This paper presents the design and implementation of an ultra-wideband impulse radio based indoor positioning system and its architecture. The operating mechanism of the complete system along with its hardware and software details are discussed. The system exploits the differential time difference of arrival technique for position estimation. Simulation and experimental results demonstrating the working of this in-house developed positioning system are provided. Good positioning accuracy of around 30 cm has been achieved from the implemented system for line-of-sight setting in a 7 m × 7 m indoor office environment.