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View Code? Open in Web Editor NEW:earth_asia: :satellite: :earth_asia: :satellite: LEOGPS - Satellite Navigation with GPS on Python!
License: MIT License
:earth_asia: :satellite: :earth_asia: :satellite: LEOGPS - Satellite Navigation with GPS on Python!
License: MIT License
๐ง ๐ง ๐ง Future work: to include single-satellite cases ๐ฐ๏ธ . The GUI should offer to the user the option of choosing single satellite processing (precise orbit determination) or dual satellite processing (relative navigation via double differencing).
To-Do:
Goal ๐ฏ : Build a feature that enables relative orbit plotting.
Feature ๐๏ธ : Allow the plot to be displayed directly on the LEOGPS GUI, in Hill Frame coordinates after RSN.
Requires ๐ง : More formation flying RINEX v2 files for validation of RSN and plotting accuracy.
๐ง ๐ง ๐ง Future Work: Inclusion of the processing statistics, such as pseudo range residuals, carrier to noise ratios, number of satellites in view, time series plot of which frequency signals were received.
๐ง ๐ง ๐ง Future Work: With the implementation of the coordinate frame transformation, tools are now available to perform both an orbit (ICRF) visualisation as well as a ground track (ITRF) visualisation.
Current solutions tested on GRACE A/B formation flying satellites, exhibit positioning errors from pseudo-range solutions on the order of ~100m, and relative navigation inaccuracies in double digit centimeters. This is two orders of magnitude worse off than expected from typical precise orbit determination results used as a comparison. Ephemeris errors accruing from the orbit interpolation of the GPS satellites seem to be responsible. Current orbit interpolation uses an 11th Order Lagrange Polynomial Interpolation. A review of current range measurement modelling, and the setup of the non-linear least squares, should be conducted.
GPS antenna offsets should be done in the spacecraft body frame. However, currently as LEOGPS has no feature to read in spacecraft attitude coordinates, it will not be able to tell the orientation of the spacecraft and thus applying GPS antenna offsets using XYZ coordinates in the orbit frame is erroneous. For now, this has been (conveniently) cast to future work, and users are advised not to set any non-zero offsets. The input box in the GUI has also been closed. Thus, all coordinates computed in LEOGPS of the spacecraft(s) are not of the spacecraft center of mass, but of the GPS antenna phase center.
Hi!
I have a situation where my GPS receivers log data at 1 Hz, but with infrequent data corruption (0.1% of the time or maybe 1 second of drop every few minutes out of collection of 4 hours), resulting in some dropping of PVT data.
Issue: Current LEOGPS cannot proceed with data with 0.1% droppage.
Solutions:
The function that is not robust against dropped data is phasep.ph2fil() in line 611 of phasesep.py. The hatch filter requires comparison to the data 1 second before, even if the selected timestep is greater than 1 second.
Any other suggestions on how to deal with this? Any suggestions also to preprocess RINEX observation file for input into LEOGPS?
Current LEOGPS basically performs pseudorange double differencing. Should eventually move towards carrier double differencing with IAR.
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