Sec. 90.315 Special provisions governing use of frequencies in the 476-
494 MHz band (TV Channels 15, 16, 17) in the Southern
Louisiana-Texas Offshore Zone.
(a) The frequency bands from 490-491 and 493-494 MHz will be
available for assignment to stations governed by this part within Zone
A. The boundaries of Zone A are from longitude 87 deg.45' on the east to
longitude 94 deg.00' on the west, and from the 3-mile limit along the
Gulf of Mexico shoreline on the north to the limit of the Outer
Continental Shelf on the south. The frequency bands from 484-485 and
476-488 MHz will be available for assignment to stations governed by
this part within Zone B. The boundaries of Zone B are from longitude
87 deg.45' on the east to longitude 95 deg.00' on the west and from the
3-mile limit along the Gulf of Mexico shoreline on the north to the
limit of the Outer Continental Shelf on the south. The frequency bands
from 478-479 and 481-481 MHz will be available for assignment to
stations governed by this part within Zone C. The boundaries of Zone C
are from longitude 94 deg.00' on the east, the 3-mile limit on the north
and west, a 281 km (175 mile) radius from the reference point at
[[Page 501]]
Linares, N.L., Mexico on the southwest, latitude 26 deg.00' on the
south, and the limits of the Outer Continental Shelf on the southeast.
These frequencies may also be assigned to fixed stations located on
shore designed to provide communications service within the zone.
(b) Offshore base/mobile, and offshore and shore fixed stations may
be authorized.
(c) F2, F3, F4, F9, and A2, A3, A4, and A9 emissions may be
authorized.
(d) Offshore stations shall afford cochannel protection to TV
stations on Channels 15, 16 and 17. Station operating parameters shall
be in accordance with the values given in table 1 of this section.
Table 1--Protection of Cochannel Television Stations by Offshore
Stations Operating in the Southern Louisiana-Texas Offshore Zone (65 dB
Protection); Maximum Effective Radiated Power
[In Watts]
------------------------------------------------------------------------
Antenna Height above sea
level meters (feet)
Distance from transmitter to co-channel TV --------------------------
station kilometers (miles) 30.5 45 61
(100) (150) (200)
------------------------------------------------------------------------
338 (210).................................... 1,000 1,000 1,000
330 (205).................................... 1,000 900 800
322 (200).................................... 800 710 630
314 (195).................................... 590 520 450
306 (190).................................... 450 400 330
298 (185).................................... 320 280 240
290 (180).................................... 250 210 175
281 (175).................................... 175 150 130
274 (170).................................... 130 110 100
265 (165).................................... 95 80 70
257 (160).................................... 65 55 50
249 (155).................................... 50 40 35
241 (150).................................... 35 30 25
------------------------------------------------------------------------
Note: To determine the maximum permissible effective radiated
power:
(1) As specified in Sec. 73.611 determine the distance between the
proposed station and the cochannel television station. If the exact
distance does not appear in table 1 of this section, the next lower
distance separation is to be used.
(2) Opposite this distance figure ERPs are given that may be used
for antenna heights of 30.5, 45 or 61 meters (100, 150 or 200 ft) ASL.
If the exact antenna height is not shown, the ERP allowed will be that
shown for the next higher antenna height.
(e) Shore stations communicating point-to-point with offshore
stations will be permitted at least the same ERP as the offshore
station, but only in the direction of the offshore station. A
directional antenna shall be used and the rearward radiated power from
the antenna in a sector &177;22\1/2\ deg. from the line joining
the shore antenna to the cochannel television station shall not exceed
those shown in table 2 of this section.
Table 2.--Maximum Rearward Effective Radiated Power Allowed for Shore Stations; Rearward Effe
ctive Radiated
Power (in Watts) From Shore Antenna in a Sector plus-minus>22\1/2\ deg. From the Line Join
ing the Shore Antenna
to the Cochannel Television Station
------------------------------------------------------------------------------------------------
----------------
Antenna height above ground in m
eters (feet)
Distance from transmitter to cochannel television station: -------------------------------------
----------------
kilometers (miles) 30.5 45 61 91.5
152.5 228
(100) (150) (200) (300)
(500) (750)
------------------------------------------------------------------------------------------------
----------------
298 (185)................................................. 320 280 240 190
125 90
290 (180)................................................. 250 210 175 125
100 60
281 (175)................................................. 175 150 130 100
70 50
274 (170)................................................. 130 110 100 75
40 35
265 (165)................................................. 95 82 70 50
35 25
257 (160)................................................. 65 55 50 40
25 20
249 (155)................................................. 50 40 35 30
20 15
241 (150)................................................. 35 30 25 20
15 10
233 (145)................................................. 25 20 18 15
10 7
225 (140)................................................. 18 15 13 10
7 5
217 (135)................................................. 13 10 9 7
5 3
209 (130)................................................. 10 8 6 5
3 2
201 (125)................................................. 7 6 5 4
3 2
193 (120)................................................. 5 4 3 3
2 1
------------------------------------------------------------------------------------------------
----------------
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Note: As an example of the use of tables 1 and 2, assume an
offshore station located 290 km (180 mi) from TV Channel 17 located in
Bude, Miss. with an antenna height of 30.5 m (100 ft). Table 1 allows
this station to operate with 250 W ERP. Now assume the shore station
communicating with the offshore station is 48 km (30 mi) from the
offshore station and 241 km (150 mi) from Bude, Miss. The shore station
antenna height is 152.5 m (500 ft) above ground. The shore station will
be allowed the same ERP as the offshore station (250 W) in the direction
of the offshore station. Table 2 indicates that the effective radiated
power in a sector plus-minus> 22\1/2\ deg. from the line
joining the shore antenna to Bude, Miss. can only be 15 W. Consequently,
a directional antenna must be used whose minimum front-to-back ratio
over this 45 deg. sector must be at least 12.2 dB. (250 W forward power
to 15 W rearward power is a power ratio of 16.6 or 12.2 dB).
(f) To provide cochannel protection to television stations, no shore
station will be allowed closer than 193 km (120 miles) from the
cochannel television station.
(g) To provide adjacent channel protection to television stations,
no shore or offshore station shall be allowed within an 128 km (80 mile)
distance of the adjacent channel television station.
(h) Mobile stations shall not operate closer to shore than 6.4 km (4
miles) beyond the three mile limit and shall not operate with an ERP in
excess of 100 watts with 9.1 m (30 ft) maximum antenna height.
(i) Mobile stations installed in aircraft shall operate 11 km (7
miles) beyond the three mile limit and shall not operate with an ERP in
excess of 1 watt or at heights in excess of 305 m (1000 feet) AMSL.
(j) The following frequency bands are available for assignment in
all services for use in the Zones as defined in paragraph (a) of this
section.
Paired Frequencies (MHZ)
------------------------------------------------------------------------
Transmit (or Receive (or
Zone receive) transmit)
------------------------------------------------------------------------
A........................... 490.01875-490.98125 493.01875-493.98125
B........................... 484.01875-484.98125 487.01875-487.98125
C........................... 478.01875-478.98125 481.01875-481.98125
------------------------------------------------------------------------
Only the first and last assignable frequencies are shown.
Frequencies shall be assigned in pairs with 3 MHz spacing between
transmit and receive frequencies. Assignable frequency pairs will occur
in increments of 6.25 kHz. The following frequencies will be assigned
for a maximum authorized bandwidth of 6 kHz: 478.01875, 478.98125,
484.01875, 484.98125, 490.01875, 490.98125, 481.01875, 481.98125,
487.01875, 487.98125, 493.01875, and 493.98125.
(k) Fixed stations operating point-to-point shall be assigned
frequencies beginning with 490.025/493.025 MHz (Zone A), 484.025/487.025
MHz (Zone B) and 478.025-481.025 MHz (Zone C) and progressing upwards
utilizing available frequencies toward the end of the band. Offshore
base/mobile stations shall be assigned frequencies beginning at 490.975/
493.975 MHz (Zone A), 484.975/478.975 MHz (Zone B) and 478.975/481.975
MHz (Zone C) and progressing downwards utilizing available frequencies
toward the beginning of the band. All frequency assignments are subject
to the conditions specified in Sec. 90.173.
[50 1997 FR 12027 , Mar. 27, 1985; 50 FR 14389 , Apr. 12, 1985, as amended at
58 FR 44959 , Aug. 25, 1993; 60 FR 37277 , July 19, 1995]
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