Synthesised Radio Modem • • • • • • • • • • • • • • X8200 X8200HP Operates on international licensed and licence free radio bands RF Bands: o 147MHz to 174MHz VHF o 400MHz to 500MHz UHF o 868MHz to 920MHz UHF Conforms to ETSI 300-220, ETSI 300-113, ETSI 300-683, MPT1329, MPT1411 Distant Modems can be monitored and configured over the radio link 17 to 99 selectable radio channels Range (500mW): o 10km to 20km line of sight o 1km to 3km in buildings RS232 & RS485 serial Interface Baud rates of 1.2K to 115.2K Commissioning and diagnostic futures Store and Forward Repeater Mode to extend range Addressable individually and globally On-line AT commands Packetised Data, and Forward Error Correction options Low power standby mode Description The X8200 Radio Modem transmits and receives half duplex serial data at baud rates of 1.2K to 115.2K by means of a FM Radio Transceiver operating on the UK and European licence exempt bands and most other world wide data frequencies. A 4K buffer memory is provided so that data can be passed asynchronously between the host and modem without the need for handshaking. The CTS output signal can be used for flow control in duplex applications. The over air data speed can be configured at either 5K bits/sec or 10K bits/sec. This is independent of the baud rate and should be set to a lower value where possible for the best radio propagation. The set up menu of the X8200 can be accessed either by a PC running any terminal emulation program like Hyper Terminal in the accessories section or remotely over the radio link. The set up menu is selected either by connecting pin 6 on the 9 way D Connector to 0v or typing $ then ESC directly after the power has been applied. The menu configuration is permanently stored on EEPROM. On-line “AT” commands can be sent to the modem to change the address configuration, repeater path or RF frequency during normal operation so that any modem can “dial up” any other modem on the network. Data can be formed into packets and passed from one modem to another. If the received packet has errors detected then the data will automatically be sent again. Both size of the data packet and the number of retries can be set in the menu. DS8200-2 April ’07 ©2007 RF Solutions Ltd, www.rfsolutions.co.uk Page 1 Synthesised Radio Modem X8200 X8200HP INDEX 1 Specification .................................................................................................3 1.1 Mechanical and Environmental ..............................................................3 2 Connections ..................................................................................................4 2.1 9 Way D Type Connector RS232/RS485 ...............................................4 2.2 LED Indicators........................................................................................5 2.3 Antenna Connector .................................................................................5 3 Operation ......................................................................................................5 4 Getting started...............................................................................................5 4.1 Basic Connection ....................................................................................5 4.2 Power Connection...................................................................................5 4.3 Factory Setting........................................................................................6 4.4 Plug and Play ..........................................................................................6 5 Configuration................................................................................................7 5.1 Access Configuration Menu ...................................................................7 5.2 Configuration Menu................................................................................8 6 Radio Transmission ....................................................................................16 7 Trouble shooting.........................................................................................18 DS8200-2 April ’07 ©2007 RF Solutions Ltd, www.rfsolutions.co.uk Page 2 X8200 X8200HP Synthesised Radio Modem 1 Specification ELECTRICAL CHARACTERISTICS Frequency Range MIN 868 458.500 400.000 TYPICAL 147.000 Channels Channel Separation Start up Time Modulation Power Supply X8200 X8200HP Baud Rate TRANSMITTER RF Power X8200 RF Power X8200HP Data Input RS232 Data Input RS485 Frequency Deviation Modulation Rate Supply Current X8200 X8200HP RECEIVER IF Frequencies Sensitivity Bandwidth Data Output RS232 Data Output RS485 Carrier Detect Supply Current X8200 X8200HP Supply Current Standby 1.1 12.5 5.0 10 10 1.2 127 25.0 10.0 F3D, F1D 12 12 5 1 -10 0 MAX 920 458.950 480.000 DIMENSION MHz MHz MHz 174.000 MHz 25.0 30.0 KHz mSecs 26 14 115.2 Vdc Vdc Kb/s 500 5 10 5 mW W V V KHz Kbps +/- 3.0 DC 10.0 340 1800 +/- 7.5 -10 0 -10 0.005 mA 45/455 0.9 KHz MHz V 10 5 10 90 150 0.007 V V V mA 0.01 mA Mechanical and Environmental Dimensions X8200 UHF 800mW Dimensions X8200HP UHF 5W Dimensions X8200HP VHF 5W Length = 140mm Width = 65mm Height = 26mm Length = 147mm Width = 65mm Height = 52mm Length = 174mm Width = 80mm Height = 58mm Operating Temperature Range -10 to +55 deg C DS8200-2 April ’07 ©2007 RF Solutions Ltd, www.rfsolutions.co.uk Page 3 NOTE UK World Si (X8200 HP Only) With $ Selected 25KHz Channel Synthesised Radio Modem 2 Connections 2.1 9 Way D Type Connector RS232/RS485 1 6 2 7 3 8 4 9 5 +VE POWER CONFIGURATION MODE RS232 RD RECEIVE DATA -VE RS485 RS232 TD TRANSMIT DATA CTS DTR (STANDBY) +VE RS485 0V Pin 1 Connection +VE 2 3 4 RD TD DTR 5 6 GND CON 7 8 –VE CTS 9 +VE DS8200-2 April ’07 X8200 X8200HP INPUT INPUT INPUT INPUT/OUTPUT OUTPUT OUTPUT INPUT INPUT/OUTPUT INPUT Description Regulated power supply. It is not advisable to use some types of switched mode power supply either to drive the X8200 radio modem or in close proximity to it. This type of power supply can produce high energy radio frequencies over a broad spectrum thereby causing interference to the received signal. RS232 Receive serial data from host RS232 Transmit serial data to host A signal of between 0v to –7V will switch the modem into standby power mode. Leave open circuit for normal use Power supply and common for host. Configuration input. Connecting 0V to this input will send the configuration menu to the host when the power is applied. It is left open circuit for normal operation RS485 Bi-directional data. Brought low by the modem when a RF carrier is detected or the receiver buffer memory is full. This can be connected to RTS on the host to inhibit data from the host in duplex operations. RS485 Bi-directional data. ©2007 RF Solutions Ltd, www.rfsolutions.co.uk Page 4 Synthesised Radio Modem 2.2 X8200 X8200HP LED Indicators Three LEDS on the front of the modem indicate the following states: TX Green RX Green POWER Red 2.3 On when modem is transmitting data. On when a RF carrier of greater than 0.9uV is detected by the modem. On when power is applied to the modem Antenna Connector BNC/TNC 3 Operation A transmission is started by sending data to RD (pin 2) or the RS485 terminals (pin7 & 9).The radio modem places this data in the transmitter buffer memory while it checks to see if the RF channel is free. If it is not then the data is stored in the buffer until the channel becomes free. If it is free then a preamble message will be transmitted so that the receiving modems can align to the incoming data. When Tx Priority is set, data will be transmitted regardless of the condition of the RF Channel. The modem will then transmit a command byte which will instruct the distant modems to perform the functions set in the menu followed by the addressing and repeater functions. The data that has been placed in the buffer memory will then be transmitted. The transmission is terminated when a gap of two data bytes is detected in the incoming data stream. If more data is sent after a gap of two data bytes then the above sequence will be repeated. When the receiving modem detects the presence of incoming data it takes CTS (pin 8) low. The repeater command byte is decoded and the transmitter address compared to the receiver address. If they are the same or if the global address of 00 is decoded or if the address mode is switched off then the data will be presented at the serial output port TD (pin 3). At the end of the message CTS is taken high. If the packetisation option is selected the receiving modem will check the CRC byte. If it is correct an ACK sent to the transmitting modem. If the CRC is incorrect a NACK is sent to the transmitting modem and the data is sent again. The number of re-trys are set in the Menu. If the repeater command is decoded or the repeater mode set in the configuration menu then the data will be stored and then re-transmitted. 4 Getting started 4.1 Basic Connection TRANSMIT RECEIVE GROUND 4.2 (TD) (RD) (0V) ON HOST TO RECEIVE (RD) ON MODEM PIN 2 ON HOST TO TRANSMIT (TD) ON MODEM PIN 3 ON HOST TO 0V ON MODEM PIN 5 Power Connection PIN 1 = POSITIVE PIN 5 = GND DS8200-2 April ’07 ©2007 RF Solutions Ltd, www.rfsolutions.co.uk Page 5 Synthesised Radio Modem 4.3 X8200 X8200HP Factory Setting The radio modem is supplied with the following settings: 4.4 X8200 Radio Modem V#.# Advanced Menu Advanced Menu Modem ID Baud Parity Odd/Even RF Power Key Transmitter RF Channel RSSI Sensitivity Comms Speed Address Mode Enable AT Instr Restore Defaults Exit without Save Save & Exit Return to Main Menu Message Tag TX Priority FEC Packetise Data Number of Retries Packet Size Logger Mode Enable Remote Access Access Remote Modem Engage Repeater Path Set Repeater Path Y 01 9600 N E 5 N 17 N 00 S N N N N N Y 0000 N N N 05 20 N Y N N 00 M01 M02 M03 M04 M05 M06 ---- M16 Plug and Play Connect three wires to the RS232 serial port of the host terminal (0V, TD and RD) as described above. Connect a regulated power supply to the radio modem. X7202 PC to Modem cables can be used along with a X7201 power supply. Configure a PC to Hyperterminal in the Accessories section to the following: Go to File and then t Properties. Set the Configuration to : 9600 Baud No Parity 1 Stop Bit XON/XOFF to OFF RTS/CTS to OFF (no handshaking) Settings should be: Terminal Keys set Emulation set to ANSI ASCII Set Up : Deselect all. Connect up a second modem in the same way. Pressing a key on one PC will transmit the character to the other. Refer to the Section 8.0 Trouble Shooting if this does not happen. DS8200-2 April ’07 ©2007 RF Solutions Ltd, www.rfsolutions.co.uk Page 6 Synthesised Radio Modem X8200 X8200HP If a second PC is not available simply power up the second modem. Configure the ID numbers and the Enable Remote Access option on both. Then use the Access Remote Modem option to display the menu of the remote modem. Fig 1 shows how an open network using the above configuration would work. All the data transmitted from one modem will be received by all of the others. This is similar to an RS485 network but instead of connecting the equipment by wire a radio modem is used. FIGURE 1 OPEN NETWORK 5 Configuration 5.1 Access Configuration Menu There are three ways the menu can be accessed: Typing $ then pressing the Esc Key as the first two characters after the Radio Modems has been switched on. Connecting Pin 6 on the D-connector to 0V on Pin 5. Then switching the Radio Modem on. Using the Remote Access feature to display the menu of a distant Radio Modem. A PC configured as a dumb terminal with the following settings should be used: 9600 Baud No Parity 1 Stop Bit Echo off DS8200-2 April ’07 ©2007 RF Solutions Ltd, www.rfsolutions.co.uk Page 7 X8200 X8200HP Synthesised Radio Modem XON/XOFF to OFF RTS/CTS to OFF (no handshaking) 5.2 Configuration Menu The vertical and horizontal arrow keys are used to move around the menu. Alternatively the numbers keys 2, 4, 6 and 8 can also be used as follows: Down arrow key or Left arrow key or Right arrow key or Up arrow key or 2 key will move the cursor down the menu 4 key will reduce the value 6 key will increase the value 8 key will move the cursor up the menu The Enter Key is used in the following function: Restore Defaults Exit without Save Save & Exit Access Remote Modem Set Repeater Path The Space Bar Key is used to delete modem ID numbers in the Repeater Path To save any changes made in the menu : Move the cursor to Save & Exit, Use the horizontal arrow key to select Y. Press the Enter Key The configuration menu shown below will be displayed when a radio modem with Modem ID set to 01 remotely accessed a radio modem with Modem ID set to 02. X8200 Radio Modem V#.# Local Advanced Menu N Modem ID 01 Baud 9600 Parity N Odd/Even E RF Power 5 Key Transmitter N RF Channel 17 RSSI N Sensitivity 00 Comms Speed S Address Mode N Enable AT Instr N Restore Defaults N Exit without Save N Save & Exit N Advanced Menu Remote N 02 9600 N E 5 N 17 N 00 S N N N N N Return to Main Menu Message Tag TX Priority FEC Packetise Data Number of Retries Packet Size Logger Mode Enable Remote Access Access Remote Modem Engage Repeater Path Set Repeater Path Local Local N 0000 N N N 05 20 N Y Y N 02 M01 M02 M03 M04 M05 M06 ---- M16 02 Remote M01 M02 M03 M04 M05 M06 ----- M16 (use space bar to delete repeater path) DS8200-2 April ’07 ©2007 RF Solutions Ltd, www.rfsolutions.co.uk Remote N 0000 N N N 05 20 N Y N N 00 Page 8 Synthesised Radio Modem Advanced Menu: Modem ID Baud Parity Odd/Even RF Power Key Transmitter RF Channel RSSI Sensitivity Comms Speed Address Mode AT Enable AT Instr Display Advanced Menu . User defined ID number. Baud Rate 1.2K to 115.2K Enable Parity. Select Parity. Set level of RF Power. Switch on Transmitter Set RF Frequency. Bar Graph of Rx Signal Set the Receiver Sensitivity Slow/Fast Enables Modem Address. AT instruction are enabled. Restore Defaults Exit without Save Set Factory Defaults. Return without saving operation without saving settings. Return to Modem and save Settings. Save & Exit Return to Main Menu X8200 X8200HP Display Main Menu. TX Priority Data transmitted priority Message Tag Adds Ident. No. to Data FEC Forward Error Correction Packetise Data Data is formed into packets with error detections and Acknowledgments. Connect CTS to RTS on Host. Sets number of retries. Sets packet size. 64-1024 Data is stored until polled. Allows distant Modem to change settings. Displays settings of remote Modem with ID on AT Path. Enable repeater path. Sets AT Path M01 to M16. Number of Retries Packet Size Logger Mode Enable Remote Access Access Remote Modem Engage Repeater Path Set Repeater Path Advanced Menu The horizontal arrows are used to select the Advanced Menu. Modem ID Number Each modem in a network can be given an individual ID number between 0 and 99 This is used for: Remote Access Menu Modem Addressing Repeater Function Packet Data Function Baud Rate Settings A baud rate is entered by moving the cursor under the current setting with the vertical arrow keys. Then by pressing the horizontal keys the value will change: BAUD RATE 115.2K 57.6K 38.4K 19.2K 9.6K 4.8K 2.4K 1.2K Parity On/Off DS8200-2 April ’07 ©2007 RF Solutions Ltd, www.rfsolutions.co.uk Page 9 X8200 X8200HP Synthesised Radio Modem If a parity bit is required use the horizontal arrow key to select Y The parity bit is only used between the host and the radio modem Odd or Even Parity O/E If parity is required either O for Odd or E for Even parity can be set by pressing the horizontal arrow keys. RF Power The RF output power can set using a number between 1 minimum and 5 maximum. The horizontal arrow keys are used to change the value. RF Channel The Radio Frequency can be set by using a number between 1 and 17. If channel 0 is selected the radio will use the DIL switch settings to select the RF frequency RF Channel 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 Frequency 458.525 458.550 458.575 458.600 458.625 458.650 458.675 458.700 458.725 458.750 458.775 458.800 458.825 458.850 458.875 458.900 458.925 DIL SWITCH (Used when RF Ch is set to 0) SW5 ON ON ON ON ON ON ON ON ON ON ON ON ON ON ON OFF OFF SW4 ON ON ON ON ON ON ON OFF OFF OFF OFF OFF OFF OFF OFF ON ON SW3 ON ON ON OFF OFF OFF OFF ON ON ON ON OFF OFF OFF OFF ON ON SW2 ON OFF OFF ON ON OFF OFF ON ON OFF OFF ON ON OFF OFF ON ON SW1 OFF ON OFF ON OFF ON OFF ON OFF ON OFF ON OFF ON OFF ON OFF In addition an ATX instruction can be used to change the RF frequency form the serial port. For example to change the RF frequency to channel 09 the instruction would be: A 41 T 54 X 58 0 30 9 39 Were the channel number is sent as two ASCII number characters 30-39 for 0-9 DS8200-2 April ’07 ©2007 RF Solutions Ltd, www.rfsolutions.co.uk Page 10 Synthesised Radio Modem DS8200-2 April ’07 ©2007 RF Solutions Ltd, www.rfsolutions.co.uk Page 11 X8200 X8200HP Synthesised Radio Modem X8200 X8200HP Key Transmitter The Key Transmitter setting switches on the transmitter so that a radio site survey can be conducted. . A second Radio Modem can be used to move around the site observing either the Rx LED or the RSSI Bar Graph. If the Rx LED is on or there are more than 3 bars on the RSSI Bar Graph then there will be good communications. RSSI Relative Signal Strength Indicator The RSSI function is used to detect radio activity on the RF Channel. It can also be used to measure the signal strength of a transmission from a distant radio modem. A maximum of nine bars will appear relating to a signal strength of 0.3uV (-112dBm) to In the Remote Access Mode the distant modem will measure its own RSSI and radio the value back to the local radio modem were it will be displayed on a bar graph in the menu. Comms Speed Two over air transmissions speeds can be selected. These are: F = 10Kbits/sec S = 5Kbits/sec Address Mode The address mode uses ID numbers to “dial up” distant modems. When the data is transmitted from a distant modem the first ID number set in the repeater path is added to the data string and used as a transmitter address. The receiving modem compares the transmitter ID in the data string with its own ID number. If they are the same the data string is passed to the serial port. In addition individual modems can be dialled up by using serial ATT and ATA Instructions to change the transmitting ID number. The ATT instruction can be used to “dial up” distant modems as shown in fig 4. The base station modern has its ID number (receiver address RXA) set to 01. The four distant stations have ID numbers 2,3,4 and 5. All of the distant modems have the first value in their Repeater Path (transmitter address TXA) set to 01. Therefore any distant modem can transmit data to the base station but not to each other. The serial ATT instruction is made up of the ASCII characters for A (41), T(54), T(54). This is then followed by the ID number of the addressed station as two ASCII numbers 30 to 39 The instruction sent by the base station to address modem with ID set to 2 will be: A 41 T 54 T 41 0 30 2 32 DATA Modem 3 can be dialled up in the same way with the instruction: A 41 T 54 T 41 0 30 3 33 DATA The instruction string will not be transmitted over the air as long as it is sent to the modem without any breaks. DS8200-2 April ’07 ©2007 RF Solutions Ltd, www.rfsolutions.co.uk Page 12 Synthesised Radio Modem X8200 X8200HP FIGURE 4 STATION ADDRESSING Global Addressing The base station can send the same data to all the modems by using the Global Address 00 (Fig 5). The following instruction would be inserted before the data by the base station host: ATT00 FIGURE 5 GLOBAL ADDRESSING Receiver Sensitivity The receiver sensitivity can be adjusted so that the modem is less likely to be affected by the presence of RF interference. This will cause a reduction in overall range. DS8200-2 April ’07 ©2007 RF Solutions Ltd, www.rfsolutions.co.uk Page 13 Synthesised Radio Modem X8200 X8200HP Restore Defaults The Factory Settings will be automatically be restored by pressing the horizontal arrow key followed by the Enter Key They will not be stored in the EEPROM until Save and Exit has be selected and the Enter Key pressed again Exit without Save The modem will return to normal operation without storing the menu settings in the EEPROM. Press the horizontal arrow key followed by the Enter Key. Save & Exit The modem will store the menu in the EEPROM and return to normal operation Press the horizontal arrow key followed by the Enter Key. Return to Main Menu Pressing the horizontal Arrow key will return to the Main Menu. Enable AT Instructions Pressing the horizontal Arrow key will allow the modem to act on AT Instructions. Message Tag The number set as a Message Tag will be transmitted at the start of each data string. It will be passed to the host at the receiving station to indicate the source of the data. The function is disabled by setting the Message Tag to 0000 TX Priority With TX Priority set N the modem will monitor the RF Carrier frequency before transmitting. This is to prevent data collisions. If it is being used then a random number delay timer is started and the transmission is attempted again when this times out. If the TX Priority is set to Y then data will be immediately transmitted regardless of whether there is an RF Carrier detected or not. This is used in environments with large amounts of RF emissions. FEC The Forward Error Correction algorithm puts redundant bytes into the data string so that it can correct the data at the receiving modem. Packetise Data The Packetised Data option is set to Y and the ID number of the destination modem is set in the Set Repeater Path. This could be a single ID number for a back to back system or multiple DS8200-2 April ’07 ©2007 RF Solutions Ltd, www.rfsolutions.co.uk Page 14 Synthesised Radio Modem X8200 X8200HP ID numbers if a repeater path is to be used. Data from the Host is stored in the modem memory. When the number of data bytes equals the number set in Packet Size or if there is a gap detected in the incoming data the CTS line is brought low. This line is connected to RTS on the Host and stops the data. A check sum is added to the data string and it is then transmitted over air. The data string is checked at the receiving modem and if no corruptions have taken place an Acknowledge is sent to the transmitting modem. This then takes the CTS line high and the sequence is repeated. If the receiving modem detects a data corruption a Not Acknowledge is sent to the transmitting modem and the data is sent again. The number of retries at set in the menu. Number of Retries The number of retries before the data is abandon can be set between 0 and 99 using the horizontal arrow key. Packet Size The number of data bytes in the data packet can be set by the following number: 2 = 64 Bytes 4 = 128 Bytes 8 = 256 Bytes 10 = 512 Bytes 20 = 1024 Bytes Logger Mode The modem will place all data from the host into its 4K buffer memory. When it receives an addressed message from a distant modem all the contents of the memory will be transmitted. Enable Remote Access Enable Remote Access is set so that a local modem can access, monitor or change the settings of a distant modem over the radio link. Access Remote Modem. The radio link can be used to display the menu of a remote modem. All the parameters can be changed including the RF Frequency and the RF Power. In addition the value of the receiver signal strength will be radio back. First set the ID number of the target modem in the first location of the Repeater Path by pressing the horizontal arrow until the number is arrived at. Press the Enter Key. If the ID number is not known then 99 can be used as a universal entry code. Please note that using 99 will address all the Radio Modems within radio range. Move the cursor to Access Remote Modem, press the horizontal arrow key to select Y. Then press the Enter Key. The menu from the target modem will be displayed along side the local modem. Any and all the parameters can be altered using the arrow keys. In addition the signal strength DS8200-2 April ’07 ©2007 RF Solutions Ltd, www.rfsolutions.co.uk Page 15 Synthesised Radio Modem X8200 X8200HP at the distant modem will be displayed as a bar graph on the RSSI setting. Save & Exit is used to update the menu of the distant modem. Note that the real ID of the distant modem has to be used. The 99 access code will note allow the menu in a distant modem to be changed. This is to prevent all the menus of radio modems within radio range from being modified. Setting Exit without Save to Y and pressing the Enter Key will disconnect the link Engage Repeater Path Data will be first set to the modem with the ID number set in MO1 it will be then repeated to modem ID set in MO2 and so on until the last ID number set in the repeater chain. ATA instruction can also be used from the Host to select different paths and different destinations. Set Repeater Path The Engage Repeater Path is set to Y. A repeater path is set up by using the horizontal keys to increment the Set Repeater Path number. When it is the same as the ID number of the repeater modem press the Enter key. The next modem in the repeater chain is set in the same way. Finally enter the ID number of the destination Modem The Space Bar is used to delete the entry. The serial ATA instruction can also be used to select a data path. It is made up of the ASCII characters for A (41), T(54), A(41). This is followed by the number of stations (two ASCII numbers) to be used in the repeater path followed by the destination station ID numbers. (two ASCII numbers). If the data string was to be transmitted to modem with ID9 and it was to be repeated at modem ID4 and then at modem ID6. The ATA Instruction would be: A T A 3 Stations ID4 41 54 41 30 33 30 34 ID6 30 36 ID9 30 39 DATA The maximum number of repeaters is 99 . 6 Radio Transmission Radio Propagation When installing a X8200 Radio Modem there are a number of factors that should be considered as they will affect the performance of the radio link. These are: Transmitter power output. Sensitivity of the receiver. Height of transmitter and receiver antenna. Length and type of the coaxial feeder cables to the antenna. These should be low loss DS8200-2 April ’07 ©2007 RF Solutions Ltd, www.rfsolutions.co.uk Page 16 Synthesised Radio Modem X8200 X8200HP RU67 type and kept as short as possible. As a rule of thumb the RF power is halved every 10m of antenna feeder. It is better to keep the signal wire long and the antenna feeder short. Type of Antenna used. Surrounding Topography. Interference for other networks operating on the same frequency. The Weather. Antennas The main types of antenna used in telemetry applications are as follows: Helical End Fed Dipole Yagi Helical Antenna The helical stub antenna is robust, low cost and physically small. It has a gain less than unity. Range of up to 2Km. End Fed Dipole The end fed dipole antenna has a unity gain. Its main application is to provide cost effective omni-directional radiation. Range 10 to 20 Km Yagi This antenna has a high gain typically twice (3dB) to ten times (10dB) the input power in the direction of orientation. It is the type of aerial commonly used in domestic televisions. The output power of a transmitter connected to a Yagi antenna has to be reduced to conform to the DTI specification. This has the advantage of reducing the overall power consumed by the transmitter without effecting the range in the direction of orientation. It also reduces interference from other users. The receiver signal is also amplified if a Yagi antenna is used thereby extended range in the direction of orientation to around 20 Km line of sight. Antenna Alignment If directional yagi antenna are used it is important to aligned them correctly. This can be done using a compass and ordinance survey maps. The alignment can be checked by selecting the Key Transmitter option at the transmitting station. A radio modem is then attached to the yagi antenna feeder at the receiving station. By selecting the RSSI option in the menu the yagi antenna can be rotated to a position of peak signal strength This will be in the direction of the transmitter beacon. Site Survey First check the occupancy of all the radio channels at all the proposed sites. This can be achieved by using an antenna, radio modem and PC. Select the RSSI option and observe the bar graph. Note any activity. Go to the RF channel option and select the next RF DS8200-2 April ’07 ©2007 RF Solutions Ltd, www.rfsolutions.co.uk Page 17 Synthesised Radio Modem X8200 X8200HP Channel. Again observe the RSSI reading and make a note of any activity. Repeat this for all the RF Channels. The radio range can be tested by erecting a radio modem, Antenna and PC at the proposed base station site. Select the Key Transmitter option. Use a second radio modem, antenna at the distant site. If the Rx LED is lit then there is a good propagation path. In addition the RSSI option can be selected for a more accurate reading of the signal strength. The propagation path can be tested by using the Access Remote Modem option. The RSSI value from each of the distant modems will be measured, radioed back and displayed Radio Propagation When installing a X8200 Radio Modem there are a number of factors that should be considered as they will affect the performance of the radio link. These are: Transmitter power output. Sensitivity of the receiver. Height of transmitter and receiver antenna. Length and type of the coaxial feeder cables to the antenna. These should be low loss RU67 type and kept as short as possible. As a rule of thumb the RF power is halved every 10m of antenna feeder. It is better to keep the signal wire long and the antenna feeder short. Type of Antenna used. Surrounding Topography. Interference for other networks operating on the same frequency. The Weather. 7 Trouble shooting No Data Transmission Check that TD and RD are connected to the 9 way D Connector correctly. This can be checked by using a voltmeter: a) b) c) Connect the Host to the Modem. With no signal present, measure the voltage between: 0V (Pin 5) and TD (Pin 3) 0V (Pin 5) and RD (Pin 2) Both should be between -5V to -15V. If only one is at a negative voltage then the RD and TD connections are reversed. No Data Reception If the RX LED on the receiver is not lighting at the same time as the TX LED on the transmitter then check the RF frequency is the same on both modems. If the RX LED is lit when no data is being transmitted then there might be another user on the channel. Select an RF channel were the RX LED is not lit. If RX LED is flickering on all RF channels then look for a source of local interference such as a switch mode power supply or a computer in close proximity. DS8200-2 April ’07 ©2007 RF Solutions Ltd, www.rfsolutions.co.uk Page 18 Synthesised Radio Modem X8200 X8200HP If there are other radio modems or radio telemetry systems operating on adjacent frequencies on the same site then the antenna on your system must be mounted at least 3m away from the antenna of the other systems. This will prevent the transmitter of one system interfering with the receiver of the other. Corrupted Data Corrupted data can be caused by poor power supplies. Check that the power supply is regulated at 12V and has a ripple of less than 50mV on load. It must also be capable of delivering an inrush current of 0.7Amps for 20mSec. when the radio modem starts its transmit cycle. The ripple voltage can be measured with a voltmeter set on A.C. volts. Radio Path The radio path can be tested by using the Access Remote Modem option. If the remote modem is in radio range and is receiving good data it will respond by displaying the signal strength of the remote modem in the RSSI option. If the remote modem does not respond then use the Key Transmitter option to permanently transmit a carrier. Go to the distant modem and observe the RX LED. It should be on. Alternatively access the set up menu and select the RSSI option. A minimum of 3 bars should be shown. DS8200-2 April ’07 ©2007 RF Solutions Ltd, www.rfsolutions.co.uk Page 19