Usage Instructions

This Python toolbox is designed for BDS PPP-B2b and Galileo HAS decoding. The key features of the NavDecoder are as follows:

1. Download tools for retrieving navigation and MGEX orbit/clock products.
2. Support for raw binary HAS data from Septentrio GNSS receivers. The system can be easily extended to support binary data from various manufacturers by extracting raw Galileo C/NAV data for input into the decoding function.
3. Support for B2b data from both Septentrio and Unicore GNSS receivers:
   • Septentrio provides raw binary format, which requires an LDPC decoder to recover plain corrections.
   • Unicore offers a plain ASCII format that can be directly processed to recover corrections.
4. Capability to save corrections in the BNC universal format.
5. Capability to save corrections in SP3 and CLK formats.
6. Provision of an archive for B2b and HAS corrections.

Main Functions

• Decoding the Septentrio HAS Binary format from the "GALRawCNAV" block: decode_HAS_sept.py
• Decoding the Septentrio B2b Binary format from the "BDSRawB2b" block: decode_B2B_sept.py
• Decoding the Unicor B2b Binary format from the "PPPB2bInfo" block: decode_B2B_UM982.py

Configuration for the decoding:

The configuration settings are located in the following section of the code:

# Start of configuration
max_orbit_delay = 300  # Maximum orbit delay in seconds
max_clock_delay = 30   # Maximum clock delay in seconds
start_date = datetime(2024, 5, 14)  # Start date for the process
process_days = 1  # Number of days to process
file_has_template = r'test_data\SEPT{}0.{}__SBF_GALRawCNAV.txt'  # Template for HAS files
nav_file_template = r'test_data\eph\BRDC00IGS_R_{}0000_01D_MN.rnx'  # Template for navigation files
corr_dir_template = r'test_data\SEPT{}_HAS'  # Directory for correction files
# End of configuration

You only need to modify the start date, processing duration, and file paths.

Directory Structure

• NavDecoder/B2b_HAS_decoder: Tools for decoding Septentrio B2b HAS data.
• NavDecoder/B2b_UM980_decoder: Tools for decoding Unicore B2b data.
• NavDecoder/bin: Contains binary executables for downloading GNSS products.
• NavDecoder/download: Contains scripts for downloading various GNSS data.
• NavDecoder/test_data: Example data for decoding.

Supported Products of the download tool

1. Broadcast Navigation Files: Supports Rinex 3.x and Rinex 4.x formats.
2. Precise Orbits/Clock Files:
   • Near-Real-Time (NRT):
     • B2B: [PPP-B2b]
     • HAS: [Galileo-HAS]
     • WUM_NRT: [WUM0MGXNRT_]
   • Rapid:
     • CNT: [CNES Real-time archive]
     • GFR: [GFZ0MGXRAP_]
     • WHR: [WUM0MGEXRAP_]
   • Final:
     • GRM: [GRG0MGEXFINX_]
     • IGS: [IGS combined solution]
     • WUM: [WUM0MGEXFINX_]
3. DCB Products: Provided by CAS.
4. IGS Sinex Coordinates File: Contains station coordinate information.
5. Rinex Navigation Files: Supports both Rinex 3.x and 4.x formats.

Python Script Functions

• cmn_tools.py: Offers essential utilities for time and coordinate conversion.
• down_eph_clk.py: Downloads orbit and clock data from IGS/MGEX data centers.
• down_PPP_products.py: Downloads navigation Rinex files (3.x and 4.x), orbits/clocks, and ISB from data centers.
• down_rinex_DSB.py: Downloads DCB products from CAS.
• down_rinex_nav_3x.py: Downloads Rinex navigation files in 3.x format.
• down_rinex_nav_4x.py: Downloads Rinex navigation files in 4.x format.
• down_rinex_obs.py: Downloads Rinex observation files.
• down_sinex_pos.py: Downloads Sinex Pos files and extracts reference coordinates for the specified station.