This paper follows the research of dual frequency and frequency alteration algorithm. The objective is to design and implement an ASIC used for ultrasonic distance measurement, and to use this ASIC to develop a local positioning system prototype. With this IP core, which can be applied in Xilinx Spartan II FPGA or more advanced FPGA. The access interface of this chip is memory mapping I/O of general 8-bit MCU. It’s suitable for any common 8-bit MCU to measure distance by ultrasound. This local positioning system can be used for peer to peer ultrasonic distance measurement. In this article, bring up a prototype that can locate mobile stations future.