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DShannon
06-14-2005, 06:21 AM
Does anyone know if it is possible to get readings from the Garmin 18 GPS in text? So that I can use Jon's program:

http://forums.parallax.com/forums/attach.aspx?a=1767

The specs on the Garmin 18 say that it can output NEMA and Garmin proprietary format...I am assuming the "proporitetary format" is the text output string.

If this is true, would I need to programmatically configure the 18 to send text? if so, how?

Thanks for any assistance!

-Dan

Jon Williams
06-14-2005, 07:30 AM
Looks like you'll need to get protocol specs from Garmin.

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Jon Williams
Applications Engineer, Parallax

Charlie Johnson
06-14-2005, 09:34 PM
Both NMEA 0183, and the Garmin proprietary sentences are text outputs. NMEA 0183 start with $G, and the Garmin one's start with $P

David B
06-15-2005, 02:34 AM
here are some examples

$GPRMC,194155,A,3755.7438,N,12202.6972,W,000.0,000 .0,180503,015.4,E*63
$PGRMT,GPS 25-LVC VER 2.50 ,P,P,L,R,P,C,30,R*43
$GPGGA,194155,3755.7438,N,12202.6972,W,1,03,2.3,32 7.4,M,-27.4,M,,*74

David

PLJack
06-15-2005, 03:06 AM
David B said...
here are some examples

$GPRMC,194155,A,3755.7438,N,12202.6972,W,000.0,000 .0,180503,015.4,E*63
$PGRMT,GPS 25-LVC VER 2.50 ,P,P,L,R,P,C,30,R*43
$GPGGA,194155,3755.7438,N,12202.6972,W,1,03,2.3,32 7.4,M,-27.4,M,,*74

David


I found this link invaluable during my GPS research.
Glenn Baddeley - GPS - NMEA sentence information
home.mira.net/%7Egnb/gps/nmea.html (http://home.mira.net/%7Egnb/gps/nmea.html)





eg2. $GPRMC,225446,A,4916.45,N,12311.12,W,000.5,054.7,1 91194,020.3,E*68
225446 Time of fix 22:54:46 UTC
A Navigation receiver warning A = Valid position, V = Warning
4916.45,N Latitude 49 deg. 16.45 min. North
12311.12,W Longitude 123 deg. 11.12 min. West
000.5 Speed over ground, Knots
054.7 Course Made Good, degrees true
191194 UTC Date of fix, 19 November 1994
020.3,E Magnetic variation, 20.3 deg. East
*68 mandatory checksum



$PGRMC,1,2,3,4,5,6,7,8,9,10,11,12,13,14*HH

1 = Fix mode (A=Automatic, 2=2D exclusively; host system must supply altitude, 3=3D exclusively)
2 = Altitude above/below mean sea level, metres
3 = Earth datum index. If the user datum index is specified (96), fields 4 to 8 must contain valid values, otherwise they must be blank.
4 = Semi-major axis, metres, 0.001 metre resolution
5 = Inverse flattening factor, 285 to 310, 10e-9 resolution
6 = Delta X earth centred coordinate, metres, -5000 to 5000, 1 metre resolution
7 = Delta Y earth centred coordinate, metres, -5000 to 5000, 1 metre resolution
8 = Delta Z earth centred coordinate, metres, -5000 to 5000, 1 metre resolution
9 = Differential mode (A=Automatic; output DGPS fixes when available otherwise non-DGPS, D=Only output differential fixes)
10 = NMEA 0183 baud rate (1=1200, 2=2400, 3=4800, 4=9600, 5=19200, 6=300, 7=600)
11 = Velocity filter (0=None, 1=Automatic, 2-255=Filter time constant; seconds)
12 = PPS mode (1=None, 2=1 Hertz)
13 = PPS pulse length, N = 0 to 48. Length (milliseconds) = (N+1)*20
14 = Dead reckoning valid time, 1 to 30, seconds
HH = Checksum



eg1. $GPGGA,170834,4124.8963,N,08151.6838,W,1,05,1.5,28 0.2,M,-34.0,M,,,*75

Name Example Data Description
Sentence Identifier $GPGGA Global Positioning System Fix Data
Time 170834 17:08:34 UTC
Latitude 4124.8963, N 41d 24.8963' N or 41d 24' 54" N
Longitude 08151.6838, W 81d 51.6838' W or 81d 51' 41" W
Fix Quality:
- 0 = Invalid
- 1 = GPS fix
- 2 = DGPS fix 1 Data is from a GPS fix
Number of Satellites 05 5 Satellites are in view
Horizontal Dilution of Precision (HDOP) 1.5 Relative accuracy of horizontal position
Altitude 280.2, M 280.2 meters above mean sea level
Height of geoid above WGS84 ellipsoid -34.0, M -34.0 meters
Time since last DGPS update blank No last update
DGPS reference station id blank No station id
Checksum *75 Used by program to check for transmission errors

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Jack