What are IMO Performance Standard for RADAR?

• Range scales of 0.25, 0.5, 0.75, 1.5, 3, 6, 12 and 24 NM should be provided. Additional range scales are permitted outside the mandatory set.  Low metric range scales may be offered in addition to the mandatory set. 
• The range scale selected should be permanently indicated.

FIXED RANGE RINGS 

• An appropriate number of equally spaced range rings should be provided for the range scale selected. When displayed, the range ring scale should be indicated. 
• The system accuracy of fixed range rings should be within 1% of the maximum range of the range scale in use or 30 m, whichever is the greater distance.

VARIABLE RANGE MARKERS (VRM)