What is the white dome ontop of a gner class 82 dvt?

Question

on the top of the gner dvt (driving van trailer) there is a white dome shaped object on the roof above the front of the dvt can anyone tell me what this is for and what does it do

Answer 1

It is a form of SatNav device, that allows the company to keep track of its vehicles. It is also used by the driver for direct link communications with home base.