Change fit_interval to seconds for GLONASS

Author: ljbade

include/libswiftnav/almanac.h

@@ -47,7 +47,7 @@ typedef struct {
   gnss_signal_t sid; /**< Signal ID. */
   gps_time_t toa;    /**< Reference time of almanac. */
   float ura;         /**< User range accuracy [m] */
-  u8 fit_interval;   /**< Curve fit interval [hours] */
+  u32 fit_interval;  /**< Curve fit interval [s] */
   u8 valid;          /**< Almanac is valid. */
   u8 healthy;        /**< Satellite health status. */
   union {

include/libswiftnav/ephemeris.h

@@ -69,7 +69,7 @@ typedef struct {
   gnss_signal_t sid; /**< Signal ID. */
   gps_time_t toe;    /**< Reference time of ephemeris. */
   float ura;         /**< User range accuracy [m] */
-  u8 fit_interval;   /**< Curve fit interval [hours] */
+  u32 fit_interval;  /**< Curve fit interval [s] */
   u8 valid;          /**< Ephemeris is valid. */
   u8 healthy;        /**< Satellite health status. */
   union {
@@ -89,12 +89,10 @@ s8 calc_sat_doppler(const ephemeris_t *e, const gps_time_t *t,
                     const double ref[3], double *doppler);
 
 u8 ephemeris_valid(const ephemeris_t *e, const gps_time_t *t);
-u8 ephemeris_params_valid(const u8 valid, const u8 fit_interval,
+u8 ephemeris_params_valid(const u8 valid, const u32 fit_interval,
                       const gps_time_t* toe, const gps_time_t *t);
 u8 satellite_healthy(const ephemeris_t *e);
 
-float decode_ura_index(const u8 index);
-u8 decode_fit_interval(u8 fit_interval_flag, u16 iodc);
 void decode_ephemeris(u32 frame_words[3][8], ephemeris_t *e);
 bool ephemeris_equal(const ephemeris_t *a, const ephemeris_t *b);
 

python/tests/test_almanac.py

@@ -43,7 +43,7 @@ def test_almanac_functions():
     'sid': {'sat': 1, 'code': 0},
     'toa': {'tow': 233472.0, 'wn': 814,},
     'ura': 900.0,
-    'fit_interval': 144,
+    'fit_interval': 144 * 60 * 60,
     'valid': 1,
     'healthy': 1,
     'kepler': {

python/tests/test_ephemeris.py

@@ -19,7 +19,7 @@ def test_sat_state():
   eph = e.Ephemeris(**{'sid': {'sat': 17, 'code': 0,},
                        'toe': {'wn': 1867, 'tow': 518400.0,},
                        'ura': 2.0,
-                       'fit_interval': 4,
+                       'fit_interval': 4 * 60 * 60,
                        'valid': 1,
                        'healthy': 1,
                        'kepler': {
@@ -71,7 +71,7 @@ def test_sat_state():
   eph = e.Ephemeris(**{'sid': {'sat': 17, 'code': 0},
                      'toe': { 'wn': 1867, 'tow': 518400.0,},
                      'ura': 2.0,
-                     'fit_interval': 4,
+                     'fit_interval': 4 * 60 * 60,
                      'valid': 1,
                      'healthy': 0,
                      'kepler': {'crs': 25.125,
@@ -102,7 +102,7 @@ def test_sat_state():
   eph = e.Ephemeris(**{'sid': {'sat': 17, 'code': 0},
                      'toe': { 'wn': 1867, 'tow': 518400.0,},
                      'ura': 2.0,
-                     'fit_interval': 4,
+                     'fit_interval': 4 * 60 * 60,
                      'valid': 0,
                      'healthy': 0,
                      'kepler': {'crs': 25.125,
@@ -133,7 +133,7 @@ def test_sat_state():
   eph = e.Ephemeris(**{'sid': {'sat': 17, 'code': 0},
                          'toe': { 'wn': 1867, 'tow': 518400.0,},
                          'ura': 2.0,
-                         'fit_interval': 6,
+                         'fit_interval': 6 * 60 * 60,
                          'valid': 1,
                          'healthy': 1,
                          'kepler': {'crs': 25.125,

src/almanac.c

@@ -234,8 +234,8 @@ u8 almanac_valid(const almanac_t *a, const gps_time_t *t)
 
   /* TODO: this doesn't exclude almanacs older than a week so could be made
    * better. */
-  /* If dt is greater than fit_interval / 2 hours our ephemeris isn't valid. */
-  if (fabs(dt) > ((u32)a->fit_interval / 2) * 60 * 60) {
+  /* If dt is greater than fit_interval / 2 seconds our ephemeris isn't valid. */
+  if (fabs(dt) > ((u32)a->fit_interval / 2)) {
     return 0;
   }
 

src/ephemeris.c

@@ -22,6 +22,9 @@
 #include <libswiftnav/ephemeris.h>
 #include <libswiftnav/coord_system.h>
 
+float decode_ura_index(const u8 index);
+u32 decode_fit_interval(u8 fit_interval_flag, u16 iodc);
+
 /** \defgroup ephemeris Ephemeris
  * Functions and calculations related to the GPS ephemeris.
  * \{ */
@@ -320,13 +323,13 @@ u8 ephemeris_valid(const ephemeris_t *e, const gps_time_t *t)
  * The function allows to avoid passing whole ephemeris
  *
  * \param valid ephemeris Valid flag after decoding
- * \param fit_interval Curve fit interval in hours
+ * \param fit_interval Curve fit interval in seconds
  * \param toe Time from ephemeris reference epoch
  * \param t The current GPS time. This is used to determine the ephemeris age
  * \return 1 if the ephemeris is valid and not too old.
  *         0 otherwise.
  */
-u8 ephemeris_params_valid(const u8 valid, const u8 fit_interval,
+u8 ephemeris_params_valid(const u8 valid, const u32 fit_interval,
                       const gps_time_t* toe, const gps_time_t *t)
 {
   assert(t != NULL);
@@ -353,8 +356,8 @@ u8 ephemeris_params_valid(const u8 valid, const u8 fit_interval,
 
   /* TODO: this doesn't exclude ephemerides older than a week so could be made
    * better. */
-  /* If dt is greater than fit_interval / 2 hours our ephemeris isn't valid. */
-  if (fabs(dt) > ((u32)fit_interval / 2) * 60 * 60) {
+  /* If dt is greater than fit_interval / 2 seconds our ephemeris isn't valid. */
+  if (fabs(dt) > ((u32)fit_interval / 2)) {
     return 0;
   }
 
@@ -415,10 +418,10 @@ float decode_ura_index(const u8 index) {
 *
 * \param fit_interval_flag The curve fit interval flag. 0 is 4 hours, 1 is >4 hours.
 * \param iodc The IODC value.
-* \return the curve fit interval in hours.
+* \return the curve fit interval in seconds.
 */
-u8 decode_fit_interval(u8 fit_interval_flag, u16 iodc) {
-  u8 fit_interval = 4;
+u32 decode_fit_interval(u8 fit_interval_flag, u16 iodc) {
+  u8 fit_interval = 4; /* This is in hours */
 
   if (fit_interval_flag) {
     fit_interval = 6;
@@ -438,7 +441,7 @@ u8 decode_fit_interval(u8 fit_interval_flag, u16 iodc) {
     }
   }
 
-  return fit_interval;
+  return fit_interval * 60 * 60;
 }
 
 /** Decode ephemeris from L1 C/A GPS navigation message frames.