User Manual
18
User's Guide Digiface USB © RME
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8.6 Clock Modes - Synchronization
In the digital world, all devices must be either Master (clock source) or Slave (clock receiver).
Whenever several devices are linked within a system, there must always be a single master
clock.
A digital system can only have one master! If the Digiface USB’s clock mode is set to 'Inter-
nal', all other devices must be set to ‘Slave’.
The Digiface USB utilizes a very user-friendly, intelligent clock control, called AutoSync. Select-
ing Optical as Clock Source, the system constantly scans the digital input for a valid signal. If
any valid signal is found, the Digiface USB switches from the internal quartz (Clock Mode –
Current Internal) to a clock extracted from the input signal (Clock Mode – Current ADAT). The
difference to a usual slave mode is that whenever the clock reference fails, the system will
automatically use its internal clock and operate in clock mode Master.
To cope with some situations which may arise in studio practice, defining a sync reference is
essential. RME’s exclusive SyncCheck technology (first implemented in the Hammerfall) en-
ables an easy to use check and display of the current clock status. Input Status indicates
whether there is a valid signal (Lock, No Lock) for the optical input, or if there is a valid and
synchronous signal (Sync). In the field Clock Mode the clock reference is shown. See chapter
26.1.
Under WDM the Digiface USB will
(has to) set the sample rate. Therefore
the error shown to the right can occur.
A stable signal with a sample rate of
48 kHz is detected (Sync), but
Windows audio had been set to 44100
Hz before. The red color of the text
label signals the error condition, and
prompts the user to set 48000 Hz
manually as sample rate.
Under ASIO the audio software sets the sample rate, so that such an error can not happen. If
the input sample rate is different then there will be no Sync indication.
With RME’s AutoSync and SyncCheck, finally anyone can master this common source of error,
previously one of the most complex issues in the digital studio world.