[time-nuts] How can I measure GPS Antenna quality?
holrum at hotmail.com
Tue Nov 22 21:46:35 EST 2016
The colored signal level vs az/el plot follows that convention... outer edge is the horizon, center point is zenith (90 degrees above the horizon). Color represents the average signal level seen at a given point in the sky.
The tricky bit is interpolating signal levels between logged points (there is a display options for showing the raw signal level data). Heather interpolates between adjacent azimuth points at each elevation angle. The interpolation extends for a maximum of 22.5 degrees azimuth from each point that had signals. Handling things like the "hole" at northern azimuth angles (for the northern hemisphere) complicates things (once you get far enough north, the horseshoe shaped signal hole becomes a closed circle). Heather builds a "clipping" structure based on the min and max elevation angles that has signals for each azimuth angle.
I'd like to try something like a Voronoi tessellation, but that gets rather nasty to implement...
> The usual "flat" plot for a 3 D pattern of a GPS antenna is to have the
radius = 90-elevation angle (so horizon is outer border), angle is
azimuth looking down on antenna, and color be power.
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