When I was in the Navy we had a 6 month range calibration we did on the fire control radar. This was in Pearl Harbor so we knew the precise distance to various buildings in Pearl City across the harbor. We would visually confirm we had the correct building lit up and adjust the range measurement circuitry. This would sometimes take 30+minutes. We used the threaten shipmates with being "Irradiated:" by the radar system as many were unaware of what that meant 
