The jailbreak tweak Bars makes it easier to see how strong the signal from your iPhone. By your signal with half signal bars at the top of your iPhone display, you no longer have to guess what that means exactly one full bar.
Bars used the original five bars left of the screen of your iPhone, but also ensures that each line is half-filled can. This will improve the signal mapped: Got a signal of 3.5 bars, you see three full bars and half-filled. Normally you would in a situation to see three or four. It was then up to you to guess where the signal is approximately located.
In the animation below shows how the lines are shown with bars.
Bars available via the repository of BigBoss