3301-dda.ib.doc
page 8 of 20
06/01/2004
ZDA-3301RH Technical specifications
Controls & alarms:
Input:
External changeover request
A ground applied to this input will emulate the operation of the front panel
switch “Change Request”.
Outputs:
Bypass
Contact closure to ground if power has failed.
General Alarm
Contact closure to ground if
a. Data Loss is detected OR
b. AIS is detected AND the AIS disable link (LK 1) is not installed.
AIS detection is defined as at least
2048 consecutive data “1”s.
Data Loss is defined as less than 120 data “1”s in 512 G.703 data rate clock
periods.
In Service (Main)
Path Indication: Transistor switch to ground if card is
Main
(if DA version is equipped).
Connectors:
Data: BNC.
Alarm:
Krone LSA plus.
In Service (Main)
Path:
Krone LSA plus.
Changeover logic:
A changeover to the companion module will occur under any of the following conditions:
Loss of input signal
AIS detection alarm (provided AIS is not disabled by link LK 1)
Loss of power
In all of the above cases switching will only occur if
companion module is able to provide an output free of the same defects and
changeover inhibit switch is not activated on either module.
Priority logic:
The priority switching in normal mode follows non-reverting logic, which dictates:
In the event of failure of main then standby DDA will assume control and become
Main
causing the failed
path DDA to become
Standby
.
This implies that when the failed path is restored that it will remain as
Standby
and not become
Main
unless either a
failure of
Main
occurs or a manual changeover is requested.
Power on reset.
When power is applied to the pair, the
power on reset
signal will set the module which was last enabled as
Main
as
Main
and the other module will be forced to act as
Reserve
.
When power is applied to a pair for the first time it may be necessary to force the desired module to become main by
pressing the
Change Request
button on the front panel of the desired module. The
Main
module will be indicated by
the
In Service
LED lighting on the front panel.