Co-channel and adjacent-channel interference predictions for the Instrument Landing System are presented in this report. Information on the various types of ground facilities involved is given first. Propagation mechanisms applicable to the 108 to 112 Mc/s frequency range are "discussed second together with the calculation of transmission loss and its variability. Third, the statistical treatment of interference problems is explained. Finally; the results of the study are presented as curves of normalized desired-to-undesired signal strength ratios versus distance from the desired station. Aircraft altitudes of 1, 000, 6, 250, 12, 000, and 18, 000 feet along with station separations ranging from 20 to 330 nautical miles were considered. Detailed procedures, mathematical formulas, and computer programs used are discussed in the Appendices.
These include the development and maintenance of the national standards of measurement and the provision of means and methods for making measurements consistent with these standards: the determination of physical constants and properties of materials; the development of methods and instruments for testing materials, devices, and structures; advisory services to government agencies on scientific and technical problems; in¬ vention and development of devices to serve special needs of the Government; and the development of standard practices, codes, and specifications. The work includes basic and applied research, development, engineering, instrumentation, testing, evaluation, calibration services, and various consultation and information services. Research projects are also performed for other government agencies when the work relates to and supplements the basic program of the Bureau or when the Bureau's unique competence is required. The scope of activities is suggested by the listing of divisions and sections on the inside of the back cover. ABSTRACT This report deals with the prediction of service volumes (i. e., service ranges in three dimensions) for VOR and TACAN air naviga¬ tion facilities in the presence of noise and interfering stations. Propa¬ gation mechanisms applicable to the frequency ranges employed are discussed first, together with calculation of transmission loss and its variability. Second, the statistical treatment of the interference problem is explained. Finally, it is shown how service volumes are determined based on transmission loss and its variations, specified or assumed criteria on signal-to-noise and signal-to-interference ratio, and the spatial relations of the aircraft, the desired facility, and the undesired facility. The results of the entire study are pre¬ sented in graphical form. Detailed procedures, mathematical formulas, and computer programs used are discussed in the Appendix. the refraction effects of the atmosphere is accounted for by assuming an earth radius 4/3 times the actual radius. This permits radio rays to be drawn as straight lines, and simplifies the determination of geometric parameters. * Order by PB number from the Office of Technical Services, U. S. Department of Commerce, Washington 25, D. C. Foreign remit¬ tances must be in U. S. exchange and must include one-fourth of the publication price to cover mailing costs. GPO 856888
The functions of the National Bureau of Standards are set forth in the Act of Congress, March 3, 1901, as amended by Congress in Public Law 619, 1950. These include the development and maintenance of the na¬ tional standards of measurement and the provision of means and methods for making measurements consistent with these standards; the determination of physical constants and properties of materials; the development of methods and instruments for testing materials, devices, and structures; advisory services to government agen¬ cies on scientific and technical problems; invention and development of devices to serve special needs of the Government; and the development of standard practices, codes, and specifications. The work includes basic and applied research, development, engineering, instrumentation, testing, evaluation, calibration services, and various consultation and information services. Research projects are also performed for other government agencies when the work relates to and supplements the basic program of the Bureau or when the Bureau's unique competence is required. The scope of activities is suggested by the listing of divisions and sections on the inside of the back cover.
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