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Fast Real Time Positioning using GNSS


Many developments in surface transportation are dependent on greater positioning accuracy as well as position integrity for improvements in safety, performance, and efficiency.  Examples include:

·       Construction (grading, paving, infrastructure mapping),

·       Maintenance (line striping),

·       Non-barrier separated toll or HOV lanes,

·       Lane keeping,

·       Infrastructure mapping, etc. 

While some applications are available today using GPS, significant time is required for units to establish the accurate and trustworthy solutions needed to support them.  New products that provide these capabilities at reasonable cost are needed if these capabilities are to become standard in vehicles.

It can also be said that radio navigation, as this area of technology is known, is a very quickly changing field that has shown and continues to show how innovative developers can be.  Currently, there are some 40 + Global Navigation Satellite System (GNSS) satellites (Global Positioning System (GPS), Wide Area Augmentation System (WAAS), Global Navigation Satellite System (GLONASS), etc) available. In addition, a ground based infrastructure, with nearly 1500 reference stations, is providing GPS observables to the National Geodetic Survey’s (NGS) Continuously Operating Reference Station (CORS) service on 1, 5, or 15 second intervals (see is available.  Other data, such as accurate ephemeris and atmospheric delay models, are available from other sources.  Couple this with the development of nationwide broadband data networks and an entire new arena of applications can now be inexpensively and reliably implemented.  Unfortunately, the industry is still focused on two markets: high accuracy survey applications using high end, expensive equipment and low accuracy, recreational grade inexpensive user equipment.  Transportation applications that support safety, performance, and efficiency fall into a middle area that is not being exploited but is a large potential market. 

This combination of data and availability has been used to a limited extent           but has not been fully exploited.  The missing part of this is the availability of software to use this data to achieve fast resolution (less than 3 seconds) and achieve high accuracy (better than 1 decimeter) with high integrity (greater 99.9%).  This was recognized as a shortcoming in the recently completed National Position, Navigation, and Timing Architecture study undertaken by the Departments of Transportation and Defense (see for details). 

While some theoretical work has been done to develop this concept, a marketable solution that could achieve a very accurate resolution with a high level of integrity in a short time period has not been proposed. 

Expected Phase I Outcomes:

The first goal of this phase is to develop a theoretical algorithm for generating a sub-decimeter solution in 3 seconds using GPS satellite data and data collected from standard GNSS reference stations.  This can be data provided by NGS or another source, but it must be publicly available data.  The second goal is to implement this algorithm such that it can make use of live satellite data and data either streamed over an internet link or broadcast from one of the several low/medium frequency broadcast stations around the country.    

Expected Phase II Outcomes:

Phase II will focus on developing a stand-alone product that provides the user community with integrity, accuracy, and fast solutions implemented in a finished cost effective product.

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