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Compute speed in kts. Speed is linear, but relative to earth centered

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coordinates.
This commit is contained in:
curt 2005-08-29 03:06:42 +00:00
parent c8c6fe4fe6
commit 7473730b85
2 changed files with 23 additions and 1 deletions
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3
utils/GPSsmooth/MIDG-II.cxx
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@ -258,6 +258,9 @@ void MIDGTrack::parse_msg( const int id, char *buf, MIDGpos *pos, MIDGatt *att )
vely = (int32_t)read_swab( buf, 20, 4 );
velz = (int32_t)read_swab( buf, 24, 4 );
// cout << " vel = " << velx << "," << vely << "," << velz << endl;
double vel_cms = sqrt( velx*velx + vely*vely + velz*velz );
double vel_ms = vel_cms / 100.0;
pos->speed_kts = vel_ms * SG_METER_TO_NM * 3600;
// flags
flags = (uint8_t)read_swab( buf, 28, 1 );

21
utils/GPSsmooth/MIDG_main.cxx
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@ -8,7 +8,9 @@
#include <plib/net.h>
#include <plib/sg.h>
#include <simgear/constants.h>
#include <simgear/io/lowlevel.hxx> // endian tests
#include <simgear/math/sg_geodesy.hxx>
#include <simgear/timing/timestamp.hxx>
#include <Network/net_ctrls.hxx>
@ -37,6 +39,7 @@ static string file = "";
// Master time counter
float sim_time = 0.0f;
double frame_us = 0.0f;
// sim control
SGTimeStamp last_time_stamp;
@ -45,6 +48,10 @@ SGTimeStamp current_time_stamp;
// altitude offset
double alt_offset = 0.0;
// for speed estimate
// double last_lat = 0.0, last_lon = 0.0;
// double kts_filter = 0.0;
bool inited = false;
@ -110,7 +117,19 @@ static void midg2fg( const MIDGpos pos, const MIDGatt att,
fdm->phidot = 0.0;
fdm->thetadot = 0.0;
fdm->psidot = 0.0;
// estimate speed
// double az1, az2, dist;
// geo_inverse_wgs_84( pos.altitude_msl, last_lat, last_lon,
// pos.lat_deg, pos.lon_deg, &az1, &az2, &dist );
// double v_ms = dist / (frame_us / 1000000);
// double v_kts = v_ms * SG_METER_TO_NM * 3600;
// kts_filter = (0.99 * kts_filter) + (0.01 * v_kts);
fdm->vcas = pos.speed_kts;
// last_lat = pos.lat_deg;
// last_lon = pos.lon_deg;
// cout << "kts_filter = " << kts_filter << " vel = " << pos.speed_kts << endl;
fdm->climb_rate = 0; // fps
// cout << "climb rate = " << aero->hdota << endl;
fdm->v_north = 0.0;
@ -396,7 +415,7 @@ int main( int argc, char **argv ) {
cout << "Track end time is " << end_time << endl;
cout << "Duration = " << end_time - current_time << endl;
double frame_us = 1000000.0 / hertz;
frame_us = 1000000.0 / hertz;
if ( frame_us < 0.0 ) {
frame_us = 0.0;
}