Ionospheric Delay Correction for Single-Frequency Receivers

Damien J Allain

Research output: ThesisDoctoral Thesis

Abstract

The majority of navigation satellite receivers operate on a single frequency and experience an error due to the ionospheric delay. They compensate for the ionospheric delay using an ionospheric model which typically only corrects for 50% of the delay. An alternative approach is to map the ionosphere with a network of real-time measurements, with either a thin shell approximation or a full 3D map. Here, a time-dependent 3D tomographic imaging technique is used to map the free electron density over the full-height of the ionosphere during solar maximum. The navigation solutions computed using corrections based upon models and thin-shell and full-height maps are compared in this project.
The models and maps are used to calculate the excess propagation delay on the L1 frequency experienced by GPS receivers at selected locations across Europe and North America. The excess delay is applied to correct the pseudo-range single frequency observations at each location and the improvements to the resulting positioning are calculated. It is shown that the thin-shell and full-height maps perform almost as well as a dual-frequency carrier-smoothed benchmark and for most receivers better than the unfiltered dual-frequency benchmark. It is also shown that the unfiltered dual-frequency method is not reliable, which is of concern as it is a proposed upgrade to current positioning systems. The improvements in positioning accuracy vary from day to day depending on ionospheric conditions but can be up to 25m during mid-day at solar maximum conditions at European mid-latitudes. The full-height corrections perform well under all geomagnetic conditions and are considerably better than thin-shell corrections under extreme storm conditions.
The transmission of the navigation correction requires a forecast, an image compression and a system of distribution across a local region. The feasibility of this is demonstrated for regions of land and near-land coastal regions across Europe.
LanguageEnglish
QualificationPh.D.
Awarding Institution
  • University of Bath
Supervisors/Advisors
  • Mitchell, Cathryn, Supervisor
Thesis sponsors
Award date1 Jul 2009
StatusUnpublished - 2009

Fingerprint

shell
navigation
ionosphere
positioning system
positioning
GPS
land
distribution
project
Europe
forecast
method
North America

Keywords

  • tomography
  • Ionosphere
  • GPS

Cite this

Ionospheric Delay Correction for Single-Frequency Receivers. / Allain, Damien J.

2009. 116 p.

Research output: ThesisDoctoral Thesis

Allain, DJ 2009, 'Ionospheric Delay Correction for Single-Frequency Receivers', Ph.D., University of Bath.
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N2 - The majority of navigation satellite receivers operate on a single frequency and experience an error due to the ionospheric delay. They compensate for the ionospheric delay using an ionospheric model which typically only corrects for 50% of the delay. An alternative approach is to map the ionosphere with a network of real-time measurements, with either a thin shell approximation or a full 3D map. Here, a time-dependent 3D tomographic imaging technique is used to map the free electron density over the full-height of the ionosphere during solar maximum. The navigation solutions computed using corrections based upon models and thin-shell and full-height maps are compared in this project. The models and maps are used to calculate the excess propagation delay on the L1 frequency experienced by GPS receivers at selected locations across Europe and North America. The excess delay is applied to correct the pseudo-range single frequency observations at each location and the improvements to the resulting positioning are calculated. It is shown that the thin-shell and full-height maps perform almost as well as a dual-frequency carrier-smoothed benchmark and for most receivers better than the unfiltered dual-frequency benchmark. It is also shown that the unfiltered dual-frequency method is not reliable, which is of concern as it is a proposed upgrade to current positioning systems. The improvements in positioning accuracy vary from day to day depending on ionospheric conditions but can be up to 25m during mid-day at solar maximum conditions at European mid-latitudes. The full-height corrections perform well under all geomagnetic conditions and are considerably better than thin-shell corrections under extreme storm conditions. The transmission of the navigation correction requires a forecast, an image compression and a system of distribution across a local region. The feasibility of this is demonstrated for regions of land and near-land coastal regions across Europe.

AB - The majority of navigation satellite receivers operate on a single frequency and experience an error due to the ionospheric delay. They compensate for the ionospheric delay using an ionospheric model which typically only corrects for 50% of the delay. An alternative approach is to map the ionosphere with a network of real-time measurements, with either a thin shell approximation or a full 3D map. Here, a time-dependent 3D tomographic imaging technique is used to map the free electron density over the full-height of the ionosphere during solar maximum. The navigation solutions computed using corrections based upon models and thin-shell and full-height maps are compared in this project. The models and maps are used to calculate the excess propagation delay on the L1 frequency experienced by GPS receivers at selected locations across Europe and North America. The excess delay is applied to correct the pseudo-range single frequency observations at each location and the improvements to the resulting positioning are calculated. It is shown that the thin-shell and full-height maps perform almost as well as a dual-frequency carrier-smoothed benchmark and for most receivers better than the unfiltered dual-frequency benchmark. It is also shown that the unfiltered dual-frequency method is not reliable, which is of concern as it is a proposed upgrade to current positioning systems. The improvements in positioning accuracy vary from day to day depending on ionospheric conditions but can be up to 25m during mid-day at solar maximum conditions at European mid-latitudes. The full-height corrections perform well under all geomagnetic conditions and are considerably better than thin-shell corrections under extreme storm conditions. The transmission of the navigation correction requires a forecast, an image compression and a system of distribution across a local region. The feasibility of this is demonstrated for regions of land and near-land coastal regions across Europe.

KW - tomography

KW - Ionosphere

KW - GPS

M3 - Doctoral Thesis

ER -