Solidyne 462dsp, User Manual

Page: 15 / 38

SOLIDYNE 462
dsp - broadcast digital processor Page 15
seen in AGC indicator who will have to indicate 15
dB with strong program signal, lowering to 8 dB or
less when the signal reduces. If the program
signal level abruptly falls, the indication “HOLD”
appears.
Overload warning (OVL):
appears in the main
screen when the input signal reaches +10 dBm;
that is to say, +8 dB before the ‘digital clipping'
threshold (placed at +18 dBm). The indication
disappears last 5 sec if the clipping disappears.
The digital input fulfills recommendation AES-K12,
applied to broadcasting, which takes as reference
for 0 VU a digital input level of - 12 dBFS.
This implies 12 dB of headroom. The user cannot
modify the input level when digital input is used.
3.2.2 OUTPUT SETUP
OUT LEVEL:
It refers to the analogical output. Level is
fixed at
+4dBm.
DIG. OUT:
Define the sample rate of the AES-3 output.
It can be 96 KHz or 48 KHz.
MPX Level:
Define the MPX output level. It can
change from 2V to 5V peak to peak.
You must set the value according to the value that
the transmitter needs to reach the 100% of
modulation (75 KHz deviation).
PRE-EMPHASIS:
Allows to adjust the pre-emphasis
curve according to the regulations of your country
(I.E.: Europe = 50uS; USA, ASIA, Latin-American
=75uS)
3.2.2.1 Adjusting 100% of modulation in FM
For this adjustment use a program material of high
density; with voice and music (i.e.: commercial
spots). Select the program “08:MaxLoudness” (it
produce high output level). Next change the MPX
output level until obtaining 75 KHz of deviation,
measured with a Monitor of Modulation (like the
Solidyne VA16) or with the modulator meter of the
transmitter. For fine adjustment of the 100% you
can use the input gain control of the transmitter’s
exciter.
In the daily use of the processor, probably the
indicators of modulation of needle type overpass
the 100%. This can be due to over-impulses of the
ballistics or to that it responds to values average
of sine wave and the indication is erroneous with
the high processed audio. Please see the
following notes.
3.2.2.2 Notes about FM
Remember that many countries follow the
recommendations on modulation of the FCC
(USA). Recommendation 73268 indicates that the
FM must stay all the high that is possible, but
without exceeding 100% in peaks of frequent
recurrence
(“In no case is it to exceed 100 % on
peaks of frequent recurrence”) . This indicates that
in transitory peaks (and no frequent) 100% of
modulation can be surpassed staying within the
legal frame.
The 462dsp processor is designed to fulfill this
FCC Norm
, being allowed to surpass 100% in no
recurrent peaks slightly. When fitting the
modulation, verifies the norms of its country.
When making the programs; take in count if there
is an UNIQUE program for the whole day. In that
case commitment solutions will be use to accept
all types of voices and music that the Radio emits.
Using the remote control from PC, diverse
programs can be created. This eliminates the
commitments, so each program will be the optimal
for that type of music or voice. In addition, this
automation eliminates the listener’s ear fatigue
associate with the radio stations that use rigid
processors.
3.2.3 PROCESSOR SETUP
MIC PROCESSING PGM:
MICstart input allows to
change the processing program when the operator
activates the microphones at the console, applying
a specific processing to obtain high impact voices.
This is a very useful feature, since it’s not possible
to obtain an adjustment that sounds optimal for
music and voice simultaneously; for being two
audio signals morphologically different. The attack
and recovery times of the AGC differ sensibly for
both cases; and must be carefully fit to avoid that
its action is audible.