christian b / GPS

Mbed library to handle GPS data reception and parsing

Dependents:   GPS_U-blox_NEO-6M_Code

Features

  • All positionning parameters are contained into a global data structure.
  • Automatic nema string parsing and data structure update.
    • GSA,GGA,VTG and RMC
  • Convert latitude and longitude to decimal value.
  • Converts latittude,longitude and altitude to ECEF coordinates.

Planed developement

  • Test library for RTOS use.
  • Complete the nema parsing decoders (couple of parameters are not parsed yet and not present in the data structure).
  • Add conversion tool to get ENU coordinates.

Diff: defines/WGS84.h

Revision:
0:0c1aa5906cef
diff -r 000000000000 -r 0c1aa5906cef defines/WGS84.h
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/defines/WGS84.h	Wed Aug 06 01:37:39 2014 +0000
@@ -0,0 +1,34 @@
+/*   
+     a   the equatorial earth radius
+     f   the "flattening" parameter ( = (a-b)/a ,the ratio of the
+         difference between the equatorial and polar radii to a;
+         this is a measure of how "elliptical" a polar cross-section
+         is).
+
+        The eccentricity e of the figure of the earth is found from
+    
+        e^2 = 2f - f^2 ,  or  e = sqrt(2f-f^2) .
+*/
+//For WGS84, 
+
+#define A   6378137.0
+#define RF  298.257224
+#define F   1/RF
+#define E   sqrt(2*f-f^2)
+
+ /*
+         a   = 6378137 meters
+       (1/f) = 298.257224
+
+(the reciprocal of f is usually given instead of f itself, because the
+reciprocal is so close to an integer)
+
+Given latitude (geodetic latitude, not geocentric latitude!), compute
+
+                                  1
+        C =  ---------------------------------------------------
+             sqrt( cos^2(latitude) + (1-f)^2 * sin^2(latitude) )
+
+and
+        S = (1-f)^2 * C .
+*/
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