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. “D” signifies the alert was acknowledged, set by ACK 1 command. |
|
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. |
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.