Microwave Photonic Interferometric System for Monitoring Delay and Temperature of Optical Cables deployed in Radio Telescope Arrays

The on-field validation of a fiber delay monitoring system (FDMS) based on a microwave Michelson’s interferometer operating over optical fiber is presented. The FDMS has been designed for monitoring the impact of optical cables installed in radioastronomy applications. The system was tested in the second version of the Aperture Array Verification System (AAVS), which represents the prototype for the upcoming low frequency radioastronomy plant Square Kilometre Array (SKA-Low), installed on site at the Murchison Radio Observatory, in Western Australia. The FDMS has been used to monitor two different typologies of cable installation: Surface Laid and Underground Buried. This work shows that the behavior of the delay measurement agrees with the measured average temperature of the cable, which depends on several aspects other than the air temperature. The FDMS can be used also to estimate the average temperature effects of the fiber optic cables.