The distance spacing tables used by the REC LPFM Search Tool will be updated for foreign allotments to show the maximum spacing necessary to prevent interference.
Currently, the FCC provides for domestic distance spacing between LPFM and full power and translator facilities on co-channel and first-adjacent channels, both the legally required minimum as well as the spacing required to assure that LPFM station service contours will not receive any overlap from the full power station’s interference contour. The higher “full spacing” figures are not legally binding but they assist LPFM applicants to find the best possible channels. REC has presented these channels as available but “with potential interference”. The FCC has never provided this on the Canadian and Mexican facility protection charts. This is also the value that will appear on the Channel Report under RCIC (Required to Clear Interference Contour). This functionality was also added to allow REC back-end tools such as SuperCoordinator choose the best possible channel for locations near the international borders.
The FCC rules for LPFM protections for Canadian and Mexican stations require that the interference contours of LPFM stations do not overlap the service contours of foreign stations. This is similar to protecting domestic stations with one major difference. There is no 20 km “buffer zone” around the service contour of the full power station like there is with domestic stations. This is why the required distance separations between compatible Mexican allotments are exactly 20 km less than the US allotments on co-channel. Canada’s differences are shorter because Canada protects their FM stations to larger service and interference contours:
United States |
Canada |
Mexico |
|||
Class |
Service Contour* |
Class |
Service Contour |
Class |
Service Contour |
A |
28.3 km (60 dBu) |
A |
38.7 km (54 dBu) |
AA** |
28.3 km (60 dBu) |
B1 C3 |
44.7 km (57 dBu) 39.1 km (60 dBu) |
B1 |
50.8 km (54 dBu) |
B1 |
44.7 km (57 dBu) |
B C2 |
65.1 km (54 dBu) 52.2 km (60 dBu) |
B |
65.1 km (54 dBu) |
B |
65.1 km (54 dBu) |
C1 |
72.3 km (60 dBu) |
C1 |
86.4 km (54 dBu) |
C1 |
72.3 km (60 dBu) |
C |
91.8 km (60 dBu) |
C |
96.7 km (58 dBu) |
C |
91.8 km (60 dBu) |
* - US service contours do not include 20 km “buffer zone” that applies to LP10 and LP100.
** - Mexico also as a Class A service which is similar to the old US Class A service (3kw @ 100m HAAT) and has a service contour of 18.6km (60 dBu).
REC will update our distance separation charts for Canada as follows for no interference received:
Foreign Station Class |
LP10 |
LP50 |
LP100 |
LP250 |
||||
Co-channel |
First-adjacent |
Co-channel |
First-adjacent |
Co-channel |
First-adjacent |
Co-channel |
First-adjacent |
|
Low Pwr. |
63 |
31 |
65 |
32 |
66 |
33 |
67 |
35 |
A1 |
63 |
31 |
65 |
32 |
66 |
33 |
67 |
35 |
A |
116 |
63 |
117 |
64 |
118 |
65 |
120 |
67 |
B1 |
146 |
83 |
150 |
85 |
152 |
86 |
153 |
87 |
B |
172 |
102 |
177 |
103 |
178 |
104 |
179 |
106 |
C1 |
206 |
133 |
210 |
135 |
211 |
136 |
212 |
137 |
C |
209 |
148 |
213 |
149 |
214 |
150 |
216 |
152 |
There are no changes to the minimum required distances We are only adding these recommended distances to distinguish LPFM channels that may not be subject to interference.
REC will update our distance separation charts for Mexico as follows for no interference received:
Foreign Station Class |
LP10 |
LP50 |
LP100 |
LP250 |
||||
Co-channel |
First-adjacent |
Co-channel |
First-adjacent |
Co-channel |
First-adjacent |
Co-channel |
First-adjacent |
|
Low Pwr. |
32 |
15 |
34 |
17 |
35 |
18 |
36 |
19 |
A |
79 |
40 |
81 |
41 |
82 |
42 |
83 |
44 |
AA |
90 |
47 |
91 |
48 |
92 |
49 |
94 |
51 |
B1 |
134 |
73 |
135 |
74 |
136 |
75 |
138 |
77 |
B |
175 |
102 |
177 |
103 |
178 |
104 |
179 |
106 |
C1 |
175 |
108 |
177 |
110 |
178 |
111 |
179 |
112 |
C |
201 |
140 |
202 |
141 |
203 |
142 |
205 |
144 |
There are no changes to the minimum required distances We are only adding these recommended distances to distinguish LPFM channels that may not be subject to interference.