Prototype of a regional total electron content (TEC) monitoring system based on GNSS

Signals from Global Navigation Satellite System (GNSS) are affected by a delay when they travel through the ionosphere, affecting the performance of the GNSS positioning service. In order to correct this delay the Total Electron Content (TEC) in the path between the satellite and the receiver can be used. Several agencies around the world generate TEC maps using networks of GNSS receiver and physics-based ionospheric models. Development of monitoring systems that report TEC in real-time is a major concern for aerial navigation based on the use of GNSS. This work presents a proposal for a prototype of a TEC monitoring GNSS-based system for the Mexican territory. In the first part of this work we present a brief review of an ionospheric technique based on observations from GNSS receivers to calculate the delay introduced by the ionosphere. Some tests of TEC measurements applying this GNSS technique over the Mexican territory are presented in order to identify the behaviour of the ionosphere in this region. A description of the elements which integrate the prototype to monitor TEC and their functions (Implementation of TEC monitor, communication network, server sink data-base) is presented. The results of regional TEC status generated by the prototype are presented. We use the TEC registered by the prototype to generate the correction of GNSS single positioning calculation. In addition using TEC estimations we perform an evaluation of positioning error correction for aerial navigation based on GNSS. This evaluation is done considering technical regulation statements of the International Civil Aviation Organization (ICAO). Currently the National Oceanic and Atmosphere Administration (NOAA) of the USA through the system named US-TEC deliver TEC maps for the North America region. However this system includes an annotation that says that these TEC estimations should be avoided for regions outside the CONUS as the uncertainty in the modelled TEC is expected to be large in those regions. US-TEC maps are generated using a dense network of GNSS receivers as sources of data which are located inside the US territory. Although TEC values are reported for Mexico, the US-TEC GNSS network does not include receivers located in this territory. With this prototype, we intend to generate the basis for a system which reports the TEC over the Mexican territory in order to be applied in high performance GNSS applications.