The wide use of
the satellite to distribute the audio signal,
arose the need of employing for each satellite
downlink a Stereo Coder, a RDS Coder and a
Composite Processor, last winning device in
the "war of loudness".
The main goal of FM radio stations today is
to reach an extreme sound power together with
a cristal clear quality of the audio material.
Till now there was not an equipment that combined
all these features together.
The only technical solution to reach a
better loudness was the employment of agressive
clipping circuits, that inevitably increased
distortions with consequent loss of details
and audio quality.
Thanks to winning technical solutions, AEV
has developed Stargate that ensures to the
broadcasters the desired loudness maintaining
a great audio quality.
STEREO CODER
It employs a digital modulator at a
sampling rate of 32x that generates
frequencies at 19 and 38 KHz for respectively
the pilot and subcarrier. The employment
of a great quantity of "samples"
offers a better spectrum clarity and
mantains the MPX signal constant. The
stereo separation levels are constantly
over 65 dB.
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RDS
CODER
The
RDS coder has the same characteristics
of AEV
RDS 4500, including
the possibility to be programmed remotely
from satellite. This feature is an
unavoidable "benefit" in
those applications that require the
employment of equipment like Stargate
multicoder.
All Stargate multicoders connected
to the serial port of the satellite
downlink can be programmed directly
from the network main station.
Furthermore,
Stargate RDS coder is able to transmit
the PTY service that contains the
new description of the broadcast formats.
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RDS PROGRAMS TRANSMITTED
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PI (Programm Identifier)
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EON (Enhanced Other Network) |
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PS (Programm Service Name)
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FT (Fast Tuning) |
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TP (Traffic Programm) |
LIC (Language Identifier) |
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TA (Traffic Announcement) |
PTYN (Programm Type Name) |
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AF (Alternative Frequencies)
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ECC (Extended Country Code) |
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PTY (Programm Type) |
LI (Linkage Identifier) |
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RT (Radiotext) |
TMC (Traffic Message Channel) |
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CT
(Clock Time) |
PIN (Program Item Number) |
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M/S (Music-Speech) |
TDC (Transparent Data Channel) |
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DI (Decoder Identifier) |
IH
(In House Application) |
COMPOSITE PROCESSOR
In order to limit the overshoots, Stargate
uses "DSP-Filtering" system
composed with a couple of digital low-pass
filters, an exclusive AEV "hybrid",
that allows not only a phase linear design,
but also dinamically flat responses together
with 115 dB/oct slope.
The quality of this system grants a perfect
spectrum clarity up to 15 KHz. At the
modulator output another "Safety
Clipping" stage removes the remaining
overshoots produced by the filters.
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Audio
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