SERVICE MANUAL
Document No
Date of Origin
Date of REV
51-L-DSR004
98-10-21
PAGE REV.
0
PAGE
7/102
S-00-005(96.03.27)
REV.1
3. Overview
The DRX100 DSR(Digital
Satellite
Receiver)
is only for BSKYB receiption
which
is a CAM (Conditional
Access Module)
type receiver
not a FTA(Free
To Air) type.
The DRX100 operates
with a built-in
Open TV OS (OPERATING
SYSTEM)
software.
The signal that has been received
from the satellite(ASTRA)
antenna
goes to the
LNB(Low
Noise Blockdown
Conversion)
and then is transfered
to I/Q signals
for
QPSK demodulation.
After the QPSK demodulation
the signals
are converted
to
digital
bitstreams.
As the bitstreams
are scrambled
it goes to the DEMUX after
it has been descrambled
by the CAM. The channels
are identified
by PIDs and
transfered
to the A/V decoder.
The A/V decoder
manages
MPEG decoding
and seperates
video and analogue
signals.
The video signal is encoded
to analogue
composite
signals
from the video encoder
IC(STV0119)
and the audio is digital
to analogue
convered
by varios sampling
ratio to the final TV/VCR scart outputs.
The video encoder(STV0119)
has a macro
vision anti-recording
function
to prevent
recording
by a VCR.
The Digibox
CAS(Conditional
Access System)
is from NDS(News
Data System)
and
provides
an IEE1394
port for high speed data access,
a 33.6kbps
modem with a
G729 voice encoder
built-in,
a RS232 port for serial communication
and various
in/output
connectors
for external
devices.
The CPU conbines
the functionality
of the STB transport
IC and system
microcontroller
in a single device which controls
various
interfaces
like ;
memories,
smart card access,
front panel & the de/encoder
interfaces.
Figure 3.1 Set Top Box architecture
