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Treating unknown deterministic signals as noise is a handy practice. That's how the GPS system works. Modelling the actual reflectivity of the satellites in order to fully calculate the light pressure terms would be a bear. Easier to just model in process noise. Ditto for modelling changes to the index of refraction in the troposphere.
Th…
Treating unknown deterministic signals as noise is a handy practice. That's how the GPS system works. Modelling the actual reflectivity of the satellites in order to fully calculate the light pressure terms would be a bear. Easier to just model in process noise. Ditto for modelling changes to the index of refraction in the troposphere.
These unknowns do not look like Gaussian noise if you look at the error residuals. But the system works anyway, albeit not as accurate as theoretically possible. That is, the required error allowances have to be turned up higher than what they would need to be if the noise was Gaussian with the same standard deviation.