WisyCom MRK 950 EX, Инструкция по эксплуатации

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Pag. 6
MRK950 dual true diversity receiver
MRK950: main block diagram
Receiver - 1- A
Receiver - 1- B
Receiver - 2- A
Receiver - 2- B
Div
ersit
y
micr
oc
on
tr
oller
Div
ersit
y
micr
oc
on
tr
oller
Analog
audio
processor
Analog
audio
processor
Digital
audio
processor
Communic
.
net
w
or
king
micr
oc
on
tr
.
Receiver supervisor
microcontroller
and user interface
Front panel
Dig
ital output
Antenna
bias
control
A
B
A
nt
enna inputs
Line
Com
Line unbal.
GPI
Line
Com
Line unbal.
GPI
AES/EBU
word clock
Ethersound
USB
Ethernet
Link
Analog processor : the signal is filtered by a high
pass filter (30Hz) and then splitted in two different
circuits, the audio processor and the data signalling
subcarrier detection and demodulation. The audio
processor has these sections: the de-emphasis (50
microseconds), the low pass filter (20KHz), the ex -
cludible ENR expander. The audio signal is now ready
for the audio output drivers.
Data signalling detection and demodulation:
the data subcarrier is filtered with a four sections
band pass filter with a bandwidth of about 50Hz, fol -
lowed by an ultra narrow band crystal filter (3Hz).
Each filter has its own data demodulator, one for
medium speed data detection at the output of the
first filter and one at low speed data detection at the
output of the second filter. All the two demodulators
are connected to the supervisor microcontroller for
the data battery detection and signalling.
Digital audio processor: the demodulated signal
is filtered by an anti aliasing low pass filter and then
converted in the digital domain with a 96KHz 24bit
audio A/D converter. The digital signal processor
(DSP), capable or 40 bits floating point operation,
replicates all the analog functions with very high ac-
curacy, ultra low distortion and without typical an-
alog problems like components tolerances or long
term drifts or temperature drifts etc. The high speed
audio algorithms implemented in assembler into the
MRK950 maintains the audio delay at about 700 mi-
croseconds, making it ideally for live events and to
keep audio delay as short as possible. The DSP unit
also filters and demodulates the data carrier and
communicates all the parameters and informations
to the supervisor microcontroller. The audio output
goes to the digital outputs board options (AES/EBU
or Ethersound) or is converted in the analog domain
with a high quality 24 bits 96KHz D/A converter and
an anti-aliasing filter.
Audio output drivers : the audio signal, selected
between the analog processor output and the digi-
tal audio board codec output (depending on setup
defined into the active noise reduction system),
is splitted in three parallel ways, LINE , COM and
HEADPHONE MONITOR amplifier.
The HEADPHONE MONITOR amplifier is controlled by
the buttons on the front panel and by the volume
knob. The monitor output depends on the squelch
and on the tone squelch only in the TSQ ON selec -
tion. In TSQ OFF and in TSQ ADV the monitor output
is muted only by the squelch control.
The two ways, LINE and COM , are identical and the
audio quality is exactly the same. Each audio driver
has a VCA for the soft switching of the audio signal
and the muting functions, controlled by the supervi-
sor microcontroller. After the VCA, an electronically
balanced amplifier drives the output signal, directly
or thru a very low impedance screened audio trans-
former (optional). The audio output without trans -
former could withstand up to +52 Vdc of phantom
supply with no damage and up to 100V with trans -
former.