RME Audio Hammerfall Digiface, Руководство пользователя

Страница: 20 / 78

20
User's Guide HDSP System Digiface
© RME
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 con-
nected to input ADAT3. The Hammerfall DSP is set to AutoSync mode. As expected, Sync-
Check 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 input ADAT3. Because
the ADAT recorder is not receiving any signal 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 105 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.