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Performance Evaluation of the Early CNAV Navigation Message

Steigenberger, Peter and Montenbruck, Oliver and Hessels, Uwe (2015) Performance Evaluation of the Early CNAV Navigation Message. In: ION ITM 2015, pp. 155-163. ION ITM 2015, 26.-28. Jan. 2015, Dana Point, USA.

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Following an initial test campaign in June 2013, the GPS Directorate has initiated a pre-operational routine generation and transmission of the Civil Navigation Message CNAV starting on 28 April 2014. The new message is broadcast by Block IIR-M satellites on the L2C signal as well as the L2C and L5 signals of the Block IIF satellites. The improved resolution and larger number of parameters in the new CNAV ephemeris message offers a notably reduced ephemeris fitting error and largely avoids the discontinuities of consecutive ephemeris messages from the same upload. CNAV data of the Block IIR-M and IIF satellites have been collected since the start of transmission using a small set of globally distributed receivers offering an almost continuous coverage. Based on comparison with precise ephemerides of the International GNSS Service (IGS), a Signal-in-Space Range Error (SISRE) of about 1.1 m is obtained for the CNAV message whereas it is 0.6 m for the legacy navigation message (LNAV). This degraded performance is related to less frequent CNAV updates resulting in prediction times of up to four days. For a three week period with a daily CNAV update rate almost the same SISRE is obtained as for LNAV. Complementary to the SISRE analysis, the new Inter-Signal Corrections (ISCs) have been monitored, which enable users to correctly account for differential code biases (DCBs) when using other signals than the L1/L2 P(Y)-code observations in real-time positioning applications. The broadcast ISC values agree with DCBs derived in the frame of the IGS Multi-GNSS Experiment and DCBs from the Center for Orbit Determination in Europe on the 0.1 – 2 ns level depending on the ISC type. While users of the the civil L1C/A and L2C signals have, so far, experienced a notably degraded positioning, the ISCs now enable a single point positioning accuracy that is fully competitive with that of semi-codeless P(Y)-code receivers.

Item URL in elib:https://elib.dlr.de/94983/
Document Type:Conference or Workshop Item (Speech)
Title:Performance Evaluation of the Early CNAV Navigation Message
AuthorsInstitution or Email of AuthorsAuthors ORCID iD
Steigenberger, PeterDLR/GSOChttps://orcid.org/0000-0003-1905-6699
Date:January 2015
Journal or Publication Title:ION ITM 2015
Refereed publication:No
Open Access:No
Gold Open Access:No
In ISI Web of Science:No
Page Range:pp. 155-163
Keywords:GNSS; GPS; Navigation Message; CNAV; LNAV
Event Title:ION ITM 2015
Event Location:Dana Point, USA
Event Type:international Conference
Event Dates:26.-28. Jan. 2015
Organizer:Institute of Navigation
HGF - Research field:Aeronautics, Space and Transport
HGF - Program:Space
HGF - Program Themes:Space Technology
DLR - Research area:Raumfahrt
DLR - Program:R SY - Technik für Raumfahrtsysteme
DLR - Research theme (Project):R - Vorhaben Infrastruktur und Unterstützung für Raumflugbetrieb
Location: Oberpfaffenhofen
Institutes and Institutions:Space Operations and Astronaut Training
Deposited By: Steigenberger, Peter
Deposited On:03 Feb 2015 09:25
Last Modified:25 May 2016 15:28

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