RPM2A

EW N 24 April 2007 Radiometrix Hartcran House, 231 Kenton Lane, Harrow, HA3 8RP, England Tel: +44 (0) 20 8909 9595, Fax: +44 (0) 20 8909 2233 RPM2A UHF Radio Packet Modem The UHF Radio Packet Modem (RPM2A) is a low cost intelligent radio packet modem that enables a two way radio network/link to be simply implemented between a number of digital devices. The RPM2A uses addressable data packets with error checking, packet acknowledgements and retransmissions to achieve a reliable transparent wireless data link. Built for ease of use and rapid installation, the serial interface ensures direct connection to microprocessors or to RS232 port via RS232 driver while remote configuration enables post installation setup of the modem. Features Addressable point-toAddressable point-to-point Point-toPoint Point-to-Multipoint and broadcast modes Inverted Inverted RS232 interface at 5V or 3VCMOS level DTE speed 600-115200bps DTE 600Overall throughput: Overall Single 5V or 3V supply Single 15mA 15mA during data streaming at maximum rate Flow Flow control – Hardware (CTS), None0 Available Available on 433.92MHz or 434.42MHz Usable Usable range up to 300m BuiltBuilt Built-in command line configuration BuiltBuilt Built-in RF link diagnostics Remote overRemote over-air unit configuration Low Low operating current, Auto standby mode Conforms 220489Conforms to European ETSI EN 300 220-3 and EN 301 489-3 Dimensions: Dimensions: 39mm X 23mm X 10mm 17kbps with ACK with 28kbps without ACK Figure 1: RPM2A-914-17 Applications Telemetry Telemetry and telecontrol EPOS EPOS equipment, barcode scanners, belt clip printers, stock control, job allocation barcode Remote Remote data acquisition system, data loggers InIn In-building, environmental monitoring and control systems HighHigh High-end security and alarm signalling Automated Automated Monitoring and Control Systems Fleet management, vehicle data acquisition Radiometrix Ltd. UHF FM Radio Packet Modem page 1 INTRODUCTION The RPM2A is a self-contained Radio Packet Modem module that requires only a simple antenna, 5V supply and a serial I/O port on a host microcontroller or PC. The module provides all the RF circuits and processor intensive low level packet formatting and packet recovery functions required to inter-connect any number of devices with serial port in a radio network. A continuous stream of serial data downloaded by a Host microcontroller into the RPM2A serial receive buffer is transmitted by the RPM2A’S transceiver and will "appear" in the serial buffer of the addressed RPM2A within radio range. transmit / receive download download HOST upload RPM2A upload HOST Figure 2: Point to point wireless link with RPM2A + Host microcontroller 1. FUNCTIONAL DESCRIPTION The RPM2A is a connection oriented modem module for sending and receiving serial data via an RF communications link. The RPM2A handles all necessary protocol related functions of validation and retries to ensure error free and uninterrupted data is sent over the communications link. All data transfers between a pair of RPMS are fully acknowledged, thus preventing the loss of data. Bit coding and checksums are used on the data packets to ensure the validity of the received data at the remote end. Radio Packet Modem D0 Radio Packet Modem (RPM) 9.216MHz Host µController Fast Radio Packet Controller (FRPC) 8.192MHz BiM2A Transceiver 64kbps Figure 3: RPM2A block diagram Radiometrix Ltd. UHF FM Radio Packet Modem page 2 1.1 OPERATING STATES The RADIO PACKET MODEM has three normal operating states: • SHUTDOWN • STANDBY • CONNECTED SHUTDOWN The SHUTDOWN state is entered by asserting the WAKE/DTR input pin high (Vcc). It effectively forces the RPM2A into a suspended state. Communications cannot be made with the RPM2A in this state. WAKE/DTR pin should be pulled Low by host or connected to 0V to Enable the RPM2A. STANDBY Immediately after power up and during normal operation, the RPM2A will automatically enter standby mode where it is waiting for a connection request from a remote RPM2A module. While in this mode a remote connection request can be received which will place the RPM2A into a connected state allowing it to then start receiving data from the remote unit. The connected host device can also send data to the RPM2A via the serial interface which will force the module to send a connection request to the remote RPM2A module, thus effectively setting up a logical connection between two units and allowing data to be transferred. CONNECTED On receipt of a connection request from a remote unit, the RPM2A immediately enters a connected state. This effectively allows the RPM2A modems to start sending and receiving data. In-coming data is sent to the host via the serial port in the same form as it was given to the remote RPM2A module. Figure 4: RPM2A transmitting data at 28kbps during ZMODEM file transfer to a remote RPM2A Radiometrix Ltd. UHF FM Radio Packet Modem page 3 2 The Host Interface 2.1 SIGNALS The connection to the RPM2A is a full duplex serial interface supporting baud rates from 600bps to 115200bps. Additional control signals are provided to assist in flow control, configuration and power saving in the RPM2A. side views 39 mm 33mm 5mm 10 mm 23 mm top view RF GND 1 RF 2 RF GND 3 RX SELECT 4 TX SELECT 5 GND 6 TXD/AF 7 D3 8 D2 9 SIGNAL 10 RST 11 22 GND 21 Vcc 20 DEFAULT 19 RXFLOW/CTS 18 RXD 17 TXD 16 WAKE/DTR 15 SETUP 14 RESET 13 RXR 12 RXA 36.5mm 39 mm recommended PCB hole size: 0.9 mm pin pitch: 2 mm 23 mm Figure 5: Physical dimensions and pinouts Pin name RF GND RF RXSELCT TX SELECT TXD/AF D3 D2 SIGNAL RST RXA RXR RESET SETUP WAKE/DTR TXD RXD CTS DEFAULT VCC GND Pin 1, 3 2 4 5 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 6, 22 Pin Function RF signal ground RF signal Receiver Select Transmitter Select Transmitted Data or demodulated signal FRPC Data line FRPC Data line Preamble Detect FRPC reset Receive Acknowledge Receive Request Reset Enter Setup Wake or Shutdown Serial transmitted data Serial Received data Clear To Send Force 9600bps Vcc Supply Ground In/Out Input or Output Input or Output Input or Output Input or Output NC NC Output NC NC Output Input Input Input Input Output Output Input Input - Description BNC casing/coax braid connection Antenna pin/coax core connection Internal RF Receiver Enable to BiM2A or RF Receiver Active Indicator Internal RF Transmitter Enable to BiM2A or RF Transmitter Active Indicator Transmitted Packetised Data to BiM2A Analogue Demodulated signal from BiM2A Internal data line between RPM and FRPC Internal data line between RPM and FRPC Valid preamble indicator Resets FRPC which also isolates BiM2A RPM to FRPC download Request Acknowledge Valid Data packet indicator Hardware reset of the RPM2A Enter RPM2A configurator after a RESET Wakes RPM2A when low, shuts down when high Host (DTE) to RPM2A serial transmit data RPM2A to host (DTE) serial received data Hardware flow control of data from host (DTE) Force the RPM2A serial interface to 9600bps +5VDC or +3VDC regulated supply Supply Ground internally connected to GND Notes: 1. RXD/TXD lines are true data 2. Active low SETUP, DEFAULT inputs require external 10kΩ pull-up to VCC. 3. Logic levels are 5V CMOS unless 3V variant is used. 4. WAKE pin should be pulled to ground if DTE cannot provide DTR signal 5. TXSELECT, RXSELECT, SIGNAL, RXR, CTS can be connected to LEDs via 1kΩ series resistors Radiometrix Ltd. UHF FM Radio Packet Modem page 4 2.2 RADIO PACKET MODEM RESET RESET The Reset signal is internally pulled up to Vcc via a 10kΩ resistor. A reset aborts any transfers in progress and restarts the RPM2A. HOST DRIVEN RESET Minimum low time: 1.0 µs, after reset is released (returned high). The host should allow a delay 1ms after reset for the RPM2A to initialise itself. 2.3 HOST TO RADIO PACKET MODE DATA TRANSFER Data is transferred between the RPM2A and the HOST using an asynchronous serial protocol. The default protocol settings are 8 data bits, no parity and 1 stop bit (8n1). The baud rate setting for the serial interface is user settable from 600bps to 115200bps. TXD Data from the connected host (DTE) is received by the RPM2A through TXD pin. CTS A single handshake line, CTS, controls the flow of data into the RPM2A. The serial receive buffer of the RPM2A is 96 bytes deep. The CTS will be asserted High (VCC) by the RPM2A when the receive buffer hits approximately 66% full. It is advisable to limit the number of characters sent to the RPM2A after the CTS control line is asserted. This will help to reduce the possibility of lost data due to internal buffer overruns in the RPM2A. The RPM2A will clear the CTS when the internal serial receive buffer falls below 33% full. RXD Upon the RPM2A receiving data from a remote unit, the received data is sent to the connected host (DTE) device through the RXD pin.. 2.4 ENTERING RADIO PACKET MODEM CONFIGURATOR Configuring the RPM2A is accomplished by using a built-in command line configurator. The configurator is entered by asserting the SETUP input of the RPM2A while resetting the RPM2A. SETUP Holding SETUP low during a reset cycle will force the modem into the configurator. The state of this input is checked while the RPM2A starts up from either power on or reset. HOST DRIVEN SETUP The Setup pin may either be driven by the host (recommended) to enable host controlled configuration of the RPM2A or pulled up to VCC via a suitable pull-up resistor (10kΩ). 2.5 FORCING DEFAULT SERIAL BAUD RATE Asserting this pin low forces the RPM2A to start-up with a default baud rate of 9600bps, 8 data bits, one stop and no parity. DEFAULT During a RESET the HOST must hold DEFAULT low to force the RPM2A serial interface to default to 9600bps. This is ideal if the serial baud rate has been forgotten or incorrectly set. HOST DRIVEN DEFAULT The DEFAULT pin may either be driven by the host (recommended) or pulled up to VCC via a suitable pull-up resistor (10kΩ). 2.6 FORCING RADIO PACKET MODEM INTO SLEEP MODE Asserting the WAKE input high forces the modem into a low power sleep mode. This effectively shuts down the RPM2A and prevents it from sending or receiving any data. It is a method for conserving power when the modem is not required. WAKE / DTR During normal operation WAKE pin can be pulled high to force the RPM2A to shutdown into low power sleep mode. HOST DRIVEN WAKE The WAKE pin may either be driven by the host (recommended) or pulled Low to 0V. Radiometrix Ltd. UHF FM Radio Packet Modem page 5 TECHNICAL SPECIFICATION General Operating Voltage Operating Current ACKMODE ON Transmitting Receiving ACKMODE OFF Transmitting Receiving Auto-Standby Power-down Standard Operating frequency TX spectral bandwidth @ -40dBc Operating Temperature Configuring options Interface Serial Interface Serial Protocol Serial Signals Power down Control Serial Handshaking DTE Interface Speed Air Interface Speed Overall throughput – Acknowledged – Unacknowledged 5VDC or 3VDC Average 15mA (Data streaming) Average 15mA (Data streaming) Average 14mA (Data streaming) Average 15mA (Data streaming) 4mA (Waiting for Connection) 70µA 433.92MHz 250kHz -20ºC to +70ºC Built-in command line configurator Inverted RS232 at 5V or 3V CMOS level 8 data/1 stop/no parity RXD, TXD, CTS, WAKE Via WAKE/DTR signal Selectable as CTS signal or none 600/1200/2400/4800/9600/19200/38400/57600/115200 bps 64kbps 17kbps (max) 3.6kbps (slots) 1.8kbps (slotsw) 28kbps (max) 3.6kbps (slots) 1.8kbps (slotsw) -100dBm for 1ppm BER -110dBm (max) +10dBm -40dBm max Receiver Sensitivity LO leakage (conducted) Transmitter Output Power (typical) Spurious Emissions Note: 1. 2. RPM2A uses BiM2A (64kbps UHF Wide Band FM) transceiver for its RF interface. Please refer to BiM2A data sheet for further details on the RF specification. BiM2A consumes 14mA on transmit and 11mA on receive Radiometrix Ltd. UHF FM Radio Packet Modem page 6 3.0 RADIO PACKET MODEM CONFIGURATION 3.1 ENTERING THE CONFIGURATOR The RPM2A is configured by entering the built-in software configurator. Current argument can be displayed by entering parameter / command without argument 3.2 USER CONFIGURABLE PARAMETERS CONFIG Valid range DEFAULT Valid range RESET Display a list of the current RPM2A configuration. This will also set FLOW control to none to enable simple 3 wire serial communication None Set all RPM2A configuration settings to their factory default values. None Exit the modem and force a software reset. Any changed parameters will take effect after the modem has restarted. When exiting the configurator, the HOST device must ensure the SETUP pin is high otherwise the configurator will be re-entered after the reset. None Sets the unit number. Two RPM2A modules can communicate with each other provided they have matching Unit numbers and Site codes. 0 0 to 15 Sets the Site address The site number is used to distinguish between groups of operating modems. The site code is an address extension to the unit number. 0 0 to 7 Updates the unit number value. This command is used for changing the unit number in RAM without updating the unit number stored in EEPROM. This enables the RPM2A to support point-to-multipoint communications. Upon using this command the configurator is exited and the modem operation is resumed. The modem is not reset when the configurator is exited. 0 0 to 15 Sets the host interface baud rate. The changed baud rate will take effect after resetting the RPM2A. 9600 600, 1200, 2400, 4800, 9600, 19200, 38400, 57600, 115200 Sets the on-air data throughput. Three possible settings are provided. max: sets the maximum data throughput of the RPM2A. slots: effectively reduces the on-air throughput. This opens up ‘time slots’ allowing other RPM2A pairs, operating within close proximity, equal opportunity to transmit data. slotsw: increases the ‘time slots’ even further to allow more RPM2A pairs to operate. max max, slots, slotsw Valid range UNIT default Valid range SITE default valid range ADDR default Valid range BAUD default valid range THRUPUT default valid range Radiometrix Ltd. UHF FM Radio Packet Modem page 7 FLOW default valid range SERDLY Sets the serial flow control between the host and RPM2A. Using no flow control enables the RPM2A to be used with a 3 wire serial link (TXD, RXD, GND). Care must be taken in order to prevent overflowing the 96 byte serial receive buffer in the RPM2A. Using hardware flow control enables the RPM2A to control the flow of serial data being received. none hw, none Sets the serial data receive to packet transmit delay. When the RPM2A receives the first byte of data from the host, it starts a timer running. Either a full buffer of data to send or a timeout of this timer will allow the packet to be transmitted. Fine tuning this delay for the baud rate the RPM2A is operating at can significantly increase throughput while reducing unnecessary transmissions. 2 (x10ms) 2 to 255 (x10ms) Sets the action of the WAKE input. Setting shutdown to ON will cause the RPM2A to monitor the WAKE input. When WAKE is taken high the RPM2A will be forced into low power sleep mode, thus reducing current consumption. Subsequently lowering the WAKE input will bring the RPM2A out of low power sleep mode. SHDN should be set to OFF or WAKE pin should be pulled Low when the host (DTE) cannot provide DTR control signal to wake RPM2A in a 3-wire serial interface. On on, off Sets the number of data retry attempts. RF interference can cause a transmitted data packet to be lost or corrupt on reception. If this happens the RPM2A will retransmit any unacknowledged transfer. The transmission will be retried the specified number of times before the link to the remote unit is considered ‘lost’ and the data purged. 5 1 to 63 Enables the startup message. The startup message is enabled by default, thus giving an immediate indication of the operation of the RPM2A. The message can be disabled prior to deployment of the RPM2A module. On on, off Enables transfer acknowledgements. This function enables packet transfer acknowledgements to be returned for every outgoing packet. Packet acknowledgements aid in the delivery of error free and consistent data transfers between a pair of modems. Disabling the acknowledgements results in higher data throughput between modems, but does not protect against lost data due to RF interference. It should be disabled while using RPM2A in a broadcast mode. On on, off Enables remote configuration. Over-air remote configuration of a RPM2A module is possible once it has been enabled. The remote command is used to send remote configuration commands. See the following chapter for a overview of remotely configuring a RPM2A module. On on, off Starts the radar test. Used as a range or confidence test between RPM2A modules within the same site. Unit number between 0 and 15. UHF FM Radio Packet Modem page 8 default valid range SHDN default valid range RETRY default valid range STRTMSG default valid range ACKMODE default valid range REMOTE default valid range RADAR parameter Radiometrix Ltd. To configure the RPM2A the HyperTerminal should be set with the following settings. Figure 6: Serial Port settings to use RPM2A Configurator Hardware flow control should be disabled. Default baud rate of the RPM2A is 9600bps. However if the default baud rate of the RPM2A is changed then the baud rate of the HyperTerminal should be matched or DEFAULT pin should be pulled Low to force the RPM2A baud rate to 9600bps. Figure 7: RPM2A configuration using HyperTerminal User configurable parameters described in section 3.2 should be entered in the command prompt > followed by Carriage Return (CR) key. Then SETUP should be pulled-up to VCC and RPM2A should be RESET to exit the configurator and for the new parameters to be used by RPM2A. Radiometrix Ltd. UHF FM Radio Packet Modem page 9 4.0 EXTENDED RADIO PACKET MODEM FEATURES 4.1 THROUGHPUT The RPM2A supports three rates, max (17kbps), slots (3.6kbps) and slotsw (1.8bps), of over-air throughput. MAX: When set to maximum and streaming data at the RPM2A, the data is sent as quick as possible. For host baud rates above 9600bps, data is transmitted continuously with minimal delay between sequential packets. When this occurs, there is effectively no airtime for another pair, operating in close proximity, to transmit without causing collisions. The maximum over-air throughput that can be achieved is 17kbps with ACK and 28kbps without ACK.. Figure 8: RPM2A streaming data with ACK at maximum throughput In Figure 8, RS232 serial data bytes accumulated in the receive buffer is transmitted as two 10kbps bursts by transmitting RPM2A with gaps just enough to receive ACK from receiving RPM2A. Figure 9: RPM2A streaming data without gap for anotherRPM2A pair For continuous data transmission at baud rates above 9600bps (with ACK) or 19200bps (without ACK), hardware flow control should be used to prevent the host from causing receive buffer overrun errors. RPM2A will signal CTS pin to stop/allow the host depending on its Receiver Buffer level. Radiometrix Ltd. UHF FM Radio Packet Modem page 10 SLOTS: Setting the throughput to SLOTS provides a method of opening about 85ms ‘time slots’ for other RPM2A pairs operating in close proximity. The effective streaming on-air throughput between a pair of RPM2A is effectively reduced to approximately 3.6kbps (with/without ACK). Figure 10: RPM2A operating in slots throughput mode with ACK for each transmission SLOTSW: This setting effectively widens the SLOTS to about 185ms, reducing the over-air throughput to approximately 1.8kbps (with/without ACK). It allows more RPM2A pairs to share the same frequency. Host should obey CTS flow control signal from RPM2A when using SLOTS or SLOTSW mode. Figure 11: RPM2A operating in slotsw throughput mode Overall throughput of the RPM2A is fixed according to thruput mode selected. Effective throughput will vary according to the file transfer protocol used. ZMODEM is the most popular and fastest protocol but it still adds its own header, CRC, link control bits to the data packet being transmitted reducing the actual throughput. Radiometrix Ltd. UHF FM Radio Packet Modem page 11 4.2 Remote Configuration Remote configuration of a RPM2A module is possible using the REMOTE command from within the configurator. The remote RPM2A unit should be on or in auto-standby mode. Initially the REMOTE command is used to enable and disable the ability to remotely configure a module, as described in section 3.2: User Configurable Command. Once remote configuration is enabled the REMOTE command is then used to issue configuration commands to a remote RPM2A. The format for the remote command then becomes: REMOTE The of the remote RPM2A must be known in order for the remote configuration request to be executed on the appropriate RPM2A module. The to be executed can be any of the following: Baud 600,1200,2400,4800,9600,19200,38400,57600,115200 Unit 0 to 15 Site 0 to 7 Shdn on/off Flow hw/none Serdly 2 to 255 Retry 1 to 63 Strtmsg on/off The is optional, and if not specified the setting for that command is returned and displayed. 4.3 POINT-TO-MULTIPOINT The RPM2A can be used for point-to-multipoint communications. One module must be considered to be the master, which is used to address up to 15 remote units in any one site. During normal operation, the base unit can be set to address another unit dynamically by entering the configurator and using the ADDR command to change the unit address. Upon execution of this command, provided the parameters are correct, the configurator is exited immediately. A period (‘.’) is sent to the connected host device to indicate that the change has been registered and the RPM2A is now ready for communications to the new unit address. ADDR is very similar to the Unit command, except that ADDR does not update the stored EEPROM unit value. As the EEPROM has a limited number of write cycles, using ADDR for addressing multiple units in a point to multipoint network is recommended. Also, the ADDR command will exit the configurator immediately, which is required to resume communications very quickly. 4.4 BROADCAST MULTIDROP The RPM2A has a broadcast mutidrop mode which provides a mechanism for building a large networks. This mode of operation is determined by the configuration command keyword ACKMODE being set to OFF. In broadcast mutidrop mode, the RPM2A does not implement network layer functionality related to data packet routing, acknowledgement and retries. The connected host device should provide network layer functionality. The site code and unit address is still used by the radio modem when working in broadcast multidrop mode. For a given multipoint network all radio modems within a group must contain the same site code and unit address. Radiometrix Ltd. UHF FM Radio Packet Modem page 12 4.5 RADAR: DIAGNOSTIC TEST Built into the configurator is a diagnostic test suitable for range testing and link confidence testing. The Radar test effectively sends a small request packet to a remote unit then waits for a reply. The remote unit must not be in the configurator otherwise it will not respond. Upon receipt of a positive response from the remote unit, a success is recorded before the process is repeated. This test will continue indefinitely until it is ended by a key press. 4.6 Radio Packet Modem Error Handling The RPM2A’s radio decoder module is deliberately non bit error tolerant, i.e. no attempt is made to repair corrupt data bits. All of the redundancy in the code is directed towards error checking. For an FM radio link using short packet lengths, packets are either 100% or so grossly corrupt as to be unrecoverable. By the same reasoning, the Host is not informed or sent corrupt data since corrupt information is of little value. The RPM2A implements packet acknowledges, timeouts and re-transmission to accomplish reliable error handling. Ordering information Part number European: 869.85MHz RPM2A-433-17 RPM2A-433-17-3V RPM2A-433-17-SMA RPM2A-433-17-3V-SMA RPM2A-433-17-ANT RPM2A-433-17-3V-ANT Notes: 1. Standard RPM2A module will be supplied with neither the connector nor antenna and RF pin (2). 2. If an SMA (or Reverse Polarity SMA) connector or 1/4 wavelength wire antenna is soldered on the protruding PCB section for SMA connector, then the RF pin (2) should be cropped with side cutters for better RF performance. 3. If the RF output is going to be taken from the RF pin (2) to on-board antenna or connector on the host PCB (motherboard) via 50Ω microstrip, the protruding section of the RPM2A PCB can be cut along the width of the RPM2A to remove the redundant connector section. 4. RPM2A is supplied with 7mm long pins which need to be trimmed to mount the module as close as possible to the host PCB (motherboard). Ideally, the black coloured plastic spacer on the RPM2A pinheader should be touching (resting on) the host PCB. Supply 5V 3V 5V 3V 5V 3V Yes Yes Yes Yes Yes Yes SMA Connector SMA Antenna Radiometrix Ltd. UHF FM Radio Packet Modem page 13 Radiometrix Ltd. 5V Appendix A UHF FM Radio Packet Modem Figure 12: Example circuit to make radio modem with DCE type RS232 interface page 14 Hartcran House 231 Kenton Lane Harrow, Middlesex HA3 8RP ENGLAND Tel: +44 (0) 20 8909 9595 Fax: +44 (0) 20 8909 2233 sales@radiometrix.com www.radiometrix.com Copyright notice This product data sheet is the original work and copyrighted property of Radiometrix Ltd. Reproduction in whole or in part must give clear acknowledgement to the copyright owner. Radiometrix Ltd Limitation of liability The information furnished by Radiometrix Ltd is believed to be accurate and reliable. Radiometrix Ltd reserves the right to make changes or improvements in the design, specification or manufacture of its subassembly products without notice. Radiometrix Ltd does not assume any liability arising from the application or use of any product or circuit described herein, nor for any infringements of patents or other rights of third parties which may result from the use of its products. This data sheet neither states nor implies warranty of any kind, including fitness for any particular application. These radio devices may be subject to radio interference and may not function as intended if interference is present. We do NOT recommend their use for life critical applications. The Intrastat commodity code for all our modules is: 8542 6000. R&TTE Directive After 7 April 2001 the manufacturer can only place finished product on the market under the provisions of the R&TTE Directive. Equipment within the scope of the R&TTE Directive may demonstrate compliance to the essential requirements specified in Article 3 of the Directive, as appropriate to the particular equipment. Further details are available on The Office of Communications (Ofcom) web site: http://www.ofcom.org.uk/radiocomms/ifi/ Information Requests Ofcom Riverside House 2a Southwark Bridge Road London SE1 9HA Tel: +44 (0)845 456 3000 or 020 7981 3040 Fax: +44 (0)20 7783 4033 information.requests@ofcom.org.uk European Radiocommunications Office (ERO) Peblingehus Nansensgade 19 DK 1366 Copenhagen Tel. +45 33896300 Fax +45 33896330 ero@ero.dk www.ero.dk