[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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