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NGS Electronic Distance Measurement Instrument Calibration Base Line Program

NGS Electronic Distance Measurement Instrument Calibration Base Line Program. Kendall Fancher Chief, NGS Instrumentation & Methodologies Branch. What is a CBL?.

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NGS Electronic Distance Measurement Instrument Calibration Base Line Program

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  1. NGS Electronic Distance Measurement Instrument Calibration Base Line Program Kendall Fancher Chief, NGS Instrumentation & Methodologies Branch

  2. What is a CBL? • A standard Electronic Distance Measurement Instrument (EDMI) Calibration Base Line (CBL) consists of four stable monuments set in a nearly straight line. • When properly spaced, a four-monument CBL design allows for measuring 6 distinct distances of varying lengths along the CBL range. • All distances associated with the CBL are initially measured using high precision EDMI on an order of one magnitude or better of the instruments which will be calibrated using the CBL. • To properly determine EDMI scale error a CBL should be at least 900 m in length and would ideally be 1000 meters or more in overall length.

  3. Why Use a CBL? • To determine or verify instrument constants and provide assurance measured distances meet accuracy specifications. • To monitor instrument measuring accuracy as well as operating precision capabilities over time.

  4. Definition of Terms

  5. NGS EDMI CBL Program (1974-1996) • In 1974 NGS began establishing EDMI CBLs for external use. • CBLs of this time period included a “taped” section. • No other Federal agency was providing a mechanism for calibrating EDMI. • A CBL established in 1963 in Beltsville, MD served as the “Master” CBL. • The Corbin “Master CBL” was established in 1977 • Provided traceability to a National Standard Unit of Length. • Provided a means of check calibrating instrumentation used to establish other CBLs. • NGS directly participated in all EDMI CBL measurements. • NGS partners set CBL marks and provided support during field measurements. Former NGS employee Raymond W. Tomlinson

  6. NGS EDMI CBL Program (1996-2010) • In 1996 NGS approved of an NGS EDMI Calibration Base Line Policy. • Partners wishing to establish or reestablish a local EDMI CBL would enter into a cooperative agreement with NOAA/NGS. • NGS was reimbursed for expenses associated with implementing the CBL program. • NGS no longer provided a taped segment of the CBL. • The NGS EDMI CBL program provided 2 ways to participate. • An equipment loan to a state or local government agency qualified to make the field measurements - $500 per CBL plus shipping. • NGS personnel would make the field measurements - $2,500 per CBL. Former NGS employees, Matt Lowe and Gene Hart Former NGS employees, Paul Bolain and Donald Hules

  7. NGS EDMI CBL Program (2010-Present) In 2010 NGS revised the NGS EDMI CBL program policy. The revised CBL program offered 2 ways to participate. • If a state had a NGS Geodetic Advisor, then CBL measurements within that state were overseen by the NGS Advisor at no cost , except for shipping of equipment. • If a state did not have a NGS Geodetic Advisor, then CBL measurements in that state would be overseen directly by a NGS employee, the interested party would pay for NGS travel expenses and shipping costs. Notice – NGS State Geodetic Advisor program transitioned to a Regional Geodetic Advisor program on 10/01/2016. NGS employee Steven Breidenbach – Corbin, VA

  8. CBL (TIER 1) Distribution

  9. CBL Monumentation Stability Over Time Total of 401 CBLs

  10. Current CBL Program Procedures 1 – NGS receives a request from a partner to establish or reestablish a local CBL in their area for inclusion in the NGS CBL database. 2 – After receiving NGS approval to proceed, the partner follows procedures provided in NOS NGS 8 “Establishment of Calibration Base Lines” to set the CBL monuments. 3- Before the local CBL measurements are undertaken, NGS owned instrumentation is check-calibrated using the Master CBL located in Corbin, VA. 4- NGS owned instrumentation is used to establish or reestablish the local CBL, following procedures provided in NOS NGS 8. * The measurements required to establish or reestablish the local CBL is a cooperative effort, typically involving direct participation by NGS. 5- After the local CBL measurements are completed , NGS owned instrumentation is check-calibrated using the Master CBL located in Corbin, VA. 6 – NGS conducts a quality review of the local CBL data and if everything is in order loads into the NGS CBL database.

  11. Proposed CBL Program Procedures 1 – NGS receives a request from a partner to establish or reestablish a local CBL in their area for inclusion in the NGS CBL database. 2 – After receiving NGS approval to proceed, the partner follows procedures provided in a revised version of NOS NGS 8 “Establishment of Calibration Base Lines” to set the CBL monuments. 3- Before the local CBL measurements are undertaken, partner owned instrumentation (meeting specifications provided in a revised version of NOS NGS 8) is check-calibrated using a Tier 1 CBL located in the partner’s local area. 4- Partner owned instrumentation is used to establish or reestablish the Tier 2 CBL, following procedures provided in a revised version of NOS NGS 8. * The measurements required to establish or reestablish the local CBL are undertaken by the partner. 5- After the local CBL measurements are completed , Partner owned instrumentation is check-calibrated using the same Tier 1 CBLused in step 3. 6 – NGS conducts a quality review of the local CBL data and if everything is in order loads into the NGS CBL database.

  12. Significant Changes in Policy/Procedures • NGS Partners will make all necessary distance observations, using their own instrumentation, to establish or reestablish a local CBL. • A local active CBL can be used for check calibration of instrumentation (before and after) when establishing or reestablishing a CBL - opposed to the current requirement that only the Corbin Master CBL can be used for this purpose. • There will be two classifications of CBLs; Tier 1 and Tier 2 to designate whether a CBL was established by NGS (Tier 1) or by a NGS Partner (Tier 2).

  13. Advantages of Changes for Partners • Proposed changes should serve to make the program sustainable into the future. • Ability to maintain a CBL in the local area. • Partners will no longer have to pay for shipping of NGS equipment or NGS travel related expenses to participate in the program. • Allows NGS Partners to establish/reestablish local CBLs on their timeframe.

  14. Advantages of Changes for Users • The NGS EDMI CBL webpage will be updated to include an interactive map enabling the user to download CBL data specific to their local CBL. • The Interactive map will allow the user to quickly assess the active/inactive status of a CBL. • New software CALIBRATE will be available for download by the user from the NGS EDMI CBL webpage. Allows for data collection and analysis within same software package. • NGS will be able to evaluate CBL usage in order to better meet user’s needs into the future. • Increased potential for a CBL to be locally available.

  15. Opportunity to Provide Feedback http://www.geodesy.noaa.gov/CBLINES/calibration.html

  16. Questions? Former NGS employee Claude Stevens

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