HA-NDGPS April 2002 Workshop Proceedings

Table of Contents

1. Forward
2. Introduction
3. Jim Arnold
4. Jim Radice
5. Ben
6. Kendall
7. Question and Answer
   

Foreword

The Nationwide Differential Global Positioning System (NDGPS) Modernization Program is a multiagency effort to examine the viability of long baseline carrier phase differential correction techniques. Phase I of this program analyzes broadcasting GPS observables from a single NDGPS site, Hagerstown, MD, to aid in determining the appropriate signal structure and compression techniques to support long range carrier phase operations. Phase II will install a second facility near Hawk Run, PA, enabling multiple baseline carrier and code phase navigation solutions.

During the development of this project it was decided to have participation from other organizations. To ensure that participants fully understood what data would be available and how it could be used, a workshop was held in Silver Spring, MD, at the National Oceanic and Atmospheric Administrations auditorium.

This document is the proceedings generated from that workshop.

NOTICE

This document is disseminated under the sponsorship of the Department of Transportation in the interest of information exchange. The United States Government assumes no liability for its contents or use thereof. This report does not constitute a standard, specification or regulation.

The United States Government does not endorse products or manufacturers. Trade and manufacturers' names appear in this report only because they are considered essential to the object of this document.

Introduction

The Federal Highway Administration (FHWA), in association with the U.S. Coast Guard, National Geodetic Survey (NGS), and several other government agencies, is implementing a High Accuracy - Nationwide Differential Global Positioning System (HA-NDGPS) capability for test purposes at the Nationwide Differential Global Positioning System (NDGPS) facility in Hagerstown, MD. The signal in space can be received by anyone with appropriate receiver equipment.

The accuracy of this broadcast correction is expected to enable 10 centimeter (95 percent) dynamic accuracy within 200 miles of the broadcast facility. The goals of the program are to:

• Enable Dynamic Positioning at the Centimeter Level throughout the NDGPS Network
• Coexist with the current NDGPS Broadcast
• Minimize the incremental cost of adding High Accuracy DGPS to NDGPS Sites
• Utilize existing broadcast antenna, reference stations, and site infrastructure
• Incremental Cost ~$75,000/ Existing Site

Background

Using the U.S. Coast Guard's Maritime Differential GPS service as its base, a seven agency group began deploying the NDGPS service in 1998 with the implementation of the Appleton, WA, facility. Since that time, roughly 80 percent of the country has been covered with this low frequency broadcast of differential corrections. This service offers 1- to 3-meter accuracy (95 percent), 5 second integrity, and 99.97 percent availability. This level of service has enabled many surface-based applications, but many more require higher accuracy with equivalent integrity and availability. It is the goal of the HA-NDGPS program to develop a long-range method of providing a higher accuracy radionavigation solution in order to promote the development of applications that would not otherwise be available in the foreseeable future.

Workshop

On April 17, 2002, FHWA, NGS, and the U.S. Coast Guard sponsored a workshop on the HA-NDGPS concept at the National Oceanic and Atmospheric Administrations (NOAA) auditorium in Silver Spring, MD. This document compiles all the presentations from that workshop into a single proceeding for distribution.

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