EDGE (Enhanced Data rates for Global Evolution) is a future wireless communication system, offering high bit rates and packet services based on the GSM system. To increase the data rates a new modulation, 8-PSK, is introduced. Changing the modulation makes the system more sensitive to noise than the ordinary GSM system. The purpose of this thesis is to evaluate the sensibility of this new modulation form. In all wireless communication there are imperfections in the system such as quantization errors, clipping effects and phase errors. The new modulation has less euclidean distance between adjacent symbols and is therefore more affected by noise sources than GSM today. Simulations are made to evaluate the different disturbances and to see how the constellation is affected. These disturbances are divided into three different parts (hard limiting, quantization and imperfections in modulation/demodulation).