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
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 (500 KB PDF)
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.
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)
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:
- (1) Receiver characterization for comparison with results obtained in April at the anechoic chamber at the U.S. Army Research Laboratory;
- (2) Evaluation of Out Of Band Emission (OOBE) interference at prescribed and proposed levels with Long Term Evolution (LTE) uplink and downlink signals;
- (3) GPS/GNSS signal acquisition characterization; and
- (4) Antenna characterizations.
Anechoic chamber test setup
- September 2016 presentation to CGSIC (821 KB PDF)
- Federal Register announcement of July testing
- Federal Register announcement of April testing
- DOT announcement of April testing
- Non-disclosure agreement (PDF)
- Draft test plan (426 KB PDF)
- Public comments on draft test plan (regulations.gov)
NEW March 2017 Workshop
March 30, 2017
10 a.m. - 4 p.m. (EDT)
1150 18th St. NW, Suite 910
Washington, DC 20036
The U.S. Department of Transportation will host its sixth workshop on the GPS Adjacent Band Compatibility Assessment effort.
The purpose is 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.
This workshop is open to the general public by registration only. For those who would like to attend the workshop, we request that you register no later than March 27, 2017. Please use the following link to register:volpecenterevents.webex.com (external site)
- 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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