[time-nuts] GPS antenna setup: how good?

[Mark Sims]

If you are running a Thunderbolt,  the beta 3.0 version of Lady Heather has a couple of tools in the S)urvey menu that might come in handy.

First is the 3)D fix mode.  This will put the receiver into 3D fix mode and plot the results.  The wider the resulting dispersion of data points,  the poorer the antenna setup.  When in 3D fix mode the program writes a LLA.LLA file (or is it TBOLT.LLA?) of all the fixes.

The 3D fix mode does not save the fix data in memory,  only on the screen.   For best results you should not change operating modes when running a 3D survey.  The program now does save the LLA fix background image in memory so you can redraw the screen without losing the plot.  

The other is the S)urvey A)ntenna  commands.   The S)ignals option will show the average signal level seen at each lat/lon point.  When the program exits,  it writes a TBOLT.SIG file with the data.

You should collect data for 24 hours (not 12).   The satellite orbits repeat every 12 hours,  but the atmosphere runs in 24 hours cycles.  Also the tbolt only tracks 8 sats at a time,  but there can be 12 visible.  Running for 24 hours allows more of the sats to be tracked.   		 	   		  
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