2006 02 21

NCAD established Erla in 1996 as a valued community resource.  Now in our tenth year of operation, we invite new support to secure, continue, and expand the public service of Erla  indefinitely.  This message is to facilitate dialogue with the new lead agency, in turn enlisting support from unlimited entities which continue to benefit from Erla.  Affiliates may include: NGS, KY Trans, ODOT, InDOT, Utilities, OKI Regional Council of Governments, NKAPC, CAGIS, and Kenton County Airport Board.

Here are a few elements contributing to the value of Erla:

1a.  Erla was the first CORS installed within the Eastern US interior -- bounded by waters of the Great Lakes, Atlantic Ocean, and Mississippi River -- including all but distant (coastal) boundaries of 14 states:  NY, PA, WV, VA, NC, SC, GA, FL, AL, TN, IL, IN, OH, KY.  

Thus Erla, is the "grandfather" to all other CORS within this vast, eastern, inland US area.  That is, it is longest running; and thereby most equilibrated to a higher positional accuracy, with a higher reliability, asymptotically converging within the global polyhedron of baselines between CORS around the globe.  Since 1996, each CORS added within that area initially obtains its new position using Erla, and continues to equilibrate with Erla.

1b.  Erla endures.  Nationally, 135 CORS were established prior to 1997.  Among those there are only 16 that today continue to provide hourly files of observations at 5 second intervals, and are fully monumented with high-quality Supplemental Reference Monuments.

2a. Erla is the most stable, according to the 1998 02 02 report by Dr. Snay, CORS Director, with regard especially to the vertical component which has become of primary significance to the national program Height Modernization

This stability is expected based on:  (1) the location of Erla on the crown of the nation's most stable geological formation, the Cincinnati Arch.  (2) Erla is mounted into one solidified flue of 110-year-old, 58x31 chimney, founded central to and connected with a unified perimeter building foundation constructed in 1895, on Ordovician bedrock, since undisturbed.

2b.  Reliable, current, positional stability is the primary feature of a valued CORS, and obtains from a record of performance, measured by NGS after analysis of data downloaded daily from each national CORS.  The record of stability is reported for each CORS at www.ngs.noaa.gov/CORS by way of two charts, one providing the most current 60 days of service, and another covering the entire life of service by that CORS.  Repeatability is reported as the Root Mean Square of deviation from the mean, for each positional component (X,Y,Z or Easting, Northing, Up:  N,E,U).  CORS users are best served when total rms is low, both in most recent past, and consistently over the life of the CORS.

2c.  Compiling data for the 16 CORS whose startup date occurred prior to 1997, and which are fully monumented with Supplemental Reference Monuments, and which continue to provide hourly data at 5 second intervals, Erla is among the nation's most stable.  The combined Horizontal + Vertical Score for the most recent 60 days at Erla is 1.03cm, second to SHK1 in NJ .83cm.  The combined H+V Life Score at Erla is 1.82cm, 3rd behind TMGO in CO 1.65, and WIS1 in WI 1.72.  Averaging 60-day and Life Scores, Erla rms is second lowest among the only 4 sites scoring under 1.5cm:  TMGO 1.36, Erla 1.43, WIS1 1.44, PPT1 1.44.  

3. Erla is the only CORS in Ohio, Indiana, and Kentucky, with complete Supplemental Reference Monumentation; and said Monumentation, installed by NGS in the autumn of 1997, is of high quality, based on the report at www.ngs.noaa.gov/CORS.

4. Erla is operated and maintained by NCAD Corporation, assuring, over 9.5 years, data availability at a rate exceeding 99.99%.

5. Erla, since 2003, continues to be the solitary contributor to the NTRIP Real-Time GNSS Network CORS, providing real-time dual-frequency corrections available over the internet to GPS rovers linked by cellular communications.  Real-time accuracy results of 1" at Erla degrade approximately 1ppm as distance from Erla increases.

6. Erla is located at the Erlanger Reference Center, a highly-efficient research / training center, able to be extended for adjunct monitoring of:  meteorology, seismicity, air quality, etc.

7. The Erlanger Reference Center may be eligible for promotion to National Spatial Reference Center, while inviting public outreach and visitation, and even contributing to commerce and tourism.  Erla is at the Gateway to the South / North, where options could be developed yanking dollars from pockets originating in Canada, Michigan, Pennsylvania, Illinois... or any southeastern US state. This may further extend the important contribution made to Kentucky by this Northern Gateway, and to Cincinnati where stops are not currently encouraged.

8. Erla is located at the intersection of Ohio, Indiana, and Kentucky, serving as kingpin to integration of these adjusted states, all sharing the keystone Cincinnati Arch, in this first, three-dimensional, nation-wide adjustment, under way this year by NGS, of the National Spatial Reference System.

9. Erla is at the center of the Eastern North American population.  No other MSA in North American is within 800 miles of more than 60% of the North American population.  Map at http://ncad.net/GI/TGIF/TGIF.htm.

10. Erla is 7 miles from, and at the same elevation as, the Cincinnati Northern Kentucky International Airport, able to provide secure primary or secondary reference service for GPS-aided flight.

11. Erla is closest to the Brent Spence Bridge augmentation project now underway to facilitate traffic on one of the nation's most important freeway arteries, converging interstates: 71, 74, and 75.

With loving response to the challenge  "Ask not what your country can do for you.  Ask what you can do for your country!", john was thrilled to invest about $40,000 into his homeland, providing to many a best-quality GPS reference service obviating the need for similar expenditure by those many.  Because CORS was new, there was no business model in place to guide and finance the start-up of this unique public service.  Now that more of us know the value, perhaps there is consideration for continuing this service.  

Thank you for your enquiry and please visit this rapidly evolving public service facility, about which we all should be proud.

Respectfully, and faithfully yours,


john r. schmidt, M.S.


NCAD Corporation http://ncad.net



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