[Federal Register Volume 75, Number 58 (Friday, March 26, 2010)]
[Notices]
[Pages 14658-14659]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2010-6814]


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DEPARTMENT OF TRANSPORTATION

Research and Innovative Technology Administration


Invitation for Public Comment on Mitigation Options for Global 
Positioning System Satellite Vehicle Number 49

AGENCY: Research and Innovative Technology Administration, DOT.

ACTION: Notice, request for public comments.

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SUMMARY: The U.S. Government is providing notice that it is actively 
considering several mitigation options prior to changing the health 
status of Global Positioning System (GPS) satellite IIR-20M (satellite 
vehicle number 49--SVN 49) from unhealthy to healthy. The potential 
mitigations are each designed to reduce the impact of the unique nature 
of the SVN 49 signal to a portion of the user segment. The mitigations 
are described in an Appendix posted in the public docket. The 
mitigations are intended only for use with the SVN 49 satellite and 
will not be implemented for any other GPS satellite. Responses from 
this public comment period will be considered during the final decision 
to choose which mitigation(s) to implement.
    After successful implementation of the selected mitigation(s), U.S. 
Government leaders will determine the conditions necessary to set SVN 
49 healthy. It is anticipated this timeline will occur over the next 
one to three years. Please review the posted Appendix and submit 
concerns or adverse impacts that may affect your user equipment to the 
Docket.
    Two teleconferences will be hosted by the U.S. Air Force GPS Wing 
to discuss the mitigation options. These will be held on March 26, 2010 
and April 30, 2010 at 4 PM EDT. The teleconference number is 1-800-366-
7242 passcode: 6530000. Please note that if you want a 
specific comment made during either telephone conference included in 
the docket, you must submit a public comment to the docket as outlined 
below.

DATES: Comment Period: Written comments should be submitted by May 28, 
2010.

ADDRESSES: You may submit comments identified by RITA Docket ID Number 
RITA 2010-0002 by any of the following methods: Federal eRulemaking 
Portal: Go to http://www.regulations.gov. Follow the online 
instructions for submitting comments.
    Mail: Docket Management Facility: U.S. Department of 
Transportation, 1200 New Jersey Avenue, SE., West Building Ground 
Floor, Room W12-140, Washington, DC 20590-0001.
    Hand Delivery or Courier: West Building Ground Floor, Room W12-140, 
1200 New Jersey Avenue, SE., Washington, DC, between 9 a.m. and 5 p.m. 
ET, Monday through Friday, except Federal holidays.
    Fax: 202-493-2251.
    Instructions: Identify docket number, RITA 2010-0002, at the 
beginning of your comments. To receive confirmation that DOT received 
your comments, include a self-addressed stamped postcard containing the 
Docket number.
    All comments received by DOT will be posted at http://www.regulations.gov.
    All comments/questions will be posted electronically without change 
or edits, including any personal information provided.
    Privacy Act: Anyone is able to search the electronic form of all 
comments/questions filed in our dockets by the name of the individual 
submitting the comment or question (or signing the comment, if 
submitted on behalf of an

[[Page 14659]]

association, corporation, business entity, labor union, etc.). You may 
review DOT's complete Privacy Act Statement in the Federal Register 
published on April 11, 2000 (65 FR 19477-78) or you may visit http://DocketInfo.dot.gov.
    Confidential Business Information: If you wish to submit any 
information under a claim of confidentiality, you should submit three 
copies of your complete submission, including the information you claim 
to be confidential business information, to the address given below 
under FOR FURTHER INFORMATION CONTACT. In addition, you should submit a 
copy from which you have deleted the claimed confidential business 
information to the docket. When you send a comment containing 
information identified as confidential business information, you should 
include a cover letter setting forth the reasons you believe the 
information qualifies as ``confidential business information''. (49 CFR 
7.17)

FOR FURTHER INFORMATION CONTACT: Ms. Karen Van Dyke, DOT/RITA, 1200 New 
Jersey Ave., SE., Washington, DC 20590, 202-366-3180, 
[email protected] or Lt. Col. James Lake, 310-653-3613, 
[email protected].

SUPPLEMENTARY INFORMATION:

Background

    The GPS satellite SVN 49 has a unique signal that may result in 
degraded performance for some GPS user equipment. This satellite 
currently operates with the navigational message set in an unhealthy 
state to prevent any adverse impact to users. To minimize the adverse 
impacts, several mitigations are under consideration. Each mitigation 
is intended for a specific user group and can be used with or without 
the other mitigations. All mitigations are intended for use with SVN 49 
only and no changes will be made regarding other GPS satellites. The 
mitigations are briefly described as:
     Set SVN 49 healthy with current 152m Antenna Phase Center 
(APC) and associated clock offsets.
     Set SVN 49 healthy with factory default APC and clock 
offset.
     Users switch to multipath-resistant receivers to minimize 
adverse impact from SVN 49 signal.
     Modify receiver software to use look-up table corrections 
to account for unique SVN 49 signal.
     Increase SVN 49 User Range Accuracy (URA) minimum value to 
3 by changing bits in the GPS data message that allow user equipment to 
de-weight or exclude SVN-49 signals.
     Remove data modulation from L2 P(Y)-code to mitigate 
impact to high precision users.
     Change L2C PRN code to a ``unique sequence'' to prevent 
L2C users from including SVN 49 in their solutions.
     Change SVN-49 from PRN-01 to PRN-32 to prevent updates to 
WAGE users.
     Use spare health code so future users could use SVN 49 
despite unhealthy setting.
    More information is presented in the Appendix posted in the public 
docket. Implementation of each mitigation is contingent upon several 
factors including cost, number of users impacted, schedule, and the 
needs of the U.S. Government. If you would like to submit a public 
comment concerning these proposed actions, please follow the 
instructions listed above.

    Issued in Washington, DC, on March 22, 2010.
Robert L. Bertini,
Deputy Administrator.
[FR Doc. 2010-6814 Filed 3-25-10; 8:45 am]
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