Pag. 13
high performances microphone system
OPERATING INFORMATIONS
RF Level led bars
Two RF level led bars for each receiver indicate mea-
sured RF level at the antenna input of the receiver
in the selected channel. For a typical diversity re-
ception it is a good starting point to consider that
the two signals should have the same average level
over time, but this could be different while moving
the transmitter on the stage. The important issue is
that moving the transmitter on the stage, the diver-
sity has to work switching from one receiver to the
other receiver as indicated by the two blue leds on
the top of the bars. When the RF levels of the two
inputs have similar level, the diversity control enable
the two receiver at the same time, further increasing
the S/N ratio at the audio output.
Modulation led bar
The third led bar of each receiver indicates current
channel modulation as percentage of nominal de-
viation (not the audio output level). The difference
between modulation and audio level is because nor-
mally there is a preemphasis on audio transmission
and some manufacturer uses different compres-
sion values and different audio frequency equaliza
-
tion. Therefore to have the maximun efficiency of
the radio channel it is important to use the highest
modulation bandwidth possible, in respect to the dy-
namic range of the audio signal and the manufac-
turer specifications. If the receiver MRK950 has the
DSP board option, the scale of the modulation will
be changed according to the nominal modulation of
the type of microphone and manufacturer selected
in the NOISE REDUCTION SYSTEM. The modulation
led bar is blank when the squelch and/or the tone
squelch opens the audio output circuit (or if there
is no modulation on the transmitter, of course). Ad
-
just the gain of the audio chain in the transmitter to
have in the maximum modulation peaks the 100%
of modulation bandwidth, leaving the next 6dB of
modulation margin before clipping (red PEAK led) for
extra sound pressure margin. If the audio level is
not exactly known, be conservative and adjust the
microphone gain in a lower position to avoid clip-
pings during the working session.
Battery indication
On the main display of each receiver is always well
visible the battery status of the transmitter (area 12
of the main view). The resolution of the indication
depends on the transmitter. Wisycom transmitters
send 8 levels of battery charge status, other com-
petitors 6 or 4 or 3 level (full, half, empty).
When the transmitter is a Wisycom, the display of
the batteries indicate the correct icon and the per-
centage of the charge but, when the charge reach
the 25% the battery area on the display became
flashing, when the charge reach the
12,5%
, the
illumination of the display is
flashing to give an
high visibility alarm
to the user.
