Abstract:A method for navigation signals down sampling was presented in this study by combining RF direct sampling and digital down conversion. An analysis of navigation signals at frequencies that close to 1.2 GHz and 1.5 GHz was performed. Firstly, bandpass sampling principle was used to select appropriate sampling frequency for the completion of RF direct sampling to navigation signals. Then cascaded integrator comb filter and Half-Band(HB) filter were adopted to carry out decimation filter to the sampled signals, thus realizing the purpose of reducing sampling frequency. Finally, the navigation signals of 5 frequencies were simulated in Matlab, RF direct sampling of the navigation signals was accomplished and the sampling frequency was reduced. The original navigation signal was recovered and separated. It proves the methods of RF direct sampling and digital down conversion are feasible.