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M7 Heatsinking and Duty Cycle

The M7 transceiver has a 5-watt RF power output rating.  In a typical application the units is in Standby or Receive mode most of the time.  A small fraction of the time, it is transmitting.  But when it transmits, the M7 begins heating up, dissapating about 8 watts of heat.   This depends upon the RF power output setting and the DC input voltage. 

The temperature of the M7 enclusure must be kept below 60 degrees celcius, (140 farenheit) for proper operation of the unit.  For GPS transponder operation, there is no problem doing this, because the duty cycle is low.  But, if the M7 is used to send data, and is on the air a lare percentage of the time, then the enclusure’s temperature will begin to rise.  The following chart shows the case temperature at 25% and 50% Duty cycle. 

M7 Duty Cycle

 
M7 Duty Cycle

You can see in the chart, that the M7’s enclosure temperature gets hotter if the DC input voltage is higher, or if the duty cycle is higher.  

For example, if the DC input voltage is 10V, and the unit is operated at 25% transmit duty cycle, then the enclosure temperature would be about 42 degrees C.  Given the same duty cycle, the enclosure temperature would be 46 degrees if the DC input were to be 14 volts. 

Raveon offers a heatsink option for the M7.  The heatsink is large finned heatsink that covers the top of the M7, and is secured on with thermally-conductive epoxy.  When this heatsink is attached, the M7 will stay cooler.  The following chart illustrates this:

 m7dutycycle-heatsink

The above data is the M7’s enslosure temperature with a heatsink secured to it.  The heatsink covers the top of the enclosure and uses normal air convection (no fan).  It reduces the case temperature by about 4-8 degrees.  

If a CPU cooling fan or similar fan were added instead, the case temperature rise would be only a few degrees above ambient.

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Connecting the M7 to a Lowrance display

The M7 GX series of GPS transponders may be directly connected to a Lowrance Globalmap 540C or a Globalmap 840C navigation display. When connected, the Lowrance display map will show the location of the vehicle it is in PLUS the location of all other M7 transponders within radio range.  This unique feature allows one to quickly, easily, and inexpensively, make a mobile AVL system for tracking cars, trucks, racecars, construction equipment, or any thing Raveon’s M7 GX transponder may be installed on.

Both the 540C and 840C have built-in interfaces for a “NMEA 0183” devices, which is another way of saying that they can connect to other devices using a serial cable.   The NMEA 0183 is an RS232 serial connection that typically operates at 4800 baud.  It is used to exchange waypoint and other information between displays, GPS devices, and transponders.

When Raveon’s M7 GX transponder is connected to the Lowarnce diplay using the NMEA 0183 connection, the M7 transponder can put icons on the screen of the Lowrance display.  As the transponder received updated positions from other vehicles, it updates the position of the icons on the Lowrance display.

Lowrance 540C and 840C Wiring

From the Lowranace technical manual, here is how their NMEA 0183 interface works:

NMEA 0183 Cable Connections

NMEA 0183 is a standard communications format for marine electronic equipment. For example, an autopilot can connect to the NMEA interface on the GlobalMap 540c and receive positioning information.  The GlobalMap 540c can exchange information with any device that transmits or receives NMEA 0183 data. See the following diagram for general wiring connections. Read yourother product’s owner’s manual for more wiring information.

NMEA 0183 Wiring  (Data cable)

To exchange NMEA 0183 data, the GlobalMap 540c has one NMEA 0183 version 2.0 communication port. Com port one (Com-1) can be used to receive NMEA format GPS data. The com port can also transmit NMEA format GPS data to another device.  The four wires for the com port are combined with the Power Supply cable and NMEA 2000 Power cable to form the power/data cable (shown earlier). Com-1 uses the yellow wire to transmit, the orange wire to receive and the shield wire for signal ground. Your unit does not use the blue wire.540cwiring-to-m7

Wiring the DB9

The Lowrance’s “Data Cable” must be connected to the M7 transponder.  This connection will allow the M7 to put icons on the screen of the Lowrance display, showing the location of other tracked vehicles.  The Raveon M7 GPS transponder uses a 9-pin “DB9” connector to connect to the Lowrance.  Solder the Lowrance data cable wires onto a DB9 connector and plug the DB9 into the M7 transponder as shown below:db9-lowrance-31

The orange wire goes to pin two of the DB9, the yellow wire to pin 3, and the shield braid of he cable connects to pin 5 of the DB9.  The blue wire is trimmed off.

The extra wires on the Lowrance display called NMEA 2000 power are typically not used in a vehicle installation, and may be wrapped up with electrical tape and tucked away.

Configuring the Lowrance

Set the NMEA communication of the Lowrance to 4800 baud.

Configuring the M7 GX Transponder

Raveon has a designed the M7 GX transponder to work with Lowrance Display or any other NMEA 0183 display that can accept the “$GPWPL” NMEA message.   The $GPWPL is an industry standard message that the Lowrance displays and many other GPS displays interpret as a waypoint command.  The M7 GX outputs this $GPWPL message to put icons on the screen of the Lowarance, and to move the icons around on its screen.

To configure the M7 transponder to output the $GPWPL message, set the M7 GX to GPS mode 2.  To do this, put it into the configuration mode by send the +++ into the serial port.  The M7 will respond with an OK.  Type GPS 4 and press enter to put it into GPS 4 mode.  GPS 4 is the mode that causes the M7 GX to output $GPWPL messages whenever it receives a status/position message over the air.

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Trimble Copernicus GPS Receiver

Internal to Raveon’s M7 series of GPS transponders is a GPS receiver module made by Trimble.  It is their Copernicus II GPS receiver module.  Many of the M7’s performance specifications are driven by the use of this receiver module.  The Copernicus II is ideally suited for vehicle tracking systems, AVL, asset tracking, and personal location.   Details of the module are available on Trimble’s website at: 

http://www.trimble.com/embeddedsystems/copernicus2.aspx?dtID=overview&

The following is a summery of the Copernicus GPS modules features and performance:

Overview

Trimble’s Copernicus® GPS receiver delivers proven performance and Trimble quality for a new generation of position-enabled products. It features the Trimble revolutionary TrimCore™ software technology for extremely fast startup times and high performance in foliage canopy and urban canyon environments. The Copernicus module is a complete 12-channel SBAS (which includes WAAS, EGNOS) capable GPS receiver in a thumbnail-sized module. Each module is manufactured and factory tested to Trimble’s highest quality standards.

Key Features:

  • 2.54 mm T x 19 mm W x 19 mm L
  • 94 mW typical continuous tracking
  • Supports SBAS (WAAS, EGNOS)
  • Active or passive antennas
  • NMEA, TSIP, TAIP protocols
  • RoHS-Compliant (Pb-free)

The sensitive Copernicus II GPS receiver can autonomously acquire GPS satellite signals and quickly generate reliable position fixes in extremely challenging environments and under poor signal conditions The unit also accepts aided GPS (A-GPS) data for faster startups in very weak conditions.  The Copernicus II GPS module is a complete drop-in, ready-to-go receiver that provides position, velocity, and time data in a user’s choice of three protocols Trimble’s powerful TSIP protocol offers complete control over receiver operation and provides detailed satellite information.

PERFORMANCE SPECIFICATIONS

Accuracy (24 hr static)

  • Horizontal. <2.5 m 50%, <5 m 90%
  • SBAS. <2.0 m 50%, <4 m 90%
  • Altitude. <5 m 50%, <8 m 90%
  • SBAS. <3 m 50%, <5 m 90%
  • Velocity. 0.06 m/sec
  • Static PPs. +/- 60ns RMS
  • PPS (Stationary Mode “indoor” @ -145dBm). +/-350ns

Acquisition (Autonomous, -130dBm, 50%)

  • Reacquisition. 2 s
  • Hot Start. 3 s
  • Hot Start without battery backup. 8 s*
  • Warm Start. 35 s
  • Cold Start. 38 s

Sensitivity (unaided)

  • Tracking . -160 dBm
  • Acquisition. -146 dBm
  • Receiver Dynamics. 2G
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TDMA Time Slots (Multiplexing Time Division)

Raveon’s M7-GX AVL transceiver uses a  Time Division Multiple Access (TDMA) protocol to transmit position, status, and data over the air.  TDMA protocols greatly increase the available channel bandwidth but they require more system planning than conventional carrier-sense methods. 

With a TDMA system, each radio in the system is assigned a time slot to use for sending its data (data being GPS postion, status, or ASCII data).  Because only one radio transmits in any single timeslot, there is never any interference between radios.  Hundreds of GPS tracked vehicles or assets may be all located in the same place, and still communicate without interference – an impossible task with conventional radio systems.

The M7 radio’s TDMA timing may be configured by the system installer to optimize it for a particular application.  The TDMA slot width and the number of slots maybe configured to achieve the maximum system performance.  Each TDMA slot needs to be long enough so that the complete GPS position/status message can be sent in it. 

  Table 1 below shows the recommended slot times for various over-the-air data rates.

Over-the-air rate

Radio Bandwidth

Number of Modulation Levels

Position /Status Transmission Duration

Recommended TDMA SLOTTIME in mS

4800bps  (ATR2=3)

12.5kHz

2

70mS

100  (200 with repeaters)

8000bps  (ATR2=4)

12.5kHz

4

50mS

50 (150 with repeaters)

9600bps  (ATR2=5)

25kHz

2

45mS

50 (100 with repeaters)

14400bps (ATR2=10)

25kHz

4

30mS

50 (100 with repeaters)

Use the ATR2 x command to set the over the air rate.  Use the SLOTTIME xx to set the TDMA slot time.  The SLOTTIME must be wide enough to accommodate a Position/Status transmission from the GPS.  Refer to the Table 1 above to determine how long a position/status transmission will take.  The factory default for a stock RV-M7-UC-GX radio is 200mS slots, 4800 baud over-the-air.  This is an excellent compromise between speed and communication range.

The TDMA Frame Length

The TDMATIME is the length of one TDMA frame/epoch.  A TDMA frame contains small time slots where each radio is allowed to transmit in.  The slots are sequentially numbered.  For example, in the configuration below, the TDMA frame is configured to have 20 slots.

Figure 1

TDMA Time Slots / Multiplexing Time Division

Radio number 1 transmits in Slot 1. Radio number 2 in slot 2… 

TDMA Frames have a pre-set number of slots, and once the TDMA Frame Time has passed, the frame restarts at slot 0 again.  Slot 0 is reserved for future base-station control signals.  The length of a TDMA Frame is set with the TDMATIME xx command. 

 Figure 2

TDMA Time Slots / Multiplexing Time Division versus CDMA

In the M7 GX radio, the TDMA Slot Time is programmable, in 50mS increments.  The SLOTTIME xx command is used to set the slot width.  Typically it is set at 50, 100, 150, or 200mS.  The factory default is 200mS. 

For example, with a TDMATIME of 4 second, and a SLOTTIME of 200mS, there are enough slots to support 19 radios reporting every 4 seconds.  The Frame will repeat every 4 seconds so every 4 seconds, each of the 19 radios has 200mS of air-time available.   Figure 3 depicts this configuration.

 Figure 3

 tdma4

Configuration 1 below shows the slot timing with a 1200 baud M7 GX radio using 750mS time slots.

 Configuration 1

1200baud with repeaters
TDMA Frame time, 20 seconds
750mS time slots
  Slot Number Time (S) into frame Radio ID
20-second TDMA Frame for all mobile units in the system 0 0 –
1 0.75 1
2 1.5 2
3 2.25 3
4 3 4
5 3.75 5
6 4.5 6
7 5.25 7
8 6 8
9 6.75 9
10 7.5 10
11 8.25 11
12 9 12
13 9.75 13
14 10.5 14
15 11.25 15
16 12 16
17 12.75 17
18 13.5 18
19 14.25 19
20 15 20
21 15.75 21
22 16.5 22
23 17.25 23
24 18 24
25 18.75 25
26 19.5 26
     

Configuration 2 below shows the slot timing with a 4800 baud M7 GX radio using 200mS time slots.

 Configuration 2

4800baud with repeaters
TDMA Frame time, 10 seconds
200mS time slots
  Slot Number Time (S) into frame Radio ID
10-second TDMA Frame for all mobile units in the system 0 0 –
1 0.2 1
2 0.4 2
3 0.6 3
4 0.8 4
5 1 5
6 1.2 6
7 1.4 7
8 1.6 8
9 1.8 9
10 2 10
11 2.2 11
12 2.4 12
13 2.6 13
14 2.8 14
15 3 15
16 3.2 16
17 3.4 17
18 3.6 18
19 3.8 19
20 4 20
21 4.2 21
22 4.4 22
23 4.6 23
24 4.8 24
25 5 25
26 5.2 26
27 5.4 27
28 5.6 28
29 5.8 29
30 6 30
31 6.2 31
32 6.4 32
33 6.6 33
34 6.8 34
35 7 35
36 7.2 36
37 7.4 37
38 7.6 38
39 7.8 39
40 8 40
41 8.2 41
42 8.4 42
43 8.6 43
44 8.8 44
45 9 45
46 9.2 46
47 9.4 47
48 9.6 48
49 9.8 49
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Creating and Adding Maps to RavTrack PC

Creating and Finding Map Images

All GPS Tracking software programs need some source of image files to overlay the position of the things being tracked.  The Internet provides a rich source of map images, and this page identifies some of the better sources.  If you find others, please let us know about them. 

RavTrack PC GPS Tracking Software by Raveon uses uses map files stored in the “.maplib” format.  This format was developed by Franson for display geo-referenced map images.   Virtually any type of image may be converted to a “.maplib” file, using the built-in calibration tool within RavTrack PC.   Images or maps that are in the  .jpg, .tiff, .bmp, and .gif file format may be converted.  Aditionally, any file in the “.geotiff” file format may be inported as a .maplib file, and the calibration in the .geotiff file will be used.

Below are some links to websites that provide map imagery for GPS tracking use. 

Topographic Maps in .geotiff format

Low-cost topo  maps, pre-calibrated in .geotiff format.  

Map Image Service

Digital Data Services Inc. provides custom map service.  Contact them if you would like them to create a custom map image for your location.  Remember to ask for the file in .geotiff format, so that you do not have to calibrate it when using it with RavTrack PC. 

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M7 Firmware Updating

Overview

This Technical Brief describes how to upload firmware into the RV-M7 transceiver. The RV-M7 series transceivers utilize a Phillips ARM-based Microprocessor with internal FLASH memory.

All RV-M7-GX series transceiver use an LPC2136 processor, which has 256kB of flash memory.

Phillips Semiconductor provides a utility to upload firmware into the microprocessor. Their program is called “LPC2000 Flash Utility” This utility may be used in the field to upload new firmware into the RV-M7 series transceivers.

Procedure

1.0 Uploading Firmware

1. Extract the .zip files if the firmware update was supplied in .zip format.

2. Open the Philips Flash Utility Installation.exe file inside the LPC21xx folder. The version must be V2.2.3 or higher. Version 2.2.3 is available <here>. Walk through the installation steps to install the Philips Flash Utility program. The Utility program should open when the installation is complete. The Utility program window is shown below.

Philips Flash Utility

3. Select the appropriate COM port from the Connected To Port pull-down menu.

4. Set the baud rate to 19200 from the Use Baud Rate pull-down menu.

5. Set the XTAL Freq (kHz) to 20000.

6. Select the appropriate file to upload to the modem. The file name will end in a .hex extension.

7. Remove the four Phillips panhead screws securing the modem’s rear panel to the housing. You don’t need to disconnect the SMA GPS cable from the rear panel.

8. Carefully remove the rear panel from the modem housing. The internal SMA GPS cable has a 2” service loop to allow access to the modem’s CONFIG button. The CONFIG button location is shown below.

configbutton

9. Set a DC power supply for +12VDC. Set the power supply output OFF.

10. Connect the PC serial port to the modem’s DB9 front panel connector.

11. Connect the modem’s green 2-pin power connector to the power supply.

12. Press and hold the modem CONFIG button. Set the power supply output to ON, wait approximately 2 seconds, and release the CONFIG button. If these steps were performed correctly the modem’s current draw should be approximately 30mA.

13. Press the Read Device ID button on the Philips Utility program window to establish communication with the modem. A reset message saying “Please reset your LPC2000 board now and then press OK!” will appear. DO NOT RESET POWER TO THE MODEM. Press the OK button. A “Read Part ID Successfully” message will appear in the lower left corner of the Flash Utility program window.

Note: When the Read Device ID button is pressed the Utility program may display a “Cannot communicate with test board!” message. Disregard this message. Press the OK button and press the Read Device ID button again to establish communications with the modem.

14. Press the Upload to Flash button on the Philips Utility program window to upload the 2F700GXB5.hex file to the modem’s flash memory. The Utility program will display a “File Upload Successfully Completed” in the lower left corner when the file upload is completed.

15. Repeat steps 7 through 14 for any additional units.

2.0 Configuring the Modem

1. Close the Philips Flash Utility program.

2. Open a terminal program with port settings of 8 data bits, no parity, 1 stop bit, and flow control off. The bps setting will depend on the previous modem configuration of the ATBD setting. For modem ID: 0001 and 0002 set the bps setting to 38400 and for modem ID: 0003 set the bps setting to 4800.

3. Set a DC power supply for +12VDC.

4. Connect the PC serial port to the modem’s DB9 front panel connector.

5. Connect the modem’s green 2-pin power connector to the power supply.

6. Type “+++” on the terminal program to enter the modem’s configuration mode.

7. Configure the product per the user manual.

Upgrading to version B10 Firmware

Version B10 introduced a number of new features and parameters in the M7 radio. Because these new features have parameters stored in EEPROM, the new features must be manually initialized on radios that have a previous version of the firmware. Any radio with a current firmware version less than B10, must have the following commands executed. If the firmware in the radio is already B10 or higher, you will not need to do the following commands.

Once the version B10 (or higher) firmware has been loaded into the radio, execute the following commands:

Set the radio back to factory defaults

AT&F <enter>

Set the group code to 0

ATGP 0 <enter>

Set the charge pump current

CPUMP 13<enter>

Set the channel frequency

ATFX xxx.xxxx<enter> All previously stored frequencies were probably erased with B10

Recalibrate RSSI

AT$A 340<enter> The A/D reading at -100dBm

AT$B 530<enter> The A/D reading at -70dBm

If the radio is a –GX version (GPS )

GPS&F<enter>

GPS X <enter> where X is the desired GPS mode of operation

SLOTQTY 1<enter> Set the number of tdma slots to 1 .

Re-calibrate RF power output calibration

AT$P xx <enter> adjust XX value so that the RF power output is correct. Use a wattmeter connected to the M7 to read the power. Monitor the current craw, and ensure it does not exceed 2.8A.

AT$R -10 PA temperature compensation.

Upgrading to Version B24 Firmware

Since B10, a number of new features and parameters in the M7 radio. Because these new features have parameters stored in EEPROM, the new features need to be initialized before the radio will work. Normally, this is done at the factory, but it you are upgrading the firmware in the field, you should execute the following commands after you have uploaded B24 into your radio.

Your MUST execute the following commands, based upon the firmware version you were upgrading from.

FREEWHEEL 120 (Only if your radio has a GPS and is a –GX version)

TDMADATA 0 (Only if your radio has a GPS and is a –GX version)

SLOTNUM -1 (Only if your radio has a GPS and is a –GX version)

ATJF 3000 Set the hardware flow control threshold.

Upgrading to Version C2 Firmware

Since B24, a number of new features and parameters in the M7 radio. Because these new features have parameters stored in EEPROM, the new features need to be initialized before the radio will work. Normally, this is done at the factory, but it you are upgrading the firmware in the field, you should execute the following commands after you have uploaded C2 into your radio.

Your MUST execute the following commands, based upon the firmware version you were upgrading from.

BANDL xxx Set the lower end of the band, in MHz. For example if your radio is a 450-470Mhz radio, the BANDL must be BANDL 450.

BANDH xxx Set the uppder end of the radio band, in MHz.

PASSWORD 0 Disables the user password feature introduced in version C of the firmware.

CPUMPL 0 Charge pump compensation at low end of the band.

CPUMPH 0 Charge pump compensation at the high end of the band.

ATCD -113 Set the carrier detect threshold to -113dBm.

Re-calibrate RF power output calibration

AT$P xx <enter> adjust XX value so that the RF power output is correct. Use a wattmeter connected to the M7 to read the power. Monitor the current craw, and ensure it does not exceed 2.8A.

AT$R -10 PA temperature compensation.

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M7 I/O Connections

The M7’s I/O Connector

On the front of the M7 series of transponders, is an Input / output (I/O) connector used to configure the unit.  This I/O connector supports RS232 serial data (422 optionally), as well as digital input and output.

The RS232 9-pin serial I/O connector is a female 9-pin D-subminiature connector having the following pins configuration. It is pinned out so that it may be plugged directly into a computer or PC’s 9-pin COM port.

db9
DB9 Female I/O connector

Front-view of DB-9 connector on modem (female)

Pin

Name

Dir

Function

Level / Specification

1

CD

out

Carrier detect

If enabled, indicates presence of carrier. Logical 0 (+ voltage on RS-232) means carrier is present. If disabled, it is asserted (0) whenever the modem is operational, and not in the configuration mode. It will be a 1 when the modem is in the configuration mode.

2

RxD

out

Receive data

Data out of the modem.

3

TxD

in

Transmit data
or
IN2

Data into the modem.

Also used as digital input IN2 for exception reporting. GND or floating for a 0, >3V for digital 1. If enabled for digital inputs, the serial data entering this pin is ignored (except in the command mode). Use the TRIGBITS command to set which bits are used as inputs.

4

DTR

in

Data terminal ready
or
IN0

Normally ignored by the RV-M7 modem. May control the power-state of the modem in low-power mode if this feature is enabled.

Also used as digital input IN0 for exception reporting. GND or floating for a 0, >3V for digital 1. Use the TRIGBITS command to set which bits are used as inputs.

5

GND

Ground connection

Signal and power ground

6

DSR

out

Data Set Ready

Normally is set to 0 when modem is powered on and running. Modem sets to a 1 when in low-power mode.

7

RTS

in

Request to send
or
IN1

Used to stop/start the flow of data coming out of the modem TxD pin. 0 = OK to send, 1 = don’t send. Leave disconnected if not used.

Also used as digital input IN1 for exception reporting. GND or floating for a 0, >3V for digital 1. Use the TRIGBITS command to set which bits are used as inputs.

8

CTS

out

Clear to send

Used to stop the flow of data going into the RxD pin from the device connected to the RV-M7. 0 = OK to send, 1 = don’t send. If the RV-M7 cannot accept more data, it will negate this signal (set to a 1).

9

Power

In/out

DC power (not ring signal)

User may supply the DC power to the modem on this pin.

Note: RS-232 signals use positive and negative voltages to represent digital 1s and 0s. A positive voltage is a 0, and a negative voltage is a digital 1.

This I/O pin-out allows the M7 to be directly plugged into a PC computer’s 9-pin serial port using a conventional 9-pin RS-232 serial cable. To connect it to a modem, or peripheral that has a serial port, you will need a “null-modem” cable.

Null Modem Cables

Sometimes, a “Null Modem” cable may be required to connect the M7 modem to another device. The specific connections are very dependent upon the type of hardware and handshaking used, but the following sections should help in configuring a null-modem cable.

How to use the handshaking lines in a null modem configuration? The simplest way is to don’t use them at all. In that situation, only the data lines and signal ground are cross connected in the null modem communication cable. All other pins have no connection. An example of such a null modem cable without handshaking can be seen in the figure below.

nullmodem
Simple Null-Modem Wiring Diagram

(Same wiring for male-to-male or female-to-femal cable)

Connector 1

Connector 2

Function

2

3

Rx

Tx

3

2

Tx

Rx

5

5

Signal ground

If you are connecting your M7 to a Lowrance or Garmin GPS display, then you will need a null-modem cable to connect the M7 to the display. Lowrance provides a serial cable for its GPSs with “pigtail” wires, so you can solder your own DB9 male connector to it, and plug the Lowrance directly into the M7.

To connect a Garmin GPS, use a null-modem cable to connect it to the M7, or the supplied Garmin serial cable and a “Null Modem Adaptor”.

Digital Inputs

The M7 GX Transponder has 3 digital inputs, called Trigger Bits. Trigger Bits are digital inputs that trigger the M7 GX to report its position and status. Normally these inputs are used for RS-232 signals, but they may be used for general-purpose digital inputs. The M7 GX may be configured to trigger a position/status report based upon the digital input bits state.

Important: If the digital input function is not needed, the TRIGBITS setting must be set to 0. This is the factory-default setting, and unexpected transmission may happen if the digital inputs are enabled and not used.

The status of all digital inputs is transmitted every time the unit reports its position.  This is not dependent upon how the TRIGBITS paramter is set. Each transmission, all digital input status is sent.

Starting with firmware version C2 and higher, the digital inputs have “memory” if they are enabled with the TRIGBITS command.  If you enable a bit or bits with the TRIGBITS command so that it triggers high, then the M7 will remember that a bit goes high if it does so, even momentarily.  For example, if a TRIGBIT bit goes high and then quickly goes back low, the M7 will remember this, and the next time it reports its position, will report the bit as “High”, even if it is low. Subsequent position transmissions will report it low, until it goes high again. If a bit is not configured as a TRIGBIT, then the M7 will report the state of the bit at the moment the GPS position is transmitted.

If you are not using digital inputs to initiate a transmission, the TRIGBITS should be set to 0. (TRIGBITS 0 command)

If the RV-M7 GX was configured to transmit less-often when it is not moving, activation of the digital inputs will override this causing the unit to report at the interval programmed with the TXRATE command. The digital inputs may be configured to be active high, active low, or active on a change in state. The following table lists the available digital inputs on the standard RV-M7 GX:

RS-232 Pin

Function

4 – DTR

Input 0

7 – RTS

Input 1

3 – TXD

Input 2

5 – Ground

GND

There are 3 commands that must be configured to use the digital inputs:

TRIGBITS x This command enables or disables individual bits for use as input triggers.

TRIGPOL x Sets the polarity of the input. 0=active high, 1=inverted, active low.

TRIGEX x Sets which bits are used to report on exception. Exception reporting is when a position/status report is generated when an input changes either low-to-high or high-to-low.

The xx parameter is the hex binary representation of the bits. Refer to the following table to see the value for x.

IN 2
(TXD)

IN 1
(RTS)

IN 0
(DTR)

Hexadecimal Representation

0

0

0

0

0

0

1

1

0

1

0

2

0

1

1

3

1

0

0

4

1

0

1

5

1

1

0

6

1

1

1

7

For example, to enable bits 0 and 2 (DTR and TxD pins) to be used as digital input, issue the following commend:

TRIGBITS 5

If the bits are to be normally active high, then the polarity must be set to 0 (TRIGPOL 0 command). To set bit 0 so that it is inverted (active low), use the following command:

TRIGPOL 1

This will cause the unit to transmit when bit 0 (DTR pin) is low.

To enable exception reporting, that is transmit when a pin changes from low-to-high or high-to-low, use the TRIGEX command. When TRIGEX is 0, all inputs are active either high or low. When a bit is set to 1 in TRIGEX, then that bit will cause the unit to transmit position/status anytime it changes state.

For example, to configure the unit to transmit position when bit 0 changes state, issue these commands:

TRIGBITS 1 (enables bit 0)

TRIGEX 1 (configures bit 0 for exception reporting)

To configure all bits to be used to report when they change, issue these commands:

TRIGBITS 7 (enables bit 0, 1 and 2)

TRIGEX 7 (configures bit 0, 1, and 2 for exception reporting)

To configure bit 0 to be used to report when it changes, bit 1 to cause a report when it goes low, and disable bit 2, use these commands.

TRIGBITS 3 (enables bit 0 and 1, disable 2)

TRIGEX 1 (configures bit 0 for exception reporting)

TRIGPOL 2 (configures bit 1 for active-low reporting)

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The $PRAVE Message Format

Overview

GPS tracking over-the-air position/status messages that the GPS transceiver and the Atlas Personal Locator may receive are sent out the serial port using Raveon’s tracking message format called the $PRAVE message. The $PRAVE message is structured like NMEA messages, and is used to pass the tracked item’s ID, location, speed, direction, altitude, temperature, and status.  The $PRAVE message format is the default message format when the GPS transponder is configured for GPS mode 2.

All GPS transponders made by Raveon utilize the $PRAVE message format, and have many other format options.

Structured like a standard NMEA GPS message, the $PRAVE message contains a rich set of location and status information. The $PRAVE message is sent out the serial port of the radio, each time the radio receives a position message over-the-air.

There are a total of 19 or 20 fields. The Odometer field is optional. If there are 19 total fields, the odometer value is not in the message. If there are 20 total fields, then the Odometer reading is present.  If you are parsing this message in software, continue parsing until you find the field with the *. If this is field 18, then there is no odometer reading. If it is field 19, then there is an odometer reading. 

Please note, the $PRAVE message is not transmitted over-the-air.  Raveon transmits GPS tracking information over-the-air in a highly compressed form of the data held in the $PRAVE message.  When an transponder ore base radio receives this over-the-air position/status report, the received information is decompressed and the data is sent  out the serial port, in one of a number different formats. One of these formats is this $PRAVE message. Other options are the NMEA $GPWPL message and the $GPTLL message. These are covered in the user manual for the M7 GX radio transponder. Raveon’s M6, M8, M21, M22 radio modems all can utilize $PRAVE messages for outputting tracking information.

$PRAVE Message Format

The $PRAVE message is sent out the RV-M7 GX when it is configured for GPS 2 mode of operation.This mode is typically used with the RavTrack PC program, or other computer programs that can process position and status information.GPS mode 2 instructs that the output be sent at 38.4K bytes/second out the serial port.

Along with ID and position information, the $PRAVE contains a host of other status information.The length of this message may exceed he standard NMEA limit of 79 characters.Any product or software that uses this message must take this into account.

Following is a list of the fields sent in this message

Field

Usage

Comments

1

$PRAVE

Raveon’s $PRAVE message Header text

2

From ID

The ID of the transponder that transmitted its position over the air. It is a hexadecimal (base 16) value.*

3

To ID

The ID that this position report was sent to. It is a hexadecimal (base 16) value.*

4

Latitude

dddmm.mmmm format. It is signed. + is north, – is south.No sign means north. Note: typically there are 4 decimal places, but as few as 0 decimal places are possible. Null field if no GPS lock.

5

Longitude

dddmm.mmmm format. It is signed. + is east, – is west.No sign means east. Note: typically there are 4 decimal places, but as few as 0 decimal places are possible. Null field if no GPS lock.

6

UTC time

The UTC time at the time the transmission was made.Hhmmss format. Null field if no GPS lock.

7

GPS Status

0=not valid position.> 0 is valid GPS.  1=GPS locked and valid position, 2=GPS locked with WAAS corrections applied

8

Num Satellites

The number of satellites in view

9

Altitude

The altitude in meters.Null field if no GPS lock.

10

Temperature

The internal temperature of the RV-M7 in degrees C. Typically this is 5-20 degrees above ambient.

11

Voltage

Input voltage to the device that sent this position.

12

IO status

A decimal number representing the binary inputs.

13

RSSI

The signal-strength of this message as measured by the receiver, in dBm. Note, if the message went through a repeater, it is the signal lever of the repeated message.

14

Speed

The speed of the device in km/hour, 0-255

15

Heading

The heading of the device 0-359 degrees.

16

Alerts

Alert codes for alerts currently indicated in the device.NULL means no alerts. Not all transponders support sending or receiving all of these alert codes.
“P” means a proximity alert.
“A”means alert.
“C” means critical alert,

“D” signifies the alert was acknowledged, set by ACK 1 command.
“N” means no motion alert,
“M” means man-down.
“T” Tamper alert or battery removed.
“I” Impact alert
“V” Vibration alert
“S” Service required

17

Spare

A spare field.May be used for UTC date in the future. Typically NULL.
18 (opt)

Odometer

 The odometer reading if available. It is in kilometers and may or may not have decimal places. Most values will have are one decimal place. NULL/empty/missing if reading is not available or transponder did not send it.

18 or 19

*

The “*” NMEA end-of-message identifier.

19 of 20

Checksum

The NMEA 0183 checksum.

 *For use certain AVL solutions including RavTrack PC this field requires a decimal value.

Example Sentence:

No Odometer Value Sent:

$PRAVE,0001,0001,3308.9051,-11713.1164,195348,1,10,168,31,13.3,3,-83,0,0,,*66

This example shows a unit at 33° 8.9051 north latitude and 117° 13.1164 east longitude.It is not moving (0 speed).Its signal strength was -83dBm.Its altitude is 168 meters.

For your curiosity or testing purposes, below is a capture of vehicle 0003 driving around the Raveon office in Vista, California.

$PRAVE,0003,0001,3308.9077,-11713.1259,154656,1,8,200,24,11.6,0,-69,0,0,,*76
$PRAVE,0003,0001,3308.9082,-11713.1262,154716,2,8,199,24,11.6,0,-64,0,0,,*7C
$PRAVE,0003,0001,3308.9084,-11713.1267,154736,2,8,198,24,11.6,0,-64,0,0,,*7C
$PRAVE,0003,0001,3308.9092,-11713.1288,154756,2,9,198,24,11.6,0,-61,4,298,,*52
$PRAVE,0003,0001,3308.9225,-11713.1239,154816,2,8,195,25,11.6,0,-62,8,18,,*65
$PRAVE,0003,0001,3308.9418,-11713.1146,154836,2,9,190,26,11.6,0,-85,3,14,,*6D
$PRAVE,0003,0001,3308.9532,-11713.1314,154842,2,9,186,26,11.6,0,-96,38,294,,*65
$PRAVE,0003,0001,3308.9654,-11713.1665,154846,2,9,182,26,11.6,0,-102,61,292,,*53
$PRAVE,0003,0001,3308.8880,-11713.1500,155010,2,9,179,29,11.6,0,-86,19,40,,*5B
$PRAVE,0003,0001,3308.9120,-11713.1327,155030,2,9,183,30,11.6,0,-72,1,206,,*57
$PRAVE,0003,0001,3308.9116,-11713.1304,155050,2,9,191,31,11.6,0,-71,0,0,,*7C

The latest Tech Notes for the $PRAVE Data Format can be found here.

$PRAVE Message With Odometer Value Sent:

$PRAVE,0845,0001,3815.0856,-8537.1406,090023,2,10,173,25,14.2,0,-88,92,4,,,1595.2*71

This example shows a unit at 38° 15.0856 north latitude and -85° 37.1406 east longitude.It is moving at 92km/h. The electronic odometer reading for in the transponder of the vehicle is 1595.2km.

$PRAVE,0739,0001,3808.4727,-8538.2088,090013,2,10,200,25,13.2,0,-107,0,0,,,1143.1*7C
$PRAVE,0281,0001,3808.4750,-8538.2567,090022,1,9,199,25,13.1,0,-110,0,0,,,1934.9*41
$PRAVE,0845,0001,3815.0856,-8537.1406,090023,2,10,173,25,14.2,0,-88,92,4,,,1595.2*71$PRAVE,0314,0001,3811.5857,-8547.6362,090024,2,10,145,25,13.2,0,-88,0,0,,,1381.5*45$PRAVE,0739,0001,3808.4726,-8538.2088,090058,2,10,200,25,13.2,0,-106,0,0,,,1143.1*73$PRAVE,0281,0001,3808.4750,-8538.2568,090107,1,9,199,25,13.1,0,-111,0,0,,,1934.9*49$PRAVE,0845,0001,3815.6565,-8537.3903,090108,2,10,178,25,14.3,0,-91,90,354,,,1596.3*7C
$PRAVE,0314,0001,3811.5856,-8547.6362,090109,2,9,145,25,13.2,0,-88,0,0,,,1381.5*72$PRAVE,0739,0001,3808.4727,-8538.2088,090143,2,10,200,25,13.2,0,-107,0,0,,,1143.1*78$PRAVE,0281,0001,3808.4753,-8538.2569,090152,1,10,199,25,13.1,0,-116,0,0,,,1934.9*74$PRAVE,0845,0001,3816.2283,-8537.6356,090153,2,10,180,25,14.3,0,-103,89,326,,,1597.4*43

The latest Tech Notes for the $PRAVE Data Format can be found here.

 

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Quick Updating of RavTrack PC 2.3 to 2.7

It is possible to upgrade RavTrack PC from version 2.3 – 2.6 to version 2.7 by simply replacing the RavTrackPC.exe file in the program directory on your computer. This avoids having to perform a full re-install of the RavTrack PC software when simply upgrading to the current version.
Click on the link below to download a copy of the latest .exe file:
http://ravtrack.com/downloads/RavTrackPCexe.zip

Once you download it to your computer, open the .zip folder by double-clicking on it.  Copy the RavTrack.exe file your RavTrack PC program directory. For most users the full path to this file is:

C:/programfiles/raveon/ravtrackpc/ravtrackpc.exe
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About This GPS Tracking Blog

This site is a web log for information about Raveon’s Real-Time GPS Tracking system called RavTrack.  It is a repository full of usefull information about GPS tracking technology, and particularily real-time tracking using VHF/UHF radio technology. 

Users of Raveon’s GPS tracking system are welcome to post helpful information about the products or their systems, or simply highlight projects they use Raveon’s real-time GPS tracking systems in.