Codeless/Semi-Codeless GPS Access Commitments

These documents describe U.S. government commitments to support codeless/semi-codeless civilian access to the current P(Y) signals and the transition to the modernized L2C and L5 signals. This transition will not affect users of consumer GPS devices that use only the basic civil signal (L1 C/A).

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2017 Federal Radionavigation Plan

Section 3.2.8 of the 2017 Federal Radionavigation Plan states the following:

Discontinuation of Codeless and Semi-Codeless GPS Access
The USG commits to maintaining the existing GPS L1 C/A, L1 P(Y), L2C, and L2 P(Y) signal characteristics that enable codeless and semi-codeless GPS access until at least two years after there are 24 operational satellites broadcasting L5. Barring a national security requirement, the USG does not intend to change these signal characteristics before then. Twenty-four satellites broadcasting the L5 signal is estimated to occur in 2024. This will allow for the orderly and systematic transition of users of semi-codeless and codeless receiving equipment to the use of equipment using modernized civil-coded signals. Note that it is expected that 24 operational satellites broadcasting L2C will be available by 2020, with the corresponding ground segment control capability available by 2023, enabling transition to that signal at this earlier date. Civilian users of GPS are encouraged to start their planning for transition now. View source (2.6 MB PDF, p. 59)

The above text supersedes the previously announced commitment in Federal Register Notice Vol. 73 No. 185 (see below) to maintain such signal characteristics through December 31, 2020.

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2008 Federal Register Notice: Preservation of Continuity for Semi-Codeless GPS Applications

A Federal Register notice issued in September 2008 provided the first public notice of the planned discontinuation of codeless and semi-codeless GPS access. The 2008 notice committed the U.S. government to supporting codeless/semi-codeless access to the GPS P(Y) signals until Dec 31, 2020, and advised users of codeless/semi-codeless GPS receivers to transition to new user equipment utilizing the modernized GPS signals (L2C, L5).

View notice at

The 2008 notice was superseded by the 2014 and 2017 Federal Radionavigation Plans (see above).

Prior to issuing the 2008 notice, the government collected public comments on the idea of the 2020 sunset date for codeless/semi-codeless GPS access. View comments at

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2009 Public Letter from Air Force Space Command

In Dec 2009, General C. Robert Kehler, Commander, Air Force Space Command, in a letter addressed to the Honorable James R. Schlesinger, confirmed the Air Force's intent to comply with the 2008 Federal Register notice and to document a commitment to phase stability for the new civil GPS signals.

View letter (250 KB PDF)

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This Interface Specification defines the GPS signals used for codeless/semi-codeless GPS access. It also defines the L2C signal designed to supplant the future need for legacy codeless/semi-codeless techniques. Revision E of the document, dated Jun 8, 2010, and all subsequent editions include new language establishing a baseline phase relationship for the L2C signal. This link leads to the IS-GPS-200 section of the Interface Control Documents page. Go there

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