Import code to generate RRLP ephemeris data from u-blox GPS receiver
taken from http://www.246tnt.com/files/rrlp-20091101.tar.bz2
diff --git a/gps.h b/gps.h
new file mode 100644
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--- /dev/null
+++ b/gps.h
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+/*
+ * gps.h
+ *
+ * Header to deal with low level GPS data
+ *
+ *
+ * Copyright (C) 2009 Sylvain Munaut <tnt@246tNt.com>
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program. If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#ifndef __GPS_H__
+#define __GPS_H__
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+#include <stdint.h>
+
+
+#define MAX_SV 64
+
+
+/* Ionosperic model data */
+struct gps_ionosphere_model {
+ /* #bits Scale factor Effective Units */
+ /* (LSB) range */
+
+ int alpha_0; /* s 8 2^-30 seconds */
+ int alpha_1; /* s 8 2^-27 s / semi-circles */
+ int alpha_2; /* s 8 2^-24 s / (semi-circles)^2 */
+ int alpha_3; /* s 8 2^-24 s / (semi-circles)^3 */
+ int beta_0; /* s 8 2^11 seconds */
+ int beta_1; /* s 8 2^14 s / semi-circles */
+ int beta_2; /* s 8 2^16 s / (semi-circles)^2 */
+ int beta_3; /* s 8 2^16 s / (semi-circles)^3 */
+};
+
+
+/* UTC model data */
+struct gps_utc_model {
+ /* #bits Scale factor Effective Units */
+ /* (LSB) range */
+
+ int a0; /* s 32 2^-30 seconds */
+ int a1; /* s 24 2^-50 seconds / seconds */
+ int delta_t_ls; /* s 8 1 seconds */
+ int t_ot; /* u 8 2^12 602,112 seconds */
+ int wn_t; /* u 8 1 weeks */
+ int wn_lsf; /* u 8 1 weeks */
+ int dn; /* u 8 1 7 days */
+ int delta_t_lsf;/* s 8 1 seconds */
+};
+
+
+/* Almanach data */
+struct gps_almanac_sv {
+ int sv_id;
+ int sv_health;
+
+ /* #bits Scale factor Effective Units */
+ /* (LSB) range */
+
+ int e; /* u 16 2^-21 */
+ int t_oa; /* u 8 2^12 602,112 seconds */
+ int ksii; /* s 16 2^-19 semi-circles */
+ int omega_dot; /* s 16 2^-38 semi-circles / s */
+ int a_powhalf; /* u 24 2^-11 meters */
+ int omega_0; /* s 24 2^-23 semi-circles */
+ int w; /* s 24 2^-23 semi-circles */
+ int m_0; /* s 24 2^-23 semi-circles */
+ int a_f0; /* s 11 2^-20 seconds */
+ int a_f1; /* s 11 2^-38 seconds / seconds */
+};
+
+struct gps_almanac {
+ int wna;
+ int n_sv;
+ struct gps_almanac_sv svs[MAX_SV];
+};
+
+
+/* Ephemeris data */
+struct gps_ephemeris_sv {
+ int sv_id;
+
+ /* #bits Scale factor Effective Units */
+ /* (LSB) range */
+
+ int code_on_l2; /* u 2 1 / */
+ int week_no; /* u 10 1 week */
+ int l2_p_flag; /* u 1 1 / */
+ int sv_ura; /* u 4 / / */
+ int sv_health; /* u 6 / / */
+ int t_gd; /* s 8 2^-31 seconds */
+ int iodc; /* u 10 / / */
+ int t_oc; /* u 16 2^4 604,784 seconds */
+ int a_f2; /* s 8 2^-55 sec / sec^2 */
+ int a_f1; /* s 16 2^-43 sec / sec */
+ int a_f0; /* s 22 2^-31 seconds */
+
+ int c_rs; /* s 16 2^-5 meters */
+ int delta_n; /* s 16 2^-43 semi-circles / s */
+ int m_0; /* s 32 2^-31 semi-circles */
+ int c_uc; /* s 16 2^-29 radians */
+ unsigned int e; /* u 32 2^-33 0.03 / */
+ int c_us; /* s 16 2^-29 radians */
+ unsigned int a_powhalf; /* u 32 2^-19 meters^(1/2) */
+ int t_oe; /* u 16 2^4 604,784 seconds */
+ int fit_flag; /* u 1 / / */
+
+ int c_ic; /* s 16 2^-29 radians */
+ int omega_0; /* s 32 2^-31 semi-circles */
+ int c_is; /* s 16 2^-29 radians */
+ int i_0; /* s 32 2^-31 semi-circles */
+ int c_rc; /* s 16 2^-5 meters */
+ int w; /* s 32 2^-31 semi-circles */
+ int omega_dot; /* s 24 2^-43 semi-circles / s */
+ int idot; /* s 14 2^-43 semi-circles / s */
+
+ int _rsvd1; /* 23 bits */
+ int _rsvd2; /* 24 bits */
+ int _rsvd3; /* 24 bits */
+ int _rsvd4; /* 16 bits */
+ int aodo; /* 8 bits Not sure it needs to be here ... */
+};
+
+struct gps_ephemeris {
+ int n_sv;
+ struct gps_ephemeris_sv svs[MAX_SV];
+};
+
+
+/* All assist data */
+#define GPS_FIELD_IONOSPHERE (1<<0)
+#define GPS_FIELD_UTC (1<<1)
+#define GPS_FIELD_ALMANAC (1<<2)
+#define GPS_FIELD_EPHEMERIS (1<<3)
+
+struct gps_assist_data {
+ int fields;
+ struct gps_ionosphere_model ionosphere;
+ struct gps_utc_model utc;
+ struct gps_almanac almanac;
+ struct gps_ephemeris ephemeris;
+};
+
+
+/* GPS Subframe utility methods (see gps.c for details) */
+int gps_unpack_sf123(uint32_t *sf, struct gps_ephemeris_sv *eph);
+int gps_unpack_sf45_almanac(uint32_t *sf, struct gps_almanac_sv *alm);
+
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif /* __GPS_H__ */
+