Seeker HL User’s Guide
Document Num., Rev. 2
May 2018
Page 9
Introduction
Chapter 2
What is the Seeker HL?
Overview
Mitigation of signal leakage within the subscriber premise is essential for
the successful operation of the subscriber’s cable and cellular services. To
thoroughly evaluate the potential for interference to subscriber services,
VIAVI has developed a patent pending approach to signal leakage
measurement which will comprehensively test the Aeronautical and LTE
bands in both fully digital and analog cable systems.
Historically, signal leakage detectors have required high levels of sensitivity
to measure signal leakage radiating from the CATV system. Measurement
within the subscriber premise and the migration to all digital services places
even greater sensitivity requirements upon the leakage detector combined
with a new requirement to simultaneously monitor for signal leakage in both
the aeronautical and LTE bands.
In laboratory experiments signal leakage measurements as low as
0.1 uV/m have proven sufficient to allow LTE signals to enter the subscriber
network and disrupt cable services. Achieving a measurement sensitivity
of 0.1 uV/m is beyond the measurement range of conventional signal leakage detectors and
requires a new approach to leakage detection within the subscriber premise.
Testing with the Seeker HL Source Transmitter
To meet the new measurement and sensitivity requirements, the Seeker HL monitors 138
MHz and 757.5 MHz simultaneously, supporting testing in both the Aeronautical and LTE
frequency bands. The Seeker HL Source Transmitter replaces the cable service with two
high-output test carriers which pressurize the subscriber cabling, revealing any damage
which may lead to service interruption from ingressing LTE carriers.
The Seeker HL Source Transmitter has two output levels: a +60 dBmV for home
certification and a +40 dBmV output level should the subscriber network prove too porous
for pinpointing the location of a leak at the higher transmit level.
The displayed leakage levels are normalized by the Seeker HL receiver to reflect the value
of the leak at nominal systems levels within the subscriber premise. The normalization
of the measured and displayed leakage levels simplifies the evaluation of leakage
severity and provides consistency for documentation of leakage levels in accordance with
established industry practices.