Inovonics 236, Installation & User Manual

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alarm on the primary Analog program source can be pro-
grammed to switch the processor input over to a Digital or
Stream input.
Audio Alarms
The Audio Loss alarms for analog, digital and streaming in-
puts are each programmed independently, but follow the
same procedure. As a typical example, we’ll program the
alarm for the analog input.
From the Main Menu go to
Setup / Inputs / Analog Input / Analog
Audio Loss .
NOTE: The Alarm box
must be checked for the
alarm to function at all.
If left unchecked, the
alarm will not trigger!
There will be no program audio failover, no front-panel or
Web interface alarm indication, no ‘tally’ output, no email or
text notifications, no SNMP trap.
Threshold On is the audio level that the program must drop
below to trigger an alarm. Moreover, the audio level must
stay below this point for the number of seconds pro-
grammed into the Time On box. Similarly, Threshold Off is the
audio level that the program must come back to, and stay
above for Time Off seconds, to reset the alarm.
The current level of the program audio shows as a shaded
bargraph behind the
Threshold On/Off
boxes. This makes it
easier to set the trip-point mark with reference to the pro-
gram audio. Of course, no audio will show unless that input
is connected. Be sure to set up the backup input source
alarm(s) when the program failover feature is used.
Processor Output Characteristics
Traditional medium wave AM broadcasting was historically
considered a ‘flat response’ system. Nevertheless, over the
years a good many AM broadcasters elected to boost the
higher audio frequencies to compensate for the declining
performance of inexpensive AM radios. Beginning in the
1980s, the U.S. NRSC (National Radio Systems Committee)
proposed a standardized pre-emphasis characteristic, plus a
‘brick-wall’ cutoff function. Both measures addressed re-
duction of man-made electrical noise and adjacent-channel
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‘monkey chatter’ interference. The proposal was subse-
quently mandated by the U.S. FCC (Federal Communications
Commission).
NRSC pre-emphasis is a ‘truncated’ 75µs curve, up about
1dB at 1kHz, and +10dB at 10kHz. The NRSC cutoff is very
steep. Response is flat to about 9.6kHz, –15dB at 10kHz,
and –50dB or more at 10.4kHz.
Characteristics common
to both NOVIA 236 out-
puts, the
ANALOG OUT
and the
AES OUT
, are
selected under Setup /
Outputs / Pre-Emphasis & LPF . The example above is the U.S.
NRSC choice, but alternative cutoffs are available for Euro-
pean 9kHz channel spacing, and for short-wave, TIS (road-
side assistance) and similar services. Cutoffs are detailed in
the Specifications on Page 4. Pre-emphasis maintains the
same general curve shape of the 10kHz NRSC standard, but
is scaled to the selected cutoff frequency in all instances.
Analog Processor Output
The Setup / Outputs / Analog Audio Output menu controls the bal-
anced analog level at the rear-panel
ANALOG OUT
XLR con-
nector. Analog Level adjusts the peak level of a symmetrical-
ly-limited program signal from –12dBu to +18dBu . The
+24dBu clipping point of the NOVIA 236 maintains suffi-
cient headroom for positive program peaks to +130%.
Digital Processor Output
The rear-panel digital
AES OUT
is controlled from Setup /
Outputs / Digital Audio Output . Here you adjust the peak level
of a symmetrically-limited program signal from –30dBFS to
0dBFS . As positive program peaks may exceed the Digital
Level noted below the slider, your maximum setting should
never exceed –3dBFS.
Also under this menu,
the
Sample Rate
of the
output may be set to
Fol-
low Input
(the same sam-
pling rate as the input,
as indicated on the screen), or to a fixed 32kHz , 44.1kHz ,
48kHz or 96kHz rate.