ComSonics QAM Marker User manual

User Guide
Document is subject to change. Please check www.ComSonics.com for updated
information.
CSI Doc. 101623-004 eRev. 1.0.5

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Limited Warranty (brief)
Hardware: ComSonics, Inc. (ComSonics) warrants to the original end user (Customer) that the new ComSonics
branded products will be free from defects in workmanship and materials, under normal use, for one (1) year
from the date of original shipment. ComSonics warrants repaired and refurbished ComSonics products for
ninety (90) days from date of shipment.
Software: ComSonics warrants to the Customer that the Workstation Application software will perform in
substantial conformance to program specifications for a period of ninety (90) days from the date of original
shipment. ComSonics warrants the media containing the software against failure during the warranty period.
ComSonics makes no warranty or representation that the operation of software products will be
uninterrupted or error-free, or defects in the software products will be corrected.
Software License (brief)
ComSonics grants you, the Customer, a limited nonexclusive license to use the accompanying software
program(s) (the Software) subject to the terms and restrictions set forth in this License Agreement. You are
not permitted to use the Software in any manner not expressly authorized by
this License. You acknowledge and agree that ownership of the Software and all subsequent copies thereof
regardless of the form or media are held by ComSonics or its suppliers.
Complete Limited Warranty and Software License Agreement documentation is printed in the back section of
this document.
Technical Support
ComSonics maintains a Technical Support Service for customer convenience.
Phone [phone] or 1-540-434-5965 Monday - Friday: 8:00 a.m. - 5:00 p.m. Eastern Time
Fax: [phone], Email: [e-mail]
Copyright
All material in this manual is the property of ComSonics, Inc. and protected under the United States copyright
law. No material shall be reproduced or used in any form or by any means (graphic, electronic, or mechanical,
including photocopying, recording, taping, or information storage and retrieval systems) without the written
permission of:
ComSonics, Inc.
1350 Port Republic Road
Post Office Box 1106
Harrisonburg, Virginia 22801 USA
Phone: [phone] USA Toll Free: [phone]
Fax: [phone]
Email: [e-mail]
Internet: www.comsonics.com
Sniffer is a registered trademark of ComSonics, Inc.
QAM Sniffer, QAM Marker, Nexus, and GeoSniffer are trademarks of ComSonics, Inc.
© 2012 ComSonics, Inc. All Rights Reserved
Document 101623-004 eRev. 1.0.5

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Table of Contents
Limited Warranty (brief).................................................................................................................................2
Electrical Safety ..............................................................................................................................................4
Introduction....................................................................................................................................................5
Components ...................................................................................................................................................6
Front Panel .............................................................................................................................................6
Back Panel...............................................................................................................................................6
Headend/Hub Installation ..............................................................................................................................8
DC Powering ...........................................................................................................................................9
Power and Alarm Indicators.........................................................................................................................10
Broadcast Insertion Considerations .............................................................................................................11
Configuration Manager Introduction (web based) ......................................................................................13
QAM Marker Manual Level Setup Procedure: Spectrum Analyzer Method................................................15
Worksheet for Manual Level Mode Setup ...........................................................................................22
Specifications................................................................................................................................................23
Limited Warranty..........................................................................................................................................25
Software License Agreement .......................................................................................................................26

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Electrical Safety
This symbol is used to alert users of possible hazard or risk in operating this equipment.
Read the instructions fully before operating this equipment for the first time.
Do NOT expose this equipment to rain or moisture!
Do not disassemble the equipment or interfere with the internal components; this will void the
warranty and create the possibility of electric shock.
If the equipment is used in a manner not specified by the manufacturer, the protection provided
by the equipment may be impaired.
Only use the provided mains lead as using other types may cause damage to the equipment,
which will void the warranty and may cause electric shock.
Clean only with a soft dry cloth.
AC Mains.
This equipment does not have a power switch. It is turned on when the power cord is plugged in.
This equipment must be grounded.
The AC power input is Double-Pole Fused, also known as Neutral Fused, and requires this equipment to
be grounded as follows:
AC input - Connect to an electrical outlet provided with a protective ground connection.
DC input - Connect the protective ground to the designated external terminal on the equipment
rear panel.
This equipment has no internal user serviceable or replaceable parts.
The rear panel fuses and screw connection adapters are the only user replaceable parts. Use only the
original factory rated fuse types; otherwise safety of the equipment may be impaired.

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Introduction
The ComSonics’ new leakage detection solution is a system which allows detection of CATV leakage in an
all-digital system without reserving any bandwidth for a discrete leakage carrier.
It is a CATV leakage detection system made up of two parts. The first part is a QAM Marker Signal
Source which is installed at a headend or hub of a CATV system. The second part is the
handheld/mobile unit for finding leaks or the GENACIS QS (GQS) mobile unit for vehicle applications.
The QAM Marker signal source generates a standard set of frequencies to allow the handheld devices
to detect leaks only from the CATV system to which they are matched. The QAM Marker signal source
can be configured differently for up to three CATV systems in an overbuild area to distinguish leaks
between the CATV systems. The handheld detectors and GQS devices must be configured to match
the appropriate QAM Marker Signal Source.
The GENACIS QS mobile unit is a GPS Enabled Automatic Cable Integrity System delivering unmatched
leakage location and management technology. It makes cable plant optimization automatic and
affordable. This hands free solution mounts easily in the cable operator’s vehicles, detecting system
leaks in real time as the technician performs their regular duties. Leak intensity and location are
recorded and uploaded by cell phone GPRS technology to the central server allowing the cable
operator to view their leaks, manage work orders and monitor results. GENACIS QS gives the ability to
proactively manage the cable plant to optimize performance and customer satisfaction.
The handheld leakage detectors and the GQS units use sophisticated methods to detect and measure
QAM Marker Signal Source leaks from the CATV system. They can differentiate a true leak from
general noise or signals originated by another marker in a co-located CATV system.
The QAM Marker Signal Source can be configured through via a network connection using a standard
web browser. An Ethernet network internet connection is required. Cable not supplied.
Unpacking - The QAM Marker Signal Source and any ordered accessories are included in a shipping
container designed to provide the maximum protection during shipment. Upon receipt, inspect the
container and contents for signs of physical damage. Notify the freight forwarder of any damage
detected.
Please dispose of the cardboard packaging carefully and recycle where possible.
Power - The QAM Marker is powered by a standard AC detachable power cord.
Allow 15 seconds for the QAM Marker to initialize after applying power.

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Components
Front Panel
The QAM Marker front panel has two indicators, a reset switch, and a marker selector.
Front Panel
1 Power - Indicates the unit is receiving power.
2 Alarm - Indicates a marker output fault condition. When the Alarm condition is on, the marker
output is shut off.
3 VHF/UHF –Indicates if marker is in the Low Frequency (VHF) or High Frequency (UHF) band
4 Reset - Press to reset a fault condition when the Alarm indicator is on.
5 Marker Identifier - The standard marker setting is 1 for monitoring QAM Marker leakage signals. Using
the selector, the marker can be set to 1, 2, or 3. The QAM Sniffer receiver marker setting must
correspond to the Marker Identifier setting on the headend QAM Marker signal source (F1 for 1, F2
for 2, F3 for 3).
Back Panel
The QAM Marker back panel provides for power, control, and signal connections.
Back Panel
AC Power with built-in fuse - Accepts standard IEC power cord.
DC Power - Dual 48 volt power, screw connection adapter included.
DC Power Fuse (2) - Protection for 48 volt power.
Alarm Remote - Connects to internal relay contacts, screw connection adapter included.
LAN - RJ45 Ethernet network connector.
Ground Binding Post - Chassis ground point.
Combined RF IN - Input for adjacent reference QAM channels combined with QAM Marker.
USB - Service port, factory use only.










+ A - + B -
48 VOLTS DC
1
2
4
3
5

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Marker OUT - QAM Marker signal output.

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Headend/Hub Installation
Important!
The adjacent QAM channels next to the QAM Marker signal AND the QAM Marker signal must be present
at the ‘Combined RF IN’ () before powering on the QAM Marker unit when using the Automatic mode.
The QAM ‘Marker OUT’() is connected to a headend/hub combiner port. If the QAM Marker signal is
NOT present in the RF IN feedback loop, the QAM Marker will continuously ramp the output signal to the
maximum possible level in an attempt to measure itself. This will likely cause the marker to be at levels
that are too high. This can be avoided by making sure the feedback loop for the RF IN Contains both the
adjacent QAM Channels and the Marker signal.
On power up, in automatic mode, the QAM Marker adjusts the ‘Marker OUT’signal level relative to the
RMS power level of the adjacent QAM channel with the lower RMS power.
The QAM Marker Signal Source uses 1 3/4 inches of rack space (1 RU) and should have free air space of at
least 1/2 inch above and to the ends of the chassis for ventilation. It needs power from the AC () or DC
() supply mains, a connection () to the headend/hub combiner network, and a connection () from
the combined headend/hub signals at test point levels if in Automatic mode (consisting of at least the
available adjacent QAM channel/s and the QAM Marker signal).
AC Power with built-in fuse - Accepts standard IEC power cord.
Refer to the Electrical Safety section on page 4.
DC Power - Dual 48 volt power, screw connection adapter included.
Refer to the DC Powering section on the next page.
DC Power Fuse (2) - Protection for 48 volt power.
Alarm Remote - Connects to internal relay contacts, screw connection adapter included.
LAN - RJ45 Ethernet network connector.
Ground Binding Post - Chassis ground point.
Combined RF IN - Input for adjacent reference QAM channels with Marker signal.
USB - Service port, factory use only.
Marker OUT - QAM Marker signal output.










+ A - + B -
48 VOLTS DC

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DC Powering
Dual 48 Volt DC Powering Recommendations.
Observe the following guidelines for using the 48 Volt DC Power option.
(DC power cables are not supplied with the equipment.)
Only use wiring rated to safely handle 48 VDC/0.5A.
Use the provided Phoenix 4-position pluggable terminal block
(Phoenix MSTB 2.5/4 - STF - 5.08).
Each terminal connection of the Phoenix plug can only accept one 24 to 12 AWG stranded wire.
Do not exceed the rated capacity.
Use the shortest possible wire length.
Always use a continuous length of wire.
Do not splice wires to attain the needed length.
Use a larger wire size (within the recommended range of 24 AWG min to 12 AWG max) to
minimize voltage drops when wires must run a long distance.
Always use similar wire size for both the ‘+’ and the ‘-‘ sections.
Use wire trays for routing where possible.
Avoid running wires near high energy or AC wiring.

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Power and Alarm Indicators
Allow 15 seconds for the QAM Marker to initialize after applying power.
Automatic Level Mode Initialization
The Alarm indicator is ON and the Power indicator flashes as the adjacent QAM channel levels and
Marker signal are measured while adjusting the QAM Marker output level. The flash rate increases
as the automatic process nears completion. When the automatic level mode has stabilized, the
power indicator is steady ON and the Alarm indicator is OFF. Either the VHF or UHF LED will light
(dependent on which marker frequency is used) a solid green to indicate that Automatic mode is
present.
Manual Mode
When the manual mode is selected, either the VHF or UHF LED will light (dependent on which
marker frequency is used) a solid orange color to indicate that manual mode is being used.
Low Level Adjacent QAM Channels
The Alarm indicator is ON and the Power indicator flashes if both adjacent QAM channels are low or
off.
Alarm Indicator ON or Flashing (Power indicator ON)
The Alarm indicator is on when an internal problem is detected. If the Alarm idicator continues to be
on after pressing the Reset button repair is needed.

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Broadcast Insertion Considerations
For maintaining maximum plant-wide shielding effectiveness, the QAM Marker signal must be available
throughout the coaxial distribution network. For that reason, installation strategy is important.
1. A single QAM Marker may serve, if the plant is configured to optically transport the broadcast
spectrum from a single location (the headend) with no further electrical conversion before each fiber
node.
2. Multiple QAM Marker units may be needed, if the headend optical output serves multiple hub
locations with recombined signaling or remapped channel plans. The QAM Marker output signal
must be combined with all other broadcast signals at the input to the final laser.
Note that the combined RF Input port must have a QAM signal level greater than -32 dBmV and no more
than +20 dBmV
1
. If the feedback signal used for the RF Input is below the required power level (-32
dBmV), a low gain amplifier can be inserted to amplify the signal to within the required limits.
Conversely, an appropriately valued pad must be inserted to reduce the level to fit inside the window if
the feedback signal is too high (> 20 dBmV).
If there are no adjacent QAMs next to the Marker location, the manual mode must be used to set the
QAM Marker level. The QAM Marker level must be set manually based upon the nearest adjacent QAM
channel amplitude. The manual output range is -10 dBmV to
+30 dBmV. The total power level of the QAM Marker must be set to be 30 dB below the total power of
the 6 / 8 MHz QAM channel. The method to properly set the QAM Marker level in manual mode is
explained in detail later in this document.
1
When measured with a spectrum analyzer set to 100 kHz resolution bandwidth (RBW). If a signal level meter is used to
monitor the reference QAM levels, add 9 dB to the mentioned values.

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The following table and text condenses and consolidates different headend/hub/node
configurations.
Type
Headend Output
Hub
Fiber Node
1
Optical
N/A
Optical > RF
2
Optical
Optical > Optical
Optical > RF
3
Optical
Optical > RF > Optical
Optical > RF
Type 1: Broadcast analog and QAM signals are combined at the headend location, fed to
one or more lasers and transported optically to one or more fiber nodes. A single QAM Marker operated
in Automatic Leveling mode can be combined at the headend location for system-wide distribution.
Type 2: Broadcast analog and QAM signals are combined at the headend location and transported to one
or more hub locations, split and transported to one or more fiber nodes. A single QAM Marker may serve
system-wide distribution depending upon the combining execution. Operation in Automatic mode
depends whether or not a RF feedback loop exists with the presence of the inserted QAM Marker signal
and either/or of the adjacent channels.
Type 3: Broadcast analog and QAM signals are partially combined at the headend location and
transported optically to one or more hub locations. At the hub location, the optical signals are down
converted to RF and recombined with locally generated content or remapped to form a desired channel
plan. The new combination is supplied to the output laser and transported optically to one or more fiber
nodes. A single QAM Marker may serve system-wide distribution if both the Marker and adjacent QAMs
are both generated at the headend. This ensures that the power ratio between the Marker and adjacent
QAMs stays the same. Operation in Automatic mode depends whether or not a RF feedback loop exists
with the presence of the inserted QAM Marker signal and either/or of the adjacent channels.

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Configuration Manager Introduction (web based)
To configure the QAM Marker by direct connection, use a cross-over type Cat 5 Ethernet cable between
the computer and the LAN port on the back panel of the unit. Make sure the computer’s Ethernet
configuration has DHCP turned OFF. Also ensure the subnet mask is set to: 255.255.255.0.
Use a straight-through Cat 5 Ethernet cable when the QAM Marker is installed and connected to your
system network. Make sure the unit’s preset address does not conflict in the existing network. If so, use
the direct connection method to change the unit’s address under Network Settings and then use Apply
Settings. Then press the Reset button on the unit’s front panel. Note: If the default IP Address is
changed, there is not a way to reset it or recall it if forgotten. Please be sure to record the new IP
address for future reference.
Steps to Program the QAM Marker box:
Open a web browser. Enter 192.168.0.50 (or the changed address) in the URL address bar.
(Recommended browsers are IE, Firefox, and Chrome.)
Click OK once the Authentication window appears. The User
Name and Password can remain blank.
The Authentication window varies per OS and browser.
(Leave the fields blank, as this step is a placeholder for development. The Authentication window shows
the first time the unit is addressed as long as the browser remains open.)
The Home page shows the QAM Marker’s
Firmware Version, MAC Address, and the Marker
Configuration Manager Version.
Network
Use this function if you want to have the marker
unit networked. Set the
desired selections and click
on the OK button.
(Clicking the OK button remembers the settings
but does not send the settings to the QAM
Marker unit.)
Use Apply Settings to send the settings to the
QAM Marker unit. REMEMBER the new IP
address and settings for future reference!

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See Apply Settings section on next page.
Apply Settings
When the desired Network Settings are set, then
click the OK button. This must be done as an
intermediate process.
Click on Apply Settings in the left panel to
complete the process. The QAM Marker reboots
and Configuration Manager returns to the Home
screen.
Important:
When the Apply Settings function is used, the QAM Marker must be locally reset by pressing the front
panel Reset button. (This step must be done in order to access the Marker Settings screen after the Apply
Settings function is used.)
Marker
Use this section to set the Marker level.
When the System Mode is set to Automatic
(level mode), the Manual Level field is grayed
out and not available.
Enabling Manual in the System Mode allows
entering an output level in the Manual Level
field.
The Marker Output can only be set to Off in
the Manual mode. Selecting the Automatic
mode locks the Marker Output to On.
The Marker Frequency is set in MHz. Use three (9) digits plus decimal when entering the frequency.
Click the SEND button to immediately change the QAM Marker’s settings. No reboot is needed.
Note: If the Marker Frequency or the Manual Level is not within range, an invalid value warning is shown.
Exit
Close the browser tab to exit the Configuration Manager. (No log-out function is needed.)

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QAM Marker Manual Level Setup Procedure: Spectrum Analyzer Method
This section contains information to assist in the setup of the QAM Marker when configured to operate
in manual mode. Power measurements will be made on both the adjacent QAM channels and the QAM
Marker power levels.
A familiarity with the operation of the QAM Marker web-based user interface and operation of
a spectrum analyzer is required. The spectrum analyzer used for this document is an Agilent N9342C. You
can use other spectrum analyzers that have similar functions and settings. The most important attribute
is that the spectrum should have a RBW of 100 Hz or better.
Section 1 - QAM Power Measurements using a Spectrum Analyzer
When measuring signals having a bandwidth greater than that of the resolution bandwidth of the
instrument used to make the measurement, a measurement bandwidth correction factor must be
applied.
256 QAM television channels have a symbol rate of 5.361 million symbols per second for a 6 MHz QAM
and 6.952 million symbols per second for a 8 MHz QAM. This corresponds to a Signal Bandwidth (SBW) of
5.361 MHz and 6.952 MHz respectively.
A Spectrum Analyzer has a number of Resolution Bandwidth (RBW) settings. The setting selected when
measuring power must be used to calculate the Bandwidth Correction factor. This is because the amount
of power measured on the Spectrum Analyzer is restricted to the RBW, thus it must be adjusted to obtain
the correct measurement.
The Bandwidth Correction factor (BWC) is calculated with the following equation:

BWC (in dB)10 *Log10 SBW (in MHz)
RWB (in MHz)


 


A Quadrature Amplitude Modulation type produces a signal with the characteristics of noise. When
measuring signals ‘noise like’ in nature and averaging the resulting logarithmic output on the screen of a
spectrum analyzer, an under-response of 2.51 dB is incurred. To compensate, add 2.51 dB to the
measurement obtained, altering the formula to:

BWC (in dB)10 *Log10 SBW (in MHz)
RWB (in MHz)


 


2.51 dB
It is possible that the spectrum analyzer uses a FFT type detector to make the power measurement. In
this case, the 2.51 dB correction does NOT apply. The correction is only for the case where a log-type
detector (usually called “sweep”) is used to measure “noise-like” signals (such as QAMs). The Marker
signal measure does not require a correction factor as it is not noise-like and is usually measured in an
FFT mode at very low RBWs ( <1,000 Hz).

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The instructions contained in this document for the spectrum analyzer control are specifically
for the Agilent N9342, shown below, however many of the menu/command structures from spectrum to
spectrum are similar.
The key functions used for the measurements in this document are as follows:
SPAN controls the amount of bandwidth shown on the display indicated and/or set by the start,
center, and stop frequency.
RBW (Resolution Bandwidth) is an important function. It is a band pass filter before the power
measurement is taken. It impacts the measurement in three important ways:
1) The measured power at the marker point is constrained to the band pass limits,
2) the noise floor decreases as the band pass range is narrowed, and
3) frequency signals close together (the QAM Marker is a good example) cannot be
resolved unless the RBW is set low enough to discriminate between them.
VBW (Video Bandwidth) determines the capability to discriminate between two different power
levels. A narrower VBW setting removes more noise in the detector output and ‘smooths’the
envelope display. Set the VBW to be 3x RBW for QAM Marker measurements.
Sweep mode has a lower RBW of 1 kHz. For a lower RBW, set the sweep mode to ‘FFT’ or ‘Auto’.
Auto mode changes settings as needed.
Span:
Start
Center
Stop
BW:
RBW
VBW
Amptd:
Y-Axis
Ref. Level
Scale
dB/Division
Peak
Marker
Sweep:
Auto
Sweep
FFT

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Section 2 - Measuring the QAM Channel Power Level
Use the following steps to measure and calculate the total QAM Power Level:
1) Set the spectrum analyzer to a 15 MHz span centered at the marker frequency. This should be a
resolution bandwidth (RBW) of 100 kHz (30 kHz for FFT mode). Set the video bandwidth filter (VBW)
bandwidth at least three times the RBW. The VBW setting is expressed as a ratio to the RBW; i.e. 3:1.
These settings appear on the bottom of the display as RBW and VBW. For a 15 MHz span, use the
SPAN and BW functions. Adjust the Reference level and the Amplitude scale, if needed, using Amptd
function.
2) Enable trace averaging mode and adjust to collect 100 samples. Wait a few seconds for the display to
stabilize. The two QAM channels adjacent to the marker signal should be within 1 dB of each other.
Record the power level of the QAM channel having the lower level as indicated on the spectrum
analyzer. In Figure 1, the QAM power is measured at 16.02 dBmV. Use the Trace function to set
averaging. Use the ‘more’ menu under Trace.
Figure 1
3) Calculate the bandwidth correction factor based on the resolution bandwidth (RBW) selected on the
spectrum (100 kHz). BWC = 10 * Log10 (5.361 / 0.1) = 17.29 dB (for 6 MHz QAM).
4) Add the measurement bandwidth correction factor of 17.29 dB to the number obtained in step 2:
16.02 + 17.29 = 33.31 dBmV.
5) The logarithmic output is averaged on the display; a correction factor of 2.51 dB must be applied. For
this example: 33.31 dBmV + 2.51 dB = QAM Power Level of 35.82 dBmV.

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Section 3 - Calculate the Required QAM Marker Power Level
The total marker power is set to a level 30 dB less (± 0.5 dB) than the calculated total QAM power level.
Example: Total QAM Power Level calculated: 35.82 dBmV. Subtract 30 dB and set the marker power to
this level. 35.82 dBmV - 30 dB = 5.82 dBmV (± 0.5 dB)
Section 4 - Measuring the QAM Marker Power
1) The QAM Marker Signal is comprised of a 1283 Hz, 1511 Hz, or 1663 Hz signal in a double sideband,
suppressed carrier, modulation scheme.
2) Set the spectrum analyzer to a 5 kHz span centered at the marker frequency. For best results, use a
RBW setting between 1 kHz and 30 Hz with 100Hz or 30Hz providing the best results. If the spectrum
analyzer does not have a RBW small enough to resolve the two sidebands, you will see a single
‘haystack’ type trace. In this case, all of the marker power is indicated by the single trace and the 3
dB correction factor is not applied. Disable the trace averaging mode.
3) As illustrated in Figure 2, the two marker sidebands and perhaps some leakage of the suppressed
carrier at the center frequency will be visible on the spectrum. Use the peak search function to
measure the power level of one of the sidebands, they both should be equal, and add 3 dB to this
value for the total marker power.
In this example: 2.82 dBmV + 3 dB = 5.82 dBmV.
In the event a single sideband of the QAM
Marker is used to measure the marker power
level, subtract an extra 3 dB (in the calculation)
to account for the other sideband’s power. In
this example, the total marker power would be
2.82 dBmV + 3 dB = 5.82 dBmV (± 0.5 dB)

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4) If the spectrum has a selectable Sweep/FFT mode, the resolution bandwidth may be further reduced
by selecting the FFT mode. The result in Figure 3 is still at a 5 kHz span but at a RBW of 30Hz.
Important to note, the indicated level of 2.31 dBmV is less than measured at the previous RBW
setting. This is an artifact of the measuring process. More accurate results are obtained if the span is
set to a lower value thus increasing the number of data points used to represent the signal on the
screen, refer to Figure 4.
FFT mode is set using the Sweep function. If the sweep mode is set to ‘Auto’ this self-adjusts.
Figure 3
In this figure the accuracy of the marker measurement is affected by
the span setting (5 kHz) being set too wide. Additional resolution is
needed to accurately detect to the true peak. Reduce the Span
setting.

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5) In Figure 4, the marker frequency from the measurement above was transferred to the center
frequency of the spectrum analyzer and the span was decreased to 500 Hz. The measured level
increased by approximately 0.5 dB, to the expected level of 2.82 dBmV.
Note: Use the Peak Search function, then ‘To Center’ to move center frequency to marker point.
Figure 4
Section 5 - Modulation Error Ratio Measurements
The QAM Marker installation should be verified not to cause interference or signal degradation to the
adjacent channels in the system. A MER measurement should be performed on the adjacent QAM
channels with the QAM Marker turned on and off. The Marker can be turned off and on via the Web
interface.