Goto Section: 90.307 | 90.311 | Table of Contents

FCC 90.309
Revised as of March 30, 2020
Goto Year:2019 | 2021
  § 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):^2 Antenna 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) 1,000 1,000 1,000 1,000 1,000 1,000 1,000 1,000 1,000 1,000
   257 (160) 1,000 1,000 1,000 1,000 1,000 1,000 1,000 1,000 1,000 800
   249 (155) 1,000 1,000 1,000 1,000 1,000 875 775 700 625 575
   241 (150) 1,000 1,000 950 775 725 625 550 500 450 400
   233 (145) 850 750 650 575 500 440 400 350 320 300
   225 (140) 600 575 475 400 350 300 275 250 230 225
   217 (135) 450 400 335 300 255 240 200 185 165 150
   209 (130) 350 300 245 200 185 160 145 125 120 100
   201 (125) 225 200 170 150 125 110 100 90 80 75
   193 (120) 175 150 125 105 90 80 70 60 55 50

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

   ^2At 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):^2 Antenna 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) 1,000 1,000 1,000 1,000 1,000 1,000 1,000 1,000 1,000 1,000
   201 (125) 1,000 1,000 1,000 1,000 1,000 1,000 1,000 850 750 725
   193 (120) 1,000 1,000 1,000 1,000 900 750 675 600 550 500
   185 (115) 1,100 1,000 800 725 600 525 475 425 375 350
   177 (110) 850 700 600 500 425 375 325 300 275 225
   169 (105) 600 475 400 325 275 250 225 200 175 150
   161 (100) 400 325 275 225 175 150 140 125 110 100
   153 (95) 275 225 175 125 110 95 80 70 60 50
   145 (90) 175 125 100 75 50

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

   ^2At 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
   200 249 155
   150 243 151
   100 233 145
   50 217 135
   25 201 125
   10 188 117
   5 180 112

   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
   200 209 130
   150 201 125
   100 193 120
   50 185 115
   25 177 110
   10 169 105
   5 161 100

   Table E—Base Station Adjacent Channel Frequencies Maximum Effective
   Radiated Power (ERP)^1
   Distance in kilometers (miles):^2 3 Antenna 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) 1,000 1,000 1,000 1,000 1,000 1,000 1,000 1,000 1,000 1,000
   106 (66) 1,000 1,000 1,000 1,000 1,000 1,000 1,000 1,000 1,000 750
   104 (65) 1,000 1,000 1,000 1,000 1,000 1,000 1,000 825 650 600
   103 (64) 1,000 1,000 1,000 1,000 1,000 1,000 775 625 500 400
   101 (63) 1,000 1,000 1,000 1,000 1,000 650 450 325 325 225
   99 (62) 1,000 1,000 1,000 1,000 525 375 250 200 150 125
   98 (61) 1,000 1,000 700 450 250 200 125 100 75 50
   96 (60) 1,000 1,000 425 225 125 100 75 50

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

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

   ^3The 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 kW ERP permitted (figures rounded)
   1                                                   795
   2                                                   630
   3                                                   500
   4                                                   400
   5                                                   315
   6                                                   250
   7                                                   200
   8                                                   160
   9                                                   125
   10                                                  100
   11                                                   80
   12                                                   65
   13                                                   50
   14                                                   40
   15                                                   30
   16                                                   25
   17                                                   20
   18                                                   15
   19                                                   12
   20                                                   10
   21                                                    8
   22                                                    6
   23                                                    5
   24                                                    4
   25                                                    3
   26                                                  2.5
   27                                                    2
   28                                                  1.5
   29                                                 1.25
   30                                                    1

   (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.
   eCFR graphic ec02ap91.010.gif

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   eCFR graphic ec02ap91.011.gif

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

   [ 43 FR 54791 , Nov. 22, 1978, as amended at  49 FR 36107 , Sept. 14, 1984;
    49 FR 49837 , Dec. 17, 1984;  58 FR 44958 , Aug. 25, 1993;  70 FR 19312 ,
   Apr. 13, 2005;  72 FR 35197 , June 27, 2007]

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