Cisco DNCS System Release 2.8.1 3.8.1 4.3.1 User Guide

If your system uses two-way communication, set up the two-way communication path for your network after you
have set up the elements that process system data. In addition to sending information to DHCTs, the DNCS must
be able to receive information from them. This is especially true if you provide PPV, VOD, or interactive services,
which require a reverse data path. The QPSK modulator and the QPSK demodulator work together to provide this
two-way communication over the out-of-band data path.

Using an out-of-band data path offers the following advantages:



DHCTs can receive system data when they are tuned to an analog channel, so you can make system

changes without interfering with the subscriber's viewing experience



The volume of  data is reduced, so you have more space to provide programming



A QPSK modulator can be connected to as many as eight demodulators. When a QPSK modulator and

demodulator(s) are connected to each other, they are referred to collectively as a QPSK modem

Note: We offer a software product that you can purchase separately to enable the DNCS to also transport
DOCSIS-compliant CMTS data. For more information about this software product, contact the representative who
handles your account.

Before you begin, you must have your network map.

To set up two-way communication, you must complete the following steps.