Understanding orbits can be called the key to understanding satellites. These videos by Nanosatisfi cover many facts about orbits.
Watch Coding For Space – Orbits 1
[youtube=http://www.youtube.com/watch?v=QGAmYLlWj2c&w=560&h=315]
This second video about orbits covers the math involved in calculating a pure circular orbit.
Watch Coding For Space – Orbits 2
[youtube=http://www.youtube.com/watch?v=qfliZl1LhvQ&w=560&h=315]
Physics Classroom: Mathematics of Satellite Motion http://www.physicsclassroom.com/class/circles/u6l4c.cfm
PLAN-13 Satellite Position Calculation Program by James Miller G3RUH
http://www.amsat.org/amsat/articles/g3ruh/111.html
Nanosatisfi http://www.nanosatisfi.com/