Master independent, multi-chain navigation Requirement –Resolution of 200 usec cross chain lane ambiguities Ambiguities are 20 usec in Europe Would also like to have identification of secondary w/o master A source of time accurate to +/- 100 usec would resolve these issues –Issues are moot in modulated environment as message/signal structure will be designed to solve them –We could do very low data rate modulation just to resolve these issues and make Loran a source of absolute time If I’ve missed something (that can be proved analytically to 1e-7), please speak up –There are many other heuristic methods (direction, cross rate TD’s mod 200, signal strength, etc, that cannot be defended.)

Present methods (that I’m aware of) Time domain (next slide is example) –Identify dual rated signals and adjust approximate clock to precise value –Master dependent at the first step, then enables master independence –Does not require cycle integrity –Requires approximate clock (see next slide for definition of approximate) Much less stringent requirements for clock but must have cycle integrity in Europe –Implemented in PC-104 –Results in solution for absolute time

Required Clock Accuracy Examples Nantucket (5930 & 9960) – * 2 * 593 = sec Nantucket & Seneca (8970) – * 897/3 = s or 9.8 hours Sylt (6731 & 7499) – * 2 * 7499 = sec Sylt & Vaerlandet (9007) – sec * 9007 = days Sylt, Vaerlandet & Bo (7001) – days * 7001 = years

Present methods (that I’m aware of) Position domain –Get a master dependent (TD based) approximate fix with subset of signals tracked Single chain triad Two LOP’s involving at least three stations Fix can contain cycle (10 usec) errors in North America, can’t in Europe –Master dependent –Does not result in solution for absolute time Could substitute 2 signals from 2 stations for dual rated signals and solve for time as in time domain method Would then provide absolute time and master independence