[Code of Federal Regulations] [Title 47, Volume 2] [Revised as of October 1, 2003] From the U.S. Government Printing Office via GPO Access [CITE: 47CFR21.116] [Page 56] TITLE 47--TELECOMMUNICATION CHAPTER I--FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) PART 21--DOMESTIC PUBLIC FIXED RADIO SERVICES--Table of Contents Subpart C--Technical Standards Sec. 21.116 Topographical data. Determining the location and height above sea level of the antenna site, the elevation or contour intervals shall be taken from United States Geological Survey Topographic Quadrangle Maps, United States Army Corps of Engineers maps or Tennessee Valley Authority maps, whichever is the latest, for all areas for which such maps are available. If such maps are not published for the area in question, the next best topographic information should be used. Topographic data may sometimes be obtained from State and municipal agencies. Data from Sectional Aeronautical Charts (including bench marks) or railroad depot elevations and highway elevations from road maps may be used where no better information is available. In cases where limited topographic data is available, use may be made of an altimeter in a car driven along roads extending generally radially from the transmitter site. If it appears necessary, additional data may be requested. United States Geological Survey Topographic Quadrangle Maps may be obtained from the Department of the Interior, Geological Survey, Washington, DC 20242. Sectional Aeronautical Charts are available from the Department of Commerce, Coast and Geodetic Survey, Washington, DC 20230. [44 FR 60534, Oct. 19, 1979, as amended at 52 FR 37783, Oct. 9, 1987]