Audio Switching - Vislink Strata RX Technical Reference Manual

9.5.2

Audio Switching

The Strata RX provides analog and/or digital audio outputs. How
this works depends on whether there is an MPEG Decoder
installed, or an FM Receiver, or both.
MPEG Decoder When the MPEG decoder circuit is used, a
flexible analog and/or digital audio switching circuit is provided
which permits configuring the receiver to provide either analog or
digital audio outputs. Figure 9-12 shows a block diagram of the
MPEG decoder audio output circuitry.
Figure 9-12: MPEG Audio Switching
ASI Input
From
COFDM
Demodulator
MPEG DECODER
MPEG Decoder + FM Receiver If desired, the RCU can
contain both an MPEG Decoder and an FM Receiver (FMR).
This circuit provides analog FM receiver video and audio
demodulation functions for either NTSC or PAL video formats
(must be specified when ordering).
When the FMR circuit is installed in an RCU housing along with
the COFDM/MPEG option, an audio switching circuit is added
which accommodates audio output switching between digital and
analog operating modes. See Figure 9-13 showing details of the
RCU audio switching circuit.
Strata RX Technical Reference Manual
ANA
Analog or Digital
Aud B audio
Audio Outputs
DIG
Analog Audio
Aud A audio
Outputs
Figure 9-13: FMR/MPEG Audio Switching
FMR
MPEG Decoder
Note that when the Strata RX RCU or RXU is operated in the
digital mode, the MPEG decoder audio outputs may be
configured for analog or digital audio outputs as shown in Figure
9-13.
Also note that the audio output wiring configuration differs
between analog and digital audio circuits. See "Audio
Connections" on page 6-7 for more details.
Theory of Operation
IF Interface
Aud B audio
Aud A audio
MPEG
ANA
Aud B audio
DIG
Aud A audio
FMR
Audio
Output
9-12