GPS Adjacent-Band Compatibility Assessment

Demand for commercial spectrum to support broadband wireless communications has led the government to consider repurposing various radio frequencies, including the satellite communications bands next to GPS.

In 2012, the National Executive Committee for Space-Based Positioning, Navigation, and Timing proposed to draft new GPS spectrum interference standards to inform future proposals for non-space, commercial use of the bands adjacent to the GPS signals. Learn more

Assessment Plan

The Department of Transportation's (DOT) approach to this task is to develop power limit criteria for transmitters in the bands near GPS. DOT prepared a GPS Adjacent-Band Compatibility Assessment Plan providing a framework for the development of the criteria.

View assessment plan, Dec 2012 (bts.gov)

The plan identifies the processes to (a) derive power limit criteria to ensure new adjacent-band applications do not disrupt current GPS services and (b) determine similar levels needed for future GPS equipment using modernized and interoperable GNSS signals. These processes will be used to develop and specify adjacent-band transmitter power limits needed to protect GPS/GNSS signals for civil applications.

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Device Testing

DOT began testing GPS/GNSS receivers in April 2016 pursuant to the final test plan published in March 2016. Device testing took place at the U.S. Army Research Laboratory at the White Sands Missile Range (WSMR) facility in New Mexico. All GPS device manufacturers had an opportunity to participate in the testing.

View test plan, Mar 2016 (500 KB PDF)
NOTE: If you are seeking information about the National Advanced Spectrum and Communications Test Network (NASCTN) testing of LTE impacts to GPS devices, which is independent of the DOT testing, please visit the NASCTN website.
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A second round of testing occurred in July 2016 at Zeta Associates in Fairfax, Virginia, and MITRE Corporation in Bedford, Massachusetts. The goals of the additional lab testing were:

Anechoic chamber with equipment being tested
Anechoic chamber test setup

Additional Information:

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March 2017 Workshop

The U.S. Department of Transportation hosted its sixth workshop on the GPS Adjacent Band Compatibility Assessment effort on March 30, 2017.

The purpose was to discuss the results from testing of various categories of GPS/Global Navigation Satellite System (GNSS) receivers to include aviation (non-certified), cellular, general location/navigation, high precision and networks, timing, and space-based receivers, as well as use-case scenarios for these categories.

Meeting Materials

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Previous Workshops

Workshop V, October 2016

To discuss the results from testing of various categories of GPS/GNSS receivers to include aviation (non-certified), cellular, general location/navigation, high precision and networks, timing, and space-based receivers. Also included a discussion on the development of use-case scenarios for these categories.

Workshop IV, October 2015

To discuss the draft test plan and provide an opportunity for questions prior to the close of the comment period.

Workshop III, March 2015

Focused on the following topics: (i) Identification of GPS and Global Navigation Satellite System (GNSS) receivers to be considered for testing that are representative of the current categories of user applications; and (ii) discussion of a GPS/GNSS receiver test plan.

Workshop II, December 2014

Focused on the following topics: (i) GPS "use case" information, with emphasis on non-government applications; (ii) identification of current GPS receivers which are representative of the current categories of GPS applications and which should be considered for testing; and (iii) feedback on the GPS Adjacent Band Compatibility Assessment program implementation plan presented during the September 2014 workshop.

Workshop I, September 2014

To discuss implementation of the Adjacent-Band Compatibility Assessment Plan, including development of GPS receiver use cases, identification of representative GPS receivers, and development of a test and analysis program.

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