Low precision and poor ability of anti-jamming are hard problems which can not be easily solved in typical method. While considering of the need for distance measuring by microwave on inner space navigation-and electro-war, spread spectrum technique, digital base band synthesizing, large scale. integrated circuit and Application Specific Integrated Circuit (ASIC) have become key techniques in microwave system of distance measuring. It is of advantage to improve measuring precision and signal processing ability, restrain EMI, expand measuring area and minish system. After a brief description about advantages and principles of measuring based on spread spectrum, a distance measuring solution based on spread spectrum technique and filed programmable gate array (FPGA) is given. The arithmetic of pseudo noise (PN) series quickly capturing and carrier frequency excursion estimating during start point tracking is described in detail. The success ratio can reach 99 percent and the measuring precision can reach 0.09 meter even in the poor signal condition of -126dBm.
