[time-nuts] OT - GPS and North
Magnus Danielson
magnus at rubidium.dyndns.org
Sun Nov 22 17:18:58 UTC 2009
Stanley Reynolds wrote:
> Notice several of the eloran/GPS receivers advertise better than one degree heading accuracy even when stationary. Wonder if this the result of the sensor using an array of ferrite bar antennas or just a magnetic compass ?
>
> "The eLoran Heading output using Loran-C provides bearing accuracy better than 1º, making the e-LORAN a practical alternative to more expensive heading devices"
> http://www.si-tex.com/2009description_e-loran.htm
As expected:
Antenna
Type Active dual-loop eLoran H-field antenna with GPS patch antenna
dual-loop H-field Loran antenna is expected. H-field antennas has a zero
in the plane of the loop. To compensate another antenna is mounted with
90 degrees difference. Now, this allows the use of the signal from both
antennas to measure the heading towards each of the LORAN stations,
which together with the position can be converted to heading towards North.
If the GPS receiver had two antennas with similar directional
characteristics, it would too be able to do similar tricks.
Cheers,
Magnus
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