Time Difference of Arrival Localization Based on Ultra-Wideband: A Synergistic Method of System and Algorithm II
Following the previous study of TDoA localization algorithms and hardware-assisted calibration, this paper develops a configurable DW1000-based ultra-wideband (UWB) platform for indoor localization with multiple anchors. Dedicated PCBs for the anchor and tag were designed to combine the DW1000 transceiver, STM32 controller interface, regulated power supply, controlled RF path, and customized antenna in one module. Three antenna candidates, including a modified circular radiator, a conventional circular patch, and a rectangular patch, were modelled in CST Studio Suite under the same conditions using a 1.2-mm F4B substrate. With the -6 dB level used as the preliminary comparison standard, the modified circular radiator obtained the widest simulated range from 6.0313 to 6.4318 GHz, giving an approximate bandwidth of 400.5 MHz. However, its -10 dB impedance bandwidth still requires further optimization before the antenna can be fabricated. The software was divided into three layers: an STM32 driver layer, a DW1000 API layer, and an application layer. This structure supports radio configuration, packet transmission and reception, timestamp reading, and future TDoA implementation. An infrared-synchronized ultrasonic unit was also developed as an additional short-range reference. It can be used to investigate UWB bias and to provide an initial region for the Taylor-series estimator. Nevertheless, one ultrasonic distance cannot independently determine a two-dimensional position or remove the clock drift between anchors. Qualitative tests were also carried out for multipath propagation, obstacle blockage, antenna orientation, and nearby wireless activity. These tests indicate several practical risks for system installation and provide a hardware and firmware basis for future synchronized multi-anchor experiments and quantitative localization evaluation.