Solidyne 542 APC, Руководство пользователя

Страница: 22 / 44

PILOT: Set the level of the pilot tone. At the factory, the pi-
lot tone is set to 9%. In areas with high radiofrequency
congestion, it can increase up to 12%, but keep in mind
that if the Pilot Tone and RDS values are increased, the au-
dio will be reduced for the same level of modulation.
RDS: Determines the modulation level of the RDS sub-car-
rier (factory 4%).
MODE: The unit can be switched to mono or stereo. When
this control is switched to MONO, the pilot tone is sup-
pressed and the MPX component signal will always be
MONO (see 3.5.3 - On monaural transmission).
Switching to mono can occur in several ways:
•
From this control.
•
Forced by preset (presets has a mono/stereo flag, see
3.4.2 - Preset Manager). In this case the control will indi-
cate "Forced to MONO by preset".
•
It can be switched manually from a computer using Lite
Commander application (requires remote IP access).
3.7.5 MPX output compensation
Figure 24: Advanced settings of stereo coder
Pilot Phase: Pilot Tone Phase Fine Tuning is an advanced
control that improves stereo separation (see 3.8.1 - About
channel separation).
SUB (L-R) adjust: Changes the level of the L-R module to
compensate mismatches that may occur in the coaxial-an-
tenna assembly (see 3.8.1 - About channel separation).
3.7.6 MPX power - ITU-R BS.412
This stage manages the power of the MPX signal accord-
ing to the recommendation of the International Telecom-
munication Union ITU-R BS.412 for European countries .
If the legislation in your country does not require
this regulation, DO NOT enable this feature ,
since it will reduce the loudness.
Recommendation ITU BS.412 was created to eliminate
interference between adjacent FM channels; since the
separation between channels in many European coun-
tries is 100 KHz. It was found that the source of the inter-
ference was the density of the program material pro-
duced by the current audio processing methods, which
generate that the carrier is continuously modulated
around 100%.
The BS.412 sets a maximum allowed value for the power
in MPX, in order to reduce the density of the modulating
signal, but maintaining the maximum modulation level at
75 KHz. There is then a double limit: maximum modula-
tion peak and average power in MPX (integrated in 60
seconds). In other words, BS.412 forces broadcasters to
decrease the volume by limiting the power allowed in
MPX. As a result of this regulation, all the radios will
sound in the air at the same level, without interfering with
each other. Recommendation BS.412 defines a maxi-
mum power level and a measurement algorithm, which
defines the reference 0 dBr for the maximum MPX power
value integrated in 60 seconds, with +0.2 dB of tolerance.
Figure 25: BS.412 MPX power time graph
Not all European countries apply the BS.412 recommenda-
tion in the same way. Some regulations allow levels higher
than 0 dBr or have staggered objectives to implement the
MPX level reduction until reaching 0 dBr.
The BS.412 ITU modulation control in the 542APC has a
control that allows the user to modify the MPX power ref-
erence level. The timeline graph allows you to visualize the
evolution of the MPX power in the last 120 seconds. Dis-
plays an integration curve of 60 seconds as established by
BS.412; and a short time integration profile.
3.7.6.1 Audio presets and BS.412
All factory presets can be used with the MPX power con-
trol. The processor will always maintain the MPX level as
allowed. When there is a power limit, it does not make
sense to use high loudness presets; because the audio will
be processed to increase the energy, and then processed
to decrease it.
One advantage of working under the ITU BS.412 regulation
is that the war for loudness disappears, and broadcasters
are able to use more dynamic range. The Solidyne 542
APC includes two factory presets optimized to work in
conjunction with the ITU BS.412 power control, that take
advantage of available dynamic range. More optimized
presets can be downloaded from www. s olidynepro.com .
Page 22 Audio Processing Core - SOLIDYNE 542 APC