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 Septemberrn2010 as the 1st Quasi-Zenith Satellite in Japan. It has thernfunctions to broadcast not only the same types ofrnpositioning signal as GPS, but also unique ones; “L1-rnSAIF” and “LEX”. SPAC (Satellite Positioning Researchrnand Application Center) has been investigatingrnapplication of QZS system (QZSS) with our industrialrnpartners, focusing high-precision “L1-SAIF” for MassrnMarket and “LEX” for Professional Market. This paperrnwould be focused on “L1-SAIF”.rn“L1-SAIF+”, an expansion of “L1-SAIF”, is consist ofrntwo types of message; “SBAS-compatible” messages andrn“SBAS-incompatible” ones. The former messages arernaimed for augmentation of satellite positioning signal, andrnthe latter message offers other types of information: suchrnas the message to shorten the time to first fix (TTFF) andrnthe short message for disaster relief and so on.rnBeing based on the results in 2011 shown above, thernplans to improve the performance of augmentationrnmessages have been investigated in 2012. The first is torninvolve the augmentation information for the QZSrnsatellite in L1-SAIF messages. As of January 2013,rnaugmentation messages only for the GPS satellites arerngenerated by the system and broadcasted via QZS-1. Byrnadding the augmentation message for QZS to L1-SAIF, itrncould be expected to improve the accuracy in positioning.rnThe second topic, mainly focused on in this paper, is tornoptimize the parameters to estimate ionospheric delay. Inrnthis system, ‘Planer Fit Model’ is used to estimate therndelay of positioning signals in ionosphere. It has beenrninvestigated to optimize the model by changing thernparameters such as the range of fit radius, the number ofrnIonospheric Pierce Points (IPPs) used in ionosphericrndelay estimation, and others. The details of therninvestigation would be discussed later.rnAnd finally, this paper would report several approachesrnto put our experimental system to more practical one.