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LTPH-UM-1109-01, Issue 1 Appendix B - Functional Operation
H2TU-C-231 List 2 January 9, 2002 59
APPENDIX B-FUNCTIONAL OPERATION
ADC HDSL2 technology provides full-duplex services at standard DS1 rates over copper wires between an
H2TU-C and an H2TU-R, which comprise one HiGain HDSL2 system. HiGain HDSL2 systems use Overlapped
Pulse Amplitude Modulation Transmission with Interlocking Spectra (OPTIS) transceiver systems to establish
full-duplex, 1.552 kbps data channels between the H2TU-C-231 and a remotely located H2TU-R.
A block diagram of the H2TU-C-231 is shown in Figure 33. The H2TU-C-231 receives a 1.544 Mbps DSX-1 data
stream from the DSX-1 digital cross-connect interface. The H2TU-C-231 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 H2TU-C-231 recognizes SuperFrame (SF) or Extended SuperFrame (ESF) framing. When the data is
unframed, the H2TU-C-231 arbitrarily defines a frame bit.
Figure 33. H2TU-C-231 List 2 Block Diagram
TIMING
The low-loop wander (0.5 UI max) of an H2TU-C-231, when used with remote units, allows the circuit to be used
in all critical timing applications, including those used to transport Stratum 1 timing.
GROUND FAULT DETECT
The H2TU-C-231 has a Ground Fault Detect (GFD) circuit which detects a ground or a resistive path to ground
on any wire of the HDSL2 loop. This makes the product compliant with the Class A2 requirements of GR-1089.
HDSL2
XCVR
Microprocessor
PowerSupply
B
A
B
Tip
+
_
34
35
Ring
HDSL2
SPAN
-48Vdc
39
15
16
19
44
Ground
32
LEDs
A
RS-232(frontpanel)
42
43
Tip
Ring
D
S
X
1
OUT
49
50
20
21
Tip1
Ring1
Alarms
LINE
LINE
IN
D
S
X
1
BRG
BRG
Pre-equalizer
Select
T1
Framer
MODESEL
Fuse alarm
Management bus
46
-180Vdc
Power
Supply
(Ground isolated
and ground fault detect)
HDSL2
Framer