$GPGGA,092750.000,5321.6802,N,00630.3372,W,1,8,1.03,61.7,M,55.2,M,,*76
$GPGSA,A,3,10,07,05,02,29,04,08,13,,,,,1.72,1.03,1.38*0A
$GPGSV,3,1,11,10,63,137,17,07,61,098,15,05,59,290,20,08,54,157,30*70
$GPGSV,3,2,11,02,39,223,19,13,28,070,17,26,23,252,,04,14,186,14*79
$GPGSV,3,3,11,29,09,301,24,16,09,020,,36,,,*76
$GPRMC,092750.000,A,5321.6802,N,00630.3372,W,0.02,31.66,280511,,,A*43
$GPGGA,092751.000,5321.6802,N,00630.3371,W,1,8,1.03,61.7,M,55.3,M,,*75
$GPGSA,A,3,10,07,05,02,29,04,08,13,,,,,1.72,1.03,1.38*0A
$GPGSV,3,1,11,10,63,137,17,07,61,098,15,05,59,290,20,08,54,157,30*70
$GPGSV,3,2,11,02,39,223,16,13,28,070,17,26,23,252,,04,14,186,15*77
$GPGSV,3,3,11,29,09,301,24,16,09,020,,36,,,*76
$GPRMC,092751.000,A,5321.6802,N,00630.3371,W,0.06,31.66,280511,,,A*45
$GPGGA is where the most important data for this project is contained, like:
Here is the full breakdown of a GGA record:
Example:
$GPGGA,123519,4807.038,N,01131.000,E,1,08,0.9,545.4,M,46.9,M,,*47
Where:
GGA - Global Positioning System Fix Data
123519 | Fix taken at 12:35:19 UTC |
4807.038,N | Latitude 48 deg 07.038' N |
01131.000,E | Longitude 11 deg 31.000' E |
1 | Fix quality: 0 = invalid |
1= GPS fix (SPS) | |
2 = DGPS fix | |
3 = PPS fix | |
4 = Real Time Kinematic | |
5 = Float RTK | |
6 = estimated | |
7 = Manual input mode | |
8 = Simulation mode | |
08 | Number of satellites being tracked |
0.9 | Horizontal dilution of position |
545.4,M | Altitude, Meters, above mean sea level |
46.9,M | Height of geoid (mean sea level) |
(empty field) | time in seconds since last DGPS update |
(empty field) | DGPS station ID number |
$GPRMC also contains a useful element for this project : Speed. We will be able to track the horizontal speed of the balloon at any given time.
Here is the full breakdown of an RMC record:
$GPRMC,123519,A,4807.038,N,01131.000,E,022.4,084.4,230394,003.1,W*6A
RMC - Recommended Minimum Sentence
Where:
123519 | Fix taken at 12:35:19 UTC |
A | Status A=active or V=Void. |
4807.038,N | Latitude 48 deg 07.038' N |
01131.000,E | Longitude 11 deg 31.000' E |
022.4 | Speed over the ground in knots |
084.4 | Track angle in degrees True |
230394 | Date - 23rd of March 1994 |
003.1,W | Magnetic Variation |
*6A | The checksum data, always begins with * |
More details of all sentences supported by the standard can be found here.
The Flex Module
The Flex Module translates the GPS sentence into our LLAP standard and transmits the data in the usual 12 character packet lengths. For example the following GPS sentence:
$GPGGA,123519,4807.038,N,01131.000,E,1,08,0.9,545.4,M,46.9,M,,*47
gets transmitted as follows:
a03$GPRMC,12
a033519,A,48
a0307.038,N,
a0301131.000
a03,E,022.4,
a03084.4,230
a03394,003.1
a03,W*6A----
Where:
a | Packet start character |
03 | the device ID of the radio module |
[9 chars] | The raw NMEA sentence broken down into 9 chars at a time |
For those of you familiar with LLAP the above will look familiar. Details of LLAP can be found in our wireless sensor manual.
Now we have the GPS coordinates delivered to the IoT gateway we are ready to proceed to the final step: the chase car scene! Type the GPS coordinates into a sat nav unit, or trusty Google maps and off we go.
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