101703-001 REV E
4/12/16
2
Introduction
The ComSonics Dual Frequency Digital (DDF) Series QAM Shadow
TM
is a compact, lightweight cable
signal leakage detector designed for in-home use. Working with ComSonics QAM Markers
TM
installed at
the local cable system head-end or hub and the new Mini Mobile Marker (M3), the QAM Shadow
TM
provides technicians with both visual and audible indications of signal leakage in both the VHF and UHF
bands allowing them to find and repair in-home leaks that would otherwise go unrepaired.
General Operation
The QAM Shadow
TM
has one multifunction button on the front.
Turning the Unit On and Off:
The QAM Shadow
TM
can be turned ON using two different methods. If the lid is closed, momentarily
pressing the front button will power the unit on. The speaker will make a brief sound to confirm power
is on. The LED at the top of the unit will begin to flash about every 15 seconds to also confirm the
power on the unit is on. The second method to turn the unit on is to simply lift the lid. The screen will
activate and a short sound will confirm the unit is turned on.
To turn the QAM Shadow
TM
OFF, press and hold the button for approximately 5 seconds. The speaker
will also emit a tone on power off. This will work with the lid either open or closed. Note, if the lid is
open, the device will emit a sound after two seconds during the button push. This initial sound is not
related to power down but rather to changing the detection frequency. Continue to hold the button for
5 seconds and the next sound will indicate power down. The screen will also turn off as well. Note:
Closing the lid does not turn the device off. The QAM Shadow
TM
can
only
be turned off via a 5 second
button push.
Modes of Operation
The QAM Shadow
TM
has two modes of operation: (1) Measure Mode and (2) Monitor Mode
The unit is in Measure Mode when the lid is
open
and the display is active. In this mode, the unit is
actively displaying any detected leakage and will simultaneously emit a warble tone as a secondary
indicator of leakage.
The unit is in Monitor mode when both the Lid is closed and the unit is powered on. In Monitor Mode
the indicator LED flashes green at every 15 second interval. If the user closes the lid while the unit is still
on, the device will automatically enter the Monitor Mode.
Detecting Cable Leakage
When cable leakage is detected, either in monitor or measure mode, the internal speaker emits a
warble tone to warn the technician. The QAM Shadow
TM
detects leakage at both 138 MHz (VHF) and
612 MHz (UHF) for standard systems using NTSC 6 MHz QAMs or at 139MHz and 614MHz for PAL based
systems using 8 MHz QAMs. The QAM Sniffer produces unique tones for each frequency detected:
lower frequency tones for 138/139 MHz leaks and a higher frequency tones for 612/614 MHz leaks. This
