GNATSS

GNATSS is an open-source software for processing Global Navigation Satellite Systems - Acoustic (GNSS-A) data for seafloor horizontal positioning. The software is a redevelopment of existing FORTRAN codes and shell scripts developed by C. David Chadwell for processing data including measurements made with Wave Gliders. Existing code, which includes proprietary routines, is developed and maintained by John DeSanto, which can be found at johnbdesanto/SeafloorGeodesy.

Notion page for project can be found here.

Using the software

This software is currently under heavy development and is not available via PyPI, the Python Package Index

You can install the software with pip directly from the main branch of the repo by running the following command:

pip install git+https://github.com/uw-ssec/offshore-geodesy@main

Once the software is installed, you should be able to get to the GNATSS Command Line Interface (CLI) using the command gnatss. For example: gnatss --help, will get you to the main GNSS-A Processing in Python help page.

Usage: gnatss [OPTIONS] COMMAND [ARGS]...

  GNSS-A Processing in Python

Options:
  --install-completion [bash|zsh|fish|powershell|pwsh]
                                  Install completion for the specified shell.
  --show-completion [bash|zsh|fish|powershell|pwsh]
                                  Show completion for the specified shell, to
                                  copy it or customize the installation.
  --help                          Show this message and exit.

Commands:
  run  Runs the full pre-processing routine for GNSS-A

Pre-processing solve routine

Currently there's a single command available in the CLI, run, which will run the full pre-processing routine for GNSS-A. You can retrieve the helper text for this command by running gnatss run --help.

Usage: gnatss run [OPTIONS]

  Runs the full pre-processing routine for GNSS-A

  Note: Currently only supports 3 transponders

Options:
  --config-yaml TEXT              Custom path to configuration yaml file.
                                  **Currently only support local files!**
  --extract-res / --no-extract-res
                                  Flag to extract residual files from run.
                                  [default: no-extract-res]
  --help                          Show this message and exit.

Currently the pre-processing routine have been tested to only supports 3 transponders, but this will be expanded in the future.

Configuration yaml file

The run command takes in a configuration yaml file, which is used to configure the pre-processing routine. By default, the program will look for a configuration file in the current working directory called config.yaml. If this file is found somewhere else, you can pass in the path to the file using the --config-yaml flag.

Here's a sample configuration yaml file:

site_id: SITE1

solver:
  # note that the coordinates are not real and are just for example
  transponders:
    - lat: 47.302064471
      lon: -126.978181346
      height: -1176.5866
      internal_delay: 0.200000
      sv_mean: 1481.551
    - lat: 47.295207747
      lon: -126.958752845
      height: -1146.5881
      internal_delay: 0.320000
      sv_mean: 1481.521
    - lat: 47.309643593
      lon: -126.959348875
      height: -1133.7305
      internal_delay: 0.440000
      sv_mean: 1481.509
  reference_ellipsoid:
    semi_major_axis: 6378137.000
    reverse_flattening: 298.257222101
  gps_sigma_limit: 0.05
  std_dev: true
  geoid_undulation: -26.59
  bisection_tolerance: 1e-10
  array_center:
    lat: 47.3023
    lon: -126.9656
  travel_times_variance: 1e-10
  travel_times_correction: 0.0
  transducer_delay_time: 0.0
  harmonic_mean_start_depth: -4.0
  input_files:
    sound_speed:
      path: /path/to/CTD_NCL1_Ch_Mi
    travel_times:
      path: /path/to/**/WG_*/pxp_tt # this option will take in glob patterns
    gps_solution:
      path: /path/to/**/posfilter/POS_FREED_TRANS_TWTT # this option will take in glob patterns
    deletions:
      path: /path/to/deletns.dat


output:
  path: /my/output/dir/

Residual file

Currently, you can extract the residual file from the run command by passing in the --extract-res flag. This will output the final resulting residual file to the output directory specified in the configuration yaml file. This file will be in Comma Separated Value (CSV) format called residuals.csv.

Contributing

Please refer to our Contributing Guide on how to setup your environment to contribute to this project.

Thanks to our contributors so far!

Open source licensing

This has a BSD-3-Clause License, which can be found here.