Pag. 5
MRK960
dual true diversity receiver
MRK960: main block diagram
Receiver - 1- A
Receiver - 1- B
Receiver - 2- A
Receiver - 2- B
Tr
ue D
iv
ersit
y
Con
tr
ol Rx 1
Tr
ue D
iv
ersit
y
Con
tr
ol Rx 2
Communic
.
and c
on
tr
ol
in
ter
fac
e
Receiver supervisor
microcontroller
and user interface
Front panel
Dig
ital
output
A
B
A
nt
enna inputs
Line 1
Line 2
Com Rx 1
Com Rx 2
AES3 Output
INFRARED
USB
Digital
audio
processor
A
nalogue output
PT
T
output
Ear-ph Left
Ear-ph Right
Ear
-
phone
work clock
Ethersound
Ethernet
The data sub carrier is digitally filtered to a very selective equivalent filter (bandwidth 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 super
-
visor micro controller for the data battery detection and signalling.
Digital audio processor(for each receiver): 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), working in double precision, replicates all the analog functions with very high accuracy, ultra low distor
-
tion and without typical analog problems like components tolerances or long term or temperature drifts etc.
The high speed audio algorithms maintains the audio delay at about 0.390 milliseconds, 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 micro controller. The audio
output goes to the digital outputs (AES3) or is converted in the analog domain with a high quality 24 bits
96KHz D/A converter and an anti-aliasing filter.
T
he analogue audio signal is routed 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 selection. In TSQ OFF
and in TSQ ADV the monitor output is muted only by the squelch control.
The two analogue audio ways,
LINE
and
COM
, has the same audio quality and are controlledy by the “Tone
squelch matrix”. Each audio driver has a VCA for the soft switching of the audio signal and the muting func
-
tions, controlled by the supervisor microcontroller. After the VCA, an electronically balanced amplifier drives
the output signal, directly or thru a very low impedance screened audio transformer (optional). The audio
output without transformer could withstand up to +52 Vdc of phantom supply with no damage and up to
100V with transformer.