User`s Manual Operations Manual Standard Definition Messenger

Operations
Manual
User’s Manual
The most important thing we build is trust.
The most important thing we build is trust.
Standard Definition Messenger Transmitter
(SDMT-C)
(SDMT-S)
OPERATIONS MANUAL
OP1920606 Rev 1
13 Apr 2011
1 of 29
GMS Inc. doing business as Cobham Tactical Communications and Surveillance
Cobham Tactical Communications and Surveillance
1916 Palomar Oaks Way, Suite 100, Carlsbad, CA 92008
Tel: 760-496-0055
FAX: 760-496-0057
www.cobham.com/tcs
Table of Contents
1. Important Warning and General Safety Information .................................................................................................5 1.1 General ...........................................................................................................................................................................................................5 1.2 RF Emissions ................................................................................................................................................................................................5 2. Acronyms ....................................................................................................................................................................................................8 3. Introduction .............................................................................................................................................................................................9 3.1 About the Manual.....................................................................................................................................................................................9 3.2 Warranty .......................................................................................................................................................................................................9 3.3 Safe Operating Procedures ..................................................................................................................................................................9 4. General System Information .....................................................................................................................................................10 4.1 Overview ....................................................................................................................................................................................................10 4.2 Key System Features............................................................................................................................................................................10 4.3 Theory of Operation ............................................................................................................................................................................10 5. Initial Checkout ..................................................................................................................................................................................12 5.1 Included Items ........................................................................................................................................................................................12 5.2 Getting Started .......................................................................................................................................................................................12 6. Hardware Overview ...........................................................................................................................................................................14 6.1 : SDMT-C ....................................................................................................................................................................................................14 6.1.1 SDMT-C Connectors ...................................................................................................................................................................14 6.1.2 Frequency Select Switches ......................................................................................................................................................16 6.2 SDMT-S Connectors.............................................................................................................................................................................18 6.2.1 SDMT-S Connectors....................................................................................................................................................................18 6.2.2 Frequency Select Switches ......................................................................................................................................................19 6.3 Inline Camera Unit (Optional) .........................................................................................................................................................19 6.3.1 SDMT Inline Camera Mount Connectors .........................................................................................................................19 7. Software Overview (if not extracted to another document) ..............................................................................21 8. Specifications .......................................................................................................................................................................................22 8.1 Video Encoding ......................................................................................................................................................................................22 8.2 Audio Encoding ......................................................................................................................................................................................22 8.3 Transport Stream ...................................................................................................................................................................................22 8.4 RS-232 Interfaces/RCU/USB ............................................................................................................................................................23 8.5 COFDM RF Output.................................................................................................................................................................................23 8.6 Modulation ...............................................................................................................................................................................................23 8.7 Power ...........................................................................................................................................................................................................23 8.8 Physical Dimensions (without mating connectors)...............................................................................................................23 8.9 Environmental .........................................................................................................................................................................................24 9. D/C (Down Converter) IF frequencies explained ........................................................................................................25 9.1 IF Frequencies .........................................................................................................................................................................................25 OP1920606 Rev 1
GMS Inc. doing business as Cobham Tactical Communications and Surveillance
2 of 29
www.cobham.com/tcs
9.2 Local and Remote Power for Down Converters ......................................................................................................................25 9.2.1 Remote Power ................................................................................................................................................................................25 9.2.2 Local Power .....................................................................................................................................................................................25 10. Cable Losses ........................................................................................................................................................................................27 10.1 Coax Cable .............................................................................................................................................................................................27 List of Tables
Table 1 – Safe Distances ..................................................................................................................................................................................... 6 Table 2 – I/O DB-44 Connector Pin Out................................................................................................................................................... 15 Table 3 – I/O DB-15 Connector Pin Out................................................................................................................................................... 20 Table 4 - DB-9 Connector Pin Out for the D/C...................................................................................................................................... 26 List of Figures
Figure 1 – Basic SDML Setup ......................................................................................................................................................................... 12 Figure 2 – SDMT-C Connectors.................................................................................................................................................................... 14 Figure 3 – Frequency Select Switches at 2014 MHz ......................................................................................................................... 17 Figure 4 - Frequency Select Switches at 924 MHz ............................................................................................................................. 17 Figure 5 – SDMT-S Connectors .................................................................................................................................................................... 18 Figure 6 – SDMT Inline Camera Unit ......................................................................................................................................................... 19 Figure 7– BDC Connectors ............................................................................................................................................................................. 26 List of Appendices
Appendix A - Bibliography ................................................................................................................................................................28 Appendix B - Cable, M2T External Breakout Cable .........................................................................................................29 OP1920606 Rev 1
GMS Inc. doing business as Cobham Tactical Communications and Surveillance
3 of 29
www.cobham.com/tcs
Revision History
Edited
by
Revision
Date
X2E
15 Jul
2010
Added note:- when scrambling mode is changed transmitter will reboot
X3
5 Apr
2011
Added FCC warnings; extracted Status & Control Software into 100M0168X1; updated Cobham branding
DRF
13 Apr
2011
Initial Release conversion of 100-M0065X3
DRF
1
Main Changes from Previous version
JC
OP1920606 Rev 1
GMS Inc. doing business as Cobham Tactical Communications and Surveillance
4 of 29
www.cobham.com/tcs
1. Important Warning and General Safety Information
1.1 General
The following information is presented to the operator to ensure awareness of potential harmful RF
(radio frequency) exposure and general hazards. With regards to potential harmful RF electromagnetic
fields the text below is only a brief summary highlighting the possible risks and how to minimize
exposure. The summary is based on OET Bulletin 65 “Evaluating Compliance with FCC Guidelines for
Human Exposure to Radiofrequency Electromagnetic Fields” (1). The user should carefully read and
comprehend the following before operating the equipment and for additional in depth information
refer to OET Bulletin 65.
1.2 RF Emissions
The FCC has set guidelines (Cleveland, Jr., Sylvar, & Ulcek, 1997) for evaluating exposure to RF
emissions that the user must be aware of when operating Cobham’s’ SDMT microwave transmitter. The
maximum power density allowed at 1500-7000 MHZ is 5mW/cm2 for occupational/controlled
exposure1 and 1mW/cm2 for general population/uncontrolled exposure2. These are the limits for
maximum permissible exposure (MPE) as called out in the FCC guidelines (for the above mentioned
frequencies).
1
“Occupational /controlled exposure limits apply to situations in which persons are exposed as a
consequence of their employment and in which those persons who are exposed have been made fully
aware of the potential for exposure and can exercise control over their exposure.
Occupational/controlled exposure limits also apply where exposure is of a transient nature as a result of
incidental passage through a location where exposure levels may be above general
population/uncontrolled limits (see below), as long as the exposed person has been made fully aware of
the potential for exposure and can exercise control over his or her exposure by leaving the area or by
some other appropriate means. …….”
2
“General population/uncontrolled exposure limits apply to situations in which the general public may
be exposed or in which persons who are exposed as a consequence of their employment may not be
made fully aware of the potential for exposure or cannot exercise control over their exposure.
Therefore, members of the general public would always be considered under this category when
exposure is not employment-related, for example, in the case of a telecommunications tower that
exposes persons in a nearby residential area.”
OP1920606 Rev 1
GMS Inc. doing business as Cobham Tactical Communications and Surveillance
5 of 29
www.cobham.com/tcs
Exposure is based on upon the average time spent within the RF field with a given intensity (field units
in mW/cm2). Hence it may be controlled (or at least minimized) by observing the safe distances and
time exposed as shown in Table 1. These safe distances are calculated from equations predicting RF
Fields3 with the following assumptions:
•
The transmitter maximum power is 23dBm (200 mW)
•
The antenna used has a 2dBi gain
•
The transmitter is used in a fixed location
The user (and bystanders) should remain beyond the distances from the antenna at all times as stated
in Table 1 when the transmitter is operating for no longer than the time periods indicated (keeping in
mind this is the average time).
If any of the above variables change, such as a higher gain antenna, less or more power output from the
transmitter, additional transmitters used, etc. then the safe distances would need to be recalculated.
The user can either refer to the equations predicting RF Fields as noted in the above section or call
contact Cobham for advice.
Table 1 – Safe Distances
RF Frequency
(MHz)
Occupational
controlled exposure
Limit
(mW/cm2)
Safe
Distance
(cm)
1000 to 1500
3.3
2.8
1500 to 7000
5
2.2
General population
uncontrolled exposure
Average
Time
(min)
6
SDMT Transmitter Power = 0.2W (+23 dBm)
Limit
(mW/cm2)
Safe
Distance
(cm)
0.67
6.2
1
5
Average
Time
(Min)
30
Antenna Gain = +2dbi
The transmitter, which can be operated in fixed or mobile applications, is rated at 0.2W (+23dBm) RF
power and is capable of harmful radiation if safe operating practices are not observed (see sections
above).
It should be noted that this device is an intentional radiator, hence:
Changes or modifications not expressly approved by the party responsible for
compliance could void the user’s authority to operate the equipment.
3
4
where:
S = power density (in appropriate units, e.g. mW/cm2)
P = power input to the antenna (in appropriate units, e.g., mW)
G = power gain of the antenna in the direction of interest relative to an isotropic radiator
R = distance to the center of radiation of the antenna (appropriate units, e.g., cm)
OP1920606 Rev 1
GMS Inc. doing business as Cobham Tactical Communications and Surveillance
6 of 29
www.cobham.com/tcs
NOTE: The manufacturer is not responsible for any radio or TV interference caused
by unauthorized modifications to this equipment. Such modifications could void
the user’s authority to operate the equipment.
Do not substitute any antenna for the one supplied or recommended by the manufacturer. The installer
is responsible for ensuring that the proper antenna is installed.
Antenna minimum safe operating distances should be observed as stated in section 2 above. It is the
responsibility of the qualified end-user of this intentional radiator to control the safe distances and
exposure limits to bystanders.
DC power (+12VDC) to the unit should never be applied until the antenna (or other suitable load) has
been attached to the device SMA RF output connector. Safe operating procedures must be observed
when unit is transmitting into an antenna (see sections above).
OP1920606 Rev 1
GMS Inc. doing business as Cobham Tactical Communications and Surveillance
7 of 29
www.cobham.com/tcs
2. Acronyms
This section lists and describes the various acronyms used in this document.
Name
Meaning
16 QAM
64 QAM
A/V
AES
ASI
BDC or BDCC
COFDM
CVBS/Y
C
D/C
FEC
GUI
HD
I/O
Kbaud
Kbps
Mbps
MER
MPEG
MSR
M2D
M2T
M2L
NTSC
PAL
QPSK
RF
RX
S/N
THD
SD
SDI
TX
VDC
16-state Quadrature Amplitude Modulation
64-state Quadrature Amplitude Modulation
Audio/Video
Advanced Encryption System (32 bit)
Asynchronous Serial Interface
Block down converter
Coded Orthogonal Frequency Division Multiplexing
Composite video/Luminance with S-video
Chroma video
Down-Converter
Forward Error Correction
Graphical User Interface
High Definition
Input/ Output
Kilobaud per second
Kilobits per second
Megabits per second
Modulation Error Rate
Moving Picture Experts Group
Messenger Smart Receiver
Messenger Two Decoder
Messenger Two Transmitter
Messenger Two Link
National Television System Committee
Phase Alternation Line
Quadrature Phase Shift Keying
Radio Frequency
Receiver
Signal-to-Noise Ratio
Total Harmonic Distortion
Standard Definition
Serial Digital Interface
Transmitter
Volts (Direct Current)
OP1920606 Rev 1
GMS Inc. doing business as Cobham Tactical Communications and Surveillance
8 of 29
www.cobham.com/tcs
3. Introduction
3.1 About the Manual
Cobham User Manuals focus on providing the end user an easy to understand operational instructions
to quickly setup and deploy the equipment. The Cobham Technical Operation Manuals focus on the
technical details and setup of the equipment. The Technical Manuals also provide a more in depth
explanation of the settings and specifications of the equipment that technicians can use to verify the
operational status.
3.2 Warranty
Cobham offers a 12 month standard product warranty. During this period, should the customer
encounter a fault with the equipment we recommend the following course of action:

Check the support section of the website for information on that product and any
software/firmware upgrades.

If fault persists call our support line and report the fault. If fault persists and you are informed to
return the product, please obtain an RMA number from the Cobham support department or
website and ship the equipment with the RMA number displayed and a description of the fault.
Please email the support section the airway bill/consignment number for tracking purposes.
Depending on the nature of the fault, Cobham endeavor to repair the equipment and return it to the
customer within 14 days of the item arriving at our workshops. Obviously it is impossible to cater for all
types of faults and to manage 100% replacement part availability, and delays are sometimes inevitable.
Please contact Cobham for details of packages that can be tailored to meet your individual needs,
whether they are service availability, technical training, local geographic support or dedicated spares
holdings.
3.3 Safe Operating Procedures

Ensure that the power supply arrangements are adequate to meet the requirements of VETA
product.

Operate within the environmental limits specified for the product. The transmitter will generate
considerable heat and it is the responsibility of the end user to properly heat sink the device
before using.

Electro-Static Discharge (ESD) precautions should be observed as a safe practice.

Only authorized, trained personnel should open the product. There are no functions that
required the User to gain access to the interior of the product.
OP1920606 Rev 1
GMS Inc. doing business as Cobham Tactical Communications and Surveillance
9 of 29
www.cobham.com/tcs
4. General System Information
4.1 Overview
Cobham’s Standard Definition Messenger Transmitter (SDMT-C) is one of the smallest and lowest
power consumption DVD-T (Digital Video Broadcasting-Terrestrial) compliant COFDM (Coded
Orthogonal Frequency Division Multiplexed) transmitter available. There are three SDMT models; the
SDMT-C supports standard analog video and audio signals, the SDMT-S which adds an SDI interface,
and the SDMT-A. The SMDT-A supports ASI Transport Stream inputs only. Note that the MPEG
Encoder is removed on this model. These transmitters may be supplied as standalone products or may
be configured in an optional Camera Box that is compatible with most professional cameras.
Additionally, Cobham offers a wide variety of companion products required to form a complete link.
A Standard Definition Messenger Link (SDML) is formed when one of the SDMT models is combined
with one of Cobham’s Messenger Digital Receivers, one or two external Down-Converters, antennas,
and a SD MPEG-2 decoder. The SDML uses a robust digital modulation system known as Coded
Orthogonal Frequency Division Multiplexed (COFDM) that provides frequency diversity and powerful
Forward Error Correction (FEC) algorithms. The SDML provides a robust wireless link that is effective
against the multi-path interference experienced by analog systems, and provides crisp, clear pictures in
the most difficult of terrains.
Additionally, the SDMT/DDR (Standard Definition Messenger Transmitter and Digital Diversity Receiver)
combination in SP@ML mode can provide an end-to-end latency down to approx. 198ms without the
introduction of any further MPEG encoding artifacts. This ensures that the picture you see is what is
happening now – crucial for applications such as sports coverage, surveillance, and law enforcement,
where personnel are reacting to real-time events.
This manual provides information on how to operate each of the SDMT models as well as pertinent
technical information related to the overall system. Also, refer to model identifier (on-line document),
at Cobham’s website, http://www.cobham.com/tcs, for available frequency and power configurations
along with available options.
4.2 Key System Features







Component, S-Video & Composite with Optional SDI/ASI or ASI Only Interfaces
Built in 4:2:0 MPEG-2 Video Encoder and MPEG-1 Layer II Audio Encoder
Coded Orthogonal Frequency Division Multiplexed (COFDM) Modulation
Output Frequency 0.36 to 6 GHz (In-Bands)
Low Power Consumption
Local and Remote Control Interfaces
Rugged and Compact Portable Design
4.3 Theory of Operation
The SDMT accepts Composite, S-Video, Component video, SDI/ASI (optional) as well as up to two audio
channels (Microphone or line level). The video and audio are compressed (ASI data streams are passed
through bypassing the MPEG encoder) according to MPEG specifications (Video MPEG-2 and Audio MPEG1 layer II). The MPEG-2 supports 4:2:0 Chroma sampling, MP@ML and SP@ML profiles and maintains the
OP1920606 Rev 1
GMS Inc. doing business as Cobham Tactical Communications and Surveillance
10 of 29
www.cobham.com/tcs
original signal’s video fidelity. The audio and video program element streams are multiplexed with basic
service data to indicate the service name into a DVB compliant Transport Stream (TS).
The TS stream is then sent through a DVB-T compliant FEC encoder and COFDM modulator. This is output
from the FPGA based modulator core as digital I/Q signals that are converted to Analog I/Q signals and
applied to an I/Q Modulator. The LO that provides the carrier to this I/Q modulator comes from a low
phase-noise programmable synthesizer. The modulated RF output of the I/Q modulator IC is sent through
amplifier chain and ultimately output to the outside world. Programmable attenuators in the RF processing
chain provide signal leveling.
The transmitter is microprocessor controlled. Normally the transmitter is controlled either through an RS232 or USB interface via either GMS’ MS Windows control SW or a simple command line interface. Local
Frequency control is also available via rotary switches on the side of the housing.
OP1920606 Rev 1
GMS Inc. doing business as Cobham Tactical Communications and Surveillance
11 of 29
www.cobham.com/tcs
5. Initial Checkout
5.1 Included Items
The standard SDMT kit includes the following items:

SDMT unit (example Cobham part number SDMTCCBA0NXXX)

SDMT full breakout cable (Cobham
interfaces)
part number 4009004) (Power, A/V, Data, Control
NOTE: Based on customer application Cobham may deliver a receiving system, additional cables and
antennas. Contact Cobham for further information.
The device is pre-configured by Cobham prior to shipment (based on customer requirements), thus is
ready to work “right out of the box”.
5.2 Getting Started
Prior to installing a SDMT unit into the desired target environment, an initial checkout should be
performed to ensure proper operation of the unit. The initial checkout consists of configuring a basic
SDML (Standard Definition Messenger Link).
Figure 1 – Basic SDML Setup
Figure 1 shows a basic interconnection configuration to establish a wireless SDML (NOTE: Receivers,
down converters (D/C) units and their associated hardware are sold separately). As mentioned in
OP1920606 Rev 1
GMS Inc. doing business as Cobham Tactical Communications and Surveillance
12 of 29
www.cobham.com/tcs
section 6 the SDMT may be shipped as a stand-alone unit or mounted in an Inline Camera Mount box.
SDMT stand-alone units require the use of Cobham’s breakout cable to provide power and the
necessary interfacing to communicate to the transmitter. The Inline Camera Mount boxes require a
+12 battery and most of the necessary communications can be done through the LCD front panel. The
steps necessary to set up the configuration shown in Figure 1 are shown below; the differences
between the Inline Camera Mount box and stand-alone unit are noted where applicable.
OP1920606 Rev 1
GMS Inc. doing business as Cobham Tactical Communications and Surveillance
13 of 29
www.cobham.com/tcs
6. Hardware Overview
There are two basic transmitter configurations for the SDMT:

The SDMT-C which accepts Composite, S-Video and Component Video,

The SDMT-S which accepts Composite, S-Video, Component Video, SDI and ASI inputs
In addition all two configurations of the SDMT can be mounted in an inline professional camera unit (this
is an optional enclosure for mounting the SDMT for professional camera applications). The hardware for
each configuration is shown below:
6.1 : SDMT-C
“RF-OUT”
SMA
Connector
DB-44
Connector
(I/O and
Power)
Frequency
Select
Switches
SW100
Figure 2 – SDMT-C Connectors
6.1.1 SDMT-C Connectors
6.1.1.1 RF Output
The SDMT uses a female SMA bulkhead connector for its ‘RF Output’ port.
Note: Transmitters should not be powered on without a RF load. Doing so could
cause the output power amplifier to stop working. A proper heat sink is also
required.
6.1.1.2 Input / Output (I/O)
The I/O connector is a male, high-density DB-44. It provides the interface for external power,
audio, analog video, USB, and RS-232 signals. The SDMT has a separate RS232 channel (labeled
“Control” on the external breakout cable) for control and monitoring the unit. Cobham’s SDMT
Status & Control software program (as explained in section 6.3.1.3) makes use of the RS232
OP1920606 Rev 1
GMS Inc. doing business as Cobham Tactical Communications and Surveillance
14 of 29
www.cobham.com/tcs
control lines. The RS-232 channel utilizes a 3-wire configuration. The pin out for the I/O
connector is shown in Table 2
NOTE: An additional RS232 channel (labeled “USER DATA”) is currently provided with the
external breakout cable. The “USER Data” RS232 channel is dedicated for low-rate data to be
transmitted along with the audio and video.
The USB connector is an alternate method of interfacing to the PC if DB-9 connectors are not
available..
Table 2 – I/O DB-44 Connector Pin Out
Pin
Signal
Notes
1
RS232 Data Tx
2
RS232 Data Rx
3
RS232 GND
4
Not connected
5
SDA
I^2 C bus
6
SCL
I^2 C bus
7
CVBS/Y
Dual use input.
1. Composite video in;
2. Luminance in (when used with S or Component Video).
Must be selected with Cobham’s Status & Control Software or
through the front panel of the in-line camera mount box
8
GND
GND for composite video
9
C/Pr
Dual use input.
1. Chroma video (when used with S-video);
2. Pr (red component when used with Component Video).
Must be selected with Cobham’s Status & Control Software or
through the front panel of the in-line camera mount box.
10
GND
GND for Chroma video/Pr component
11
Pb
Blue component when used with Component Video.
12
GND
GND for Pb component
13
GND
GND
14
11-15Vdc
Input power to unit
15
Not connected
OP1920606 Rev 1
GMS Inc. doing business as Cobham Tactical Communications and Surveillance
15 of 29
www.cobham.com/tcs
Pin
Signal
Notes
16
USB power, Reset
+5V
17
USB Data -
18
USB Data +
19
USB GND
20-29
Not connected
30
PA Shut Down
31
RS232 Control Tx
32
RS232 Control-Rx
33
34-36
RS232 GND
Not connected
37
38
Audio right +
Audio right -
39
Audio right line opt.
40
41
42
Audio right GND
Audio left +
Audio left -
43
Audio left line opt
44
Audio left GND
Provides a TTL signal [+3V} to enable an external PA.
Pin 39 is connected to pin 38 for audio right channel input
impedance of 600 ohms, balance in (microphone or line level)
Pin 43 is connected to pin 42 for audio left channel input
impedance of 600 ohms; balance in (microphone or line level).
6.1.2 Frequency Select Switches
There are four external rotary switches mounted into the chassis of the SDMT (see Figure 2 &
Figure 5). They are used to control RF frequency selection manually. Frequency selection can also
be controlled through Cobham status & control software; see section 6.3.1.3. The rotary switches
can be disabled or enabled using Cobham status & control software. The most significant switch
(SW100) represents 1000 MHz (0-9) units, the second switch (SW101) represents 100 MHz (0-9)
units, the third switch (SW102) represents 10 MHz (0-9) units and the fourth switch (SW103)
represents 1 MHz (0-9) units. Therefore, the highest switch selection is 9999 MHz and the lowest is
0000 MHz.
For example with the switches in the positions shown in Figure 3, the frequency will read 2014
MHz:
OP1920606 Rev 1
GMS Inc. doing business as Cobham Tactical Communications and Surveillance
16 of 29
www.cobham.com/tcs
SW100
9 0 1
8
7
6 5
2
3
4
9 0 1
8
7
6 5
0
2
2
3
4
9 0 1
8
7
6 5
1
2
3
4
9 0 1
8
7
6 5
4
2
3
4
Figure 3 – Frequency Select Switches at 2014 MHz
And with the switches in the positions shown in Figure 4, the frequency will read 924 MHz.
SW100
9 0 1
8
7
6 5
0
2
3
4
9 0 1
8
7
6 5
9
2
3
4
9 0 1
8
7
6 5
2
2
3
4
9 0 1
8
7
6 5
4
2
3
4
Figure 4 - Frequency Select Switches at 924 MHz
Note the following: if the switches are positioned for a frequency above the range of the
frequency band of the SDMT; the transmitter will default to the high side of the frequency band. If
the switches are set for a frequency lower than the transmitter frequency band, it will default to the
low side of the frequency band.
OP1920606 Rev 1
GMS Inc. doing business as Cobham Tactical Communications and Surveillance
17 of 29
www.cobham.com/tcs
6.2 SDMT-S Connectors
“RF-OUT”
SMA
Connector
“SDI/ASI
Input” BNC
Connector
Frequency
Select
Switches
DB-44
Connector
(I/O and
Power)
SW100
Figure 5 – SDMT-S Connectors
6.2.1 SDMT-S Connectors
6.2.1.1 RF Ouptut
The SDMT uses a female SMA bulkhead connector for its ‘RF Output’ port.
Note: Transmitters should not be powered on without a RF load. Doing so could
cause the output power amplifier to stop working. A proper heat sink is also
required.
6.2.1.2 Input / Output (I/O)
The I/O connector for the SDMT-S is the same as for the SDMT-C. Refer to section 6.1.1.2 and
Table 2.
6.2.1.3 SDI/ASI BNC Input Connector
The BNC connector is provided for inserting SDI (Serial Data Interface) and ASI (Asynchronous
Serial Interface) data. The SDMT-S can accept either SDI or ASI. The selection for which input
data stream is accepted is made through the Cobham Status & Control software.
OP1920606 Rev 1
GMS Inc. doing business as Cobham Tactical Communications and Surveillance
18 of 29
www.cobham.com/tcs
6.2.2 Frequency Select Switches
The frequency select switches are the same as the SDMT-C. See section 6.1.2 above for the
operational description.
6.3 Inline Camera Unit (Optional)
Figure 6 – SDMT Inline Camera Unit
6.3.1 SDMT Inline Camera Mount Connectors
There are four BNC connectors, two audio XLR, one DB-15 connector, one N type connector and
one rocker on/off power switch located on the SDMT inline camera unit for interfacing the RF,
audio, video, power and RS-232 signals. An optional LCD control front panel is also available. Inline
camera mount is shown in Figure 6.
6.3.1.1 RF Output
The SDMT in line camera enclosure uses a female N type connector (flange mount) for its ‘RF
Output’ port.
Note: Transmitters should not be powered on without a RF load. Doing so could
cause the output power amplifier to stop working. A proper heat sink is also
required.
6.3.1.2 Input / Output (I/O)
The ‘I/O’ connector is a female, DB-15. It is used to provide the interface for RS-232 signals
(control and monitoring). Cobham’s SDMT Status & Control software program makes use of the
RS232 control lines, pins 2, 3 and 5 of the DB-15 connector. The RS-232 channel utilizes a 3wire configuration. The pin out for I/O connector is shown in Table 3. A USB connection is also
provided if RS232 port is not available.
OP1920606 Rev 1
GMS Inc. doing business as Cobham Tactical Communications and Surveillance
19 of 29
www.cobham.com/tcs
Table 3 – I/O DB-15 Connector Pin Out
Pin
Signal
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
+12Vdc
RS232-Rx (CTRL)
RS232-Tx (CTRL)
Not connected
RS232-GND
I^2C_D
I^2C_C
USB Reset
USB Data USB Data +
USB GND
Not connected
RS232-Tx (DATA)
RS232-Rx (DATA)
RS232-GND
Notes
Relative to SDMT (i.e., control data is input on this pin)
Relative to SDMT (i.e., control data is output on this pin)
Common ground for both RS232 Data and Control lines
+5V
6.3.1.3 Video Input
The SDMT in-line camera enclosure uses female BNC connectors for video input. Component,
Composite or S-Video input is accepted. J3 BNC connector marked “Y/COMP” is a dual use input
connector; a) Composite Video or b) Luminance when used with Component video. J2 BNC
connector marked “C/Pr” is a dual use input connector; a) Chroma when used with S-Video or b)
Pr, the red component minus the luminance information used with Component Video. J8 BNC
connector marked “Pb” is the blue component minus the luminance information used with
Component Video. These video inputs are applicable to the SDMT-C and SDMT-S units.
6.3.1.4 Power Switch
An LED indicator rocker switch is provided for controlling power to the unit.
6.3.1.5 LCD Display
An optional LCD display with a front control panel is available for the inline camera mount unit.
Many of the control functions normally handled through the PC software interface can now be
accessed directly with the front control panel. The LCD can perform such functions as changing
frequencies, checking video lock status among many others.
6.3.1.6 SDI/ASI Input (optional)
A BNC connector is provided for Serial Digital Interface or Asynchronous Digital Interface input
data streams. This input is only applicable to the SDMT-S unit.
OP1920606 Rev 1
GMS Inc. doing business as Cobham Tactical Communications and Surveillance
20 of 29
www.cobham.com/tcs
7. Software Overview (if not extracted to another document)
Configuration, control and monitoring of the SDMT units are done by using Cobham’s’ MS Windowsbased SDMT Status & Control software program (8970908). This Graphical User Interface (GUI) program
provides the end user with a straightforward way to interface with the SDMT unit. During normal
operation, once a link is established, the SDMT GUI does not need to be active and can be disconnected
from the SDMT unit.
Refer to the Software Manual for further information.
OP1920606 Rev 1
GMS Inc. doing business as Cobham Tactical Communications and Surveillance
21 of 29
www.cobham.com/tcs
8. Specifications
The following sections outline the overall specifications for the SDMT unit.
8.1 Video Encoding
Interfaces: SDI (optional), Component, Composite or S-Video Input
Standards: NTSC or PAL
Compression Standard: MPEG-2 (per ISO/IEC 13818-2)
Profiles: MP@ML, SP@ML
Video Bit Rate: 3.7 Mbps to 15 Mbps (MP@ML)
Chrominance Profile: 4:2:0
Line Standard: 525 or 625
Horizontal Resolution: 704 pixels
Vertical Resolution: 576 (625 line) and 480 (525 line)
System Latency end to end delay: 198 mS with SDMT/DDR combination in SP@ML mode.
8.2 Audio Encoding
Analog Audio: Dual, Line-Level or Mic-Level, Differential or Single-Ended, Clip Level 12 dBm
Impedance: 600 Ohms input impedance (changeable to 2K Ohms)
Compression Standard: MPEG layer II
Audio Enable: On or Off
Bit Rates: 256 Kbit/s/ch
Sampling Frequency: 32 kHz, 44.1 kHz or 48 kHz
THD: < 0.1% maximum
Response: 20 Hz to 12 kHz, +/- 0.25dB
Crosstalk: >55 dB minimum
S/N: >60 dB RMS
8.3 Transport Stream
Standard: per ISO/IEC 13818-1
Packet Size: 188 byte
Bit Rate: Automatically set from active service settings.
ASI Input (optional): Allows MPEG2 transport stream to be inserted into the SDMT-A and
SDMT-S units through the BNC connector
OP1920606 Rev 1
GMS Inc. doing business as Cobham Tactical Communications and Surveillance
22 of 29
www.cobham.com/tcs
8.4 RS-232 Interfaces/RCU/USB
Control Port: 3-wire interface (Tx,Rx,Gnd)
USB 1.0
RCU A remote portable control unit is also available
In addition a “Data” RS232 channel is available dedicated for low-rate data to be transmitted along with
the audio and video.
8.5 COFDM RF Output
Output Frequency: 0.36 to 6 GHz (In-Bands).
Frequency step size is 500 KHz for all bands except S2 (1999-2500MHz) which is 250 KHz.
Bandwidth: Selectable 6, 7 or 8 MHz
Output Power: Up to100mW (programmable) [200mW on some models]
Connector: SMA-F
Note: Transmitters should not be powered on without a load. Doing so could cause the
output PA to stop working. A proper heat sink is also required.
8.6 Modulation
Modulation Type: COFDM w/ QPSK, 16 QAM (64 QAM available with SDMT-S and SDMT-A units
when ASI input is selected).
FEC: ½, 2/3, ¾, 7/8 (not all available, SDMT configuration type dependent)
Guard Intervals: 1/32, 1/16, 1/8, ¼ (not all available, SDMT configuration type dependent)
Spurious: 50dBc
Number of COFDM Carriers: 2k
COFDM MER: > -45dB
Standard: DVB-T compliant
8.7 Power
DC Input Voltage Range: 9 to 15 VDC
Power Consumption: 8.5 Watts to 10.8watts (SDMT configuration type dependent)
8.8 Physical Dimensions (without mating connectors)
SDMT-C unit
Size: 3.25 in. (W) x 4.5 in. (D) x 1.00 in. (H)
(8.26 cm x 11.43cm x 2.54cm)
Weight: 10.69 oz.
(303.1 grams)
OP1920606 Rev 1
GMS Inc. doing business as Cobham Tactical Communications and Surveillance
23 of 29
www.cobham.com/tcs
SDMT-S/A units
Size: 3.25 in. (W) x 4.5 in. (D) x 1.76 in. (H)
(8.26 cm x 11.43cm x 4.47cm)
Weight: 13.4 oz.
(379.9grams)
8.9 Environmental
Operational Temperature: -10 to +70 C
Humidity: Up to 100% (non-condensing)
OP1920606 Rev 1
GMS Inc. doing business as Cobham Tactical Communications and Surveillance
24 of 29
www.cobham.com/tcs
9. D/C (Down Converter) IF frequencies explained
9.1 IF Frequencies
MSR receivers (and many other digital receivers) are capable of receiving direct frequencies in the
range of approximately 49 MHz to 861 MHz. If the transmitter is not in this range then a downconverter (also refer to a BDC, block down converter) is used to convert the frequency to this range.
The frequency out of the down-converter is called the IF (intermediate frequency) which is fed to the
receiver.
Down-converters have a LO (local oscillator) which is mixed with the transmitter frequency (M2T) and
converts it to the IF frequency. MSR receivers need to know the LO (local oscillator) of the downconverter and the RF frequency of the transmitter. It then automatically calculates the IF frequency.
The IF frequency changes as the RF frequency changes. However, the LO remains constant.
On non-GMS receivers it may be necessary to program the receiver with the IF frequency directly. The
user may have to do the simple math to arrive at the IF frequency so that it can be entered into the
receiver. The down-converter LO must be known. The math involve is as follows: “LO – transmitter
frequency (or transmitter frequency – LO) = IF frequency”. For example, it the transmitter is set for
2000 MHz and the LO of the down-converter is 2800 MHz then the IF frequency is 800 MHz (28002000 = 800). The receiver will need to be set to 800 MHz to receive the transmitter frequency of 2000
MHz. Each time the transmitter frequency is changed the IF must be re-calculated and entered into the
receiver. It must also be mentioned, as you may have noticed with the equation “LO-transmitter
frequency or transmitter frequency – LO” that two answers are possible. For example 2800-2000 = 800
or 2000-2800 = -800. The negative answer may indicate the receiver wants the signal to be inverted.
9.2 Local and Remote Power for Down Converters
Customers have the option of using remote or local power.
9.2.1 Remote Power
Remote power is provided from the MSR through the BNC connector from each of the tuners
located on the rear panel. Power is turned on through the software control application (refer to the
MSR online manual). The +12Vdc provided from the receiver will travel through the coax cable to
the D/C.
If the D/C is located relatively close to the receiver then using remote power makes sense.
However, if the D/C is located at great distances away from the receiver there may be excessive DC
voltage drop in the coax cable (due to cable resistances). If this is the case then local DC power
should be considered as discussed below. If unsure of the DC voltage drop measure the DC voltage
present (using a DMM) at the end of the coax cable run; the D/C normal operating voltage is
approximately +12Vdc but can operate down to +10Vdc.
9.2.2 Local Power
Local power is provided by applying +12Vdc to pin 1, GND to pin 3 of the DB-9 connector located
on the bottom of the D/C. The +12 Volt power supply must be able to source at least 500mA. The
power switch (located on the side of the D/C) enables the user to control the ‘ON’/’OFF’ positions
for local power. If using local power then the remote power should be set to “OFF”.
OP1920606 Rev 1
GMS Inc. doing business as Cobham Tactical Communications and Surveillance
25 of 29
www.cobham.com/tcs
Figure 7– BDC Connectors
Table 4 - DB-9 Connector Pin Out for the D/C
Pin
1
3
2, 4-9
Signal
Notes
Power supply must be able to source at least
+12Vdc
500mA. Voltage should not drop below +10Vdc.
Power ground
GND
Not Connected
NC
OP1920606 Rev 1
GMS Inc. doing business as Cobham Tactical Communications and Surveillance
26 of 29
www.cobham.com/tcs
10. Cable Losses
10.1 Coax Cable
Cable losses must be taken into consideration if the D/C is located a great distance from the receiver.
As mentioned above long cable runs can contribute to more resistance in the lines and also can
contribute to signal attenuation because of the additional capacitance. Even when using a good coax
cable such as RG59/U the attenuation of the signal can be significant. For example, RG59/U coax will
drop approximately 2 dB per 100 feet at 50 MHz and 8 dB per 100 feet at 900 MHz. The intermediate
frequency (IF) in this system can fall between 49 MHz to 850 MHz. An inline amplifier matching the
cable losses should be considered if losses exceed 6 dB.
OP1920606 Rev 1
GMS Inc. doing business as Cobham Tactical Communications and Surveillance
27 of 29
www.cobham.com/tcs
Appendix A - Bibliography
Cleveland, Jr., R. F., Sylvar, D. M., & Ulcek, J. L. (1997, August). OET Bulletin 65Evaluating Compliance with FCC Guidelines for Human Exposure to
Radiofrequency Electromagnetic Fields. Retrieved March 30, 2010, from Federal Communications Commission:
http://www.fcc.gov/Bureaus/Engineering_Technology/Documents/bulletins/oet65/oet65.pdf
OP1920606 Rev 1
GMS Inc. doing business as Cobham Tactical Communications and Surveillance
28 of 29
www.cobham.com/tcs
Appendix B - Cable, SDMT External Breakout Cable
OP1920606 Rev 1
GMS Inc. doing business as Cobham Tactical Communications and Surveillance
29 of 29
www.cobham.com/tcs
Download PDF