2009 04 16   Indiana Kentucky Ohio CORS  (spreadsheet.xls)

2008 02 11   Report on Use of Erla  by NGS CORS Chief

2006 09 01  Special Sale:  RTK dual-frequency GPS receivers

2006 02 21  Continuing Erla -- beyond a Decade of Service

2003 Oct 9 -- NTRIP technology, developed in Germany, was demonstrated successfully at NCAD with two varieties of GPS rover receivers, each receiving, via serial port, a stream of RTCM 2.2 messages, over the iNternet, from CORS Erla, enabling real-time corrected GPS positions.  Real-time observations of the position results - 1 each second - was enabled by ESRI's Tracking Analyst extension on ArcView GIS 3.3.  95% of the points fell consistently within a 1" circle.    The new technology enables serial output from the Ashtech Z12  CORS Erla Reference receiver to be packetized in TCP Internet Protocol and then available to any internet user (for example via cell phone) practically anywhere on Earth.  The 2 rover receivers tested were:  Trimble 4000sse and Spectra Precision 3220.  Any GPS receiver supporting RTK is enabled for this positional capability.  More information and to enjoy a test with your equipment, please contact us at john@ncad.net or 859 727-9999.

2003 Sep 12 00:50   The original choke ring antenna, Ashtech 700936D, was returned to operation with new state-of-art SCIGN dome.  The LNA Low Noise Amplifier was replaced with new.  The original LNA was repaired and is retained for backup.

In 1995 June, the Department of Defense completed the deployment of 24 satellites, each orbiting the Earth twice per day, transmitting signals that are sensed by GPS receivers on Earth.   Processing multiple satellite transmissions simultaneously, the GPS receiver (a special purpose computer) can compute the location of its antenna to an accuracy approaching 1cm.  Thus, GPS is increasingly being discovered as the best tool for positioning by increasingly wide categories of users.

The NCAD focus as Application Engineers, is to facilitate the utilization of GPS by Surveyors and GIS managers.   Below are several documents providing background and guidance in considering your use of GPS.

Erla is a northern Kentucky CORS, provided by NCAD.   More information about Erla is provided below.   Since 1996, 5s data availability is nearly continuous and complete. This is not always reflected at NGS where the data is aggregated for public dissemination with data from other CORS.  Gaps on the NGS server are likely due to imperfections in the process for downloading data by NGS from the NCAD ftp server.   Please let us know if you can not get the data you want.

NCAD also provides historical 5s data and, by pre-arrangement, faster data, upto 2Hz.   Please let us know what you would like.  Thank you for using Erla.

2003 Sep 04 -  New programs of GPS:  WAAS, LAAS, VRS, NRT, Ntrip...  Here is a fruitful link on the former http://gps.faa.gov.  Stay tuned for more on the latter.

2003 Aug 21  The CORS Erla choke ring antenna, providing continuous service since 1996, died between 5 and 8am.  Beginning 19:00 EST 2003 Aug 21, the temporary replacement antenna is the  Spectra Precision Geodetic L1/L2 Ground Plane Model 571212238  s/n 31410509.  Calibration details are at http://www.ngs.noaa.gov/ANTCAL

2003 July 23  Why is Erla so stable?

2003 Apr 07  Nationwide CORS value rating --  being updated this year 2006.

2001 Publication Article by john Schmidt in ArcNews 2001 Fall issue: this short article is to synchronize spatial technology globally.

2000 May    Erla is cited by NGS Chief Geodesist, initially at the InterAgency GPS Board web, 2013:http://www.gps.gov/systems/gps/modernization/sa/data/, comparing before and after Selective Availability is turned off by President Clinton's Directive

1999 Dec  Spectra Precision Integrated Surveying  is now Trimble

john schmidt provides education and training with hands-on live demonstrations, in the comfort of the NCAD seminar room.  Featuring:  SP tools, spotlighting the ultimate fieldbook, GeoWin, and RTK with dual-frequency receivers fed by rooftop-mounted antennas, including Erla, the nation's most stable CORS.  GeoGenius, the all-encompassing observation-processing software provides best results and automated reports, even in NGS BlueBook format, assembled from data including SP totalStations and nearly any GPS receiver.  Watch it live with ESRI's Tracking Analyst for real-time navigation on the GIS basemap; and presenting the new ESRI product:  ArcPad.

1999  Publication The Surveyor's GIS; (G stands for Global)  Published in the Proceedings of the 1999 Conference of the Professional Land Surveyors of Ohio, is an article authored by John Schmidt applicable to all members of the GIS community.  For the Word document zipped by PKWare: Click here to download. Click here for the html version online.

1998  Mar  Press Release:  Erla:  most stable, nationwide

1997  Sep  Erla for Professionals

1997  Feb  Geodetic Surveying 1997  Message to the Professional Land Surveyors of Ohio

1997  Jan  Press Release:  Erla, Continuously Operating Reference Station (CORS)

1997  Jan  Free GPS  the rationale for CORS Erla

1996  Dec  Summary, of the 1995 UNAVCO Report evaluating GPS receivers and antennae.


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