User Manual

User's Guide HDSP AES-32 © RME
39
In case the HDSP AES-32 resides within a chain of devices receiving word clock, plug a T-
adapter into its BNC input jack, and the cable supplying the word clock signal to one end of the
adapter. Connect the free end to the next device in the chain via a further BNC cable. The last
device in the chain should be terminated using another T-adapter and a 75 Ohm resistor (avail-
able as short BNC plug). Of course devices with internal termination do not need T-adaptor and
terminator plug.
Due to the outstanding SteadyClock technology of the HDSP AES-32, we recommend not
to pass the input signal via T-adapter, but to use the card's word clock output instead.
Thanks to SteadyClock, the input signal will both be freed from jitter and - in case of loss or
drop out – be reset to a valid frequency.
24.4 Operation
The HDSP AES-32 word clock input is active when Clock Source in the Settings dialog has
been set to Word Clock, and a valid word clock signal is present. The signal at the BNC input
can be Single, Double or Quad Speed, the HDSP automatically adapts to it. As soon as a valid
signal is detected, the Settings dialog shows either Lock or Sync (see chapter 30.2). In the
status display System Clock the display changes to Word. This message allows the user to
check whether a valid word clock signal is present and is currently being used.
In Input Status the frequency of the reference signal is measured by the hardware. In this case
the frequency of the current word clock signal is measured and displayed.
The word clock output of the HDSP AES-32 is constantly active, providing the current sample
frequency as word clock signal. As a result, in Master mode the provided word clock is defined
by the currently used software. In Slave mode, the provided frequency is identical to the one
present at the currently chosen clock input. When the current clock signal fails, the AES
switches to Master mode and adjusts itself to the next, best matching frequency (44.1 kHz, 48
kHz etc.).