ogr_structs.h

The OpenGPSRec receiver software runs on the real time operating system RTAI-Linux. It compiles with

         ms_count;          // millisecond counter, 0,...,5999, synch'd to subframe start
  float  CN0;               // signal to noise ratio
} CHANNEL;

// --- correlator GP2021 channel info (statistical/visual info) ---
typedef struct 
{
  long   cod_frq,           // carrier frequency DCO
         car_frq,           // code frequency DCO
         i_prompt_20ms,     // I prompt avg'ed over 20 ms
         q_prompt_20ms,     // Q prompt avg'ed over 20 ms
         i_dith_20ms,       // I dither avg'ed over 20 ms
         q_dith_20ms;       // Q dither avg'ed over 20 ms  
  float  carrierErr,
         codeErr;
  UINT16 ch,                // which channel are we talking about?
         missed,            // total number of missed accumulations
         code_phase,        // phase in 1/2 chip increments (GP2021 slew register)
         code_dco_phase;    // code phase in 1/1024 of a 1/2 chip increments
  INT16  i_prompt,          // in-phase prompt arm
         q_prompt,          // quad-phase promt arm
         i_dith,            // in-phase early/late arm
         q_dith,            // quad-phase early/late arm
         prn,               // which PRN to use for correlation
         sourceSel;         // which RF front end to use (0 or 1)
} CHN_INFO;

// --- chanel info ring buffer ---
typedef struct
{
  INT16      ch_head,           // index of last written element, -1 : not yet written to
             leadch,            // monosat mode: master channel
             watchdog;          // ogr still alive?
  CHN_INFO   chan[CHN_RBUF_LEN];
} CHN_RBUF;

// --- nav message info ---
typedef struct
{
  INT16 idx,                         // pointer to next element
        sf_id,                       // subframe id: 1,...,5
        subframe_full;               // read 300 bits, now decode
  unsigned long subframe[11],        // 10 word a 24 data bits (index : 1,...,10 !)
                subframe_parity[11], // 10 word a 30 bits, bit 30 & 31 copy
                subframe_buffer[11]; // ring buffer
                                     // bit 0 & 1 from previous word
} NAVMSG;

// --- data required for navigation fix ---
typedef struct
{
  unsigned long tow_tic_count[NOFCHN],
                tow_1s[NOFCHN];
  INT16         epoch[NOFCHN],
                code_phase[NOFCHN], 
                code_dco_phase[NOFCHN], 
                carr_dco_phase[NOFCHN], 
                carr_cycle_lo[NOFCHN], 
                carr_cycle_hi[NOFCHN];
  int           perform_navfix;
} NAVDATA;

//  control parameters, available to both, user- and rt-module
typedef struct
{
  long          magic,
                mod_loaded,
                frq_step,
                acq_thresh,
                code_corr,
                pul_cod_c1, // PLL parameter pull_in
                pul_cod_c3, // c3 = c1+c2
                pul_car_c1, // carrier, pull-in
                pul_car_c3, 
                trk_cod_c1, // code, tracking
                trk_cod_c3, 
                trk_car_c1, // carrier, tracking
                trk_car_c3; 
  unsigned long tow_tic_count;     // time of week in units of 0.1 sec
  int           user_watch_flag;   // user prg still running?
  INT16         search_min_f,
                search_max_f,
                confirm_above_thresh_max, // acq confirmed if in 'confirm_above_thresh_max'
                confirm_count_max, // out of 'confirm_count_max' DUMPs above threshold
                pull_in_count_max, // ch_pull_in() timer
                align_count_max,   // ch_align() timer
//                phase_test,
                trans,             // transition to other mode at next DUMP
                rt_polling,        // polling active in RT module
                accum_new,
                accum_missed,
                monosat_slew,      // +1(-1) : shift +1(-1) halfchip
                leadch,            // MONOSAT mode: # of leading channel
                sec_flag,          // indicate: 1 sec passed
                min_flag,          // indicate: 1 min passed
                earlylate,         // -1 : early, +1 : late
                monosat_cod_ofs[NOFCHN];
  UINT16        nav_tic;
} RT_CTRL;

//  control parameters, available to user land prg only
typedef struct
{
  INT16         gps_week,
                cold_prn,
                almanac_valid,
                status,
                nof_trk;       // number of tracked sats
  unsigned long almanac_read;
  double        mask_angle,
                nav_upd,
                clock_offset,
                pul_cod_dampratio, // PLL parameter (pull_in)
                pul_cod_loopgain,
                pul_cod_bandwidth,
                pul_car_dampratio,
                pul_car_loopgain,
                pul_car_bandwidth,
                trk_cod_dampratio, // PLL parameter (tracking)
                trk_cod_loopgain,
                trk_cod_bandwidth,
                trk_car_dampratio,
                trk_car_loopgain,
                trk_car_bandwidth;
} CTRL;

// broadcast ionospheric delay model
typedef struct
{
  double b0, b1, b2, b3,
         al0, al1, al2, al3;       
} IONO;

// broadcast UTC data
typedef struct
{
  double a0, a1, 
         tot, 
         WNt, 
         dtls, 
         WNlsf, 
         DN, 
         dtlsf; 
} UTC;

// dilution of precision
typedef struct
{
  double hdop,         // horizontal dilution 
         vdop,         // vertical dilution
         tdop,         // time dilution
         pdop,         // position dilution of precision
         gdop;         // geometric dilution of precision (rss of pdop & tdop)
} DOPS;

/*
 * tracking is in one the following states
 * 'follow_monosat' : correlator follows channel 'trackch'
 */
enum 
{ 
  off,            // 0
  initialize,     // 1 initialize channel
  acquisition,    // 2 acquire signal
  confirm,        // 3 confirm acq signal
  pull_in,        // 4 pull in tracking loops
  align,          // 5 align to nav bit boundaries
  track,          // 6 track signal
  track_monosat,  // 7 master channel (MONOSAT mode)
  follow_monosat, // 8 slave channel follow master channel
  track_riseset,  // 9 master channel (rising/setting mode)
  follow_riseset  // a slave channel follow master channel
};

enum 
{ 
  mode_coldstart,  // start with no almanac info
  mode_warmstart,  // we have almanac information
  mode_tracking,   // valid receiver position found
  mode_navigate,   // valid receiver position found
  mode_monosat,    // all correlators track one satellite
  mode_riseset     // as 'mode_monosat', however schedule events as well
};

enum 
{ 
  none,           // do nothing
  trans2navigate, // transition to navigation mode
  trans2monosat,   // transition to monosat mode
  trans2riseset   // transition to riseset mode
};

#endif

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