RTKLib源码

源码解读，自己总结，自己看看

1?代码整体框架

1.1 RTK算法结构体

1.1.1?rtklib.h?头文件

该头文件定义了所使用到的常量、结构体、函数声明等，在其他源代码中均有使用

rnx2rtkp.c等有使用

关于PI的定义，弧度转化等

结构体的定义

函数声明

1.1.2?gtime_t? 结构体? 时间结构

typedef struct {? ? ? ?
? ? time_t time; ? ? ? ?/*（秒）有符号 64 位整数数据类型*/
? ? double sec; ? ? ? ? /*?时间的(秒)小数部分*/
} gtime_t; ?

1.1.3?obsd_t??

用来存储某个历元中的某个卫星的观测值

typedef struct {? ? ? ??
? ? gtime_t time; ? ? ? /*?接收机所用时间 */
? ? unsigned char sat,rcv;?
? ? unsigned char SNR [NFREQ+NEXOBS]; /* 信噪比，信号强度*/
? ? unsigned char LLI [NFREQ+NEXOBS]; /* loss of lock indicator */
? ? unsigned char code[NFREQ+NEXOBS]; /* code indicator (CODE_???) 卫星编码*/
? ? double L[NFREQ+NEXOBS]; /* observation data carrier-phase (cycle) ?载波*/
? ? double P[NFREQ+NEXOBS]; /* observation data pseudorange (m) 伪距*/
? ? float ?D[NFREQ+NEXOBS]; /* observation data doppler frequency (Hz) 多普勒*/
} obsd_t;

CODE?卫星编码，rtklib将GPS/GLONASS/BDS等卫星统一进行的编码

1.1.4?obs_t 结构体

该结构体存储的是所有的观测值数据。与上面的"obsd_t"呼应

typedef struct {? ? ? ?
? ? int n,nmax; ? ? ? ? /* number of obervation data/allocated */
? ? obsd_t *data; ? ? ? /* observation data records */
} obs_t;

n代表实际存储的观测值结构体的个数，nmax代表的是最多存储多少个观测值结构体，如果超过最大个数，需要重新开辟内存空间。

1.1.5? nav_t?星历数据结构体

存全部的星历数据，历书数据、精密星历、TEC格网、广播星历电离层参数、DGPS、SSR改正等信息

typedef struct {        /* navigation data type */
    int n,nmax;         /* number of broadcast ephemeris */
    int ng,ngmax;       /* number of glonass ephemeris */
    int ns,nsmax;       /* number of sbas ephemeris */
    int ne,nemax;       /* number of precise ephemeris */
    int nc,ncmax;       /* number of precise clock */
    int na,namax;       /* number of almanac data */
    int nt,ntmax;       /* number of tec grid data */
    int nn,nnmax;       /* number of stec grid data */
    eph_t *eph;         /* GPS/QZS/GAL ephemeris */
    geph_t *geph;       /* GLONASS ephemeris */
    seph_t *seph;       /* SBAS ephemeris */
    peph_t *peph;       /* precise ephemeris */
    pclk_t *pclk;       /* precise clock */
    alm_t *alm;         /* almanac data */
    tec_t *tec;         /* tec grid data */
    stec_t *stec;       /* stec grid data */
    erp_t  erp;         /* earth rotation parameters */
    double utc_gps[4];  /* GPS delta-UTC parameters {A0,A1,T,W} */
    double utc_glo[4];  /* GLONASS UTC GPS time parameters */
    double utc_gal[4];  /* Galileo UTC GPS time parameters */
    double utc_qzs[4];  /* QZS UTC GPS time parameters */
    double utc_cmp[4];  /* BeiDou UTC parameters */
    double utc_sbs[4];  /* SBAS UTC parameters */
    double ion_gps[8];  /* GPS iono model parameters {a0,a1,a2,a3,b0,b1,b2,b3} */
    double ion_gal[4];  /* Galileo iono model parameters {ai0,ai1,ai2,0} */
    double ion_qzs[8];  /* QZSS iono model parameters {a0,a1,a2,a3,b0,b1,b2,b3} */
    double ion_cmp[8];  /* BeiDou iono model parameters {a0,a1,a2,a3,b0,b1,b2,b3} */
    int leaps;          /* leap seconds (s) */
    double lam[MAXSAT][NFREQ]; /* carrier wave lengths (m) */
    double cbias[MAXSAT][3];   /* code bias (0:p1-p2,1:p1-c1,2:p2-c2) (m) */
    double wlbias[MAXSAT];     /* wide-lane bias (cycle) */
    double glo_cpbias[4];    /* glonass code-phase bias {1C,1P,2C,2P} (m) */
    char glo_fcn[MAXPRNGLO+1]; /* glonass frequency channel number + 8 */
    pcv_t pcvs[MAXSAT]; /* satellite antenna pcv */
    sbssat_t sbssat;    /* SBAS satellite corrections */
    sbsion_t sbsion[MAXBAND+1]; /* SBAS ionosphere corrections */
    dgps_t dgps[MAXSAT]; /* DGPS corrections */
    ssr_t ssr[MAXSAT];  /* SSR corrections */
    lexeph_t lexeph[MAXSAT]; /* LEX ephemeris */
    lexion_t lexion;    /* LEX ionosphere correction */
} nav_t;//所有星历总的结构体

1.1.6 sol_t：结果结构体

定位/解算结果的参数

typedef struct {        
    gtime_t time;       //GPST时间
    double rr[6];       /* 位置、速度结果 (m|m/s) */
                        /* {x,y,z,vx,vy,vz} or {e,n,u,ve,vn,vu} */
    float  qr[6];       /* 位置估计协方差阵 (m^2) */
                        /* {c_xx,c_yy,c_zz,c_xy,c_yz,c_zx} or */
                        /* {c_ee,c_nn,c_uu,c_en,c_nu,c_ue} */
    float  qv[6];       /* 速度估计协方差阵 (m^2/s^2) */
    double dtr[6];      /* receiver clock bias to time systems (s) */
    uint8_t type;       /* type (0:xyz-ecef,1:enu-baseline) */
    uint8_t stat;       /* solution status (SOLQ_???) */
    uint8_t ns;         //有效卫星数
    float age;          //差分龄期
    float ratio;        //模糊度固定Ratio值
    float thres;        //模糊度固定的Ratio阈值
} sol_t;

SOLQ?参数，定位模式的选择，解的类型状态

1.1.7 eph_t

存储了卫星星历中的卫星参数，主要是开普勒参数

typedef struct {        /* GPS/QZS/GAL broadcast ephemeris type */
    int sat;            /* satellite number */
    int iode,iodc;      /* IODE,IODC */
    int sva;            /* SV accuracy (URA index) */
    int svh;            /* SV health (0:ok) */
    int week;           /* GPS/QZS: gps week, GAL: galileo week */
    int code;           /* GPS/QZS: code on L2, GAL/CMP: data sources */
    int flag;           /* GPS/QZS: L2 P data flag, CMP: nav type */
    gtime_t toe,toc,ttr; /* Toe,Toc,T_trans */
                        /* SV orbit parameters */
    double A,e,i0,OMG0,omg,M0,deln,OMGd,idot;
    double crc,crs,cuc,cus,cic,cis;
    double toes;        /* Toe (s) in week */
    double fit;         /* fit interval (h) */
    double f0,f1,f2;    /* SV clock parameters (af0,af1,af2) */
    double tgd[4];      /* group delay parameters */
                        /* GPS/QZS:tgd[0]=TGD */
                        /* GAL    :tgd[0]=BGD E5a/E1,tgd[1]=BGD E5b/E1 */
                        /* CMP    :tgd[0]=BGD1,tgd[1]=BGD2 */
    double Adot,ndot;   /* Adot,ndot for CNAV */
} eph_t;

1.1.8?prcopt_t?配置存储

算法处理选项结构体

typedef struct {        /* processing options type  处理类型 */
    int mode;           /* positioning mode (PMODE_???)  单点定位/基线啥的 处理类型 */
    int soltype;        /* solution type (0:forward 前向,1:backward 后向,2:combined 都有) */
    int nf;             /* number of frequencies (1:L1,2:L1+L2,3:L1+L2+L5) 处理频率*/
    int navsys;         /* navigation system */
    double elmin;       /* elevation mask angle (rad) 高度截至角 */
    snrmask_t snrmask;  /* SNR mask 信噪比*/
    int sateph;         /* satellite ephemeris/clock (EPHOPT_???) 星历的配置*/
    int modear;         /* AR mode (0:off,1:continuous,2:instantaneous,3:fix and hold,4:ppp-ar) 模糊度固定模式*/
    int glomodear;      /* GLONASS AR mode (0:off,1:on,2:auto cal,3:ext cal) */
    int bdsmodear;      /* BeiDou AR mode (0:off,1:on) */
    int maxout;         /* obs outage count to reset bias */
    int minlock;        /* min lock count to fix ambiguity */
    int minfix;         /* min fix count to hold ambiguity */
    int ionoopt;        /* ionosphere option (IONOOPT_???) */
    int tropopt;        /* troposphere option (TROPOPT_???) */
    int dynamics;       /* dynamics model (0:none,1:velociy,2:accel) */
    int tidecorr;       /* earth tide correction (0:off,1:solid,2:solid+otl+pole) */
    int niter;          /* number of filter iteration */
    int codesmooth;     /* code smoothing window size (0:none) */
    int intpref;        /* interpolate reference obs (for post mission) */
    int sbascorr;       /* SBAS correction options */
    int sbassatsel;     /* SBAS satellite selection (0:all) */
    int rovpos;         /* rover position for fixed mode */
    int refpos;         /* base position for relative mode */
                        /* (0:pos in prcopt,  1:average of single pos, */
                        /*  2:read from file, 3:rinex header, 4:rtcm pos) */
    double eratio[NFREQ]; /* code/phase error ratio */
    double err[5];      /* measurement error factor */
                        /* [0]:reserved */
                        /* [1-3]:error factor a/b/c of phase (m) */
                        /* [4]:doppler frequency (hz) */
    double std[3];      /* initial-state std [0]bias,[1]iono [2]trop */
    double prn[5];      /* process-noise std [0]bias,[1]iono [2]trop [3]acch [4]accv */
    double sclkstab;    /* satellite clock stability (sec/sec) */
    double thresar[4];  /* AR validation threshold */
    double elmaskar;    /* elevation mask of AR for rising satellite (deg) */
    double elmaskhold;  /* elevation mask to hold ambiguity (deg) */
    double thresslip;   /* slip threshold of geometry-free phase (m) */
    double maxtdiff;    /* max difference of time (sec) */
    double maxinno;     /* reject threshold of innovation (m) */
    double maxgdop;     /* reject threshold of gdop */
    double baseline[2]; /* baseline length constraint {const,sigma} (m) */
    double ru[3];       /* rover position for fixed mode {x,y,z} (ecef) (m) */
    double rb[3];       /* base position for relative mode {x,y,z} (ecef) (m) */
    char anttype[2][MAXANT]; /* antenna types {rover,base} */
    double antdel[2][3]; /* antenna delta {{rov_e,rov_n,rov_u},{ref_e,ref_n,ref_u}} */
    pcv_t pcvr[2];      /* receiver antenna parameters {rov,base} */
    unsigned char exsats[MAXSAT]; /* excluded satellites (1:excluded,2:included) */
    char rnxopt[2][256]; /* rinex options {rover,base} */
    int  posopt[6];     /* positioning options */
    int  syncsol;       /* solution sync mode (0:off,1:on) */
    double odisp[2][6*11]; /* ocean tide loading parameters {rov,base} */
    exterr_t exterr;    /* extended receiver error model */
} prcopt_t;

1.1.9?输出文件结构体

设置输出结果的格式

typedef struct {        /* solution options type 输出文件类型，例如有哪些要输出、用哪个椭球体*/
    int posf;           /* solution format (SOLF_???) */
    int times;          /* time system (TIMES_???) */
    int timef;          /* time format (0:sssss.s,1:yyyy/mm/dd hh:mm:ss.s) */
    int timeu;          /* time digits under decimal point */
    int degf;           /* latitude/longitude format (0:ddd.ddd,1:ddd mm ss) */
    int outhead;        /* output header (0:no,1:yes) */
    int outopt;         /* output processing options (0:no,1:yes) */
    int datum;          /* datum (0:WGS84,1:Tokyo) */
    int height;         /* height (0:ellipsoidal,1:geodetic) */
    int geoid;          /* geoid model (0:EGM96,1:JGD2000) */
    int solstatic;      /* solution of static mode (0:all,1:single) */
    int sstat;          /* solution statistics level (0:off,1:states,2:residuals) */
    int trace;          /* debug trace level (0:off,1-5:debug) */
    double nmeaintv[2]; /* nmea output interval (s) (<0:no,0:all) */
                        /* nmeaintv[0]:gprmc,gpgga,nmeaintv[1]:gpgsv */
    char sep[64];       /* field separator */
    char prog[64];      /* program name */
} solopt_t;

1.1.10?ssat_t?卫星状态控制结构体（过程信息）

typedef struct {        /* satellite status type */
    uint8_t sys;         //卫星导航系统
    uint8_t vs;          //有效卫星单一标志
    double azel[2];      //方位角，高度角
    double resp[NFREQ];  //伪距残差
    double resc[NFREQ];  //载波相位残差
    uint8_t vsat[NFREQ]; //有效卫星标志
    uint16_t snr[NFREQ]; //信噪比
    uint8_t fix [NFREQ]; //模糊度的状态，浮点解、固定解
    uint8_t slip[NFREQ]; /* cycle-slip flag */          
    uint8_t half[NFREQ]; /* half-cycle valid flag */
    int lock [NFREQ];   /* lock counter of phase */
    uint32_t outc [NFREQ]; //载波中断计数
    uint32_t slipc[NFREQ]; /* cycle-slip counter */
    uint32_t rejc [NFREQ]; /* reject counter */
    double gf[NFREQ-1]; /* geometry-free phase (m) */
    double mw[NFREQ-1]; /* MW-LC (m) */
    double phw;         /* phase windup (cycle) */
    gtime_t pt[2][NFREQ]; /* previous carrier-phase time */
    double ph[2][NFREQ]; /* previous carrier-phase observable (cycle) */
} ssat_t;

1.1.11?rtk_t：rtk控制结构体

typedef struct {        /* RTK control/result type */
    sol_t  sol;			//结果结构体                         
    double rb[6];        //基准站位置、速度
    int nx,na;         	 //na为除模糊度外参数数、nx为加上模糊度参数数
    double tt;           //当前历元和先前历元时间差
    double *x, *P;       //浮点解和协方差
    double *xa,*Pa;      //固定解和协方差
    int nfix;            //number of continuous fixes of ambiguity
    ambc_t ambc[MAXSAT]; //模糊度控制结构体数组
    ssat_t ssat[MAXSAT]; //卫星状态控制结构体数组
    int neb;             //错误信息的缓冲区长度
    char errbuf[MAXERRMSG];//错误信息缓冲区
    prcopt_t opt;        //处理选项
} rtk_t;

1.2?satno()?卫星编码函数

按照HPS、GLONASS、GAL等卫星依次往后编号

extern int ?satno ? (int sys, int prn);

extern int satno(int sys, int prn)
{
    if (prn<=0) return 0;
    switch (sys) {
        case SYS_GPS:
            if (prn<MINPRNGPS||MAXPRNGPS<prn) return 0;
            return prn-MINPRNGPS+1; //如果是GPS的X卫星，重新编号就是...
        case SYS_GLO:
            if (prn<MINPRNGLO||MAXPRNGLO<prn) return 0;
            return NSATGPS+prn-MINPRNGLO+1; //如果是GLOSS的X卫星，在GPS卫星基础上编号，续
        case SYS_GAL:
            if (prn<MINPRNGAL||MAXPRNGAL<prn) return 0;
            return NSATGPS+NSATGLO+prn-MINPRNGAL+1;
        case SYS_QZS:
            if (prn<MINPRNQZS||MAXPRNQZS<prn) return 0;
            return NSATGPS+NSATGLO+NSATGAL+prn-MINPRNQZS+1;
        case SYS_CMP:
            if (prn<MINPRNCMP||MAXPRNCMP<prn) return 0;
            return NSATGPS+NSATGLO+NSATGAL+NSATQZS+prn-MINPRNCMP+1;
        case SYS_LEO:
            if (prn<MINPRNLEO||MAXPRNLEO<prn) return 0;
            return NSATGPS+NSATGLO+NSATGAL+NSATQZS+NSATCMP+prn-MINPRNLEO+1;
        case SYS_SBS:
            if (prn<MINPRNSBS||MAXPRNSBS<prn) return 0;
            return NSATGPS+NSATGLO+NSATGAL+NSATQZS+NSATCMP+NSATLEO+prn-MINPRNSBS+1;
    }
    return 0;
}

参数16进制向二进制转换有规律

#define SYS_NONE    0x00                /* navigation system: none */
#define SYS_GPS     0x01                /* navigation system: GPS 1*/
#define SYS_SBS     0x02                /* navigation system: SBAS 10*/
#define SYS_GLO     0x04                /* navigation system: GLONASS 100*/
#define SYS_GAL     0x08                /* navigation system: Galileo 1000*/
#define SYS_QZS     0x10                /* navigation system: QZSS 16^1=16 10000*/
#define SYS_CMP     0x20                /* navigation system: BeiDou */
#define SYS_IRN     0x40                /* navigation system: IRNSS */
#define SYS_LEO     0x80                /* navigation system: LEO */
#define SYS_ALL     0xFF                /* navigation system: all */

1.3?rtkpos()?接口调用逻辑

该函数处理的是单个历元的所有卫星观测值数据，实现单历元定位，我们需要多次调用处理全部数据。我们在VS中查看调用层级

Main( )函数中调用postpos( )函数，postpos( )调用execses_b( )进行基准站的处理，基准站下遍历每个流动站(execses_r)，数据处理使得对应的基准站和流动站结合起来，将处理好结合的流动站/基准站数据进行调用execses( )函数进行定位，procpos( )遍历基准站/流动站每个历元，每个历元数据使用rtkpos( )进行处理实现单历元定位