Cartoon of the GPS reflection method. The angle of the satellite signal with respect to the planar surface is e, the elevation angle. The direct signal is shown in blue. The reflected signal travels a further distance (shown in red); the GPS receiver measures the interference between the direct and reflected signals. Examples of this interference are given in the middle of the figure. e is the angle of the satellite with respect to the horizon.
<a href="//commons.wikimedia.org/wiki/User:Kristinemlarson" title="User:Kristinemlarson">Kristinemlarson</a>
<span class="int-own-work" lang="en">Own work</span>