International audienceSatellite navigation signals demodulation performance ishistorically tested and compared in the Additive WhiteGaussian Noise propagation channel model which wellsimulates the signal reception in open areas. Nowadays,the majority of new applications targets dynamic users inurban environments; therefore the GNSS signalsdemodulation performance has become mandatory to beprovided in urban environments. The GPS L1C signaldemodulation performance in urban environments is thusprovided in this paper. To do that, a new methodologyadapted to provide and assess GNSS signalsdemodulation performance in urban channels has beendeveloped. It counteracts the classic method limitationswhich are the fluctuating received C/N0 in urbanenvironments and the fact that each received message istaken into account in the error rate computation whereasin GNSS it is not necessary. The new methodology thusproposes to provide the demodulation performance for‘favorable’ reception conditions together with statisticalinformation about the occurrence of these favorablereception conditions. To be able to apply this newmethodology and to provide the GPS L1C signaldemodulation performance in urban environments, asimulator SiGMeP (Simulator for GNSS MessagePerformance) has been developed. Two urbanpropagation channel models can be tested: thenarrowband Perez-Fontan/Prieto model and the widebandDLR model. Moreover, the impact of the received signalphase estimation residual errors has been taken intoaccount (ideal estimation is compared with PLL tracking)