Viavi CT-X User manual

Determine Estimated CT-4 and CT-X Levels
This procedure is not to be used to set or adjust the CT-4/CT-X levels but to verify if the
measured level is within the appropriate limits and determine the CT-4/CT-X needs to be
adjusted.
Note: We will only look at the two typical frequencies in this document.
Prerequisite
Please Review CT-4 Getting Started Guide
Please Review CT-X Getting Started Guide
System Requirements
ONX 620 or ONX630
Any forward test points
Quick Review
CT-4 has a fixed injection of 138 MHz and 612 MHz See Figure 1
Figure 1: Typical injection Frequencies
Procedure
Measure adjacent QAM Channels to 612 MHz and 138 MHz
•Ch. 88 or 89, and 16 or 17 respectively
•Log channel power levels for each
•Measure the peak value of the dual CW’s combined (Not in Low-Res mode)
•612 MHz and 138 MHz
•Log peak value of both frequencies
CT-4 and CT-X Quick Verify

2
Proper Levels, no action required
•Ch 88 or 89 power level -24 dBc to -25 dBc = acceptable level
•Ch 16 or 17 power level -24 dBc to -25 dBc = acceptable level
If any of the above is not true, schedule headend visit
Connect signal to port 1 of the ONX
CATV Home Screen
select
“Channel Check”
Figure 2: Channel Check
Channel Check Setup
select
“Start”
Figure 2: Channel Check Start

3
ONX builds channel plan and provides
measurement for all channels in the plan
Figure 2: Channel Check Start
Note the Power Level of the selected Channels

4
Downstream Spectrum Setup (612 MHz)
Downstream Spectrum Setup (612 MHz) Continued

5
Downstream Spectrum Setup (138 MHz)
Downstream Spectrum Setup (138 MHz) Continued

6
Measured Results
(612 MHz) (138Mhz)
Note: These are approximate levels to verify leakage levels are within the expected
limits. If levels are off by 3 dB too low, then leakage readings will be cut by ½.
Example:
A 20 microvolt leak would by only 10 microvolts.