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Improving Loran Coverage with Low Power Transmitters

Published online by Cambridge University Press:  01 December 2009

Sherman C. Lo ,
Benjamin B. Peterson ,
Tim Hardy  and
Per K. Enge
Sherman C. Lo*
Affiliation:
(Stanford University)
Benjamin B. Peterson
Affiliation:
(Peterson Integrated Geopositioning)
Tim Hardy
Affiliation:
(Nautel)
Per K. Enge
Affiliation:
(Stanford University)
*
(Email: daedalus@stanford.edu)
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Abstract

Enhanced Loran (eLoran) is currently being implemented to provide back up to global navigation satellite systems (GNSS) in many critical and essential applications. In order to accomplish this, eLoran needs to provide a high level of availability throughout its desired coverage area. While the current Loran system is generally capable of accomplishing this, worldwide, there remain a number of known areas where improved coverage is desirable or necessary. One example is in the middle of the continental United States where the transmitter density is not adequate for providing the desired availability for applications such as aviation in some parts. This paper examines the use of lower power, existing assets such as differential GPS (DGPS) and Ground Wave Emergency Network (GWEN) stations to enhance coverage and fill these gaps. Two areas covered by the paper are the feasibility and performance benefits of using the antennas at these sites.

Using DGPS, GWEN or other existing low frequency (LF) broadcast towers requires the consideration of several factors. The first is the ability of the transmitting equipment to efficiently broadcast on these antennas, which are significantly shorter than those at a Loran station. Recent tests at the US Coast Guard Loran Support Unit (LSU) demonstrated the performance of a more efficient transmitter. This technology allows for the effective use of smaller antennas at lower power levels. Second is the ability to broadcast a navigation signal that is compatible with the Loran system and the potential DPGS broadcast (when using a DGPS antenna). The paper examines some possibilities for navigation signals. The goal is to develop a suitable low power signal that enhances navigation and is feasible for the transmission system.

The second part of the paper examines the benefits of using these stations. The benefits depend on the location of the stations and the ability seamlessly to integrate them within the existing Loran infrastructure. Analysis of these factors is presented and the coverage benefits are examined.

Keywords

eLoranDGPS antennaGWENLF broadcast towers
Type
Research Article
Information
The Journal of Navigation , Volume 63 , Issue 1 , January 2010 , pp. 23 - 38
Copyright
Copyright © The Royal Institute of Navigation 2009

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References

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