26
Redbox User Handbook No 1
DIGIT
AL A
UDIO C
ONVERTERS - RB
-SC2
DIGITAL AUDIO CONVERTERS
4
The FREQUENCY button allows selection of the master sample frequency from one of 32kHz,
44.1kHz, 48kHz, 88.2kHz, 96kHz, 176.4kHz or 192kHz. The CS DATA button defines the
content of the channel status bits embedded within the digital audio stream, and can be
forced to either Professional Mode (PRO), Consumer Mode (CON) or to follow the mode of
the input (FOLLOW).
The SYNC button is used to select the synchronisation input, from the AES/EBU sync input,
the Wordclock input or, for X-Lock, the other digital input. The X-Lock synchronisation
allows the unit to act as a bi-directional sample rate converter with the output of sample
rate converter 1 syncing the input of sample rate converter 2 and vice versa so that they
follow each other. The application for the X-Lock mode is so that the RB-SC2 can be inserted
between 2 digital devices which run at different sample rates, such as a PC recorder
and a digital player. Using the RB-SC2 in X-Lock mode ensures that the 2 devices remain
synchronised at all times regardless of the sample rate of the 2 devices.
Fig 4-2: RB-SC2 X-Lock Sync Mode
The SYNC button will also select the operating mode of the unit as described below. If an
optional video sync board is fitted then 2 sync LEDs light together to show the active video
sync.
Master Mode
In this mode the unit receives a digital audio signal, which is passed to the sample rate
converter and then re-formatted for the digital serial transmitter (IEC958). The sample rate
converter clock signal is generated internally from an on board master clock at a selectable
rate (32kHz, 44.1kHz, 48kHz, 88.2kHz, 96kHz, 176.4kHz or 192kHz).
Slave Mode
In this mode the unit is synchronised to an external source, using the digital audio sync,
or to the TTL level Word Clock. The FREQUENCY LED will indicate the synchronised sample
frequency and if no sync is present, no output will be generated.
X-Lock Sync Mode
Sample
Rate 1
Sample
Rate 2
System 1
RB-SC2
System 2
Clock
Recovery
Clock
Sync
Clock
Sync
RX
TX
SRC
Clock
Recovery
RX
TX
SRC
