Gravity GPS/GNSS and gravity compass using sun and moon tidal gravity signal

Nils Berglund: A simplistic model for tides – instantaneous forcing at https://www.youtube.com/watch?v=XH7tvGb42s4

The easiest model that works precisely is to use the positions of the sun, moon, and earth from JPL Horizon. Then for a particular point on earth (station) calculate the vector GM/r^2 acceleration of the sun acting on the station, minus the sun acting on the center of the earth. Add the moon acting at the station minus the moon acting on the center of the earth. Then add the centrifugal acceleration of the station because of the earth rotation. The vector acceleration is precisely what is measured by a superconducting gravimeter or three axis gravimeter. It only requires a linear regression (constant and slope) for each axis ( 6 numbers total) to fit 1 month of data almost exactly. I have notes on YouTube, Hackaday IO, ResearchGate, Twitter(X). It is not the water tide but the actual gravity at the stations. You can use it to locate yourself and to determine direction of each axis. Richard Collins, The Internet Foundation