PairGain 150-1143-42, Manual

Page: 12 / 46

Functional Description 150-451-142-04, Revision 04
4 October 8, 1998 HDU-451 List 4B
F
UNCTIONAL
D
ESCRIPTION
HiGain utilizes PairGain’s Two-Bits, One-Quaternary (2B1Q) HDSL
transceiver systems to establish two full-duplex 784 kbps data channels (total
of 1.568 Mbps) between the HLU and a remotely mounted HRU-412 HiGain
Remote Unit. Each HDU-451 increases the total span of the CSA by
approximately 12,000 feet (24 AWG) or 9,000 feet (26 AWG).
A block diagram of the HDU-451 is shown in Figure 2 on page 5 . The
HDU-451 power supply uses the 100 to 200 Vdc power feed voltage received
on the simplex pairs to p5V and -5 Vdc required by the HDU-451
circuitry. The power feed is passed to the HDSL output, via the Output Span
Voltage Control relay, to power one other HiGain module, either a second
HDU-451 or the remote HRU-412. If two doublers are used, the remote
module must be a locally powered HRU-412 List 7 or List 8 unit.
The maximum power dissipation of the HDU-451 is 6 watts.
O
UTSIDE
E
NCLOSURE
D
EPLOYMENT
R
ULES
Take care when deploying the HDU-451 in sealed multislot outside
enclosures, such as the PairGain 3-slot HRE-423 or 4-slot HRE-454
enclosures. To avoid excessive heat build up, follow the deployment rules
shown in
Table 2 on page 6 (HRE-423 and HRE-450) or Table 3 on page 7
(HRE-454). These tables limit the number of doublers that can be housed
reliably in either the HRE-423 or HRE-454 enclosures. In the tables:
•
the maximum ambient temperature column refers to the outside air
temperature
•
the occupied slots column designates which slots (1, 2, 3, or 4) can be
occupied for each condition
For example, if the occupied slots for the HRE-423 are 1 and 3, the doublers
are located in slots 1 and 3 with slot 2 empty. If the occupied slots for the
HRE-454 are 2 and 4, the doublers are located in slot 2 and 4 with slots 1 and
3 empty. If other then the specific slot arrangements are used, then the next
lower temperature deployment rule must be used.