Solidyne 562dsp, User Manual

Page: 7 / 44

SOLIDYNE 562 dsp EVOLUTION – FM broadcast digital processor Page 7
arrives with low level (or too high), the processor
automatically compensate its input gain so that the
output level is unvarying.
If the input signal falls abruptly, the AGC holds its
current value; to avoid an undesirable effect
known as “breathing”, that appears when the
signal is very low and the AGC compensates their
gain excessively increasing the background noise
in the voice intervals. This feature knows as
Gated-AGC.
In normal operation this indicator will have to work
at
middle scale
(15 dB)
The following indicators show the action of the
multiband compressor. There are five
compression bands called
loudness bands
(LF,
M1, M2, HF, SH). These indicators (like the AGC)
show the gain reduction applied to the signal, for
that reason they “grow downwards”.
Band LF corresponds to bass notes of the audio,
below 160 Hertz, M1 and M2 to mid tones and HF
and SH to the highs.
The LOUDNESS concept associates to the
sensation of sonorous power perceived by the
human ear. With no need to exceed the maximum
percentage of modulation fixed by the law, the
processor can obtain that the radio sounds
stronger. The radio with better processing will be
the one that better sounds in the dial.
As will be explained later, another objective of the
processing is to increase the energy in the entire
audio spectrum, to produce the maximum possible
modulation in the RF carrier, which is translated in
greater
radiated energy, improving the
transmission reach in marginal areas. For this, the
processor applies a complex procedure of
compression on each audio band, producing
greater sensation of loudness to the ear.
The size of each luminous bar indicates the
compression degree at every moment. Its effects,
obviously, changes according to the different
types of music and voice; but in general can say
that when a band indicator begins to light (values
up to 10 dB) the action is smooth and is totally
accepted by the human ear. With values of 15 dB
or greater will notice a greater “sonorous force”,
being a level of extreme processing.
Another important value to consider is the
recovery time.
This is the time that takes a band
in recovering its previous gain. This is evident at
first viewing the indicators. The slower it’s the
recovery, the processing sound soft and the music
sounds natural. However, when they are fast, an
increase of the loudness takes place, but the
sound can becomes more “rough”.
“AES In”
indicates if the unit is using the digital
input. It activates just at the moment at which the
digital data enter.
= digital input
= analog input
“MPX Out”
indicates that the processor is using
the internal FM stereo coder.
Finally; the screen shows the name and number
of the
current program
. You can explore the
programs list turning the JOG; but a program is
not active until you load it pressing briefly the
wheel.
A
program
is a set of values stored in an internal
memory.
You access to the
MAIN MENU
(the right screen)
by pressing and hold the JOG wheel. From here
you can access to all functions and features of the
processor.