Research: Assessment evaluates GNSS receivers’ tolerance of adjacent band

March 22, 2017  - By

By Stephen Mackey, Hadi Wassaf, Karen Van Dyke, Christopher Hegarty, Karl Shallberg, John Flake and Terence Johnson.

OOBE Levels associated with LTE signal power used in testing.

OOBE Levels associated with LTE signal power used in testing.

The Adjacent Band Compatibility Assessment evaluated the adjacent radiofrequency band power levels that can be tolerated by GPS and GNSS receivers, to advance the U.S. Department of Transportation’s understanding of the extent to which such power levels impact devices used for transportation safety purposes, among other applications. The paper describes the testing approach and data analysis used to develop interference tolerance masks (ITMs) based on a 1-dB carrier-to-noise-ratio (CNR) degradation. DOT and other participants tested 80 GPS/GNSS receivers in an anechoic chamber. Four types of testing were conducted which involved a linearity test, 1-MHz Bandpass Noise, 10-MHz Long Term Evolution (LTE), and effects of third order intermodulation.

This paper also presents the resulting ITMs and puts forward a recommendation for the bounding ITM for each GPS/GNSS receiver category. Given a particular use case scenario, the significance of these bounding ITMs is that they provide information that is necessary for the downstream analysis to determine the maximum Effective Isotropic Radiated Power (EIRP) that can be tolerated in the adjacent radiofrequency bands on a per category basis. The paper discusses acquisition results as they relate to the 1-dB CNR degradation limit, and a cross comparison for some of the receiver results between radiated and conducted tests incorporating the appropriate antenna characterization data.

Presented at ION ITM, January 2017.

This article is tagged with , , , , and posted in From the Magazine, GNSS, Transportation

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3 Comments on "Research: Assessment evaluates GNSS receivers’ tolerance of adjacent band"

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  1. William K. says:

    Adjacent channel interference has always been an issue in communications systems, so it is not a surprise that it may be a challenge in the location sensing systems. So now we have two questions: first, didn’t anybody think about that when they created the receiver specifications? And second: What were they thinking when they decided that another service could be positioned nearby? Given that the GPS/ GNSS functions are so very important to such a wide segment of the population, why even consider allowing some junk entertainment operation locate in any area that might possibly interfere? Since good receiver selectivity was never enforced previously, it is way too late to change it now. The entertainment market people can waste a different chunk of spectrum.

  2. Oscar L. Colombo says:

    What is the title of the paper?
    Cannot find it without knowing that.
    Thank you.

    • Tom Willems says:

      The title of the paper is “DOT GPS Adjacent Band Compatibility Assessment Test Results”, presented in Session A4 at the ION ITM 2017.