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Issue 9: Future Directions and Research

Space Based Real-Time Kinematic GPS for National Geodetic Survey Texas Height Modernization

S. D. Lyle and D. M. Mulcare

Download the full paper in PDF (408 KB)


Height Modernization is a program in NOAA's National Geodetic Survey (NGS) that uses the Global Positioning System (GPS) and other new technologies to increase the accuracy of elevation measurements that comprise the vertical portion of the National Spatial Reference System (NSRS). Height Modernization Program within NGS is working with states to improve the height component of their survey control networks and related products. Texas A&M University- Corpus Christi (A&M-CC) was designated as the recipient of a grant under the Program during the most recent Congressional cycle. In order to best coordinate and manage the activities funded by the grant, A&M-CC has established the Texas Spatial Reference Center (TxSRC).

TxSRC will assist state agencies, private companies, public utilities and federal agencies in their efforts to improve the statewide network of control points as well as to support their use of GPS Continuing Operating Reference Stations (CORS). TxSRC plans to support the development of a statewide system of broadcasting Networked Transport of RTCM via Internet Protocol (NTRIP) for RTK-GPS. TxSRC will research methods of using NTRIP to locate and to collect information on geodetic monuments. NTRIP use is being considered as a way to overcome the limitations of RTK. Current RTKGPS implementations require cellular or radio modem connections as the mechanism for receiving differential corrections. This infrastructure is not available in many remote and rural areas of Texas.

It is proposed that a space-based (SB) RTK-GPS should be used to provide corrections in areas where no other corrections can be obtained without additional terrestrial infrastructure development. The proposed solution uses the Hughes Network System's Directway broadband internet satellite to send corrections to remote sites. Data would be received at the remote site and then locally broadcast to rover users. This SB-RTK-GPS will allow TxSRC to utilize the existing network of CORS sites. The CORS will be used to generate the corrections that provide NTRIP. This research will investigate the configuration concerns and other and technical aspects of this proposed methodology.


  • Reprinted with permission from The Institute of Navigation ( and The Proceedings of the 18th International Technical Meeting of the Satellite Division of The Institute of Navigation, (pp. 1079-1082). Fairfax, VA: The Institute of Navigation.


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