Wavelet compression of gravity correction data

A method comprising:

• performing a discrete wavelet transform on raw gravitational deflection data to produce coefficients;
• performing a lossless compression on the coefficients to produce compressed coefficients;
• and,
• storing the compressed coefficients in a memory of a vehicle navigation system.

A method for using compressed wavelet transform coefficients in order to correct outputs of inertial sensors for gravitational deflections, wherein the compressed wavelet transform coefficients comprise gravitational deflection data that is first converted to discrete wavelet coefficients by a discrete wavelet transform and wherein the wavelet transform coefficients are then compressed to form the compressed wavelet transform coefficients, and wherein the method comprises:

• generating an inertial sensor signal relating to a navigational state of a vehicle;
• accessing the compressed discrete wavelet coefficients from a memory based on a position of the vehicle;
• decompressing the accessed coefficients;
• performing an inverse discrete wavelet transform on the decompressed coefficients to produce gravitational compensation data;
• and,
• compensating the inertial sensor signal based on the gravitational compensation data.