8
and the NO button to abort the changes.
RESTORE Time
The restore time represents the number of
seconds that a valid restore condition is
required before the leased line is verified
as fault free. A valid restore condition is
defined as at least 2 seconds of signal
above the restore threshold in the previous
5 seconds.
The unit of measurement is in seconds
MENU : Restore Time
STATUS : 010Sec
The button can now be used to edit the
restore time, the display changes as
follows:
EDIT : Restore Time
OPTION : 010Sec
The and buttons can be used to
change the value between 001and 60
seconds in 1 second intervals.
The NO button to abort the changes.
Override Menu
This menu allows the user to force the
ABU master into a specific state.
NOTE: This function will be cleared following a
power cycle.
MENU : Override
STATUS: Off
The button is used to select the avail-
able options, the display changes as fol-
lows:
MENU : Override
OPTIONS: Off
The available options are:
off
Aux. Force audio to AUX. input
ISDN Force audio to ISDN audio is present
Main Force audio to main input.
Note: The manual override can itself be overridden
by the remote override functions
MASTER ALGORITHM
State 1
In this state the ABU master is independ-
ently monitoring both the left and right
hand audio feeds for a fault condition, as
defined by the backup time and backup
level parameters. This state will be exited
on one of the following events
Right channel audio fault
Left Channel audio fault
ISDN call connected
manual override
remote override
State 2
This state is initiated when a ISDN backup
call is required. The state will attempt to
dial the configured ISDN numbers and
establish a connection. It will only switch
the main audio across when the presence
of audio has been verified.
The presence of audio is defined as a signal
greater than the “backup level” + 2dBm for
a duration of 1 second in the previous 5
seconds.
If either the audio or ISDN fails then
control passes to state 3.
State 3
This state will start the CD player and
switch the main audio feed over to the
AUX. input. Once selected, the ISDN line is
dialled every 2 minutes until a valid con-
nection is established with audio. If such a
connection is achieved then control will
pass to state 2. Otherwise control will
remain with state 3 until either the fault
has cleared or a override occurs.
State 4
This state is initiated when a single audio
input has been classified as faulty. Essen-
tially the unit will proceed to feed the
remaining good input channel to both the
output channels. This will provide a
pseudo monoised service.
