NIST Technical Note 1937 Development of Laboratory Test Methods for RF-Based Electronic Safety Equipment: Guide to the National Fire Protection Association 1982 Standard Audrey K. Puls William F. Young Kate A. Remley Jacob Healy Luis A. Gonzalez This publication is available free of charge from: https://doi.org/10.6028/NIST.TN.1937 NIST Technical Note 1937 Development of Laboratory Test Methods for RF-Based Electronic Safety Equipment: Guide to the National Fire Protection Association 1982 Standard Audrey K. Puls William F. Young Kate A. Remley Jacob Healy Luis A. Gonzalez RF Technology Division Communications Technology Laboratory This publication is available free of charge from: https://doi.org/10.6028/NIST.TN.1937 October 2016 U.S. Department of Commerce Penny Pritzker, Secretary National Institute of Standards and Technology Willie May, Under Secretary of Commerce for Standards and Technology and Director Certain commercial entities, equipment, or materials may be identified in this document in order to describe an experimental procedure or concept adequately. Such identification is not intended to imply recommendation or endorsement by the National Institute of Standards and Technology, nor is it intended to imply that the entities, materials, or equipment are necessarily the best available for the purpose. National Institute of Standards and Technology Technical Note 1937 Natl. Inst. Stand. Technol. Tech. Note 1937, 74 pages (October 2016) CODEN: NTNOEF This publication is available free of charge from: https://doi.org/10.6028/NIST.TN.1937 ______________________________________________________________________________________________________ Executive Summary The National Institute of Standards and Technology (NIST) with support from the Department of Homeland Security has been working with the National Fire Protection Association (NFPA) to develop standards and test methods for radio-frequency personal alert safety systems (RF PASS). The RF PASS systems are incorporated into a firefighter’s gear and are used to alert a base station This when the firefighter is in distress, has been motionless for more than 30 seconds, or to alert the publication firefighter in case an evacuation is necessary. The material here covers the development of several test methods either already adopted by the NFPA or targeted for future revisions of NFPA 1982 Personal Alert Safety Systems. These test methods represent five RF PASS deployment conditions: a highly reflective (high multipath) RF is environment, a prescribed amount of attenuation in a point-to-point communication link, a multi- available hop connection path, in-band wireless activity, and temporary exposure to high-power, in-band RF interference. The data and developed testing are based on currently used RF PASS frequencies: 450 MHz, 900 MHz, and 2.4 GHz. free This technical note uses various experimental setups that utilize a combination of equipment of including, but not limited to, spectrum analyzers, signal generators, power combiners, anechoic charge chambers, and reverberation chambers. Specific experimental setups are discussed in the sections in which they apply. from: In developing the test methods, several key aspects of the test setup are investigated in detail. For example, electric field uniformity within the test chambers, created by different antennas, was https://doi.org/10.6028/NIST.TN.1937 examined to determine which antenna would provide the lowest variability in signal level over the testing plane. In support of the multipath test, the RF reflective behavior of a reverberation chamber was evaluated. Finally, interference testing required establishing the duty cycles and power levels appropriate for anticipated deployment environments. Supporting material from previous RF PASS in-field testing, along with correlated RF propagation measurements are used to set test parameter values. For example, the attenuation values used for the various links represent typical conditions measured in the field and reported in prior NIST work. Some in-field data are also used in establishing the interference duty cycles and power levels. The ultimate goal was to establish methods and parameter values that mimic real deployment conditions in a laboratory setting to the extent possible. Finally, the intent of this document is to provide users of the test methods with insight into how the tests were developed and why certain procedures and values were adopted. This document is not intended to give step-by-step directions on how each test should be conducted. Rather, the material contained in this document should answer questions that may arise during the application of the tests. Thus, the aim is to capture the insight gained by the test developers in a manner that will allow others to obtain the same understanding in a shorter time period. i ______________________________________________________________________________________________________ Development of Laboratory Test Methods for RF- Based Electronic Safety Equipment: Guide to the National Fire Protection Association 1982 This Standard publication Audrey K. Puls, William F. Young, Kate A. Remley, Jacob Healy, and Luis A. Gonzalez RF Technology Division National Institute of Standards and Technology is available 325 Broadway, Boulder, CO 80305 Abstract: We discuss a variety of standardized test methods that have been developed to assess free radio-frequency personal alert safety systems (RF PASS) that are used as “firefighter down” beacons. The test methods found in this document represent five RF PASS deployment conditions: of a highly reflective (high multipath) RF environment; a prescribed amount of attenuation in a point- charge to-point communication link; a multi-hop reception path; in-band wireless activity; and temporary exposure to high-power, in-band RF interference. The tests and corresponding data are based on from: current RF PASS frequencies: 450 MHz, 900 MHz, and 2.4 GHz. The test environments, tests, and measured data are discussed in detail to accompany the National Fire Protection Association’s https://doi.org/10.6028/NIST.TN.1937 standard “NFPA 1982: Personal Alert Safety Systems.” Key words: anechoic chamber; firefighter; interference; multipath; personal alert safety system; point-to-point radio communications; path loss; radio-wave propagation; reverberation chamber; wireless system. ii ______________________________________________________________________________________________________ Contents Executive Summary ......................................................................................................................... i 1. Introduction ................................................................................................................................. 1 This 2. Field Uniformity Tests ................................................................................................................ 2 2.1 Calculating Field Uniformity ................................................................................................ 3 publication 2.2 Effect of Antenna Type ......................................................................................................... 6 2.3 NIST Field-Uniformity Measurement Results...................................................................... 8 2.3.1 462 MHz ........................................................................................................................ 8 is available 2.3.2 915 MHz ........................................................................................................................ 9 2.3.3 2.4 GHz .......................................................................................................................... 9 2.3.3.1 Uniformity Testing with 13 Collection Points ...................................................... 10 free 2.3.3.2 Uniformity Testing with 25 Collection Points ...................................................... 11 of 2.3.4 Conclusion ................................................................................................................... 13 charge 2.4 Field Uniformity Measurement Uncertainty Analysis ........................................................ 14 2.4.1 Type A Uncertainties ................................................................................................... 14 from: 2.4.2 Type B Uncertainties ................................................................................................... 14 https://doi.org/10.6028/NIST.TN.1937 2.4.3 Combined Uncertainty ................................................................................................. 14 3. Multipath Test and Reverberation Chambers ........................................................................... 16 3.1 Introduction ......................................................................................................................... 16 3.2 Background ......................................................................................................................... 18 3.3 Quality of the Reverberation Chamber ............................................................................... 19 3.4 Calibration Process ............................................................................................................. 19 3.5 Multipath Testing of an RF PASS System ......................................................................... 20 3.6 Results ................................................................................................................................