Captain, I get a figure of over a hundred million tons mass; and calibrating the scope images gives us a length of nearly two miles.
"Greylorn"
John Keith Laumer
What they did was called "calibrating" the scale.
"Letters of a Radio-Engineer to His Son"
John Mills
This is calibrating your set by the known wave-lengths of distant stations.
"Letters of a Radio-Engineer to His Son"
John Mills