background image

HERMES RADIO MODEM

OPERATING INSTRUCTIONS

(1892 1300)

SPECIALIST RF DESIGNS

© Copyright Wood & Douglas 2002

Version: 1.3

Issue: July 2002

LATTICE HOUSE

BAUGHURST

BASINGSTOKE

UK RG26 5LP

Tel: +44 (0) 118 981 1444

Fax: +44 (0) 118 981 1567

Summary of Contents for 1300

Page 1: ...IO MODEM OPERATING INSTRUCTIONS 1892 1300 SPECIALIST RF DESIGNS Copyright Wood Douglas 2002 Version 1 3 Issue July 2002 LATTICE HOUSE BAUGHURST BASINGSTOKE UK RG26 5LP Tel 44 0 118 981 1444 Fax 44 0 118 981 1567 ...

Page 2: ... 14 4 7 Software Version Information AT I9 15 4 8 Command Mode Guard Time AT S154 15 4 9 Centre Radio Frequency AT S155 15 4 10 Received Signal Strength Indication RSSI AT S156 16 4 11 Radio Channel AT S157 17 4 12 Data Quality AT S158 17 4 13 Squelch AT S159 18 4 14 Transmission Power AT S160 19 4 15 Channel Step Size AT S161 20 4 16 Test Message Period AT S162 20 4 17 Over Air Symbol Rate AT S16...

Page 3: ...Operating conditions 32 6 3 Vibration Specifications 32 6 4 Type Approvals 32 LIST OF FIGURES Figure 1 Timing Information 9 Figure 2 Front View of Casting 31 Figure 3 Rear View of Casting 31 Figure 4 3U Enclosure 31 LIST OF TABLES Table 1 Data Connections 5 Table 2 Power Connections 6 Table 3 Timing Data 9 Table 4 RSSI Levels 16 Table 6 Squelch Levels 18 Table 7 Power Levels for G MAX Radios 19 Ta...

Page 4: ...e types are available to suit different applications The Hermes uses 4 Level Frequency Shift Keying FSK technology to achieve a RF link data rate of 19 200 baud in a 25kHz channel spacing and 9 600 baud in a 12 5kHz channel spacing One of the radio transceivers the G Max family used inside the Hermes is designed for harsh environments and operates over a wide temperature range and a high vibration...

Page 5: ...tate 4mA 5 Signal Ground 6 DSR RS232 level output Set ve after power is applied to the modem or when the DTE host processor sets DTR ve The output is active when the modem is ready to receive data The time taken for the output to become active is 50ms from when DSR or power is applied to the modem 7 RTS RS232 level input The RTS input must be set ve for both data and configuration Data is ignored ...

Page 6: ...wer Supply Ground isolated from enclosure 6 I2 C Bus Clock engineering use only 7 0V chassis of enclosure 8 I2 C Bus Data engineering use only 9 Power Supply Ground isolated from enclosure Table 2 Power Connections 2 3 RF Connector The RF connection to the modem is a female TNC bulkhead connector 2 4 Front Panel Indications There are 3 LED indicators which show the operation of the unit as follows...

Page 7: ... channel is free before inputting data The timing of the power handshaking and data transfer is shown in Figure 1 for the G MAX radio running at 9600 baud over air in a 12 5kHz channel and for the SXn50 series of radios running at 19 200 baud over air in a 25kHz channel 3 2 Handshaking Operation During Transmit and Receive The DTE must set the RTS input for the modem to accept data The RTS input c...

Page 8: ... baud rate of 19 200 set the data rates to 38 400 baud Some applications running under the Windows operating system output the data with gaps between single or groups of characters In some cases this can reduce the character rate below the over air data rate When this occurs the system will assume that the input data has finished and will turn the transmitter off when the input data buffer is empt...

Page 9: ...o CTS output 0 5 0 5 t3 CTS output to Data input 0 1 0 1 t4 Data input to RF output non FEC mode 25 25 Data input to RF output FEC mode 25 25 t5 RF output to CD output at RX end 5 2 5 t6 CD output to data output non FEC mode 30 30 CD output to data output FEC mode 50 45 t7 Data input to Data output non FEC mode 50 45 Data input to Data output FEC mode 75 55 Table 3 Timing Data ...

Page 10: ...ocked during Command Mode If the string is input without a CR LF then the string is transmitted as normal data Note that one or more consecutive characters in the input data are held in the modem until it is determined that it is not a string The configuration mode is only accepted if the RTS line is set The string is only accepted if this string is the first three characters and there has been no...

Page 11: ...2 Command Syntax 4 2 1 Note Capital letters MUST be used for all command instructions 4 2 2 All syntax commands with multiple n s accept multiple formats For example if nnn is specified in the command string then the following will be valid 1 or 1 01 or 01 001 or 001 4 2 3 The commands for reading registers have the form AT S158 CR LF The answer to this query is nnn CR LF 4 2 4 After setting a par...

Page 12: ... Parity at the RS232 input to the transmitter has no effect and is not transmitted The 8 data bits can be used to transmit 7 data bits 1 parity bit In this case the modem has to be set to no parity The number of stop bits at the RS232 input to the transmitter can be 1 or more The number of stop bits at the receiver RS232 output is fixed at 1 This is to avoid congestion of the output data When the ...

Page 13: ...ith reduced Bit Error Rate BER performance with the FEC turned off or lower speed improved BER with the FEC turned on Figure 1 and the associated table give the timing information for both modes of operation The command is Format mode AT F n CR LF Where n 0 mode with FEC n 1 high speed mode without FEC Default n 1 non FEC mode Read AT F CR LF Read Return n CR LF Example AT F 1 CR LF ...

Page 14: ...ong data packets with a programmed period between each packet set with register S162 The message data sent is The quick brown fox jumps over the lazy dog CR LF Each line of data is pre ceded by XX where XX is a line number which increments from 00 99 The data is transmitted until stopped by the ATI3 0 or AT I 10 commands or ending command mode n 4 Adds the Output Data quality and Signal level data...

Page 15: ...d mode string is less than this guard time then the data string is assumed to be part of the data This includes the gap between the last received data byte and the first The command is AT S154 nnn CR LF Where nnn 0 to 255 ms Default 10 Read AT S154 CR LF read the setting Read Return nnn CR LF Example AT S154 10 CR LF set 10 msec time delay 4 9 Centre Radio Frequency AT S155 The channel change syst...

Page 16: ...efore the CR LF If the wrong centre frequency is entered the modem will respond with the following error message and the entry will be ignored ERROR CR LF 4 10 Received Signal Strength Indication RSSI AT S156 This request to the modem gives a response of nn CR LF where the nn is the value of the Received Signal Strength of the radio carrier present at the antenna at that time The returned value of...

Page 17: ...quencies The command for setting the radio channel is AT S157 n CR LF Where n 0 to 99 Default 0 which is printed on screen as 00 Read AT S157 CR LF Read Return nn CR LF Example AT S157 10 CR LF sets the channel to 10 4 12 Data Quality AT S158 This request for data gives an indication of the quality of the data reception The signal quality is read from the modem system at the end of each received p...

Page 18: ...hannel to be busy which could reduce the occupancy of the system Squelch Level Level at RF Input dBm 2dB 1 112 2 110 to 112 3 108 to 110 4 105 to 108 5 103 to 105 6 101 to 103 7 99 to 101 8 97 to 99 9 95 to 97 10 95 Table 6 Squelch Levels The command for setting the squelch is AT S159 n CR LF Where n squelch threshold with value 1 to 10 Default 2 Read AT S159 CR LF Read Return nn CR LF Example AT ...

Page 19: ...s the 2 levels for the SXn50 range Power Level Output Power for 1W G MAX Output Power for 2W G MAX mW nominal dBm nominal Tolerance dB mW nominal dBm nominal Tolerance dB 1 16 12 3 31 15 3 2 25 14 3 50 17 3 3 40 16 3 79 19 3 4 63 18 1 5 126 21 1 5 5 100 20 1 5 200 23 1 5 6 158 22 1 5 316 25 1 5 7 251 24 1 5 500 27 1 5 8 398 26 1 5 794 29 1 5 9 631 28 1 5 1260 31 1 5 10 1000 30 1 5 2000 33 1 5 Tabl...

Page 20: ...10 kHz n 2 12 5 kHz n 3 20 kHz n 4 25 kHz Default n 2 12 5 kHz Read AT S161 CR LF Read Return n CR LF Example AT S161 1 CR LF sets 10 kHz channel step If a channel step size is entered which is not a multiple of the centre frequency an error is returned and the entry ignored This is to ensure that only valid frequencies on multiples of the channel step size are allowed based on the centre frequenc...

Page 21: ...nables the number of preamble blocks each block equals 6 bytes that are transmitted before each data packet to be changed This preamble allows for the rise time of the transmitter as well as the minimum number of blocks required by the receiver This allows the system performance to be changed to enable the modem to be used with different transceiver equipment The command format is as follows AT S1...

Page 22: ...ch pattern Read AT S166 CR LF Read Return n CR LF Example AT S166 2 CR LF sets 4 mismatches allowed 4 20 Invert Symbol AT S167 Note engineering function only This command controls the polarity of the transmit and receive audio between the FX929 modem IC and the transceiver and allows for different transceivers to be used with the modem The command format is as follows AT S167 n CR LF Where n 0 RX ...

Page 23: ...elch and preamble 4 22 Enable Disable Receive Output Data AT D This command disables output of any received data Note that the CD output continues to operate when the data output is disabled The command is of the format AT D n CR LF Where n 0 disable output n 1 enable output Default n 1 enabled Read AT D CR LF Read Return n CR LF Example AT D 1 CR LF enables receiver data output 4 23 Enable Disabl...

Page 24: ...F Example AT F 458 5 CR LF sets 458 5MHz AT F 458 500000 CR LF sets 458 5MHz Note that frequencies in multiples of either 12 5kHz or 10kHz only are acceptable If a whole number of MHz is entered a must be entered before the CR LF If the frequency entered is outside the 99 channels or the frequency is invalid the modem responds with the following error message and the entry is ignored ERROR CR LF 4...

Page 25: ...and mode guard time 429 850000 centre frequency XX RSSI if no received data 1 10 otherwise 00 radio channel XXX data quality if no received data 66 256 otherwise 02 squelch 05 power 2 channel step size 020 test message period 2 over air baud rate 08 preamble blocks 0 frame synch tolerance 0 invert symbol 050 squelch delay 1 enable disable receive data output 429 850000 radio frequency Note where n...

Page 26: ...LF The modem responds with Flash Programmer karfl3 Ver 1 00 03 Date 24 10 2001 To update firmware upload Hermes upgrade hex file using a terminal program that can send 8 bit binary data Hermes 2001 Wood Douglas Ltd When this message has been output the code loader software is ready for the new code data to be uploaded As each line of code is accepted the modem responds with one of 4 responses line...

Page 27: ...mes 2001 Wood Douglas Ltd Apply a DC reset to the modem before using the modem If an error in the data is received the modem responds with Flash Programming Failed Hermes 2001 Wood Douglas Ltd If power is lost or some other problem occurs before the upload is completed the next time the modem is powered on it automatically requests new data by outputting the above message This repeats until the co...

Page 28: ...to the modem PCB The Hermes is supplied in 2 different mechanical versions One of these uses a rugged enclosure suitable for wall mounting The second version is housed in a 3U high euro cassette for mounting in a standard 19 rack 5 2 RS232 Port Parameters The communication with the host processor is via a standard RS232 port The data levels are as per the RS232 specification with logic 0 being a p...

Page 29: ... Max SXn50 TX Power 500mW with 100 duty cycle 1W with maximum duty cycle of 50 2W with maximum duty cycle of 20 10 programmable levels Hi Power setting 500mW with 100 duty cycle Lo Power setting 5mW Operating Frequencies 340 360MHz 400 470MHz SX150 140 200MHz SX450 390 490MHz SX850 868 870MHz Switching bandwidth frequency range over which unit can operate without adjustment 8MHz SX150 4 MHz SX450 ...

Page 30: ...gress when mounted vertically The lid has an IP65 rated gasket to ensure no water ingress The outline dimensions of the casting are 169 3 x 129 2 x 38 5mm 6 67 x 5 09 x 1 52 The weight of the unit using a G MAX radio is 612g 21 6oz The weight of the unit using a SXn50 radio is 600g 21oz 6 1 2 3U Rack Mounting Enclosure The modem can also be supplied in a 3U high 5HP wide by 101mm rack mount enclos...

Page 31: ...Hermes Operator Note Page 31 of 32 Figure 2 Front View of Casting Figure 3 Rear View of Casting Figure 4 3U Enclosure ...

Page 32: ...ns When the G MAX transceiver is used the casting version of the modem meets the MIL STD 810E 514 4 specification 6 4 Type Approvals The equipment meets the requirements of the following specifications EMC ETS 300 279 Type Approval ETS 300 113 Low Voltage Directive Directive 73 23 EEC A Technical Construction File is being prepared which will be reviewed by a Notified Body to ensure that all the r...

Reviews: