Viavi CT-X, Руководство пользователя

Страница: 24 / 46

CT-X User’s Guide
22137813, Rev. 000 Feb 2020 24
Chapter 2 Setting up Your CT-X
CT-X setup
The CT-X injects a proprietary modulated or dual CW carrier tag across the entire downstream
bandwidth in up to 4 locations (up to 4 signature tags with the proprietary modulated signal
and 8 with the dual CW tag).
Each frequency can be independently enabled, which provides the ability to monitor any
of the signals simultaneously or each one individually. These carriers are injected between
channels in the guard band so as not to cause interference to the adjacent channels.
As an example, when using a standard SCTE channel lineup and you have a mix of Seeker Ds
and Seeker Xs, we recommend two of the four leakage carriers be injected into the system at
138 MHz and 612 MHz, which is the guard band between the channels that reside on either side
of those two frequencies.
Ideally, you want a good mix of low, mid, high, and ultra high frequencies to provide good
coverage across the start and stop frequencies of your channel lineup.
In all cases, the two carriers should be injected in the guard band between QAMs or analog
carriers based on which type of channel resides at each frequency.
Overview
Over the next few pages, we’ll cover each of the following steps:
y
Locating positions for signals between channels
y
Measuring metrics of adjacent channels prior to injecting signals
y
Injecting signals at recommended offset from adjacent channels
y
Measuring metrics of adjacent channels to assure an acceptable MER
y
Adjusting signals as needed to remove any impairment on signals
y
Recording final signal offsets for use in Seeker configuration
Required equipment
You’ll need the following equipment to configure the CT-X for your plant:
y
Instrument capable of channel performance measurements, such as:
– Digital channel power
– MER
– BER
y
Spectrum analyzer for level measurements, equipped with DTV analyzer:
– BW of 1220 MHz
– RBW of 10 kHz minimum, 30 Hz preferred