Measurement System for the Performance Assessment of GNSS Receivers

Abstract

With the continuing spread of distributed measurement and control systems (e.g. Cyber-Physical Systems, Industry 4.0) there is an increased need to implement synchronized sampling and actuation over the components of a distributed system. To achieve this goal, the clocks of the system must be synchronized, including the ones doing sampling and actuation. In most cases local synchronization alone is not enough; It is also needed to keep in sync with a global reference time in order, for example, to be able to implement timestamps based on global time and simultaneous sampling across system components that are spatially distributed (operate on different sites). This global reference time mostly means one which is provided by a GNSS (Global Navigation Satellite System) service, such as GPS. In these systems, it is the master clock which is responsible for attaining (e.g. via a GNSS receiver) and keeping the global reference time. It can then pass it on in the local communication network, usually using IEEE 1588 (Precision Time Protocol). It follows, that thus, the characteristics of such systems are heavily limited by the precision, accuracy and reliability of the used GNSS receiver. Our paper thus is about the examination of potentially promising GNSS receivers for which we developed a custom measurement system. This includes the design of a test PCB, the writing of a PC data collecting program, the formulation of MATLAB scripts which process the collected data, and the validation of the data collecting system via GNSS receivers simulated by TI evaluation boards. We also conducted measurements with the system on the Quectel L86 GNSS receiver, the results of which are presented in the paper.