基于RTKLIB 2.4.3.b34版本L1-L5双频定位解算

之前版本在配置文件中L1+L5的选项，但是并没有实现L1+L5双频结算功能，在2.4.3.b34版本中直接去掉L1+L5选项。

若想实现L1+L5双频解算可对2.4.3.b34版本进行略微改动（2.4.3.b34版本对数据读取部分进行了优化，实现L1+L5更方便）

实现L1+L5双频解算一般两种策略：

（1）在数据读取时，将L2与L5数值调换储存位置

（2）在数据处理时，在处理L2频率时，让其跳过

我选用的是第一种方法：在数据读取时，将L2与L5数值调换储存位置，（个人认为：方法（1）优点：不管什么定位模式，数据解算部分无需改动，都可以直接正常处理）

2.4.3.b34版本对设置信号索引函数 set_index() 进行了优化，使策略（1）实现L1+L5双频解算更加方便

/* set signal index ----------------------------------------------------------*/
static void set_index(double ver, int sys, const char *opt, char tobs[MAXOBSTYPE][4], sigind_t *ind)

只需改动两个地方，我为了方便直接设置了一个宏定义判断，在头文件中宏定义 ‘L5_TO_L2’ 即可处理L1+L5双频，不定义即可处理L1+L2双频

两处改动均在 rtkcmn.c文件中

改动1： 交换L2与L5储存位置索引

/* GPS obs code to frequency -------------------------------------------------
 *  改动前 */
static int code2freq_GPS(uint8_t code, double *freq)
{
    char *obs=code2obs(code);
    
    switch (obs[0]) {
        case '1': *freq=FREQ1; return 0; /* L1 */
        case '2': *freq=FREQ2; return 1; /* L2 */
        case '5': *freq=FREQ5; return 2; /* L5 */

    }
    return -1;
}
/* GPS obs code to frequency -------------------------------------------------
 * 改动后 */
static int code2freq_GPS(uint8_t code, double *freq)
{
    char *obs=code2obs(code);
    
    switch (obs[0]) {
        case '1': *freq=FREQ1; return 0; /* L1 */
#ifdef L5_TO_L2      /* 实现l1+l5 @Zhehua Yang */
        case '5': *freq=FREQ5; return 1; /* L5 */
        case '2': *freq=FREQ2; return 2; /* L2 */
#else
        case '2': *freq=FREQ2; return 1; /* L2 */
        case '5': *freq=FREQ5; return 2; /* L5 */
#endif
    }
    return -1;
}

改动2：交换L2与L5优先级索引

/** 改动前 */
static char codepris[7][MAXFREQ][16]={  /* code priority for each freq-index */
    /*    0         1          2          3         4         5     */
    {"CPYWMNSL","PYWCMNDLSX","IQX"     ,""       ,""       ,""      ,""}, /* GPS */
    {"CPABX"   ,"PCABX"     ,"IQX"     ,""       ,""       ,""      ,""}, /* GLO */
    {"CABXZ"   ,"IQX"       ,"IQX"     ,"ABCXZ"  ,"IQX"    ,""      ,""}, /* GAL */
    {"CLSXZ"   ,"LSX"       ,"IQXDPZ"  ,"LSXEZ"  ,""       ,""      ,""}, /* QZS */
    {"C"       ,"IQX"       ,""        ,""       ,""       ,""      ,""}, /* SBS */
    {"IQXDPAN" ,"IQXDPZ"    ,"DPX"     ,"IQXA"   ,"DPX"    ,""      ,""}, /* BDS */
    {"ABCX"    ,"ABCX"      ,""        ,""       ,""       ,""      ,""}  /* IRN */
};
/** 改动后 */
#ifdef L5_TO_L2
    static char codepris[7][MAXFREQ][16]={  /* code priority for each freq-index */
        /*    0         1          2          3         4         5     */
        {"CPYWMNSL","IQX"     ,"PYWCMNDLSX",""       ,""       ,""      ,""}, /* GPS */
        {"CPABX"   ,"IQX"     ,"PCABX"     ,""       ,""       ,""      ,""}, /* GLO */
        {"CABXZ"   ,"IQX"     ,"IQX"       ,"ABCXZ"  ,"IQX"    ,""      ,""}, /* GAL */
        {"CLSXZ"   ,"IQXDPZ"  ,"LSX"       ,"LSXEZ"  ,""       ,""      ,""}, /* QZS */
        {"C"       ,""        ,"IQX"       ,""       ,""       ,""      ,""}, /* SBS */
        {"IQXDPAN" ,"DPX"     ,"IQXDPZ"    ,"IQXA"   ,"DPX"    ,""      ,""}, /* BDS */
        {"ABCX"    ,""        ,"ABCX"      ,""       ,""       ,""      ,""}  /* IRN */
    };
#else
    static char codepris[7][MAXFREQ][16]={  /* code priority for each freq-index */
        /*    0         1          2          3         4         5     */
        {"CPYWMNSL","PYWCMNDLSX","IQX"     ,""       ,""       ,""      ,""}, /* GPS */
        {"CPABX"   ,"PCABX"     ,"IQX"     ,""       ,""       ,""      ,""}, /* GLO */
        {"CABXZ"   ,"IQX"       ,"IQX"     ,"ABCXZ"  ,"IQX"    ,""      ,""}, /* GAL */
        {"CLSXZ"   ,"LSX"       ,"IQXDPZ"  ,"LSXEZ"  ,""       ,""      ,""}, /* QZS */
        {"C"       ,"IQX"       ,""        ,""       ,""       ,""      ,""}, /* SBS */
        {"IQXDPAN" ,"IQXDPZ"    ,"DPX"     ,"IQXA"   ,"DPX"    ,""      ,""}, /* BDS */
        {"ABCX"    ,"ABCX"      ,""        ,""       ,""       ,""      ,""}  /* IRN */
    };
#endif

 

2.4.3.b34版本频率是用 code2freq_GPS() 这些函数得到的，因为在改动1中已经进行了改动，所以L5频点的频率与与观测值是对应关系无需进行其他改动。