User Manual

User's Guide HDSPe AES © RME
39
In case the HDSPe AES 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 HDSPe AES, 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 HDSPe AES word clock input is active when Clock Source in the Settings dialog has been
set to Word and a valid word clock signal is present. The signal at the BNC input can be Single,
Double or Quad Speed, the HDSPe automatically adapts to it. As soon as a valid signal is de-
tected, the Settings dialog shows either Lock or Sync (see chapter 30.2). In the status display
Clock Source the display changes to Current: 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 HDSPe AES 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.).