one of the most complex issues in the digital studio world.
An example to illustrate this: The
ADAT1 and ADAT2 inputs are
receiving signals from a digital
mixing desk that has been set to
clock mode 'Internal' or 'Master'.
An ADAT recorder is connected to
the ADAT3 input. The Hammerfall
DSP is set to AutoSync mode. As
expected, SyncCheck shows that
the ADAT1 and ADAT2 inputs are
in sync (as they are driven by the
same clock from the mixing desk),
but shows ‘Lock’ instead of 'Sync'
for the ADAT3 input. Because the ADAT recorder is not receiving any signals from HDSP or
from the mixer, it will generate its own clock at a rate which is (almost) the same as the sample
frequency of the mixing desk - but not identical.
Remedy: To drive the ADAT recorder from its digital input, set it to slave mode (DIG), and con-
nect the input to the HDSP’s ADAT3 output. The Hammerfall DSP is already in sync with the
mixing desk, so it will send an identical (synchronous) signal to ADAT3 out. The ADAT recorder
will lock onto this, its output will also be in sync. The signal from the ADAT recorder is now fully
in sync with the signals from the mixing desk.
Thanks to its AutoSync technique and lightning fast PLLs, the HDSP is not only capable of
handling standard frequencies, but also any sample rate between 28 and 103 kHz. Even the
word clock input, which most users will use in varispeed operation, allows any frequency be-
tween 28 kHz and 103 kHz.
At 88.2 or 96 kHz: If one of the ADAT inputs has been selected in ‘Pref Sync Ref’, the sample
frequency shown in the field
SPDIF Freq. differs from the one shown in ‘AutoSync Ref’. The
card automatically switches to S/MUX mode here, because ADAT optical inputs and outputs
are only specified up to 48 kHz. Data from/to a single input/output is spread over two channels,
the internal frequency stays at 44.1 or 48 kHz. In such cases, the ADAT sample frequency is
only half the SPDIF frequency.