4280-dda.ib.rev0.doc
Page 13 of 17
11/03/2009
Operation
Stand-alone operation:
When used in a stand-alone situation, that is non-hand shaking mode, the DDA-4280 behaves as a standard
2.048 Mb/s G.703 distribution amplifier.
One input is electronically split into four outputs. On loss of power to the unit the input is automatically bypassed to
output 1 via on board relays.
A loss of power alarm and general alarm (loss of signal, AIS detect) is provided by relay contacts to open circuit via
the Krone connector on the rear assembly, see
Installation
section of this manual for connections.
Front panel LEDs indicate the presence of a valid input signal (In Service (Main) – green), the absence of a valid
input signal (Data Loss – Red) and the detection of an alarm indication signal within the inputted signal (AIS – Red).
The Standby LED (green) is not used in the stand-alone operation.
The front panel
change
switches do not work when used in a stand-alone operation.
Handshake operation:
When used in the handshake mode, two cards fit side by side plugged into a ZDA-4300RH. The ZDA-4300RH
provides the necessary interconnect controls to automatically switch between the input signals to the outputs,
provided that the toggle switch on the front panels of the units are set to Change Allow and not Change Inhibit.
Automatic switching parameters are set by a loss of input condition and switch SW3 settings as described in the
Configuration
section of this manual.
When the toggle switch is set to
Change-Inhibit
both automatic and manual switching of the input signals is not
possible.
When the units are first turned on one unit will take the responsibility of being
In Service (Main)
whilst the other will
become the
Standby
unit. It may be necessary to manually swap the two states if they do not start in the required
configuration by pressing the front panel manual switch on the unit that is desired to be acting as the
In Service
module. Note that in order to do so the toggle switch should also be set to the
Change-Allow
position on both
modules.
Loss of power alarms and general (loss of signal, AIS detect) alarms are provided by relay contacts to open circuit
via two Krone connectors on the rear assembly. External changeover request is also provided via these same Krone
connectors.
In Service (Main)
tally indication is via a third Krone connector, see
Installation
section of this manual
for connections.
Front panel LEDs, on both units, indicate the presence of a valid input signal (In Service (Main) – green, or
Standby - green ), the absence of a valid input signal (Data Loss – Red) and the detection of an alarm indication
signal within the inputted signal (AIS – Red).