When line of sight between two radios is disrupted, a repeater may need to be utilized. This video will explain situations in which repeaters are necessary and how they actually work.
Dr. Jan Noordhof is an independent principal consultant with over 20 years experience in radio standard development, software engineering, systems programming, telecommunications, embedded system design, and teaching at a number of universities.
Tait Radio Academy is a free online resource for all things radio. You can find more at www.taitradioacademy.com.