Products from VIAVI/Trilithic for detecting signal leakage
Leakage means undesired emissions of signals from an HFC plant, which can lead to transmission problems, loss of transmission quality and service disruption.
CLI – Cumulative Leakage Index
CLI is the total amount of radio frequency (RF) signal that escapes or infects the cable system.
Main causes of leakage
Improper installation
Component corrosion
Poor product design
Cable breakage
Poor connections/connectors
Damage of network components
Ingress means RF or electric energy that enters the coaxial
environment, egress means the RF signal leaking out of the coaxial
environment which leads to a loss of power and overall signal strength
of the cable system.
Reasons to monitor for leakage
Prevent interference with other signal sources like cell phones
Eliminate ingress
Locate physical problems in the HFC plant and improve system performance
VIAVI/Trilithic offers solutions for detecting leakage in the HFC plant as well as in the customers home.
Leakage detecting solutions
CT-4 Channel Tagger
The CT-4 is used in combination with Seeker D and Seeker D Lite and uses just on RU in a 19“ rack. The CT-4 works in two ways:
Digital: Inserts tagged signal into the aeronautical (135-139 MHz) and LTE bands (610,5-615 MHz)
Analog: A tag frequency is modulated on an analog carrier and in the aeronautical band there is a CW carrier injected. The carriers are injected at 30 dB (LTE) and 36 dB (aeronautical) below adjacent carrier to eliminate risk of affecting those channel/digital services.
Seeker D Lite
This device is used in combination with the CT-4 or the Seeker D Lite Transmitter.
Customers with taggers already in place can use that tag for in home testing with the Seeker D Lite. Seeker D Lite Transmitter can also be used at the ground block to certify the integrity of the home.
Seeker HL
The Seeker HL only works in combination with the Seeker HL Transmitter and is used in the customers home installation. The Seeker HL can also
detect leakage in the LTE and aeronautical band with a very high
sensitivity:
0.1 µV/m @ 138 MHz
0.4 µV/m @ 757.5 MHz
Seeker D with MCA III
For mobile application the Seeker D is combined with the MCAIII. The CT-4
in the headend is used as signal tagger. During the drive-out the
technician leaves the Seeker D in the mobile mount, where it is
connected to the vehicle power, an antenna, and a GPS receiver. The
Seeker MCA III automatically monitors leakage outbreaks and records the
data with a time/date stamp and the leak’s GPS location.
Uploading data records to a server can be fully automated, occurring whenever the vehicle enters a base location, via an operator-controlled Wi-Fi hotspot.
Early Detection Notifications
When a set threshold level within the Seeker has been surpassed, the Leakage Analysis Workshop (LAW) will email an EDN (Early Detection Notification) to insure that large leaks will be identified immediately. This
automatic process helps keep the technician from being distracted while
driving or working.
