This is what ICAO Annex 10 vol III says about erp . . .
2.2.1.2 POWER
Recommendation.— On a high percentage of occasions, the effective radiated power should be such as to provide
a field strength of a least 75 microvolts per metre (minus 109 dBW/m2) within the defined operational coverage of the
facility, on the basis of free-space propagation.
2.2.1.3 Modulation. A peak modulation factor of at least 0.85 shall be achievable.
2.2.1.4 Recommendation.— Means should be provided to maintain the average modulation factor at the highest
practicable value without overmodulation.
PS Wassit mean?
