Abstract: The LWD method has many advantages the traditional cable borehole survey because of its higher accuracy, higher geologic strata resolution capacity, much less time and cost. To meet the current logging technology needs, A data acquisition and processing system for electromagnetic propagation resistivity logging while drilling is designed．The acquisition system structure, acquisition Program, the digital design of LWD is introduced, the design and the implementation of each functional module discussed．The system which is designed on the basis of the high precise DSP and FPGA implements signal pretreatment, high speed A/D control and digitalization of the phase sensitive demodulation etc, optimizes the acquisition and processing system and supplies a new way for the development of logging while drilling．Experimental results show that system performance has reached the design requirement.

Key words: logging while drilling, electromagnetic propagation resistivity logging, digital signal processing, high speed A/D, phase sensitive demodulation