TY - JOUR

T1 - Benefits of receiver clock modeling in code-based GNSS navigation

AU - Krawinkel, Thomas

AU - Schön, Steffen

N1 - Funding information: The authors would like to thank Andreas Bauch and Thomas Polewka of PTB for their support and commitment during execution and analysis of the clock comparisons. We also acknowledge the very helpful comments of the two anonymous reviewers. Furthermore, we thank IGS, CODE, and ESOC for their free to use GNSS products which were a valuable contribution to our case study. This work was funded by the Federal Ministry of Economics and Technology of Germany, following a resolution of the German Bundestag (Project Number: 50NA1321).

PY - 2015/8/8

Y1 - 2015/8/8

N2 - Due to the limited frequency stability and poor accuracy of typical quartz oscillators built-in GNSS receivers, an additional receiver clock error has to be estimated in addition to the coordinates. This leads to several drawbacks especially in kinematic applications: At least four satellites in view are needed for navigation, high correlations between the clock estimates and the up-coordinates. This situation can be improved distinctly when connecting atomic clocks to GNSS receivers and modeling their behavior in a physically meaningful way (receiver clock modeling). Recent developments in miniaturizing atomic clocks result in so-called chip-scale atomic clocks and open up the possibility of using stable atomic clocks in GNSS navigation. We present two different methods of receiver clock modeling, namely in an extended Kalman filter and a sequential least-squares adjustment for code-based GNSS navigation using three different miniaturized atomic clocks. Using the data of several kinematic test drives, the benefits of clock modeling for GPS navigation solutions are assessed: decrease in the noise of the up-coordinates by up to 69 % to 20 cm level, decrease in minimal detectable biases by 16 %, and elimination of spikes and subsequently decrease in large position errors (35 %). Hence, a more robust position is obtained. Additionally, artificial partial satellite outages are generated to demonstrate position solutions with only three satellites in view.

AB - Due to the limited frequency stability and poor accuracy of typical quartz oscillators built-in GNSS receivers, an additional receiver clock error has to be estimated in addition to the coordinates. This leads to several drawbacks especially in kinematic applications: At least four satellites in view are needed for navigation, high correlations between the clock estimates and the up-coordinates. This situation can be improved distinctly when connecting atomic clocks to GNSS receivers and modeling their behavior in a physically meaningful way (receiver clock modeling). Recent developments in miniaturizing atomic clocks result in so-called chip-scale atomic clocks and open up the possibility of using stable atomic clocks in GNSS navigation. We present two different methods of receiver clock modeling, namely in an extended Kalman filter and a sequential least-squares adjustment for code-based GNSS navigation using three different miniaturized atomic clocks. Using the data of several kinematic test drives, the benefits of clock modeling for GPS navigation solutions are assessed: decrease in the noise of the up-coordinates by up to 69 % to 20 cm level, decrease in minimal detectable biases by 16 %, and elimination of spikes and subsequently decrease in large position errors (35 %). Hence, a more robust position is obtained. Additionally, artificial partial satellite outages are generated to demonstrate position solutions with only three satellites in view.

KW - Allan deviation

KW - Clock coasting

KW - GNSS

KW - Receiver clock modeling

UR - http://www.scopus.com/inward/record.url?scp=84938784008&partnerID=8YFLogxK

U2 - 10.1007/s10291-015-0480-2

DO - 10.1007/s10291-015-0480-2

M3 - Article

AN - SCOPUS:84938784008

VL - 20

SP - 687

EP - 701

JO - GPS solutions

JF - GPS solutions

SN - 1080-5370

IS - 4

ER -