Low-cost GNSS sensors for monitoring applications

Among several instruments and techniques that can be used for monitoring purposes, GNSS technology has undergone a fast evolution and provides a large choice of solutions. Despite the best performances can be achieved by using double frequency geodetic receivers, capable to maintain high precisions even for wide-scale monitoring, in the recent years, several interesting solutions were presented in the low-cost market. In this work, a monitoring system based on a couple of low-cost GNSS receivers has been developed and tested in the field (Ponte Motta in Cavezzo - Modena, Italy). The two receivers were positioned about 50 m from each other and data were acquired at 1-Hz frequency. The position solutions were calculated both in post processing, through two different free and open-source software packages, and using an embedded RTK processor. The analysis aims to assess on one hand the capability of the system to perform the monitoring of slow displacements with the best possible precision, and, on the other hand, the performances of the real-time solutions that can be used for early warning purposes. The precisions evidenced by the tests show that such low-cost instrumentation can be used for many monitoring purposes, especially considering the cost that is about a tenth of geodetic instruments.