egulations as for the spurs have been discussed at the ITU (International Telecommunication Union) and a subject of the intermodulation (IM) products is surely included in its discussions. In multi-carrier transmission systems, although the in-band IM products have been significantly investigated and evaluated, the accurate evaluation of the IM products outside the pass-band necessitates the equivalent conditions to the actual operations because the IM products deeply depend on the operating conditions of the concerned radio equipment. On the other hand, in case of communication satellites, it is difficult and is not a practical way to prepare the operating conditions that simulate the actual operations at the testing time flame of equipment. In this paper, a correlation between the IM products outside the pass-band, which have been discussed, and the operating conditions of the concerned radio equipment is clearly shown by the quantitative evaluations based on experiments. This paper also discusses a suitable thinking way of parameters (mean power, the necessary bandwidth) in the multi-career transmission systems, and the evaluations of the IM products that behave as the spurs outside the pass-band by using the generally used parameters for the radio equipments, NPR