Customer Service Center

• PosApp (SimGEN / SimREPLAYplus / SimREPLAY)
• GPS navigation data

1. Go to menu [Options-->General Options]
2. Enable "Dump navigation data"
3. Run the scenario (normal speed or turbo speed)
4. For GPS legacy navigation data, PosApp creates a binary file called "Nav_dump.bin"

You can decode the binary file using the "GPS L1C/A Nav Data Extract" utility via menu [Tools-->General Utilities]
 

But to decode the binary file for yourself:-

1. The Nav_dump.bin file is essentially just a sequence of "records" each containing
       - the time into the run
       - the satellite id
       - the nav bits for a sub-frame of GPS Nav Data (6s).
2. A set of data "records" is written for all enabled GPS satellites every 6s in the run.
3. Each "record" is defined as follows:
                   struct Bin_nav_data
                   {
                       int run_time_secs_i;
                       unsigned char sat_id;
                       unsigned char nav_bits[60];
                   };
   
4. The file is opened as follows:
                   std::string &bin_file_name=< insert file name here (Nav_dump.bin) with path as required >;
                   FILE *in_file_ptr;
                   in_file_ptr = fopen( bin_file_name.c_str() );
   
5. Each sub-frame of nav data is read using:
                   Bin_nav_data data;
                   fread( &data, sizeof(data), 1, in_file_ptr );
   
6. The 60 bytes of the nav_bits array are in chronological order, i.e data.nav_bit[0] is transmitted first.
7. Each byte (char) of nav_bits contains 5 bits of Nav Data.
       - These occupy the MS locations such that bit7 is the first to be transmitted and bit 3 the last. (Bits 2 to 0 are unused).