ATL TELECOM USER GUIDE
AM2048A OS/OM
53
10
10.1 OPTICAL
TRANSMISSION
The optical transmission interface module is designed to operate over a single optical fibre.
This is accomplished using an optical duplexer, which integrates a laser and a photodiode in a
single package. Both directions are transmitted at the 1310nm optical window, leaving the
1550nm window free. The interface module encodes the DSL framed data using a 5B6B block
code for error monitoring and spectral shaping.
Sub-carrier modulation is used to increase the separation between the upstream and
downstream directions. Baseband transmission is used from ELU to NTU, whereas the other
direction is modulated onto a carrier.
For transmission over single-mode fibre, order the AM2048 OS.
For transmission over multi-mode fibre, order the AM2048 OM.
The AM2048A OS and AM2048 OM are Class I products in accordance with EN60825-1 and
therefore inherently safe.
Primary Rate
Interface
Micro
Controller
G703
75/120
ohms
User Interface Module
Optical Transmission Module
Laser
Driver
Clock
Recovery
Analogue Rx
and
Channel
Separation
Filter
Optical
Duplexer
ATL
Tranceiver
Codec
Chip
ATL
HDSL
Interface
Chip
1 0 S Y S T E M O V E R V I E W
52
ATL TELECOM USER GUIDE
AM2048A OS/OM
