A Multi-Antenna GNSS-Over-Fiber System for High Accuracy Three-Dimensional Baseline Measurement

A novel multi-antenna global navigation satellite system that uses fibers to transmit signals from multiple remote antennas to a local station with real-time microwave-photonics-based fiber length monitoring is proposed for high accuracy three-dimensional (3D) baseline measurement. In the proposed approach, microwave-photonics-based fiber length monitoring is employed to obtain the delay difference between the different GNSS channels. With the obtained delay difference information, we use the carrier-phase single-difference (SD) algorithm to calculate the 3D baseline, which is able to improve the vertical precision of the 3D baseline measurement as compared with the use of the carrier-phase double-difference (DD) algorithm. Experimental results show that the 3D baseline measurement precision using the SD algorithm is within 2 mm and the vertical positioning precision is improved by over three times compared with the approach using the conventional DD algorithm.