FM based indoor localization and mapping system with real-time implementation on FPGA

Indoor localization and mapping has become very crucial part of pervasive computing in recent times. Conventional outdoor techniques using GPS, Wi-Fi, and Cellular Networks have proved expensive and unconventional for indoor mapping. This document presents unique method of real time indoor localization and mapping using FM and ASK wave transceivers implemented using Phased Locked Loop and Field Programmable Gate Array (FPGA). Localization is procured with respect to three FM transmitters tuned at different frequencies. The geometrical wave model of these transmitters renders family of circles, where radius of each circle represents ‘Received Signal Strength Indicator’ (RSSI) value corresponding to a particular transmitter. Solving this family of circles for a common point yields the location of object with respect to the transmitters. Object is installed with customized FPGA core and 3 FM receivers tuned to respective transmitter frequencies. RSSI values from each FM receiver are resolved into 4 bit digital values inclusively. FPGA acquire and process values from FM receivers via 3 parallel I2C buses which provide real time response. Unwanted continuous FM radiation is prevented by the use of wireless control over FM transmitters. Overall, a low cost solution is obtained to create a digital map which localizes and tracks objects in real-time.