DISTANCE MEASUREMENT USING TDOA METHOD BASED ON LORA PROTOCOL

Abstract

The article focuses on the implementation of distance measurement between objects using the Time Difference of Arrival (TDoA) method, specifically through the Round-Trip Time of Flight (RTToF) technique, based on the LoRa protocol and utilized by the SX1280 transceiver. The aim of the article is to detail the temporal characteristics of packet exchange and formalize the calculation of distance. The key parameters significantly affecting measurement accuracy are identified as Bandwidth (BW) and Spreading Factor (SF). The research includes a comprehensive analysis of error sources, such as Reference Oscillator Error (timing offset) and Multipath Propagation, and provides formulas for their quantification. A multi-stage correction methodology is proposed, incorporating Frequency Error Correction (based on FEI), LNA Compensation (based on RSSI), Statistical Filtering (using the median), Polynomial Curve Correction, and Environment-Specific Correction. The results obtained from field measurements indicate that with this comprehensive correction approach, a ranging precision of approximately 1 meter can be achieved in controlled line-of-sight conditions. Furthermore, practical outdoor applications demonstrate mean errors below 10 meters even at distances exceeding 1 km. Conclusions: The implementation and comprehensive correction of RTToF measurements using the LoRa-based SX1280 module allow for the achievement of high accuracy while maintaining an acceptable balance between precision, time-on-air (energy consumption), and communication range, which is crucial for object detection and positioning systems.