Inovonics HD Radio SiteStreamer+ SOFIA 568, Инструкция по установке и эксплуатации

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2.5dB lower than the figure shown. However, the concept of
600-ohm sources and terminations in professional audio prac-
tices date back to the days of transformer coupling, leased
telephone lines and ‘repeat coils,’ and the notion of impedance
matching is nowadays generally disregarded.
Also with regard to the analog output level, the dBu notations
beside the slider actually refer to the r.m.s. average level of a
sine-wave tone with a peak value corresponding to 100% FM
carrier modulation (±75kHz monaural carrier deviation at
400Hz), or nominal ‘full’ HD Radio modulation.
The
Digital Level (dB
FS
):
slider adjusts the rear-panel XLR AES3
digital program line output between –30dBFS and 0dBFS. Levels
in this case are dBFS peak values at the output, again corre-
sponding to ±75kHz mono-FM carrier deviation, or ‘full’ HD Ra-
dio modulation. An accepted and appropriate setting for this
slider would be in the neighborhood of –12dBFS, allowing suffi-
cient headroom for FM carrier overmodulation, acknowledging
that the average off-air program level will usually be so uncom-
fortably close to the peak level as not to demand a more con-
servative headroom buffer.
In general, the
Dante/AoIP Level (dB
FS
):
requires the same con-
siderations as the AES digital output and may be set similarly.
The
Stream
audio output references the Web-listening utility,
which is independent of AoIP streaming. Web-listening relates
to the little loudspeaker icon at the top of each SOFIA 568 Web
interface page, which can be clicked-on by as many as 10 users
at the same time who have Internet access to the unit.
The streaming
Format:
defaults to the popular
MP3
standard,
although it may be reset to
OGG
, a family of audio file types
that may enjoy a slight sonic advantage over MP3, in addition to
being free from licensing encumbrances.
The streaming
Bitrate:
defaults to
128kbps
, generally judged as
acceptable for all-but-critical radio listening. For unbelievably-
poor network conditions the bitrate can be reduced all the way
down to 32kbps, or for high-quality audio over a local LAN, up
to 256kbps.
The stream
Sample Rate:
may also be changed, from the broad-
cast-plant default of
44100Hz
, to other sampling rates between
16kHz and 48kHz. Again, network limitations or specific in-
stallations may dictate this setting.
A unique and useful feature of the SOFIA 568 is the ability to
add-in a fixed
Audio Latency (Sec):
delay that may help overcome
deficiencies of an uncertain network connection. Rather than
allowing network latency to degrade packet transmission, build-
ing-in an intentional delay of a few seconds gives the system
time to reassemble the data with fewer errors with just a few
seconds’ temporal inconvenience.