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.
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 ......
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.
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.
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.
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.
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.
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.
4.1.3 Power and Data Connector Dual purpose connector: DC input 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.
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.
• 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).
6 CONFIGURING THE TRANSMITTER 6.1 Status Monitoring There are two status LEDs on the front panel of the unit Power LED Green = DC power is applied to the unit. Flashing = normal operation PA LED 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.
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.
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 .
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.
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.
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.
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.
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.
