The RB-SD1 silence detection unit is a 1U
rack-mount device used to monitor an
unattended stereo studio feed and in the
event of the signal going quiet after a
given period the unit will switch through an
alternative stereo audio signal. This signal
could be a recorded message (e.g. normal
service will be resumed, etc), a feed from a
CD player or minidisc machine, or an
alternative recorded programme. Controls
are provided to start external equipment
and to provide remote status indication.
It has 2 balanced stereo audio inputs with
the maximum input level being +28dBu.
Each input is user-defined as either the
main source or auxiliary source and both
sources are monitored for failure, each
having a remote failure alarm. In the event
of the main source dropping below a preset
level for a pre-determined amount of
time, the unit will automatically switch
through to the auxiliary signal. The silence
detect level is adjustable between -60dBu
and -15dBu in 3dB steps via a 16 position
rotary switch on the rear panel. The silence
interval can be adjusted between 2
seconds to 30 seconds in 2 second steps, or,
alternatively, set to 2 minutes 5 seconds
also via a 16 position rotary switch on the
rear panel. The audio outputs use stereo
professional balanced XLR-3 male
connectors.
The unit can operate in 2 modes -
automatic or manual. In both modes it will
automatically switch over to the auxiliary
source on detecting silence. When the main
signal is again detected it will either return
to the main signal automatically or manually
depending on the mode chosen. The RB-SD1
has a number of remote operational
features. Remote outputs provide separate
relay contact closures for failure of the main
and auxiliary inputs. You can also control
remotely all of the front panel switches for
source selection, mode selection and signal
Restore. You can remotely start and stop
another piece of equipment on alarm failure
and main signal Restore respectively. Also,
the longest silence time (2min 5sec) can be
set remotely, which is useful if you are
expecting to broadcast a long silence.
The unit can be configured to alarm when
either the left or right channel of the main
input source fails, or if the whole stereo signal fails. There are also options to set the
remote start output as momentary or
latched, to disable switching to the auxiliary
input on alarming and to increase the gain
on the auxiliary input so that an unbalanced
input can be used, for example, from a
domestic minidisc player.
Front panel LED indicators show individually
left and right programme and alarm
conditions for both the main and auxiliary
inputs. The status of the source, mode and
alarm state are also shown on the front
panel with LED indicators.
Additionally, the RB-SD1 can be
programmed for specific applications which
can be defined on power-up of the unit.
Contact Sonifex for further information if
you have a particular requirement. (Refer to
the handbook on the website for
information on current configurations).
The RB-SD1 has been designed to have a
passive signal path through the main input,
so if power to the unit fails, the signal input
will still be routed through to the output.
This is essential for applications such as
installation at transmitter sites, where a
power failure to the unit should not prevent
the audio input signal from being output to
the transmitter.