Manual

Chapter 10 - RB-SD1 Silence Detection Unit
Redbox User Handbook 10-1
10. RB-SD1 Silence Detection Unit
10.1. Introduction
Fig 10-1: RB-SD1 Front Panel
The RB-SD1 Silence Detect 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 minidisk machine, or an alternative recorded program. 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 pre-set 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 return 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.
RESTORE
ALARM
MODE
AUTO
SOURCE
MAIN B
LED ON
LED OFF
LED FLASH
MAIN A
PRESS RESTORE
MANUAL NORMAL
MAIN
ALARMALARMPROG PROG
LEFT RIGHT
LEFT RIGHT
AUX
A
LARM
A
LARMPROG PROG
RB-SD1
SILENCE DETECT