Operation of Sub-meter Class Augmentation System and Demonstration Experiments with Quasi-Zenith Satellite 'MICHIBIKI' in 2011-2012 and Further Challenge in 2012

摘要

"MICHIBIKI" (QZS-1), was launched on September 2010 as the 1st Quasi-Zenith Satellite in Japan. It has the functions to broadcast not only the same types of positioning signal as GPS, but also unique ones; "L1-SAIF" and "LEX". SPAC (Satellite Positioning Research and Application Center) has been investigating application of QZS system (QZSS) with our industrial partners, focusing high-precision "L1-SAIF" for Mass Market and "LEX" for Professional Market. This paper would be focused on "L1-SAIF". "L1-SAIF+", an expansion of "L1-SAIF", is consist of two types of message; "SBAS-compatible" messages and "SBAS-incompatible" ones. The former messages are aimed for augmentation of satellite positioning signal, and the latter message offers other types of information: such as the message to shorten the time to first fix (TTFF) and the short message for disaster relief and so on. Being based on the results in 2011 shown above, the plans to improve the performance of augmentation messages have been investigated in 2012. The first is to involve the augmentation information for the QZS satellite in L1-SAIF messages. As of January 2013, augmentation messages only for the GPS satellites are generated by the system and broadcasted via QZS-1. By adding the augmentation message for QZS to L1-SAIF, it could be expected to improve the accuracy in positioning. The second topic, mainly focused on in this paper, is to optimize the parameters to estimate ionospheric delay. In this system, 'Planer Fit Model' is used to estimate the delay of positioning signals in ionosphere. It has been investigated to optimize the model by changing the parameters such as the range of fit radius, the number of Ionospheric Pierce Points (IPPs) used in ionospheric delay estimation, and others. The details of the investigation would be discussed later. And finally, this paper would report several approaches to put our experimental system to more practical one.