How to check/calculate efficiency of Radar ?

1. Switch on the radar set and get a picture.
2. Change over to the range scale specified by the manufacturer (usually the 1.5M range scale).
3. See that the PL selector switch is in the ‘short pulse’
4. Set the clutter suppression and differentiator controls to minimum or off positions.
5. Set gain as usual.
6. Operate spring loaded “performance monitor” switch and a feather or a cartwheel – pattern will appear on the screen.
7. Measure off the maximum length of the feather (or the maximum radius of the cartwheel) with the help of the VRM. Any error of the VRM must be allowed for.
8. Relative efficiency % = (present length of feather/ maximum length in the past result) * 100

Results  below 80 % is  unreliable,