Explaining the movie
The Signal is a mediocre movie featuring mostly a group of teen-hackers on their way to Defcon.
The wider story arch is entirely up for the interpretation, however the movie premise is fresh and simple: Turn the tables on Area51 folklore.
In the age where hundreds of thousands of movies are made each year, anything fresh that is well executed deserves one or two extra ratings points.
Area51: Humans / Analysis
Reverse Area51: Aliens / Synthesis
Note that the opposite term of analysis is synthesis.
Some see this movie as an inside joke. Personally I do not, though I guess technically speaking that is true.