Abstract
This paper presents a novel 434MHz asynchronous time difference of arrival (A-TDOA) Indoor Localization System (ILS) using three CC1101 ultra low power radio transceivers from Texas Instruments as asynchronous measuring receivers for time difference of arrival estimation. The three deployed TDOA measuring units are not required to be precisely synchronized in contrast to conventional TDOA localization systems where stringent time synchronization is required between measuring units. Time synchronization is achieved by using a reference transmitter to record the time offset in two TDOA measurements. Actual TDOA measurements are obtained by compensating the time difference measurements for real transmitter using time offsets caused by asynchronous receivers. The implemented system demodulates the obtained time difference pulses to mitigate the clock jitter effect and provides voltage levels corresponding to time differences which are mapped to distance differences. The performance of implemented ILS is evaluated using two sets of real time indoor measurements to estimate the position of mobile transmit node in two dimensional space. The positioning accuracy of implemented system is better than 1.8m along with telemetry data reception capability and low DC power consumption. (C) 2017 Wiley Periodicals, Inc.