Cisco Headend System Release 2.5 用户指南
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DHCT Status Reporting Utility
78-738186-01 Rev B
DHCT Delay Value Saturation Report,
Continued
QPSK Range Extension Feature
The Model D9482 QPSK Modulator is designed to be capable of successfully
connecting to and operating DHCTs within a distance of approximately 128 km
round trip (64 km each way when forward and reverse paths are equal). This
distance limitation is mainly due to the width of the ranging slots defined in the
Digital Audio-Visual Council (DAVIC) standard for operation over the hybrid
fiber-coax (HFC) plant.
Some cable service providers prefer to physically locate the QPSK hardware in the
Some cable service providers prefer to physically locate the QPSK hardware in the
headend and extend coverage to DHCTs that are farther from the QPSK modulator
than the currently allowable maximum distance. This optional feature, known as the
QPSK Range Extension Feature for the Model D9482 QPSK Modulator, allows
Explorer DHCTs to sign on to the system and operate properly at extended distances
from the QPSK modulator.
Note: Refer to QPSK (Release A62) Software Upgrade and Installation Instructions, part
Note: Refer to QPSK (Release A62) Software Upgrade and Installation Instructions, part
number 740224, for additional details about distances between the QPSK modulator
and DHCTs, as well as additional details about the QPSK Range Extension Feature.