§ 87.23 - Supplemental information required.

(a) To minimize harmful interference at the National Radio Astronomy Observatory site at Green Bank, Pocahontas County, WV, and at the Naval Radio Research Observatory site at Sugar Grove, Pendleton County, WV, an applicant for a new station license (other than mobile, temporary base, temporary fixed or Civil Air Patrol), or for modification of an existing license to change the frequency, power, antenna location, height or directivity within the area bounded by 39′15′ N. on the north, 78′30′ W. on the east, 37′30′ N on the south and 80′30′ W on the west, must first notify the Director, National Radio Astronomy Observatory, Attn: Interference Office, Post Office Box No. 2, Green Bank, WV 24944, in writing, of the geographical coordinates of the antenna, antenna height, antenna directivity, frequency, emission and power. The application to the Commission must show the date notification was made to the Observatory. The Commission will allow twenty (20) days after receipt of its copy of the notification for comments or objections. If a timely response is received, the Commission will consider the comments or objections.

(b) Geographical coordinates of Commission facilities which require protection are listed in § 0.121(c). Applications for stations (except mobile stations) which will be located within 80 km (50 miles) of the referenced coordinates are examined to determine extent of possible interference. A clause protecting the monitoring station may be added to the station license.

(c) Each application for a station license to operate in the vicinity of Boulder County, CO, under this part must give due consideration, prior to filing applications, to the need to protect the Table Mountain Radio Receiving Zone from harmful interference. These are the Research Laboratories of the Department of Commerce, Boulder County, CO. To prevent degradation of the present ambient radio signal level at the site, the Department of Commerce seeks to ensure that field strength at 40°07′50″ N latitude, 105° 14′40″ W longitude, resulting from new assignments (other than mobile stations) or from the modification or relocation of the existing facilities do not exceed the following values:

Frequency rangeField strength (mV/m) in authorized bandwidth of servicePower flux density 1 (dBW/m 2) in authorized bandwidth of serviceBelow 540 kHz10−65.8540 to 1600 kHz20−59.81.6 to 470 MHz102−65.8470 to 890 MHz302−56.2Above 890 MHz12−85.81 Equivalent values of power flux density are calculated assuming a free-space characteristic impedence of 376.7 (approximately 120 pi) ohms.2 Space stations shall conform to the power flux density limits at the earth's surface specified in appropriate parts of the Commission's rules, but in no case should exceed the above levels in any 4 kHz band for all angles of arrival.

(d) Each applicant is responsible for determining whether proposals for a new or modified station require envionmental information. Applicants should refer to § 1.1307 to identify those actions for which environmental information must be submitted.