gov.noaa.nmfs.inport:39910 eng UTF8 dataset National Geodetic Survey resourceProvider NGS Communications and Outreach Branch (301) 713-3242 (301) 713-4172 ngs.infocenter@noaa.gov pointOfContact 2025-07-24T18:57:36 ISO 19115-2 Geographic Information - Metadata Part 2 Extensions for imagery and gridded data ISO 19115-2:2009(E) Calibration Base Lines for Electronic Distance Measuring Instruments (EDMI) Calibration Base Lines 1974 creation 1974 publication NOAA/NMFS/EDM 39910 https://www.fisheries.noaa.gov/inport/item/39910 WWW:LINK-1.0-http--link Full Metadata Record View the complete metadata record on InPort for more information about this dataset. information https://www.ngs.noaa.gov/CBLINES/calibration.shtml WWW:LINK-1.0-http--link Citation URL Online Resource download A calibration base line (CBL) is a precisely measured, straight-line course of approximately 1,400 m used to calibrate Electronic Distance Measuring Instruments (EDMI). A CBL usually consists of four segments ranging from 150 to 1,400 m whose lengths are measured with two high precision EDMI. Since the program began in 1974, NGS has established more than 300 base lines throughout the United States in cooperation with government agencies, universities and professional groups. Participating organizations must select a suitable site that is accessible for public use and install the base line markers 2 to 3 months before measurements are taken. Published CBL distances are available from the National Geodetic Survey, 301-713-3242 or ngs.infocenter@noaa.gov. For more information, please refer to: [1] NOAA Technical Memorandum NOS NGS-8 - Establishment of Calibration Base Lines (1994). [2] NOAA Technical Memorandum NOS NGS-10 - Use of Calibration Base Lines (1977). Both publications are available in pdf from http://www.ngs.noaa.gov/PUBS_LIB/pub_index.html. CBL's provide surveyors with a means to detect and correct errors in Electronic Distance Measuring Instruments (EDMI). These highly accurate base lines provide a locally accessible standard for length measurement.In addition, NGS makes available the PC program CALIBRAT. This program is used to determine the scale and constant corrections for electronic distance measuring instruments by utilizing measurements taken over previously determined base lines. The formulas used in the program are found in NOAA Technical Memorandum NOS NGS-10, "Use of Calibration Base Lines." onGoing NGS Communications and Outreach Branch (301) 713-3242 (301) 713-4172 ngs.infocenter@noaa.gov pointOfContact NGS Communications and Outreach Branch (301) 713-3242 (301) 713-4172 ngs.infocenter@noaa.gov custodian asNeeded Geodetic/Global Positioning theme NOS Data Explorer Topic Category Calibrations Distances EDMI Geodetic/Global Positioning Topographic Data oceans theme U.S. Exclusive Economic Zone United States place DOC/NOAA/NOS/NGS > National Geodetic Survey, National Ocean Service, NOAA, U.S. Department of Commerce dataCentre Global Change Master Directory (GCMD) Data Center Keywords 2017-04-24 publication 8.5 Earth Science Data and Information System, Earth Science Projects Division, Goddard Space Flight Center (GSFC), National Aeronautics and Space Administration (NASA) https://forum.earthdata.nasa.gov/app.php/tag/GCMD%2BKeywords GCMD Keyword Forum Page Global Change Master Directory (GCMD). 2025. GCMD Keywords, Version 22. Greenbelt, MD: Earth Science Data and Information System, Earth Science Projects Division, Goddard Space Flight Center (GSFC), National Aeronautics and Space Administration (NASA). URL (GCMD Keyword Forum Page): https://forum.earthdata.nasa.gov/app.php/tag/GCMD+Keywords information custodian NGS Metadata Library project InPort otherRestrictions Cite As: National Geodetic Survey, [Date of Access]: Calibration Base Lines for Electronic Distance Measuring Instruments (EDMI) [Data Date Range], https://www.fisheries.noaa.gov/inport/item/39910. NOAA provides no warranty, nor accepts any liability occurring from any incomplete, incorrect, or misleading data, or from any incorrect, incomplete, or misleading use of the data. It is the responsibility of the user to determine whether or not the data is suitable for the intended purpose. otherRestrictions Access Constraints: None otherRestrictions Use Constraints: None otherRestrictions Distribution Liability: none unclassified NOAA Data Management Plan (DMP) NOAA/NMFS/EDM 39910 https://www.fisheries.noaa.gov/inportserve/waf/noaa/nos/ngs/dmp/pdf/39910.pdf WWW:LINK-1.0-http--link NOAA Data Management Plan (DMP) NOAA Data Management Plan for this record on InPort. information crossReference eng; US geoscientificInformation location -175 -67 18 71 | Currentness: Publication Date 1974 Both mark-to-mark and horizontal distances are published. When the suggested grade specifications are met, it is a simple matter to place the instruments or reflectors at about the same height above the monuments. A direct comparison with the published mark-to-mark data can then be made. Unless steps are taken to set the instruments or reflectors such that the measured distances are in the horizontal plane between monuments, computations are required to compare the observed distances with the published horizontal values. Text (Unstructured) NGS Communications and Outreach Branch (301) 713-3242 (301) 713-4172 ngs.infocenter@noaa.gov distributor https://www.ngs.noaa.gov/CBLINES/calibration.shtml WWW:LINK-1.0-http--link https://www.ngs.noaa.gov/CBLINES/calibration.shtml Downloadable Data download dataset Accuracy The accuracy of each distance segment is determined through a least squares adjustment procedure on the assumption the data points were established in a straight line. Accuracies are on the order of 0.1 to 0.3 mm per line segment. Actual accuracies are stated on each individual CBL document. Horizontal Positional Accuracy The coordinates for each CBL are generally scaled from a topo map or positioned using a GPS unit. Vertical Positional Accuracy The published elevations are for distance reduction purposes only. They are not tied to the the National Vertical Datum. The relative differences between elevations are better than +/-12 mm. Completeness Report none Conceptual Consistency none Calibration Base Line monuments are set on a straight line by the requesting organization. After a sufficient time to allow for settling, the base line is measured with two high accuracy short range EDMI on 2 separate days. Observations will be made such that all segments are measured, forward and backward, on each of the 2 days with both instruments. For a 4 monument base line, this will provide a total of 12 distinct observations with each instrument per day. A total of 48 observations during the 2 days will have been taken. Observations are field checked prior to submittal to NGS for adjustment. NGS will check the EDMI before and after each project to insure the observations meet length standards set by the National Bureau of Standards. All observations are then adjusted through a least squares adjustment procedure and thoroughly checked prior to publication.Process Date Range is 1974-present