General Instrument C6M-II User manual

C6M-II
Commander 6 Modulator
Installation Manual
®
ENT
20 80 87.5 95
520 25 30 50
REF OFF
VIDEO OFF
VIDEO B
AUX IF
PRGM IF
REMOTE
-20dB
TEST
RF OUT
VIDEO video modulation (%)
audio deviation (kHz)
C6M-II

Caution
These servicing instructions are for use by qualified personnel only. To reduce the risk of electrical shock, do not perform any servicing other
than that contained in the Installation and Troubleshooting Instructions unless you are qualified to do so. Refer all servicing to qualified service
personnel.
FCC Compliance
This equipment has been tested and found to comply with the limits for a Class A digital device, pursuant to Part 15 of the FCC Rules. These
limits are designed to provide reasonable protection against harmful interference when the equipment is operated in a commercial environment.
This equipment generates, uses, and can radiate radio frequency energy and, if not installed and used in accordance with the Installation Manual,
may cause harmful interference to radio communications. Operation of this equipment in a residential area is likely to cause harmful interference
in which case the user will be required to correct the interference at his own expense. Any changes or modifications not expressly approved by
General Instrument could void the user’s authority to operate this equipment under the rules and regulations of the FCC.
Canadian Compliance
This Class A digital apparatus meets all requirements of the Canadian Interference-Causing Equipment Regulations.
Cet appareil numérique de la classe A respects toutes les exigences du Règlement sur le matériel brouilleur du Canada.
Special Symbols That Might Appear on the Equipment
The symbol shown on the left, a reaching hand in a triangle with a slash through it, is intended to alert the user and
service personnel of the possibility of equipment damage or degradation of performance due to Electrostatic
Discharge (ESD) event.
The exclamation point, within an equilateral triangle, is intended to alert the user to the presence of important
installation, servicing, and operating instructions in the documents accompanying the equipment.
For continued protection against fire, replace all fuses only with fuses having the same electrical ratings marked at
the location of the fuse.
Copyright © 1997 by General Instrument Corporation.
All rights reserved.
No part of this publication may be reproduced in any form or by any means or used to make any derivative work (such as translation,
transformation or adaptation) without written permission from General Instrument.
General Instrument reserves the right to revise this publication and to make changes in content from time to time without obligation on the part of
General Instrument to provide notification of such revision or change.
General Instrument provides this guide without warranty of any kind, either implied or expressed, including, but not limited, to the implied
warranties of merchantability and fitness for a particular purpose. General Instrument may make improvements or changes in the product(s)
described in this manual at any time.
Commander 6 is a registered trademark of General Instrument Corporation.

Contents
Section 1 Introduction
Using This Manual ...................................................................................................... 1-2
Related Documentation .............................................................................................. 1-2
Document Conventions .............................................................................................. 1-2
If You Need Help .......................................................................................................... 1-3
Calling for Repairs ...................................................................................................... 1-3
Section 2 Overview
Options ........................................................................................................................ 2-1
C6M-II-MOB Kit ...................................................................................................... 2-2
C6-DC ..................................................................................................................... 2-2
C6-RC-II Kit ............................................................................................................ 2-2
C6M-II-SE Kit .......................................................................................................... 2-2
Model Conventions ..................................................................................................... 2-3
Front Panel Controls and Displays ............................................................................ 2-3
Rear Panel Connectors ............................................................................................... 2-5
The Menu System ........................................................................................................ 2-8
Using the Menus ..................................................................................................... 2-9
Changing a Menu Item ............................................................................................ 2-9
Main Menu .............................................................................................................. 2-10
Option Menu ........................................................................................................... 2-11
Video Menu ............................................................................................................. 2-13
Audio Menu ............................................................................................................. 2-13
Remote Menu ......................................................................................................... 2-14
Warning Messages ...................................................................................................... 2-15
Section 3 Installation
Before You Begin ........................................................................................................ 3-1
Mounting the Modulator ............................................................................................. 3-1
Checking the Operation .............................................................................................. 3-2
Switching Capabilities ................................................................................................ 3-3
Without the MOB Option Board ............................................................................... 3-3

ii Contents
With the MOB Option Board .................................................................................... 3-3
Automatic Gain Control ............................................................................................... 3-4
IF AGC .................................................................................................................... 3-4
Baseband AGC (Optional) ....................................................................................... 3-4
Audio Parameters ........................................................................................................ 3-5
Audio Impedance ..................................................................................................... 3-5
Audio Level .............................................................................................................. 3-5
Stereo Encoder (Optional) ....................................................................................... 3-5
Selecting the RF Channel Frequency Plan ................................................................. 3-5
Typical Interconnections ............................................................................................. 3-6
Basic Video and Audio Interfacing ............................................................................ 3-6
Satellite Link Connection .......................................................................................... 3-7
Satellite Link Connection with C6M-II-SE ................................................................. 3-8
Video Scrambling ..................................................................................................... 3-9
CW Output .............................................................................................................. 3-10
Stereo IF Interfacing ................................................................................................ 3-11
Composite Baseband Interfacing ............................................................................. 3-12
CMTS / MVP II / C6M-II Connections ...................................................................... 3-13
C6R-VCII / CMTS / MVP II / C6M-II Connections ..................................................... 3-14
Section 4 System Block Diagrams
Video to IF Modulation System ................................................................................... 4-1
Audio to IF Modulation System .................................................................................. 4-2
IF Switching and AGC System .................................................................................... 4-4
IF to Channel Converter System ................................................................................. 4-5
Appendix A Specifications
RF Output ..................................................................................................................... A-1
IF ................................................................................................................................... A-1
Video ............................................................................................................................ A-1
Audio ............................................................................................................................ A-2
General ......................................................................................................................... A-2
Appendix B Frequency Plan
Appendix C Changing a Menu Item
Appendix D Signal Priority Chart

Contents iii
Appendix E Application Notes
C6-LPF600 ................................................................................................................... E-1
Summary ................................................................................................................ E-1
Discussion .............................................................................................................. E-1
Specifications .......................................................................................................... E-2
Figures
Figure 1-1 Front and rear views of the C6M-II .............................................................. 1-1
Figure 2-1 C6M-II front panel ....................................................................................... 2-3
Figure 2-2 C6M-II rear panel with options installed ....................................................... 2-5
Figure 2-3 Menu relationships ...................................................................................... 2-8
Figure 3-1 Rack mounting ............................................................................................ 3-2
Figure 3-2 Operational check connections .................................................................... 3-3
Figure 3-3 Basic video/audio interfacing ....................................................................... 3-6
Figure 3-4 Satellite link connection ............................................................................... 3-7
Figure 3-5 Satellite link connection with stereo encoder................................................ 3-8
Figure 3-6 MVP II / C6M-II IF interfacing ...................................................................... 3-9
Figure 3-7 MVP II / C6M-II interfacing using the CW output .......................................... 3-10
Figure 3-8 C6M-II / CMTS IF interfacing ....................................................................... 3-11
Figure 3-9 External composite baseband connection.................................................... 3-12
Figure 3-10 C6M-II / MVP II / CMTS interfacing ............................................................. 3-13
Figure 3-11 C6R-VCII / CMTS / MVP II / C6M-II connections ......................................... 3-14
Figure 4-1 Video to IF modulation system .................................................................... 4-1
Figure 4-2 Audio to IF modulation system .................................................................... 4-2
Figure 4-3 IF switching and AGC system ..................................................................... 4-4
Figure 4-4 IF to channel converter system ................................................................... 4-5
Figure E-1 Typical installations of C6-LPF600 .............................................................. E-1
Tables
Table 2-1 Required revision levels .............................................................................. 2-1
Table 2-2 Description of controls and displays............................................................. 2-3
Table 2-3 Description of rear panel connections .......................................................... 2-6
Table 2-4 Description of Main menu items .................................................................. 2-10
Table 2-5 Description of Option menu items ................................................................ 2-11
Table 2-6 Description of Video menu items ................................................................. 2-13
Table 2-7 Description of Audio menu items ................................................................. 2-13
Table 2-8 Description of Remote menu items .............................................................. 2-14
Table 2-9 Description of flashing messages ................................................................ 2-15

C6M-II Installation Manual
Section 1
Introduction
The C6M-II is a state-of-the-art television signal modulator for the most demanding CATV
applications. The system is packaged in a space saving 1.75-inch high rack-mounted housing
and uses efficient switching power supply regulators to minimize power consumption and heat.
Features of the C6M-II include:
n 1 GHz tuning capability
n Frequency selection in 12.5 kHz steps or channel map
n Automatic source signal switching
n Front panel user-friendly interface keypad
n Easy to read LED display for system operational maintenance
n Remote monitoring and control option
n BTSC integrated stereo encoder option
n dc power option
Front and rear views of the C6M-II are shown below without any options.
Figure 1-1
Front and rear views of the C6M-II

1-2 Introduction
C6M-II Installation Manual
Using This Manual
This manual includes information and instructions required to install and operate the C6M-II.
Section 1 Introduction provides a brief description of the C6M-II, related documentation, the
helpline number and information about repair.
Section 2
Overview describes the C6M-II, identifies the front panel displays and controls,
describes the rear panel connectors, and explains the menu system.
Section 3
Installation provides instructions on how to install and operate the C6M-II.
Section 4
System Block Diagrams describes functions of the unit with block diagrams.
Appendix A
Specifications provides the technical specifications for the C6M-II.
Appendix B
Frequency Plan lists the Frequency Plan.
Appendix C
Changing a Menu Item illustrates how to change a menu item.
Appendix D
Signal Priority Chart provides the priority chart for IF.
Appendix E
Application Notes provides instructions for installing the C6-LPF600 (928-363-000)
or equivalent filter.
Related Documentation
The following documents describe equipment which can be used with the C6M-II:
n Modulating Video Processor Model MVP-II Installation Manual
n Satellite Receiver/Decoder Model C6R-VCII Installation Manual
n Stereo Encoder Model CMTS Installation Manual
Although these documents provide information that may be of interest to you, they are not
necessary to install or operate the C6M-II modulator.
Document Conventions
Before you begin using the C6M-II, familiarize yourself with the stylistic conventions used in
this manual:
SMALL CAPS Denotes silk screening on the equipment, typically representing front and rear-panel
controls, I/O connections and indicators (LEDs).
* (asterisk) Indicates that there are several versions of the same model number and the information
applies to all models. When the information applies to a specific model, the complete
model number is given.

Introduction 1-3
C6M-II Installation Manual
If You Need Help
If you need assistance while working with the C6M-II, call the General Instrument Technical
Response Center at 1-888-GEN-INST (1-888-436-4678). The Technical Response Center is
open from 8:00 a.m. to 9:00 p.m. Eastern Time, Monday through Friday. When the Technical
Response Center is closed, emergency service only is available on a call-back basis.
When contacting the Technical Response Center from outside the United States, please use our
main switchboard number, 1-215-674-4800, extension 4200.
Calling for Repairs
If repair is necessary, call the General Instrument Repair Facility at 1-800-227-0450 for a
Return for Service Authorization (RSA) number before sending the unit. The RSA number
must be prominently displayed on all equipment cartons. The Repair Facility is open from
8:00 a.m. to 5:00 p.m. Central Time, Monday through Friday.
If calling from outside the United States, dial your appropriate international access code, then
dial 52-891-40739, to contact the Repair Facility.
When shipping equipment for repair, follow these steps:
 Pack the unit securely.
 Enclose a note describing the exact problem.
 Enclose a copy of the invoice that verifies the warranty status.
 Ship the unit PRE-PAID to the following address:
GI Communications
2009 McKenzie Road
Suite 102
Carrollton, TX 75006
Attn: RSA #___________

C6M-II Installation Manual
Section 2
Overview
The C6M-II is a frequency agile modulator offering an output frequency range from 50 MHz to
1 GHz. All standard, HRC, IRC, and EIA frequencies are available either by keying in the
frequency or using the convenient channel maps.
The C6M-II provides local control by using a front panel user interface. This interface is a
menu system that provides easy access to operating parameters that are microprocessor
controlled for precision, accuracy, stability, and reliability.
Upon frequency or channel selection, the microprocessor automatically engages internal
bandpass filters, ensuring that a combined carrier-to-noise (c/n) ratio of greater than 60 dB is
always maintained with no external filtering required. The c/n performance is guaranteed in
multi-channel combined systems up to 149 channels with a typical performance of 63 dB c/n,
normalized to 4 MHz.
The precision frequency stability of the C6M-II meets the band frequency accuracy
requirements for the FCC. The FCC mandated frequency offsets of +12.5 kHz and +25 kHz are
generated automatically. The C6M-II also exceeds all FCC RF and baseband signal
performance requirements.
Options
The options available for the C6M-II are:
n Modulator Option Board, model C6M-II-MOB Kit
n DC Power Option Board, model C6-DC
n Remote Control Option Board, model C6-RC-II Kit
n Stereo Encoder Option Board, model C6M-II-SE Kit
The C6M-II must have a minimum firmware revision to install the options. The following table
provides the required revision level.
Table 2-1
Required revision levels
Option C6M-II Firmware Revision
C6M-II-MOB 2.0 or higher
C6-RC-II 1.0 or higher
C6M-II-SE 2.0 or higher
The firmware revision can be found using the Option menu. If the revision in not correct,
please contact General Instrument Technical Response Center for assistance.

2-2 Overview
C6M-II Installation Manual
C6M-II-MOB Kit
The C6M-II-MOB accessory module provides baseband audio and video switching, audio and
video AGC, a 4.5 MHz audio subcarrier input, and switched IF input capabilities. The video
switching system includes video A signal sensing to allow automatic switching to video B input
when the video A signal is absent. The audio A and audio B input selection is controlled by the
same circuitry as the video switch section, ensuring the audio input switching follows the video
selection automatically. A rear panel connection allows external control of the input source
switching.
Defeatable video and audio AGC is for applications involving baseband signal levels. Preset
modulation levels are maintained despite fluctuations in the audio/video input levels from the
source or resulting from switching between baseband sources.
An additional IF signal input labeled PROGRAM is identical to the AUX IF switching except
that it has a lower switching priority. The PRGM IF switch is used for program switching or
automatic program replacement when video A and/or video B are absent.
The MOB accessory also accepts the external 4.5 MHz input. The 4.5 MHz input is for audio
interfacing to the output of a stereo encoder, satellite receivers, or demodulator.
C6-DC
The dc power input option accepts a dc input in the range of −20 to −60 Vdc. This option, which
includes a dc-to-dc converter and a rear panel dc inlet, replaces the standard ac power input.
This option is only available from the factory.
C6-RC-II Kit
The C6-RC-II accessory module allows the modulator to be remotely control via a personal
computer. All front panel controls, operating parameters, and adjustments can be monitored
and changed from a remote location. This kit includes a remote control communications board
with an RS-485 type interface using RJ-12 connectors.
C6M-II-SE Kit
The C6M-II-SE is a stereo encoder option for generating stereo sound. It encodes baseband
audio based on BTSC standards, and employs dbx-TV noise reduction circuitry to ensure a
quality signal. This option does not have Second Audio Program (SAP). For SAP applications,
the CMTS should be used.