Calibration Base Lines for Electronic Distance Measuring Instruments (EDMI)
Data Set (DS) | National Geodetic Survey (NGS)GUID: gov.noaa.nmfs.inport:39910 | Updated: October 17, 2023 | Published / External
Summary
Short Citation
National Geodetic Survey, 2025: Calibration Base Lines for Electronic Distance Measuring Instruments (EDMI), https://www.fisheries.noaa.gov/inport/item/39910.
Full Citation Examples
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.
Distribution Information
-
Text (Unstructured)
Downloadable Data
None
None
Controlled Theme Keywords
geoscientificInformation, location
Child Items
No Child Items for this record.
Contact Information
Point of Contact
NGS Communications and Outreach Branch
ngs.infocenter@noaa.gov
(301) 713-3242
Metadata Contact
NGS Communications and Outreach Branch
ngs.infocenter@noaa.gov
(301) 713-3242
Extents
1974 - Present
Item Identification
Title: | Calibration Base Lines for Electronic Distance Measuring Instruments (EDMI) |
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Short Name: | cbl |
Status: | Completed |
Publication Date: | 1974 |
Abstract: |
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. |
Purpose: |
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." |
Notes: |
1294 |
Supplemental Information: |
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. |
Keywords
Theme Keywords
Thesaurus | Keyword |
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ISO 19115 Topic Category |
geoscientificInformation
|
ISO 19115 Topic Category |
location
|
UNCONTROLLED | |
NOS Data Explorer Topic Category | Geodetic/Global Positioning |
None | Calibrations |
None | Distances |
None | EDMI |
None | Geodetic/Global Positioning |
None | oceans |
None | Topographic Data |
Spatial Keywords
Thesaurus | Keyword |
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UNCONTROLLED | |
None | U.S. Exclusive Economic Zone |
None | United States |
Physical Location
Organization: | National Geodetic Survey |
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City: | Silver Spring |
State/Province: | MD |
Data Set Information
Data Set Scope Code: | Data Set |
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Maintenance Frequency: | As Needed |
Data Presentation Form: | document |
Distribution Liability: |
none |
Support Roles
Data Steward
Date Effective From: | 1974 |
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Date Effective To: | |
Contact (Organization): | NGS Communications and Outreach Branch |
Email Address: | ngs.infocenter@noaa.gov |
Phone: | (301) 713-3242 |
Fax: | (301) 713-4172 |
Distributor
Date Effective From: | 1974 |
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Date Effective To: | |
Contact (Organization): | NGS Communications and Outreach Branch |
Email Address: | ngs.infocenter@noaa.gov |
Phone: | (301) 713-3242 |
Fax: | (301) 713-4172 |
Metadata Contact
Date Effective From: | 1974 |
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Date Effective To: | |
Contact (Organization): | NGS Communications and Outreach Branch |
Email Address: | ngs.infocenter@noaa.gov |
Phone: | (301) 713-3242 |
Fax: | (301) 713-4172 |
Point of Contact
Date Effective From: | 1974 |
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Date Effective To: | |
Contact (Organization): | NGS Communications and Outreach Branch |
Email Address: | ngs.infocenter@noaa.gov |
Phone: | (301) 713-3242 |
Fax: | (301) 713-4172 |
Extents
Currentness Reference: | Publication Date |
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Extent Group 1
Extent Group 1 / Geographic Area 1
W° Bound: | -175 |
|
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E° Bound: | -67 | |
N° Bound: | 71 | |
S° Bound: | 18 |
Extent Group 1 / Time Frame 1
Time Frame Type: | Continuing |
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Start: | 1974 |
Access Information
Security Class: | Unclassified |
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Data Access Constraints: |
None |
Data Use Constraints: |
None |
Distribution Information
Distribution 1
Download URL: | http://www.ngs.noaa.gov/CBLINES/calibration.shtml |
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Distributor: | |
Description: |
Downloadable Data |
File Type (Deprecated): | ASCII Text |
Distribution Format: | Text (Unstructured) |
URLs
URL 1
URL: | http://www.ngs.noaa.gov/CBLINES/calibration.shtml |
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URL Type: |
Online Resource
|
Activity Log
Activity Log 1
Activity Date/Time: | 2012-12-11 |
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Description: |
Date that the source FGDC record was last modified. |
Activity Log 2
Activity Date/Time: | 2017-04-05 |
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Description: |
Converted from FGDC Content Standards for Digital Geospatial Metadata (version FGDC-STD-001-1998) using 'fgdc_to_inport_xml.pl' script. Contact Tyler Christensen (NOS) for details. |
Activity Log 3
Activity Date/Time: | 2018-02-08 |
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Description: |
Partial upload of Positional Accuracy fields only. |
Data Quality
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. |
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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 |
Lineage
Process Steps
Process Step 1
Description: |
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 |
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Catalog Details
Catalog Item ID: | 39910 |
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GUID: | gov.noaa.nmfs.inport:39910 |
Metadata Record Created By: | Tyler Christensen |
Metadata Record Created: | 2017-04-05 13:07+0000 |
Metadata Record Last Modified By: | SysAdmin InPortAdmin |
Metadata Record Last Modified: | 2023-10-17 16:12+0000 |
Metadata Record Published: | 2018-02-08 |
Owner Org: | NGS |
Metadata Publication Status: | Published Externally |
Do Not Publish?: | N |
Metadata Last Review Date: | 2018-02-08 |
Metadata Review Frequency: | 1 Year |
Metadata Next Review Date: | 2019-02-08 |