Freewave Radios to work with Novatel GPS units
FreeWave radios for Novatel RTK GPS and ADCP
The following is from:
- Introduction
For accurate GPS position, velocity, and time information during river discharge measurements, WERC has several Novatel Smart-V1 GPS receivers in base + rover pairs. The base GPS averages its position, then begins transmitting correction data to the rover GPS on the boat with the ADCP sensor. A pair of FreeWave radios, or serial data radio modems, can be used for this (Bluetooth is another option), with a radio connected to each GPS unit.
The Novatel GPS units have two serial com ports, COM1 and COM2, which are accessed on connectors labelled J2 and J3 respectively. We use COM2/J3 to carry the GPS RTK corrections data via radio on both the base and rover systems, at 115,200 baud.
The FreeWave radios are configured as master or slave, where only the master can initiate a connection to the slave radio. But once a connection is established there is no difference between the radios, and serial data is moved in either direction.
The most flexible arrangement is to configure the radio for the base GPS as a slave, and the rover GPS radio as master. With this setup the base system can sit there for as long as necessary, hours or days, but its radio will only consume significant power when a rover system is connected to it.
- setting and/or checking radio configuration
Connect the radio serial port to a computer using a straight-through cable, and run a terminal program (e.g., putty, hyperterm, minicom, etc.) at 19200 baud with a connection to the computer serial port.
Press or toggle the setup button or switch on the FreeWave radio. This should cause the radio's main menu to appear on the terminal. Also, the three radio LEDs will be green when the radio is in setup mode.
Note the radio serial number at the top of the main menu. This is a 7-digit number, usually formatted to look like a phone number. The base radio number will need to be added to the rover/boat radio callbook.
The radio setup menus are navigated by pressing a single number or letter key, usually with no RETURN required. Use the ESC key to exit from a menu or action.
0 menu -- set radio operating mode
The base radio will be set to mode 4, point-to-point slave/repeater
The boat/rover radio will be set to mode 0, point-to-point master 1 menu -- set radio serial port baud rate
Set the radio serial port to 115,200 baud. Other parameters should be 8 data bits, 1 stop bit, no parity. 2 menu -- radio callbook
On the boat/rover radio, find or enter the base radio serial number as one of the numbered entries in the callbook. To set it at entry 0, press 0, then enter the target radio number, then press ESC. Confirm that the expected number is shown for that entry.
Also on the boat/rover radio, press C to set the entry to call, and press the entry number for the base radio. With the rover radio in operating mode 0, it will try to connect to that radio whenever powered up.
The callbook is not important on the base radio since it is a slave and will not initiate calls. 3 menu -- radio parameters
On the base (slave> radio only one entry is significant (the others will be set in operation by the master radio). Entry 6 for slave security must be disabled with the value 1 (note: not 0!).
On the boat/rover/master radio several entries are important.
The frequency key value should be different from other FreeWave radios that may be operating in the area. A value of 1 or 2 should be safe. If interference is observed or suspected a different value can be tried. The WERC North Slope Radio Network uses frequency keys 9 (toolik), 4 (toolik2), 6 (deadhorse), ? (sagriver),
Transmit power should usually be the maximum value, e.g., 9 or higher.
Slave security should be turned off with value 1. If slave security is enabled (value 0), the slave (base) radio will not allow a connection to the master (boat/rover) unless the master radio number is in the slave radio's callbook.
Other parameters are important but please refer to the FreeWave manual for details.
Sample menu-3 entries for FGR radios:
(0) FreqKey 2
(1) Max Packet Size 8
(2) Min Packet Size 9
(3) Xmit Rate 1
(4) RF Data Rate 3
(5) RF Xmit Power 10
(6) Slave Security 1
(7) RTS to CTS 0
(8) Retry Time Out 255
(9) Lowpower Mode 0
(A) High Noise 0
(B) MCU Speed 0
(C) RemoteLED 0
(Esc) Exit to Main Menu
Sample menu-3 entries for older DGR radios:
(0) FreqKey 1
(1) Max Packet Size 8
(2) Min Packet Size 9
(3) Xmit Rate 1
(4) RF Data Rate 3
(5) RF Xmit Power 9
(6) Slave Security 1
(7) RTS to CTS 0
(8) Retry Time Out 255
(9) Lowpower Mode 0
(Esc) Exit to Main Menu
4 menu -- diagnostics
Optional. Menu 4 can be useful to diagnose failing or weak connections. The status of the last connection should be shown. Press ESC to exit back to the main menu, or ENTER to see more detailed information.
- appendix: FreeWave radio basics
The FreeWave serial data modem radio has a single serial com port in DCE, data communications equipment or modem, configuration, so it can connect to a computer serial port (which is DTE, data terminal equipment) with a straight-through, male to female serial cable.
To configure a FreeWave radio, connect it to a computer (laptop) serial port using a straight-through serial cable, provide 12 V power, and hit the setup switch, which may be either a momentary-on toggle switch or a recessed momentary pushbutton. The computer will need to be running a serial terminal emulator program, e.g., HyperTerminal, Putty, Minicom (for linux), etc.., and will need to be set for 19200 baud.
Note that the FreeWave setup interface, when accessed via the setup button, is always at 19200 baud. When in setup mode, all three LEDs on the FreeWave radio front panel will be green, and this pattern is only indicative of setup mode.
In setup mode the FreeWave radio presents a main menu, and accepts single-number command entries, with no Enter/Return key required for most settings.
