150-431-115-01, Revision 01
Appendix C - Functional Operation
HLU-431 List 1E
September 22, 1998
49
A
PPENDIX
C - F
UNCTIONAL
O
PERATION
PairGain 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 PairGain 2-Binary 1, Quartenary (2B1Q)
HDSL transceiver systems to establish two, full-duplex, 784 kbps data channels between the HLU-431 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-431 is shown in
. The HLU-431 receives a 1.544 Mbps DSX-1 data stream
from the DSX-1 digital cross connect interface. The HLU-431 contains a DS1 frame synchronizer controlled by
an 8-bit microprocessor that determines the type of framing on the DS1 stream and synchronizes to it. The
HLU-431 recognizes Super Frame (SF), including D4, or Extended Super Frame (ESF) framing. When the data
is unframed, the HLU-431 arbitrarily defines a frame bit.
Figure 23.
HLU-431 Block Diagram
HDSL 1
XCVR
MICROPROCESSOR
GND 17
POWER
SUPPLY
B
A
B
BAT 35
FUSE
ALARM
25
STATUS
A
FRAME GND I
ALARM
RS-232
MNGBUS 46
22
30
49
55
TIP
RING
HDSL 2
XCVR
47
41
TIP 1
RING 1
HDSL 2
13
7
TIP
RING
HDSL 1
D
S
X
1
RCV
5
15
TIP 1
RING 1
FACTORY
BURN-IN
R143
JP2
20
LINE
LINE
XMT
D
S
X
1
BRG
BRG
MUX
DEMUX
PRE-
EQUALIZER
SELECT
T1
FRAMER
MODE SEL (ACO)
-140V
OR
±100V
POWER
SUPPLY
(GROUND
ISOLATED)