This paper presents a method for evaluating the maximum bit error probability (BEP) of a digital communication system subjected to interference by measuring the amplitude probability distribution (APD) of the interfering noise. Necessary conditions for the BEP evaluation are clarified both for the APD measuring receiver and the communication receiver considered. A method of defining emission limits is presented in terms of APD so that the worst BEP of a communication system does not exceed a required permissible value. The methods provide a theoretical basis for a wide variety of applications such as emission requirements in compliance testing, dynamic spectrum allocations, characterization of an electromagnetic environment for introducing new radio systems, and evaluation of intra-system interference.