— 11 —
dBuV is also displayed.
When the
RF
bargraph falls below this tic mark during nor-
mal receiver operation, it initiates a carrier-loss alarm and
causes
LOW SIGNAL
to flash on the LCD screen.
As a starting point, you might set the carrier-loss trigger
point about half the way down from the top of the
RF
bargraph as shown in the illustration. This should allow for
typical signal fading over the receive path, but will still alert
the user to a valid carrier loss or transmitter power prob-
lem.
Push the knob again and the right-hand tic mark will blink.
Turn to knob to set the tic mark (and its numerical value) to
a point that the carrier level must attain to reset the alarm,
maybe a few segments above the left tic mark. Push the
knob again to set these points in memory and release the
menu.
LOW SIGNAL
alarm settings relating to delays and intervals
are accessed with the Web interface, along with the setup of
other fault alarms that can dispatch email and SMS/text
messages. This is detailed beginning on Page 23.
Signal-to-Noise and Multipath
(Menu Screen 3)
This screen displays two additional signal-quality measure-
ments. Numerical values are assigned to each of these
readouts as well, but these numbers are relative and arbi-
trary and do not relate to any fixed measurement parame-
ter.
SN
is a first-order approximation of the signal-to-noise qual-
ity of the received signal. This measurement takes several
signal quality factors into account, but is strictly a relative
indication. No hard-and-fast rule can be derived from this
display, except that “more is better.”
Likewise,
MP
gives a relative indication of multipath (signal
reflection) effects that the transmission encounters on its
trip to the receiver. Multipath effects introduce noise and
distortion into FM programs, and causes errors in digital
signals that can translate into dropouts and echoes. The
object here is to keep
MP
as low as possible.
00
is ideal and
should be attainable when receiving a solid signal.
The
RF
,
SN
and
MP
numerical values are handy metrics when
installing a rooftop antenna. In locating and aiming the an-
— 12 —
tenna, do everything you can to maximize
RF
and
SN
, and to
minimize
MP
.
Monitor Source Switching
(Menu Screen 4)
The SiteStreamer™ normally monitors the FM or HD Radio
off-air broadcast, but it can also switch to an external audio
feed applied to the rear-panel
AES3 DIGITAL LINE INPUT
jack. This allows, for example, an A/B comparison between
the air signal and the program audio feed to the exciter.
This snapshot shows the
primary, default moni-
toring mode, the off-air
Radio
signal. Push the
knob and turn it to se-
lect
AUX Input
.
Now, with
SOURCE:AUX
Input
showing, press
the knob a second time
to highlight
AUX Gain:
setup. Input sensitivity
is normally ‘unity’: a dig-
ital 0dBFS tone will take
the front-panel meter to
0dB
. You can turn the
knob to introduce gain,
however, so that the
front-panel meter read-
ing of
0dB
(or ‘zero-VU’) can equate either to 0dBFS, or to
–18dBFS, –20dBFS or –24dBFS.
Program Audio Levels
(Menu Screen 5)
Menu Screen 5 presents accurate bargraph metering of pro-
gram audio levels. This is a peak-responding meter with a
floating peak-hold function.
100% modulation is de-
noted by the large block
opposite the
0dB
mark-
ing on the panel. The
meter resolves +1, +2
and +3dB above 0dB,
and from 0dB down it is calibrated in 0.5dB steps to –15dB,
and then in 1dB steps to –21dB.
Содержание INOmini 638 SiteStreamer
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