150-451-104-02, Revision 02
Product Overview
HDU-451 List 4
September 18, 1998
1
P
RODUCT
O
VERVIEW
PairGain’s HiGain Model HDU-451 List 4 low power Doubler Unit (
) extends the range of the HiGain repeaterless T1 transmission
system. When installed between a HiGain Line Unit (HLU) with
doubler-powering capability, and a HiGain Remote Unit (HRU), the
HDU-451 enables 1.544 Mbps transmission over an extended Carrier Serving
Area (CSA) range of approximately 24,000 feet of 24 AWG or 18,000 feet of
26 AWG wire. Customers can use two doublers in series to triple the normal
CSA range (36,000 feet on 24 AWG).
The HDU-451 mounts in a single slot of any industry standard 400 mechanics
shelf or in equivalent enclosures manufactured by PairGain Technologies. All
HiGain modules comply with the applicable requirements of
TR-TSY-000063 (Network Equipment Building System (NEBS) Generic
Equipment requirements) and TR-TSY-000499 (Transport System Generic
Requirements - TSGR).
D
ESCRIPTION
AND
F
EATURES
HDU-451 List 4, HiGain Doubler Unit features:
•
Powered by any doubler-compatible HLU - no local power required
•
Front Panel HDSL Status Display
•
Front panel jacks for test access
•
Lightning and power cross protection on the HDSL interfaces (both
sides)
•
Front Panel Doubler loopback LED indicator
•
Low power dissipation
The HDU-451 List 4 is identical to the List 3, except its response time to an
HDSL Span 2 or 3 HDSL loss of sync condition has been reduced to 50
milliseconds. This enables the system to switch from the main primary circuit
to the backup protect circuit when any span loses sync. The List 4 has also
been enhanced for compatibility with both the metallic sealing current of the
HRU-412, List 7 and 7A, and the simplexed sealing current of the HRU-412,
List 8 and 8A, and HRU-402 remote units.
