RF Central | RFX-BRK | Specifications | RF Central RFX-BRK Specifications

The information contained in this manual remains the property of RF Central and may not
be used, disclosed or reproduced in any other form whatsoever without the prior written
permission of RF Central.
RF Central reserves the right to alter the equipment and specification appertaining to the
equipment described in this manual without notification.
RFX-BRK
OPERATORS MANUAL
Copyright 2006 RF Central
RFX-BRK
Issue 1
page 1 of 19
CONTENTS
1
2
3
4
5
6
7
8
9
GENERAL SAFETY INFORMATION............................................................................3
1.1
Health & Safety......................................................................................................4
1.2
Maximum RF Power Density Limits.......................................................................5
1.3
Issue Status...........................................................................................................5
INTRODUCTION ..........................................................................................................6
SPECIFICATIONS........................................................................................................7
3.1
RFX-BRK Transmitter Specifications.....................................................................7
FRONT PANEL LAYOUT AND PIN CONNECTIONS ..................................................8
4.1.1
Analogue video (BNC connector) ...................................................................8
4.1.2
Audio Connector.............................................................................................8
4.1.3
Power and Data Connector ............................................................................9
4.1.4
RF O/P ...........................................................................................................9
CIRCUIT DESCRIPTIONS .........................................................................................10
5.1
Audio / Video Encoder.........................................................................................10
5.2
COFDM Modulator ..............................................................................................11
5.3
Power Amplifier ...................................................................................................11
5.4
Maintenance of the RFX-BRK .............................................................................11
CONFIGURING THE TRANSMITTER........................................................................12
6.1
Status Monitoring.................................................................................................12
6.2
Preset configuration rotary selector switch ..........................................................12
6.3
Remote set-up of the 16 preset configurations. ...................................................13
PREPARING FOR OPERATION ................................................................................16
7.1
The RFX-BRK Transmitter ..................................................................................16
7.1.1
Antennas ......................................................................................................16
7.1.2
Transmitter checks .......................................................................................16
7.2
The Receiving Equipment ...................................................................................16
7.3
Transmitter / Receiver tests.................................................................................17
Appendix A .................................................................................................................18
Example of 16 Factory pre-sets..................................................................................18
Appendix B .................................................................................................................19
RFX-BRK
Issue 1
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1 GENERAL SAFETY INFORMATION
The information that follows, together with local site regulations, must be studied by
personnel concerned with the operation or maintenance of the equipment, to ensure
awareness of potential hazards.
WARNING- RF Power Hazard : High levels of RF power are present in the unit. Exposure
to RF or microwave power can cause burns and may be harmful to health.
Switch off supplies before removing covers or disconnecting any RF cables, and before
inspecting damaged cables or antennas.
Avoid standing in front of high gain antennas (such as a dish) and never look into the open
end of a waveguide or cable where RF power may be present.
Users are strongly recommended to return any equipment that requires RF servicing to RF
Central.
WARNING- GaAs / BeO Hazard : Certain components inside the equipment contain
Gallium Arsenide and Beryllium Oxide that are toxic substances. Whilst safe to handle
under normal circumstances, individual components must not be cut, broken apart,
incinerated or chemically processed. In the case of Beryllium Oxide, a white ceramic
material, the principal hazard is from the dust or fumes which are carcinogenic if ingested,
inhaled or entering damaged skin.
Please consult your local authority before disposing of these components.
CAUTION- Tantalum Capacitors : When subjected to reverse or excess forward voltage,
ripple current or temperature these components may rupture and could potentially cause
personal injury.
CAUTION : This system contains MOS devices. Electro-Static Discharge (ESD)
precautions should be employed to prevent accidental damage.
RFX-BRK
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1.1
Health & Safety
Exposure to Non Ionising (RF) Radiation/Safe Working Distances
The safe working distance from a transmitting antenna may be calculated from the
relationship:
D=
√
PT. GR
4π.w
in which D = safe working distance (metres)
PT = transmitter or combiner power output (watts)
GR = antenna gain ratio = anti log (gain dBi ÷10)
w = power density (watts/square metre)
The RF power density value is determined by reference to safety guidelines for exposure
of the human body to non-ionising radiation. It is important to note that the guidelines
adopted differ throughout the world and are from time-to-time re-issued with revised
guidelines. For RF Central use, a maximum power density limit of 1w/m² is to be applied
when calculating minimum safe working distances. Appendix A refers.
Important Note: It must be remembered that any transmitting equipment radiating power
at frequencies of 100 KHz and higher, has the potential to produce thermal and athermal
effects upon the human body.
To be safe:
a)
Operators should not stand or walk in front of any antenna, nor should they allow
anyone else to do so.
b)
Operators should not operate any RF transmitter or power amplifier with any of its
covers removed, nor should they allow anyone else to do so.
Worked examples
Antenna
Type
OMNI
HELIX
PARABOLIC
DISH
Gain (dBi)
4
20
35
Gain Ratio
2.5
100
3,162
Transmitter Power
2W
4W
1
1
4
5.6
22.5
32
10W
1.5
9
50
30W
2.5
15.5
87
MINIMUM SAFE DISTANCE (METRES)
RFX-BRK
Issue 1
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1.2
Maximum RF Power Density Limits
The RF Radiation Power Density limit figure recommended by RF Central is based upon
guideline levels published in:
a.
IEEE standard C95.1 1999 - IEEE Standard for Safety Levels with respect to
Human Exposure to Radio Frequency Electromagnetic Fields, 3 KHz to 300 GHz.
b.
Guidelines for Limiting Exposure to Time-varying Electric, Magnetic &
Electromagnetic Fields (up to 300 GHz) published in 1998 by the Secretariat of the
International Commission on Non-Ionising Radiation Protection (ICNIRP).
Both documents define guideline RF power density limits for "Controlled" and
"Uncontrolled" environments. An uncontrolled environment is defined as one in which the
person subjected to the RF radiation may be unaware of and has no control over the
radiation energy received. The uncontrolled environment conditions can arise, even in the
best regulated operations and for this reason the limits defined for the uncontrolled
environment have been assumed for the RF Central recommended limit.
Documents a) and b) also show the RF power density guidelines to be frequency
dependent. Different power density / frequency characteristics are presented in the two
documents. To avoid complexity and to avoid areas of uncertainty, RF Central
recommends the use of a single power density limit across the frequency range 100 KHz
to 300 GHz. The 1w/m² power density limit we recommend satisfies the most stringent of
the guidelines published to date.
Footnote:
The IICNIRP document may be freely downloaded from the internet at
www.icnirp.de/emfgdl (PDF file).
1.3
Issue Status
Issue
Issue 1
RFX-BRK
Date
6 Jan. 2006
th
Changes
first issue
Issue 1
page 5 of 19
2 INTRODUCTION
The RF Central RFX-BRK ultra compact transmitter is designed for all applications, both
indoor and outdoor, in which a very small light weight transmitter is essential to the
operation. The unit features a comprehensive range COFDM modulation formats, QPSK
16QAM, 64QAM. Set-up of the unit – e.g. RF channel, MPEG coding profile, COFDM
modulation format – is via the 16 position rotary switch on the front panel. PC software is
supplied to allow RF channel and COFDM modulation parameters to be pre-programmed
for each of the 16 preset positions.
The transmitter is a single miniature unit that contains a MPEG2 video encoder, audio
encoder, COFDM modulator, RF power amplifier and power supplies, all of which are
mounted on a single printed circuit broad inside the case.
The transmitter is designed to accept analogue video (NTSC or PAL) and 2 analogue
audios at line level. Powering is +9 to 18 VDC.
The unit can be used with a variety of RF Central antennas:
ƒ ”F1 patch”, a small low profile antenna which matches the ultra compact features of the
transmitter
ƒ Omni antennas are typically used for ground based fixed and mobile operations, or
helicopter air to ground
ƒ Low profile antennas are used for up-linking ground to air, or on-board linking
ƒ Helix antennas offer increased gain and directivity
ƒ Fan-beam antennas offer increased gain and 90 degree sector coverage.
ƒ GPS steered antenna, for helicopter air to ground
ƒ Parabolic antennas offer the highest gain, and longest operational range
At the receive site a range of RF Central digital receivers may be used. Please consult the
separate RF Central manual for information detailing the operation of receivers.
RFX-BRK
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3 SPECIFICATIONS
3.1
RFX-BRK Transmitter Specifications
Frequency Band
Tuning Range
Frequency Selection
Transmit Power
Transmit Antenna
Modulation
Modulation Modes
Data Rate
Bandwidth
Encoding Options
Latency
Video Input
Audio Input
Remote set-up
Power Requirement
Size
Weight
Environmental
1.99 – 2.50GHz band
500MHz standard bandwidth. Wider bandwidths available to special
order
Up to 16 pre-set channels, user editable in 0.5MHz steps
100mW or higher, subject to customer requirements
Interfaces with the complete range of RF Central antennas
COFDM DVB-T 2k
QPSK, 16QAM, 64QAM
FEC: 1/2 2/3 3/4 5/6 7/8
Guard interval: 1/32 1/16 1/8 1/4
4.98 to 24 Mbit/s
8MHz
MPEG 2: 4:2:0 high quality video (DVB standard)
Selectable to less than 7 frames minimum, Tx to Rx
Analogue:
Composite video (PAL/NTSC)
Analogue:
1 x stereo/ 2 x mono inputs, line level
via USB port and PC software
9 – 18VDC (10W at 12VDC)
148mm (L) x 99mm (W) x 20mm (H) (excluding connectors)
400g (14.12oz)
Temperature: -4° to +122°F
Altitude:
14,500 ft.
Humidity:
95% long term
Specifications may alter at the discretion of RF Central or to meet customer specific requirements.
RFX-BRK
Issue 1
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4 FRONT PANEL LAYOUT AND PIN
CONNECTIONS
PA
LED
DC Power
LED
RF output
Audio
inputs
Video
input
Combined
DC input and
USB port
Config select
Front panel view of the RFX-BRK
4.1.1 Analogue video (BNC connector)
Composite video, PAL or NTSC.
75Ω BNC connector
4.1.2 Audio Connector
Line level
5 Pin Lemo Plug ECG.1B.305.CLN
Pin
1
2
3
4
5
RFX-BRK
Function
0V (Screen)
Ch1 +
Ch1 Ch2 +
Ch2 -
Issue 1
page 8 of 19
4.1.3 Power and Data Connector
Dual purpose connector:
ƒ DC input
ƒ USB data port
Connector Type:
4 pin LEMO connector EGG.OB.304.CLN
Input range:
10V to 18V DC.
Pin
1
2
3
4
Function
+12V
0V
Cont. RXD
Cont. TXD
Note: operators are recommended to use the USB Data cable supplied by RF Central to
connect from the RFX-BRK to the PC.
4.1.4 RF O/P
Connector Type:
RFX-BRK
50Ω SMA
Issue 1
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5 CIRCUIT DESCRIPTIONS
RFX-BRK Simplified block diagram
DC in
Power supply
Encoder
Composite video
Video/
audio
processing
Analogue audio 1, 2
I2S
Transport
stream
MPEG coder
COFDM modulator
RF
Power
amplifier
TX RF
out
Power
supply
USB port
CDT TX
Simplified block diagram
The complete RFX-BRK board; individual functions of the PCB are as follows:
5.1
Audio / Video Encoder
The Encoder has the following main functions :
•
Analogue to Digital Video Converter, 10 bit over sampling ADC
Takes Composite Video in either PAL / NTSC format and converts to an 8bit
parallel digital video bus.
•
Audio Analogue to Digital Converter, 48kHz, 24 bit
Two high impedance analogue inputs at Line level. The audio channels are
converted into digital signals and passed to the MPEG2 Encoder.
•
MPEG2 Encoder
Compresses the video and audio. The encoder uses a suite of MPEG2
compliant compression techniques, where the data bit rate is reduced by
processing over multiple picture frames. The RFX-BRK MPEG encoder
operates at MP@ML (4.2.0) only. Low data rates down to 4 Mbps, can be
achieved.
The encoding parameters are loaded into the encoder at power up. These are
selected by the ‘preset’ rotary switch position. See 6.2
RFX-BRK
Issue 1
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• DC Power Supplies
DC/DC converters are used to generate the various supplies from the incoming
9-18V battery supply. These include 2.5, 3.3V, 5V, 8V and 1.2V.
5.2
COFDM Modulator
The normal scheme of COFDM modulation adopted by RF Central for the RFX-BRK is 2k
carriers with 8MHz RF band-width.
The COFDM modulator has been designed to take its input from the MPEG2 encoder.
This Transport stream is then modulated directly to the output frequency band (e.g. 2GHz).
This method reduces the occurrence of inter-modulated harmonic frequencies, requires
less upconvertors, and results in a smaller size for the RFX-BRK transmitter.
The modulator is automatically configured to match the data rate of the MPEG2 Encoder
as defined by the selected parameter set. See paragraph 6.2
5.3
Power Amplifier
The function of the power amplifier is to amplify the signal from the COFDM modulator to a
suitable level for transmission via the SMA-type connector into the antenna. The amplifier
is required to be highly linear to accommodate the multiple carrier signal formats employed
for digital system operation, with very low distortion (low inter-modulation between
carriers). The nominal output power is +20dBm (100mW) (band specific)
The status of the PA is provided by an LED to monitor RF output level (blue), see
paragraph 6.1
5.4
Maintenance of the RFX-BRK
To ensure good RF practice, when power is applied to the RFX-BRK, always make sure
that there is a suitable load or antenna connected to the RF output.
There are no field replaceable parts on the unit PCB. If a fault occurs with the board,
please contact RF Central for technical assistance.
RFX-BRK
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6 CONFIGURING THE TRANSMITTER
6.1
Status Monitoring
There are two status LEDs on the front panel of the unit
ƒ
Power LED
ƒ Green = DC power is applied to the unit.
ƒ Flashing = normal operation
ƒ
PA LED
ƒ Blue = the PA is on.
6.2
Preset configuration rotary selector switch
The front panel rotary selector switch allows selection of the 16 preset configurations
which are loaded into the unit.
Each RFX-BRK transmitter is pre-programmed with factory defaults for each of the 16 preset positions. The standard defaults are shown in appendix A (paragraph 8). These can
be edited and updated at any time using RF Central proprietary software through a USB
port and PC or Lap Top computer.
The following operating parameters may be set:ƒ
ƒ
ƒ
RF channel (TX operating frequency in 0.5MHz steps)
MPEG encoder bit rate
COFDM modulator operating mode
ƒ QPSK, 16QAM, 64QAM
ƒ Viterbi FEC rate
ƒ Guard interval
RFX-BRK
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6.3
Remote set-up of the 16 preset configurations.
PC software is supplied to allow each of the 16 preset rotary switch positions to be preprogrammed according the operator's desired RF channel and COFDM modulation
parameters.
The RFX-BRK transmitter is connected to the PC via the combined DC/USB Lemo
connector. When connecting to the PC the user is recommended to use the USB data
cable supplied by RF Central which is fitted with the correct Lemo connector - see 4.1.3.
The required sequence when re-programming the profile information into the RFX-BRK
transmitter is as follows:
• Connect the power/data Lemo connector into the RFX-BRK.
• Switch on the power to the transmitter.
• Connect the USB lead to the PC.
• Start the programming software by double clicking on the file
MiniDigiTXConfig.exe.
• If required change the software for the correct comm. port by selecting the tab
Comms Settings.
RFX-BRK
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To re-configure the 16 sets of profile parameters:
• Select the tab Mini TX Config.
• To open a profile already stored on the PC click File/Load Profiles , and
choose/open the required .pf file in the normal Windows manner
• Similarly, to open the file already stored in the RFX-BRK TX click TX unit/Get
Profiles
RFX-BRK
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To modify a profile double click the required profile number, this opens the Profile Edit
Form
•
Modify the frequency by typing into the box, and change the modulation, code
rate and guard interval from the drop down list.
•
Store each profile as it is updated.
•
repeat for other profiles as required
•
on completion select the Close button
•
To save the new profile to the computer click File/Save Profiles
•
To save the new profile to the RFX-BRK transmitter click TX Unit/Set Profiles
RFX-BRK
Issue 1
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7 PREPARING FOR OPERATION
EQUIPMENT PREPARATION
Before leaving the equipment base to undertake an operation it is recommended that the
following equipment checks be made.
7.1
The RFX-BRK Transmitter
7.1.1 Antennas
The unit can be used with a variety of RF Central antennas:ƒ
ƒ
ƒ
ƒ
ƒ
ƒ
ƒ
”F1 patch”, a small low profile antenna which matches the ultra compact features of the
transmitter
Omni antennas are typically used for ground based fixed and mobile operations, or
helicopter air to ground
Low profile antennas are used for uplinking ground to air, or on-board linking
Helix antennas offer increased gain and directivity
Fan-beam antennas offer increased gain and 90 degree sector coverage.
GPS steered antenna, for helicopter air to ground
Parabolic antennas offer the highest gain, and longest operational range
Full details are given in the RF Central Antennas data sheet
7.1.2 Transmitter checks
The transmitter may be powered from an external AC/DC PSU, or by batteries. Check that
any batteries to be used are fully charged and that an emergency spare battery is
available and fully charged.
Confirm that the correct pre-set RF channel and modulator operating mode is selected by
the rotary switch on the front panel.
7.2
The Receiving Equipment
The RFX-BRK mini transmitter may be used with a variety of RF Central digital receivers.
Full details on the operation of the receiver are given in the associated manuals.
When used with the RFX-BRK transmitter, the receiving equipment produces two audio
channels, analogue and AES3 digital, together with SDI and composite video monitoring port.
The RFX-RMR receiver also has an ASI output.
RFX-BRK
Issue 1
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Check that audio, video, triax, AC and DC cables of sufficient total length and are in good
condition. If extension cables are necessary ensure that the connectors are compatible and of
good quality to avoid problems at site.
Check that the receiving antenna/Receiver interfaces are clean and free from dust and other
unwanted materials.
If tripods are to be used to mount the equipment, make sure that some means of securing the
tripod or of weighting it down is provided. Gusty wind conditions may put installations at risk,
particularly when parabolic antenna dishes are to be used.
Make sure that all batteries to be used are fully charged and, whenever possible, provide a
spare with cable to connect it to the receiver.
Check that the receiver channel frequencies are compatible with those of the RFX-BRK
Transmitter. The receiver is labelled with channel number and frequency information.
7.3
Transmitter / Receiver tests
Whenever practical, set up the system and trial it before leaving for site to ensure that
all components of the system are working. Checking at base, where adjustments and
corrective actions can be made, will pay off when setting up at site.
RFX-BRK
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8 Appendix A
Example of 16 Factory pre-sets
Note: The above parameters denote factory pre-sets for the RFX-BRK and are issued for
guidance only. Some transmitters may have different configurations according to
individual customer requirements. Please consult the documentation supplied with the
equipment for the details applicable to your system. All factory pre-sets may be edited
using the RF Central proprietary software mentioned in paragraph 6.3
RFX-BRK
Issue 1
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9 Appendix B
Table of DVB-T non-hierarchical bit rates
Modulation Code rate
QPSK
1/2
2/3
3/4
5/6
7/8
16-QAM
1/2
2/3
3/4
5/6
7/8
1/32
12.1
16.1
18.1
20.1
21.1
1/16
11.7
15.6
17.6
19.5
20.5
1/8
11.1
14.7
16.6
18.4
19.4
1/4
9.95
13.3
14.9
16.6
17.4
1/2
2/3
3/4
5/6
7/8
1/32
18.1
24.1
27.1
30.2
31.7
1/16
17.6
23.4
26.3
29.3
30.7
1/8
16.6
22.1
24.9
27.6
29.0
1/4
14.9
19.9
22.4
24.9
26.1
64-QAM
RFX-BRK
Bit rate (Mbit/s)
at each guard interval (symbol fraction)
1/32
1/16
1/8
1/4
6.03
5.85
5.53
4.98
8.04
7.81
7.37
6.64
9.05
8.78
8.29
7.46
10.1
9.76
9.22
8.29
10.6
10.2
9.68
8.71
Issue 1
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