[time-nuts] OT - GPS and North

[Magnus Danielson]

Stanley Reynolds wrote:
> Yes, found this patent :
> 
> http://www.freepatentsonline.com/y2008/0186232.html
> 
> "A method and radio navigation system compass apparatus for determining true north or azimuth or orientation of a vehicle or the like by the use of integrated Loran and satellite radio navigation receivers employing crossed-loop H-field antennas for the Loran reception, or the use of at least three Loran type transmitter, or two Loran type transmitter and a synchronized clock for determining both position and azimuth. "
> 
> 
> synergy, the whole is greater than the sum of the individual parts

Traditional Directional Finding techniquest combined with positional 
information from the Loran-C is a good mix. Question is if the invention 
is that big that a good patent would hold.

> Both GPS and loran depend on the phase/frequency/time accuracy of their source, but I wonder if other signals not as accurate but maybe short-term stable could be used to improve combined stability such as TV and radio transmitters. With such a large source of possible transmitters comparison of them to GPS and loran to pick a few good ones to add both hold-over from gps and or loran loss. For example a CDMA cell site that is dependent on GPS would slowly deteriorate if GPS was lost, but a large number of CDMA cell sites would continue to work if they could be synced to another source.

You can use either the timing or direction or both from many different 
sources in combination with that of a number of different satellite 
systems in a combined pseudo-range and orientation input for a position 
and heading analysis. You can weigth in timing from several VLF sources 
in combination with the pseudo-ranges of the sats. The problem with VLF 
sources is the shift in delay due to shift in atmosphere, so their 
contribution would be limited unless fairly nearby.

> Besides the hold over capability I would be interested in ways to combine as many independent sources to improve accuracy like the use of more accurate frequency sources to improve GPS accuracy:
> http://plan.geomatics.ucalgary.ca/papers/ENC06_Paper74_WatsonetAl_v3Web.pdf
> 
> 
> Or maybe a time-nut antidote would be better ;-)

Maybe. :)

Cheers,
Magnus