超宽带系统与全球定位系统接收机的兼容性评估

SPECIAL PUBLICATION U.S. DEPARTMENT OF COMMERCE�National Telecommunications and Information Administration ASSESSMENT OF COMPATIBILITYBETWEEN ULTRAWIDEBAND (UWB)SYSTEMS AND GLOBAL POSITIONINGSYSTEM (GPS) RECEIVERS(REPORT ADDENDUM) David S. AndersonEdward F. DrocellaSteven K. JonesMark A. Settle U.S. DEPARTMENT OF COMMERCEDonald L. Evans, Secretary Michael D. Gallagher, Deputy Assistant Secretaryfor Communications and Information November 2001 ACKNOWLEDGMENTS The authors wish to thank the many organizations and persons who contributed to thecompletion of this report. In particular we wish to thank the Federal agency representatives onthe Interdepartment Radio Advisory Committee and the Interagency GPS Executive Board forproviding vital comments, information, and review of this report. We wish to thank the NTIA’s Institute for Telecommunication Sciences for their support andwork in the measurement process that is fundamental to this report. We also wish to thank thecontributing NTIA employees: Paul Roosa and Mike Doolan. EXECUTIVE SUMMARY BACKGROUND The study described in this report was undertaken by the National Telecommunications andInformation Administration (NTIA) in response to a Federal Communications Commission (FCC)Notice of Proposed Rule Making (NPRM) concerning the operation of a new class of spectrum-dependent devices, designated as ultrawideband (UWB) devices under the FCC’s rules andregulations in Part 15 of Title 47 of the Code of Federal Regulations (CFR).1 This NPRM raises anumber of questions and concerns regarding the electromagnetic compatibility (EMC) of theproposed UWB transmitting devices with those spectrum-dependent systems currently inoperation. The NTIA, as the Executive Branch agency principally responsible for developing andarticulating domestic and international telecommunications policy affecting Federal Governmentspectrum users, is particularly interested in the potential for interference to telecommunicationsinfrastructure utilizing Federal Government spectrum for critical and/or safety-of-life functions,many of which operate in spectrum designated as the restricted frequency bands for that reason.Before UWB devices can operate in restricted frequency bands used by critical FederalGovernment radiocommunication systems, NTIA must examine the potential interferenceintroduced from their proposed operations. The Global Positioning System (GPS) is an exampleof a critical radionavigation system that operates in several of the restricted frequency bands. In February of 2001, NTIA released Special Publication 01-45,Assessment of CompatibilityBetween Ultrawideband (UWB) Systems and Global Positioning System (GPS) Receivers. Thisdocument reported on measurements and analysis results obtained for the C/A code tracking andsemi-codeless GPS receiver architectures, and indicated ongoing efforts to measure and analyzethe interference susceptibility for a C/A code tracking receiver employing multiple narrowlyspaced correlators and a Technical Standard Order (TSO) C-129a compliant aviation receiver.This report serves as an addendum to NTIA Report 01-45, and details the results obtained for theremaining two receivers, and also provides a comparison to other data sets that are on the publicrecord. OBJECTIVE The primary objective of this study is to define maximum allowable UWB equivalentisotropically radiated power (EIRP)2levels that can be tolerated by GPS receivers, when usedwithin various operational applications, without causing degradation to GPS operations. NTIAthen compared these EIRP levels to the emission levels derived from the limits specified forintentional radiators in C.F.R., Title 47, Part 15.209 to assess the applicability of the Part 15 limitsto UWB devices.3 GPS SYSTEM DESCRIPTION The GPS is a space-based radionavigation satellite system providing precise position, velocity,and time information on a continuous, worldwide basis. The GPS space segment consists of a24-satellite constellation with the satellites distributed in six orbital planes at an approximatealtitude of 20,000 km. With the current configuration of the GPS constellation, there are typicallyfrom 6 to 11 satellites simultaneously visible from any point on the surface of the Earth.However, within a metropolitan area, the number of visible satellites is often reduced due toblockage from buildings or other man-made structures. GPS satellites currently transmit a spreadspectrum signal using a multiple access capability known as code division multiple access(CDMA) on two microwave frequencies: Link 1 (L1) on 1575.42 MHz, and Link 2 (L2) on1227.60 MHz. A civil coarse/acquisition (C/A) code and a quadrature-phase precision (P) codeare multiplexed on the GPS L1 frequency while only the P-code is modulated on the L2 carrier.The C/A signal supports the standard positioning service and the P signal supports the precisepositioning service. A modernization effort is currently ongoing that will add two new civ