Demonstration: E5b Signal Containing Value-Added Information Broadcast in Real Time via the SES ASTRA 5B GEO Satellite

摘要

Geostationary satellites are a very efficient mean to broadcast information to a large number of users. In the field of navigation they are currently used as Satellite Based Augmentation System (SBAS), GPS augmentation systems like EGNOS (the European SBAS) mainly designed to provide an increased level of accuracy and integrity of GPS based positioning for the benefit of aeronautical safety of life applications. Various other professional domains from agriculture to mapping are also using the SBAS signals with noticeable benefits for the efficiency and the development of these activities. Other augmentation services could be defined with such an approach to provide similar benefits to a wide range of new applications. A good candidate is high accuracy positioning for which there is a long lasting request from users requiring better than a 1m accuracy. EGNOS recently undertook a major update phase, and currently takes benefits of the entry into service of the new generation of transmitting stations: Navigation Land Earth Station Generation 2 (NLES G2), associated to the SES-5 and ASTRA 5B (its entry into service for EGNOS is expected very soon) satellites from SES, the satellite operator. Both SES-5 and ASTRA 5B host an L1 and an E5 payload. In particular, a bandwidth of 50 MHz is available within the E5 transponder. The lower part (25 MHz) is allocated to the EGNOS L5 (E5a) signal used for the NLES G2. The higher part centred on the E5b frequency is not used by EGNOS Safety of Life (SoL) service (at least at the time when this paper was written). In previous papers an optimized way to provide an additional service through the available EGNOS GEO payloads has been presented. This definition first resulted from theoretical and simulation results presented in ([1] and [2]). This research analysis hence assessed the opportunity that an L5 SoL service can exist together with a non-SoL service on the E5 repeaters of SES GEO satellites, in using two different NLES: the first one is used to generate the L1-L5 SoL signals, and the other one to generate independently the E5b signal. The latter will be referred to herein as NLES E5b. In line with previous works on the subject, this paper provides the first LIVE test results of an END-TO-END GEO E5b Precise Point Positioning (PPP) testbed demonstration jointly carried out by the French Space Agency (CNES) and Thales Alenia Space, France, with the support of SES Techcom, Luxembourg.