Can someone clarify what the "Radar filter thresholds" do?

Name:  Screen Shot 2015-05-29 at 10.42.17 PM.jpg
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In this screenshot, the defaults are 3 (yellow) and 5 (red), for example.

1 is full alert, 10 is no alert, says the pop-up bubble.

Just what does this mean? If set to 1, does that mean the radar unit will alert at the slightest signal? Would 10 mean it won't alert unless the signal has maxed out to full?