GPS World, July 2013

GNSS Modernization INNOVATION FIGURE 1 Distribution of MGEX stations supporting tracking of QZSS blue Galileo red and BeiDou yellow as of June 2013 signals in three frequency bands B1 B2 B3 and tracking of the corresponding open service OS signals is already supported by a variety of GNSS receivers With the release of a B1 OS Interface Control Document ICD at the end of 2012 the BeiDou navigation message has become publicly DFFHVVLEOH DQG XVHUV WKURXJKRXW WKH VLD 3DFL F UHJLRQ FDQ QRZ EHQH W IURP HLRX DV D VXSSOHPHQWDU RU VWDQG DORQH navigation system The Japanese Quasi Zenith Satellite System QZSS has so far only launched a single satellite but recent political decisions have paved the way for the build up of a miniconstellation of IGSO and GEO satellites Aside from a high level of compatibility with GPS QZSS has introduced new signals such as the modernized L1 Civil L1C signal and the L band Experiment LEX signal also known as L6 for high precision point positioning in the E6 band Along with this unique set of navigation signals QZSS provides innovative service features such as the L1 Sub meter class Augmentation with Integrity Function L1 SAIF or L1S message Also QZSS precedes GPS in offering the new Civil Navigation CNAV message on L2C and L5 as well as the CNAV2 message on L1C Long before their planned use in GPS these messages are now broadcast on a routine basis and contain novel information such as inter frequency corrections and Earth orientation parameters Last but not least GPS has now a total of four Block IIF satellites in orbit that transmit an operational L5 signal for DYLDWLRQ XVHUV DQG RWKHUV DQG ZKLFK À D QHZ JHQHUDWLRQ of highly stable rubidium clocks While neither L2C nor L5 are transmitted by a full constellation users and investigators can gradually familiarize themselves with these new signals that will enable encryption free dual frequency navigation services for aeronautical and other civil applications Within the International GNSS Service IGS more than 200 worldwide agencies have for many years pooled resources and permanent GNSS station data to generate precise GNSS products in support of Earth science research multidisciplinary applications and education So far this service has been restricted to two systems namely GPS FIGURE 2 Distribution of MGEX real time stations supporting tracking of QZSS blue Galileo red and BeiDou yellow as of June 2013 and GLONASS In recognition of the rapidly evolving GNSS landscape the IGS has set up the Multi GNSS Experiment MGEX to explore and promote the use of new navigation signals and constellations It will enable an early familiarization with new GNSS identify and overcome relevant challenges and prepare use of emerging navigation systems in routine IGS products MGEX comprises the buildup of a new network of sensor stations the characterization of the user equipment and space segment the development of new concepts and data processing tools and the generation of early data products for Galileo QZSS and BeiDou MGEX Receiver type Stations Observations JAVAD TRE_ G2T JAVAD TRE_ G3TH DELTA 27 E 1X 5X LEICA GR10 LEICA GR25 LEICA GRX1200 GNSS 12 E 1X 5X 7X 8Q NOVATEL OEM6 1 E 1C 5Q SEPTENTRIO ASTERX3 POLARX4TR POLARXS 4 E 1C 5Q 7Q 8Q C 2I 7I TRIMBLE NETR9 31 E 1X 5X 7X 8X C 2I 6I 7I J 1C 1X 2X 5X 6X TABLE 1 Receiver types in use within the MGEX network status as of June 2013 Observation types for Galileo E BeiDou C and QZSS J are based on RINEX 3 observation codes as reported in the submitted data files frequency bands 1 L1 E1 2 L2 B1 5 L5 E5a 6 E6 B3 7 E5b B2 8 E5ab signals C C A code I data Q pilot X data pilot They do not necessarily indicate the full tracking capabilities supported by the receivers but rather the observations made available to MGEX users from the respective stations www gpsworld com July 2013 GPS World 45