Displacements Detection with Low Cost GNSS Instruments

Low-cost GNSS receivers, once limited to basic navigation tasks, have benefited from technological advancements that have progressively improved their positioning accuracy, making them increasingly suitable for geodetic monitoring applications. This study presents a methodology for assessing the performance of low-cost GNSS systems through a controlled experimental setup established at the University of Bologna. A dedicated test network composed of five permanent stations, including a reference site equipped with a precision translation sledge, enabled the evaluation of hardware performance using both Precise Point Positioning (PPP) and the differenced approach. Three low-cost antennas (Harxon GPS1000, Tallysman TW3972, and ArduSimple AS-ANT2B) were tested against geodetic-grade systems under identical conditions. The results show that, under favorable environmental conditions and short baselines, low-cost systems can detect displacements as small as 1 mm in planimetry and 2.5 mm in height, achieving accuracy comparable to geodetic instruments. However, their performance is strongly influenced by environmental factors, particularly multipath effects. Also using PPP, the low-cost GNSS stations provided performance close to that obtained with high-end hardware, with some exceptions due to multipath.