Big Brother is Watching

This Ariel, recently replacing a much older version, sits on top of a water tower that sits on top of a nearby hill (this is Norfolk so the word "hill" is only relative). It must be able to cover quite a large area 
This one is not for mobile phones, its installed and run by the landowner and is used to keep in contact with his "troops" and equipment. I have been told that modern tractors and other gear use satellite navigation .and imaging to control their progress. In the ideal world a tractor driver now only has to turn the machine around at the end of each pass, the satnav does the rest. Also the spreading of fertilizer and weed killer is done using satellite imagery of the field, details passed directly to the distribution unit that can regulate
 the flow according to need. All this information comes via this tower.