47 C.F.R. § 90.309

Current through September 30, 2024
Section 90.309 - Tables and figures
(a)Directions for using the tables.
(1) Using the method specified in § 1.958 of this chapter, determine the distances between the proposed land mobile base station and the protected co-channel television station and between the proposed land mobile base station and the protected adjacent channel television station. If the exact mileage does not appear in table A for protected co-channel television stations (or table B for channel 15 in New York and Cleveland and channel 16 in Detroit) or table E for protected adjacent channel television stations, the next lower mileage separation figure is to be used.
(2) Entering the proper table at the mileage figure found in paragraph (a)(1) of this section, find opposite, a selection of powers that may be used for antenna heights ranging from 15 m (50 ft) to 152.5 m (500 ft) (AAT). If the exact antenna height proposed for the land mobile base station does not appear in the proper table, use the power figure beneath the next greater antenna height.
(3) The lowest power found using the tables mentioned in paragraphs (a)(1) and (a)(2) of this section is the maximum power that may be employed by the proposed land mobile base station.
(4) In determining the average elevation of the terrain, the elevations between 3.2 kilometers (2 miles) and 16 kilometers (10 miles) from the antenna site are employed. Profile graphs shall be drawn for a minimum of eight radials beginning at the antenna site and extending 16 kilometers (10 miles). The radials should be drawn starting with true north. At least one radial should be constructed in the direction of the nearest co-channel and adjacent channel UHF television stations. The profile graph for each radial shall be plotted by contour intervals of from 12.2 meters (40 feet) to 30.5 meters (100 feet) and, where the data permits, at least 50 points of elevation (generally uniformly spaced) should be used for each radial. For very rugged terrain, 61 meters (200 feet) to 122 meters (400 foot) contour intervals may be used. Where the terrain is uniform or gently sloping, the smallest contour interval indicated on the topographic chart may be used. The average elevation of the 12.8 kilometer (8 mile) distance between 3.2 kilometers (2 miles) and 16 kilometers (10 miles) from the antenna site should be determined from the profile graph for each radial. This may be obtained by averaging a large number of equally spaced points, by using a planimeter, or by obtaining the median elevation (that exceeded by 50 percent of the distance) in sectors and averaging those values. In the preparation of the profile graphs, the elevation or contour intervals may be taken from U.S. Geological Survey Topographic Maps, U.S. Army Corps of Engineers Maps, or Tennessee Valley Authority Maps. Maps with a scale of 1:250,000 or larger (such as 1:24,000) shall be used. Digital Terrain Data Tapes, provided by the National Cartographic Institute, U.S. Geologic Survey, may be utilized in lieu of maps, but the number of data points must be equal to or exceed that specified above. If such maps are not published for the area in question, the next best topographic information should be used.
(5) Applicants for base stations in the Miami, FL, urbanized area may, in lieu of calculating the height of average terrain, use 3 m (10 ft) as the average terrain height.

Table A-Base Station-Cochannel Frequencies (50 dB Protection) Maximum Effective Radiated Power (ERP)1

Distance in kilometers (miles):2Antenna height in meters (feet) (AAT)
15 (50) 30.5 (100)45 (150)61 (200)76 (250) 91.5 (300) 106 (350) 122 (400) 137 (450) 152.5 (500)
260 (162)1,0001,0001,0001,0001,0001,0001,0001,0001,0001,000
257 (160)1,0001,0001,0001,0001,0001,0001,0001,0001,000800
249 (155)1,0001,0001,0001,0001,000875775700625575
241 (150)1,0001,000950775725625550500450400
233 (145)850750650575500440400350320300
225 (140)600575475400350300275250230225
217 (135)450400335300255240200185165150
209 (130)350300245200185160145125120100
201 (125)225200170150125110100908075
193 (120)175150125105908070605550

1 The effective radiated power (ERP) and antenna height above average terrain (AAT) shall not exceed the values given in this table.

2 At this distance from transmitter site of protected UHF television station.

Table B-Base Station-Cochannel Frequencies (40 dB Protection) Maximum Effective Radiated Power (ERP)1

Distance in kilometers (miles):2Antenna height in meters (feet) (AAT)
15 (50) 30.5 (100)45 (150)61 (200)76 (250) 91.5 (300) 106 (350) 122 (400) 137 (450) 152.5 (500)
209 (130)1,0001,0001,0001,0001,0001,0001,0001,0001,0001,000
201 (125)1,0001,0001,0001,0001,0001,0001,000850750725
193 (120)1,0001,0001,0001,000900750675600550500
185 (115)1,1001,000800725600525475425375350
177 (110)850700600500425375325300275225
169 (105)600475400325275250225200175150
161 (100)400325275225175150140125110100
153 (95)2752251751251109580706050
145 (90)1751251007550

1 The effective radiated power (ERP) and antenna height above average terrain shall not exceed the values given in this table.

2 At this distance from the transmitter site of protected UHF television station.

Table C-Mobile and Control Station-Distance Between Associated Base Station and Protected Cochannel TV Station

[50 dB protection]

Effective radiated power (watts) of mobile unit and control station Distance
Kilometers Miles
200249155
150243151
100233145
50217135
25201125
10188117
5180112

Table D-Mobile and Control Station-Distance Between Associated Land Mobile Base Station and Protected Cochannel TV Station

[40 dB protection]

Effective radiated power (watts) of mobile unit and control station Distance
Kilometers Miles
200209130
150201125
100193120
50185115
25177110
10169105
5161100

Table E-Base Station Adjacent Channel Frequencies Maximum Effective Radiated Power (ERP)1

Distance in kilometers (miles):2 3Antenna height in meters (feet) (AAT)
15 (50) 30.5 (100)45 (150)61 (200)76 (250) 91.5 (300) 106 (350) 122 (400) 137 (450) 152.5 (500)
108 (67)1,0001,0001,0001,0001,0001,0001,0001,0001,0001,000
106 (66)1,0001,0001,0001,0001,0001,0001,0001,0001,000750
104 (65)1,0001,0001,0001,0001,0001,0001,000825650600
103 (64)1,0001,0001,0001,0001,0001,000775625500400
101 (63)1,0001,0001,0001,0001,000650450325325225
99 (62)1,0001,0001,0001,000525375250200150125
98 (61)1,0001,0007004502502001251007550
96 (60)1,0001,0004252251251007550

1 The effective radiated power (ERP) and antenna height above average terrain (AAT) shall not exceed the values given in this table.

2 At this distance from transmitter site of protected UHF television station.

3 The minimum distance is 145 km (90 miles) where there are mobile units associated with the base station. See sec. 90.307(d).

Table "F"-Decibel Reduction/Power Equivalents

dB reduction below 1 kWERP permitted (figures rounded)
1795
2630
3500
4400
5315
6250
7200
8160
9125
10100
1180
1265
1350
1440
1530
1625
1720
1815
1912
2010
218
226
235
244
253
262.5
272
281.5
291.25
301

(b)Directions for Using the Figures.
(1) Determine antenna height above average terrain. (According to § 90.309(a)(4) .)
(2) Locate this value on the antenna height axis.
(3) Determine the separation between the LM antenna site and the nearest protected co-channel TV station. (According to § 73.611 .)
(4) Draw a vertical line to intersect the LM/TV separation curve at the distance determined in step 3 above. For distances not shown in the graph use linear interpolation.
(5) From the intersection of the LM/TV separation curve draw a horizontal line to the power reduction scale.
(6) The power reduction in dB determines the reduction below 1 kW that must be achieved.
(7) See table F for dB/power equivalents.

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47 C.F.R. §90.309

Section 0.231 (d) of the Commission's Rules and secs. 4(i) and 303 of the Communications Act, as amended

Section 0.231(d) of the Commission's Rules and secs. 4(i) and 303 of the Communications Act, as amended