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
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