Appendix B - Functional Operation
150-432-100-02, Revision 02
58
July 18, 2002
HLU-432 List 1
A
PPENDIX
B - F
UNCTIONAL
O
PERATION
ADC’s HDSL technology provides full-duplex services at standard T1 rates over copper wires between an HLU
and an HRU, which comprise one HiGain system. HiGain systems use ADC 2-Binary 1-Quartenary (2B1Q)
HDSL transceiver systems: to establish two, full-duplex, 784 kbps data channels between the HLU-432 and a
remotely located HDU or HRU. This provides a total capacity of 1.568 Mbps between the two units.
A block diagram of the HLU-432 is shown in
. The unit receives a 1.544 Mbps DSX-1 data stream from
the DSX-1 digital cross-connect interface. The HLU-432 contains a DS1 frame synchronizer controlled by an
8-bit microprocessor that determines the type of framing on the DS1 stream and synchronizes with it. The
HLU-432 recognizes SuperFrame (SF), including D4, or Extended SuperFrame (ESF) framing. When the data is
unframed, the HLU-432 arbitrarily defines a frame bit.
Figure 29.
HLU-432 List 1 Block Diagram
T
IMING
The low loop wander (0.3 UI max) of an HLU-432, when used with compatible doublers (HDU-409,
HDU-404, or HDU-407) and remote units (HRU-402), allows the circuit to be used in all critical timing
applications, including those that are used to transport Stratum 1 timing.