Hi Guys,
I'm not qualified to contribute anything significant to your musings but I thought you might like the following. It may solve your positioning requirements.
INERTIAL NAVIGATION SYSTEM
The following- explanation, in simplified terms, is typical of all Inertial Navigation Systems* First, the aircraft knows where it is at all times. It knows this because it knows where it isn't. By subtracting where it is from where it isn't, or where it isn't from where it is (whichever is greater), it obtains a difference of deviation. The inertial system uses deviations to generate corrective commands to drive the system from a position where it is, to a position where it isn't, arriving at the position where it wasn't, it now is. Consequently the position where it is, is now the position where it wasn't, and it follows the position where it was is the position where it isn't. In the event that the position where it now is, is not the position where it wasn't, the system has acquired a variation (variations are caused by external factors, and the discussion of these factors is not considered to be within the scope of this explanation), the variation being the difference between where the aircraft is and where the aircraft wasn't. If variation is considered to be a significant factor, it too may be corrected for by the use of the Doppler system; however the aircraft must know where it was also. The "thought process" of the system is as follows; because a variation has modified some of the information which the aircraft has obtained, it is not sure where it is. However, it is sure where it isn't (within reason), and it knows where it was. It now subtracts where it should be from where it wasn't (or vice versa) and by differentiating this from the algebraic difference between its deviation and its variation, which is called error, it computes the correct information to compensate for all factors, supplying accurate navigation information.
N. A. Mwobbn
Note: The above explanation of the Inertial System is a variation of the original published in "Electronics" magazine March 1959.