LSU C4G C4G Webstore
C4G Webstore

Reference Frame NAD 83(2011) epoch 2010.00

Welcome to the LSU C4G RTN Web Portal Application! In 2001, LSU’s College of Engineering created a Center for GeoInformatics (C4G) to build new research and services in Geodesy and GeoInformatics. Over the last 13 years, C4G has established a statewide network of over 70 Continuously Operating Reference Stations (CORS), 26 of which are National CORS providing the data that ties Louisiana into the National Spatial Reference System (NSRS) defined and managed by the National Geodetic Survey (NGS). The NSRS is a consistent national coordinate system that specifies latitude, longitude, height, scale, gravity, and orientation throughout the Nation, as well as how these values change with time.

In 2006, Louisiana State Legislation made C4G’s CORS network the vertical control standard for the State of Louisiana (LA Rev Stat § 50:173.1). This infrastructure is currently the backbone for surveying in Louisiana, as well as supporting all GIS development, detailed topographic mapping, precision farming, navigation, and other location based applications.

Since 2001, LSU’s C4G has utilized these tools to become instrumental to the State of Louisiana; and exposure provided by the Center’s data has offered critical information for infrastructure elevation and roadway assessment. With the addition special software that networks and monitors this CORS infrastructure, C4G created a dynamic geodetic reference system which we host, manage and offer to subscribers as a statewide Real Time Kinematic (RTK) Virtual Reference Station (VRS) service, or simply Real-Time Network (RTN). The LSU Center for GeoInformatics operates the RTN to improve geodetic services statewide.

By using C4G’s RTN services, subscribers are automatically tied into the NSRS and Louisiana’s Vertical Geodetic Control throughout the entire State while receiving Real-Time Network GPS/GNSS positions within the 3D error space of a golf ball. As with all Global Navigation Satellite System-based positioning, C4Gnet RTN is related to orthometric datums like NAVD88 by way of a geoid model or through a local network adjustment;
the latter is accomplished by including and holding fixed several NGS benchmarks with valid coordinates.

C4Gnet RTN data are based on the NGS reference frame coordinates which are currentlty in NAD 83(2011) Position (Epoch 2010.00) adjustment.

Access to the C4G’s RTN services are available through the C4G Web Store by yearly subscription at present, provided users complete the registration process and electronically acknowledge compliance with the end-user Terms of Service agreement. C4G currently offers Real-Time Network service products under the name of C4Gnet in three different markets; surveying, agriculture and GIS/Mapping.

RTN correctors enable real-time centimeter-level precision from survey grade receivers across the state of Louisiana. The default RTK service provides correctors from VRS (modeled RTK) but it can also provide multi-station (nearest CORS), or single base (user selected CORS) modes upon request if needed. Corrector messages can be received by the rover in RTCM 2.1, 2.3, 3.1, CMR, CMR+, CMRx, and DGPS formats.

C4G’s RTN has the capability to produce Virtual Reference Station (VRS) RINEX observation files for any user specified location within the network. VRS processing combines CORS observations and network process results, with the resulting VRS RINEX observations providing improved accuracy of post-processed data by minimizing CORS proximity error. Registered users can visit the Reference Data Shop to order observation files.

C4G also redistributes CORS static data for post-processing applications. CORS observations are collected at a frequency of 1 Hz. Most CORS track GPS signals L1 C/A, L2, L2 CS (CM+CL), in addition to GLONASS signals L1 C/A, and L2-P. Hourly observation files for each CORS are available in Receiver INdependent EXchange (RINEX). Hourly data sets are available immediately after the top of the hour.

The LSU College of Engineering has a clear understanding with C4G’s constituents and partners, as well as a definitive commitment to continued success and expansion of the Center for GeoInformatics.

Technical inquiries should be directed to:

Randy Osborne
225-578-4609 or 225-328-8976

System and training inquiries should be directed to:

Clifford J. Mugnier
Chief of Geodesy