Dual-tone radio interferometric ranging using PXI

Accurate location information is crucial for wireless sensor networks (WSNs). It is quite challenging to achieve a balance between localization accuracy and cost. Recently, a dual-tone radio interferometric positioning system (DRIPS) and a DRIPS with undersampling techniques (uDRIPS) are proposed, respectively. Thanks to the special design of the dual-tone signal, both DRIPS and uDRIPS are robust to flat-fading channels. They provide promising options to achieve high accuracy with low cost. In this paper, we evaluate the performance of the ranging algorithms of DRIPS and uDRIPS using National Instruments´ PCI eXtensions for Instrumentation (NI PXI). Although both DRIPS and uDRIPS employ the same dual-tone signal, their ranging methods are different. DRIPS extracts the range-related phase information of a low-frequency signal created by squaring the received dual-tone signal, while uDRIPS directly samples the received dual-tone signal to estimate the phase information. The experimental results show that the average errors of the ranging algorithms of uDRIPS and DRIPS can be as small as 11 cm at a range of 5 m. Moreover, the ranging performance of uDRIPS outperforms that of DRIPS, as the squaring operation in DRIPS amplifies the noise.