 const long maxTimeSyncAge = (long)( 0.5 + maxTimeTol / xtalTol );
 const long rotorUpdateInterval = 200000;
 const float deg2rad = 3.1415927 / 180.0;
+const float rEarth = 6.371e6; // meters
+const float deg2m = 1.124E5; // meters/deg on great circle at msl
+const float m2rad = 1.5696E-7; // radians/m on great circle at msl
+const float knots2mps = 0.51444444; // m/s
+const float ft2m = 0.3048; //  m
 /*
  * Set addresses of EEPROM parameters 
  */

int aprsIndex = 0;
boolean aprsRdy, aprsChkFlg, aprsErrFlg, aprsBufCurrent, aprsValid;
boolean aprsFlg, aprsNewFlg;
long aprsTime, lastAprsTime; // standard time in seconds with decimal fraction to ms
float aprsLat, aprsLon, aprsAlt, aprsVg, aprsHdg;
float lastAprsAlt; // needed to keep track of prior value to calculate Vz

char term[TERMLEN], aprsfiBuf[APRSFILEN], cmdBuf[CMDLEN];
int termIndex = 0;

boolean targetValid;

long  targetTime; 
float targetLon; //lon radians
float targetLat; //lat radians
double targetAlt; //alt meters
float targetVlon; // rad/s
float targetVlat; // rad/s
float targetValt; // m/s

float targetAz;
float targetEl;

Aprs aprsObj = Aprs( "WB9SKY,KC9LIG,KC9LHW" );

