Recently, the signal quality assessment team from the National Time Service Center (NTSC) of the Chinese Academy of Sciences established Global Navigation Satellite System (GNSS) spatial signal quality assessment system based on 40m antenna in Luonan County, Shaanxi Province. 

It realizes high-precision test evaluation of GNSS satellite navigation signals by using the international initiative special evaluation system, which covers the spatial signals of the new navigation signal system of major satellite navigation systems such as BDS and GPS. 

The system uses the satellite common-view and two-way time transfer technology of NSTC to achieve synchronization between system time and UTC (Coordinated Universal Time). 

And for the first time in the world, it adopts the optical fiber transmission network standard absolute delay method and uses high-frequency standard instruments and the dedicated navigation signal test equipment to realize the closed-loop calibration of the RF signal.  

It has broken through the technical problems of broadband RF signal group delay and power precision calibration and realized innovative application of multi-disciplinary technology in the navigation field.