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Audio Loss
We’ll use
Audio Loss
as
a typical example
of a
hysteresis-type alarm.
Alarm:
must of course
be set
On
to arm this
function. The grayed-
out
Level (dB):
meter
shows the current pro-
gram level for the sta-
tion being monitored.
In this case we’re looking for a low-level program audio
condition, so the
Threshold On (dB):
setting of
–20
is what the
program level has to fall to, and remain below, for the
Time On
(Sec.)
interval of
10
seconds to initiate an alarm.
For the alarm to reset/clear,
Level (dB):
must rise back up to the
Threshold Off (dB):
value of
-15
, and remain above that figure for
the
Time Off (Sec):
period of
10
seconds.
This same logic applies to the other alarms in this hyseresis
group. Just remember that it’s both level
and
time settings that
trigger and reset these alarms.
Low Signal
and Muting
The
Low Signal
alarm is programmed in the same manner as the
Audio Loss
alarm just described. But this alarm has one feature
that the others in this group don’t.
Mute:
may be set
On
to
mute program audio when the alarm is active (triggered and
not yet reset/cleared). FM audio naturally ‘fries bacon’ when
the carrier disappears. We recommend setting
Mute:
to
On
, for
not only will it obviate an unending blast of noise, but also will
ensure that the
FM Audio Loss
alarm will trigger if the station
leaves the air.
Pilot Loss
This alarm indicates loss of the FM stereo pilot, a rare transmit-
ter plant failure mode but still an included alarm. There is no
threshold setting, just Time On (sec): and Time Off (sec):.
Multipath
Multipath effects are usually associated more with reception
problems rather than transmission faults, although an audio
processor or stereo-gen fault can appear as excessive multi-
path. Again, the current
Multipath (%):
figure is shown grayed-
out. Threshold and time settings can be programmed to trigger
an alarm for an undue condition.
RDS Alarm
Under
RDS Alarm
there are two
On / Off
settings for basic RDS
issues. Turning
RDS Loss: On
delivers an alarm when the RDS
subcarrier simply goes missing. Setting
PI Error: On
gives an
alarm when RDS is received with a PI code mismatch.
RDS data contains a PI code unique to the station. A PI mis-
match can signal a translator ‘hijacking’ by a radio hooligan, or
the less sinister condition of the expected signal going off-air
and a distant on-channel broadcast received in its place.
Summary of Contents for Inovonics 541
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