Wikipedia
Height finder
[[Image:MVAFS 1973 Radar 2.jpg||thumb|right|220px|
Mill Valley AFS height finder radar using Fan-beam antenna(1973)
]] A height finder is a ground based aircraft altitude measuring device. Early height finders were optical range finder devices combined with simple mechanical computers, while later systems migrated to radar devices. The unique vertical oscillating motion of height finder radars led to them also being known as nodding radar. Devices combining both optics and radar were deployed by the U.S. Military.