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Nationwide Differential GPS (NDGPS)Real-Time Data Streaming

Federal Geodetic Control SubcommitteeSilver Spring, MDJanuary 10, 2012

Timothy A. KleinSenior Policy Advisor/RITA NDGPS Coordinator

Timothy.Klein@dot.govNDGPS@dot.gov

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GPS-Based Applications are Critical to Major DOT Initiatives

Reliable and accurate positioning worldwide

Reduced delaysMore fuel-efficient routesIncreased system capacity with

enhanced safety

Aviation – NextGen

ITS/Connected Vehicle

Rail – Positive Train ControlReduced probability of

collisions Increased efficiency and

capacityRapid rail structure and

conditioning mapping

Enable crash prevention among vehicles and between vehicles and infrastructure

Increased mobility and reduced environmental impact

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NDGPS Applications Partners• Department of Commerce

– Continuously Operating Reference Stations– Severe Weather Forecasting – water vapor

estimates to national weather models– Space Weather Monitoring – free electron mapping

• Federal Resource Agencies (USDA, NPS, USGS)– One meter real-time positioning and navigation– Fire management and safety– Survey and mapping; GIS applications

• State, County and Local Governments, Private and Non-Profit Sectors– Lands, parks and environmental resources management– Precision agriculture– Mining and other resource management

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NDGPS Program Status• Inland (DOT) Tower Recapitalization

– Upgrade reference stations/integrity monitors/antenna– Install IP-based operations system– Upgrade transmitters– Receiving FY12 funding to begin

• Buildout Unlikely– No DOT support for construction funding– Strong support for O&M and recap

• USCG Status– Reduced requirements; budget concerns– Looking at future of broadcast system; timing backup?– FY12 study of NDGPS real-time accuracy estimates and measurements

• “Market Reality” Status– Limited interest in commercial use of broadcast signal– Few DGPS board manufacturers; firms leaving the field– No new program budgeting for civil positioning/navigation

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Potential “Best Uses” of a National Asset• Strengthening the Asset for 10 -15 Years

– But will the broadcast mission last that long?– Is there a role for streaming NDGPS observables, with or without broadcast?– Whom could this investment serve?

• Strongest Continuing User Group – CORS User Community– Robust, service availability-guaranteed CORS sites– 23% of CORS solutions use an NDGPS-CORS site– Data streaming in RTCM format test-proven (1cm horizontal, 3cm vertical)– Would prefer to maintain broadcast capability

• Continuing requirement - transportation services– Can streaming data meet dynamic accuracy requirements?– Desire to complete HA-NDGPS broadcast prototype

• Questioning requirement – Coast Guard/maritime– Can streaming data meet positioning and navigation requirements?– Can streaming data improve harbor safety?

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NGS Streaming of CORS Data (including NDGPS)

Single Baseline of 55 kms to Streaming Station

Using Trimble R8 Model 3 GNSS Using a Trimble GeoXH 2008

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Pluses:• Free• Easy to use with receiver built in support• Only one GPS receiver required• Provides real-time, dual-frequency RTK positioning. • Some streaming sites provide GLONASS data.• Open source so other entities can produce a value-added product

Minuses:• Requires cell phone coverage and an unlimited data cell plan which can be expensive • Data link drains the cell battery in relatively short amount of time (about an hour so external power is

recommended )• Lat/Long reference frame is ITRF. This can add an unnecessary level of complication to integration

with existing NAD83 referenced data.• Single baseline• The number of streaming sites is limited at this time

NGS Streaming of CORS Data (including NDGPS)