Globalstar Product Management – Technical Support

Abney Rule – Easy Way to Select Satellite Installation Site

Location, Location, Location:  One of the most important aspects of selecting the installation site for a LEO satellite phone is to choose a location that has the least amount of blockage from nearby structures.  Sometimes it is difficult to decide between two different locations.  The Abney Rule helps to simplify these decisions by providing a clear objective measure of the amount of sky blockage.  This tool works equally well for objects that are close or far away.

Abney Rule:
The easiest way to evaluate blockage from near and distant objects is to use an Abney Level.

CST/Berger 17-640 5-1/4" Abney Level  ($48, March-2013)

You look through the yellow telescope tube at an obstruction. Then, while looking through the scope, you rotate the bubble level that is mounted on the vernier until the image of the bubble’s reflection in the telescope view is centered. Then you remove the scope from your eye and read the angle of the blockage from the vernier.  This level of complexity would only be required for complicated sites, but it is a pretty easy measurement to do and, considering the low cost of the tool and the high value of a proper satellite phone installation, an Abney Rule (or equivalent) is definitely worth the investment.


Written by Joseph Crowley

March 12, 2013 at 7:19 pm

Posted in Uncategorized

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