Agreement between the Government of Canada and the Government of the United States of America Relating to the FM Broadcasting Service and the Associated Working Arrangement

Agreement between the Government of Canada and the Government of the United States of America Relating to the FM Broadcasting Service and the Associated Working Arrangement
(PDF, 316 KB, 77 pages)


Spectrum Management
Terrestrial Broadcasting Agreements and Arrangements

Note

All persons making use of this consolidation are reminded that the documents included herein are provided only for convenience of reference. This consolidation is for the guidance of those engaged in radiocommunications in Canada. The information contained in this document is subject to change without notice. While every reasonable effort has been made to ensure accuracy, no warranty is expressed or implied. For more details, please contact the Broadcast Applications Engineering Division.

The agreements and arrangements contained herein have been negotiated under the authority of the Government of Canada by the Department of Communications whose spectrum management and telecommunications programs have been transferred to Industry Canada.

Prepared by:

Industry Canada
Radiocommunications and Broadcasting Regulatory Branch
300 Slater Street
Ottawa, Ontario
K1A 0C8

via e-mail: spectrum_pubs@ic.gc.ca

All spectrum publications are now available on the Internet at: http://www.ic.gc.ca/spectrum

Publication Date: June 1997

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Department of State
Washington

February 25, 1991

Excellency:

I have the honour to refer to your note No. 149 dated November 26, 1990, with an attached Working Arrangement, proposing an agreement between the Governments of the United States of America and Canada concerning the use of the 88 to 108 megahertz frequency band for frequency modulation broadcasting (FM). The new agreement would replace the agreement between the two Governments effected by the exchange of notes of January 8 and October 15, 1947 (the 1947 Agreement).

I have the further honour to inform you that the Government of the United States of America accepts the proposals contained in your note including its attached Working Arrangement and that this exchange of notes constitutes an agreement between the two Governments, which shall enter into force on the date of this note and shall supersede the 1947 Agreement.

Accept, Excellency, the renewed assurances of my highest consideration.

For the Secretary of State:

Original signed by

Bradley P. Holmes

Enclosure:

Working Arrangement

His Excellency

Derek H. Burney,
Ambassador of Canada.

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Canadian Embassy
Ambassade du Canada

Note No. 149

Washington, November 26, 1990

Sir,

I have the honour to refer to the Exchange of Notes (January 8 and October 15, 1947) between Canada and the United States of America constituting an Agreement on the allocation of channels for radio broadcasting effective October 15, 1947 (the 1947 Agreement) and to the recent discussions between representatives of both Governments concerning the use of the 88 to 108 megahertz frequency band for frequency modulation broadcasting (FM). Furthermore, I have the honour to propose that the above-mentioned Agreement be replaced by the following.

In order to prevent undue interference between stations in the respective countries, the allotment and assignment of channels in areas adjacent to the border of Canada and the United States shall be in accordance with the conditions set forth herein and in the attached Working Arrangement.

For the purpose of this Note, the expression "Administrations" refers to the Department of Communications for Canada and the Federal Communications Commission for the United States of America. The Administrations shall exchange information and cooperate with each other for the purpose of minimizing interference and obtaining maximum efficiency in the use of FM broadcasting radio channels. To this end, the Administrations have accepted the attached Working Arrangement, including its Annexes. Tables A and B of Annex IV of the Working Arrangement may be revised by direct correspondence between the Administrations. The Administrations shall, as necessary, review the Working Arrangement and its implementation in light of domestic and international developments. Amendments to the Working Arrangement, other than revisions to Tables A and B of Annex IV, shall be accomplished by exchange of notes between the two Governments.

Notification of proposed revisions to Tables A and B of Annex IV shall be made to the other Administration in accordance with the provisions of the Working Arrangement. Assignments made within 320 kilometres of the border shall be in accordance with these Tables, as revised from time to time and shall be notified in accordance with the provisions of the Working Arrangement.

The Honourable James A. Baker, III
Secretary of State
7th Floor
Department of State
2201 C Street, N.W.
Washington, D.C. 20520

Assignments made at points which are more than 320 kilometres from the nearest point on the border of Canada and the United States will normally have no international significance and need not be notified except in cases of unusual operating parameters where the possibility exists that interference could be caused to stations of the other Administration.

If the foregoing proposals are acceptable to the Government of the United States of America, I have the honour to propose that this Note, including the attached Working Arrangement, which are authentic in English and French, and your Note in reply shall constitute an Agreement between the Governments of Canada and the United States of America which shall enter into force on the date of your reply. Upon entry into force, this Agreement shall supersede the 1947 Agreement.

This Agreement may be amended through exchange of notes between the two Governments.

Either Government may terminate this Agreement at any time by giving written notice to this effect at least one year prior to the date contemplated for such termination.

Accept, Sir, the renewed assurance of my highest consideration.

Original signed by

D.H. Burney
Ambassador

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Working Arrangement for the Allotment and Assignment of FM Broadcasting Channels under the Agreement between the Government of Canada and the Government of the United States of America relating to the FM Broadcasting Service

Effective Date: February, 1991

Contents

  1. Preamble
  2. Basic Principles
  3. Allotments and Assignments
  4. Low Power FM Stations
  5. Procedures for Notification

Annexes

1. Preamble

Mutual undertakings concerning the allotment and assignment of FM Broadcasting Channels by Canada and the United States in the area lying within 320 kilometres of their common border are set out in the Agreement between the Government of the United States of America and the Government of Canada relating to the FM broadcasting service (1989 FM Agreement). The Arrangement set out herein states the basis upon which the Canadian and the United States Administrations shall consider responses to border area FM channel allotments and assignments proposed by the other Administration pursuant to the Agreement.

2. Basic Principles

2.1 Channel designation

FM broadcast channels are allotted in the band 88 to 108 MHz and are 200 kHz wide. Their center frequencies begin at 88.1 MHz and continue in successive steps up to and including 107.9 MHz as set forth in Annex I. FM allotments and assignments are classified in accordance with 2.2 and must conform with the distance separations under 2.4.

2.2 Classification and Maximum Parameters of Allotments and Assignments

2.2.1 The classes and maximum parameters are as follows:

Classes Effective
Radiated Power
Antenna Height
Above Average Terrain
A 3 kilowatts 100 metres
B1 25 kilowatts 100 metres
B 50 kilowatts 150 metres
C1 100 kilowatts 300 metres
C 100 kilowatts 600 metres

(U.S. Class C2 shall be considered as Class B for the purposes of the above table. Canadian Class A1 shall be considered as Class A for the purposes of the above table).

2.2.2 The maximum effective radiated power (ERP) in any plane of polarization must not exceed the maximum ERP permitted for the allotment or the assignment.

2.3 Antenna heights and equivalence

2.3.1 Where antenna heights exceed those shown in 2.2.1, the effective radiated power shall be reduced to provide equivalence with maximum parameters. Equivalence means that the 1 mV/m (60 dBu) contour remains at the same location as that determined by the attached F(50, 50) propagation curves and the maximum parameters for the class of the assignment. Moreover, it is required that the interference contour for equivalent parameters not exceed that determined by the attached F(50, 10) propagation curves and the maximum parameters allowed. Where limited allotments are concerned, the agreed upon parameters shall be used instead of maximum allowable parameters.

Where assignments are concerned, (existing or proposed) transmitting site co-ordinates should be used to determine equivalence. For allotments, city reference coordinates should be used.

2.3.2 Existing stations operating with parameters in excess of those specified for the classes in 2.2.1 may continue to operate as previously notified or with equivalent parameters.

2.4 Minimum distance separation

Minimum Distance Separation Requirements in kilometres
Relation Co-Channel Adjacent Channels I.F.
kHz 200 kHz 400 kHz 600 kHz 10.6/10.8 MHz
A - A 132 85 45 37 8
A - B1 180 113 62 54 16
A - B 206 132 76 69 16
A - C1 239 164 98 90 32
A - C 242 177 108 100 32
B1 - B1 197 131 70 57 24
B1 - B 223 149 84 71 24
B1 - C1 256 181 106 92 40
B1 - C 259 195 116 103 40
B - B 237 164 94 74 24
B - C1 271 195 115 95 40
B - C 274 209 125 106 40
C1 - C1 292 217 134 101 48
C1 - C 302 230 144 111 48
C - C 306 241 153 113 48

(U.S. Class C2 shall be considered as Class B for the purposes of the above table. Canadian Class A1 shall be considered as Class A for the purposes of the above table).

2.5 Transmitter locations

An FM transmitter site shall be so located as to serve the city to which the channel is assigned and to promote the overall efficiency of the allotment plan. Transmitter sites shall be located so that the separations are not less than those set forth in 2.4 except when specifically agreed to by each Administration.

2.6 Computation of distance and azimuth

2.6.1 Where transmitter sites have been established the distance shall be determined using the coordinates of the transmitter sites. If a transmitter site has not been established, the community's reference coordinates shall be used.

2.6.2 The distance between reference points is considered to be the length of the hypotenuse of a right-angle triangle, one side of which is the difference in latitude of the reference points and the other side the difference in longitude of the two reference points, and shall be computed as follows:

2.6.2.1 Convert latitude and longitude into degrees and decimal parts of a degree. Determine the middle latitude of the two reference points (average the latitudes of the two points).

LATM = (LAT1+ LAT2)/2

2.6.2.2 Determine the number of kilometres per degree of latitude difference for the determined middle latitude.

LATK = 111.108 - 0.566 cos (2 LATM)

2.6.2.3 Determine the number of kilometres per degree of longitude difference for the determined middle latitude.

LONGK = 111.391 cos (LATM) - 0.095 cos (3 LATM)

2.6.2.4 Determine the north-south distance in kilometres.

LAT = LATK (LAT1 - LAT2)

2.6.2.5 Determine the east-west distance in kilometres.

LONG = LONGK (LONG1 - LONG2)

2.6.2.6 Determine the distance between the reference points by the square root of the sum of the squares of the distances obtained.

DIST = (LAT2 + LONG2)½

where: LAT1 and LONG1 = coordinates of one location in decimal degrees;

LAT2 and LONG 2 = coordinates of second location in decimal degrees;

LATM = middle latitude between points;

LATK = kilometres per degree of latitude difference;

LONGK = kilometres per degree of longitude difference;

LAT = north-south distance in kilometres;

LONG = east-west distance in kilometres; and

DIST = distance between two reference points in kilometres.

In computing the above, sufficient decimal figures shall be used to determine the distance to the nearest kilometre.

2.6.3 When it is necessary to calculate the angle or azimuth between true north and the connecting radial from one reference point to another, the following procedure shall apply:

2.6.3.1 Convert latitude and longitude into degrees and decimal parts of a degree.

2.6.3.2 Determine the arc length in degrees between the two reference locations.

d = cos-1:sin(LAT2)sin(LAT1)+cos(LAT2) cos(LAT1) cos(LONG-LONG2).

2.6.3.3 Calculate the azimuth. (If the second location is west of the initial location, subtract the result from 360; i.e., 360 - AZM).

\[AZM = cos^{-1} \Bigg[ \frac {sin(LAT2) - sin(LAT1)cos(d)}{cos(LAT1)sin(d)} \Bigg] \]

where:

LAT1 and LONG1 = coordinates of initial location in decimal degrees;

LAT2 and LONG2 = coordinates of second location in decimal degrees;

d = arc length between locations in decimal degrees;

AZM = angle between true north (0 degrees) and the connecting radial in decimal degrees in clockwise direction.

In computing the above, sufficient decimal figures shall be used to determine the azimuth to the nearest degree.

3. Allotments and Assignments

3.1 Allotment Tables

Tables A and B contain all Canadian and U.S. allotments respectively on Channels 201-300 made to communities within 320 kilometres of the common border.

3.2 Primary Assignments

A primary assignment is a protected station assignment authorized or operating on an allotted channel with one of the classes listed in 2.2.1.

3.3 Secondary Assignments

A secondary assignment is an unprotected station assignment authorized or operating on a channel in accordance with section 4.

3.4 Unlimited Allotment

An unlimited allotment is one on which a station may operate with maximum parameters for its class. Any allotment on which a station, by virtue of spacing, could operate with maximum parameters may qualify as an unlimited allotment and may be coordinated as such.

3.5 Specially coordinated short-spaced allotments

3.5.1 In particular instances, unlimited allotments at less than the minimum spacings may be acceptable to both countries as specially coordinated short-spaced allotments and shall be identified in the Tables with an asterisk (*).

3.5.2 Limited allotments may be specially coordinated to require assignments to operate with less than maximum parameters. Specific limitations on antenna height and power calculated in the pertinent direction (see 5.2.1) are indicated by note designations in the Tables.

3.5.3 New or changed short-spaced assignments must not result in interference or an increase in existing interference to the related station's protected service contour unless specifically agreed to by the two Administrations.

3.5.4 New or changed short-spaced assignments must be notified in accordance with section 5.2 and must be approved by the other Administration before they can be implemented.

3.6 Directional antennas

Directional antennas operated by stations occupying limited allotments may be used to render protection to other co-channel and adjacent channel stations. In the direction of limitation, a station using a directional antenna must not exceed the notified pattern values. In all other directions, the radiation may not exceed the notified pattern value by more than 2 dB. Moreover, the ratio of maximum to minimum fields of a directional antenna shall not be greater than 20 dB, except where terrain may present a problem due to signal reflections. Directional antennas may also be used by stations operating on unlimited allotments, but their use shall not prevent future increases to maximum allowable parameters.

4. Low Power FM Stations

The conditions for the operation of low power FM stations (LPFM) are as follows:

4.1 LPFM stations are secondary assignments which operate on a non-interference no-protection basis with respect to existing or future primary assignments. However, they are assigned on a protected basis with respect to each other according to their date of notification.

4.2 LPFM assignments may be made on any channel from 201 to 300, whether or not the channels are listed in the FM Allotment Tables attached.

4.3 LPFM stations may be allowed an effective radiated power not to exceed 50 watts in any direction and an interference contour (34 dBu) not to exceed 32 km subject to 4.1 and 4.2 above.

4.4 For coordination purposes, only proposals for such stations with 32 kilometres of the common border need be referred for concurrence.

4.5 Should any interference be caused by an LPFM station to a primary FM or a previously notified LPFM assignment, the offending station must immediately change to a suitable channel or cease operation. The use of a channel by an LPFM station shall not prejudice in any manner the use of this channel for a primary assignment.

5. Procedures for Notification

5.1 General

5.1.1 Proposed assignments, allotments, and changes thereto shall be notified by an exchange of correspondence between the Federal Communications Commission and the Department of Communications; such proposals may be presumed acceptable if they conform to the technical criteria set out in this Arrangement. Each Administration shall have forty-five (45) days, from the date of receipt of the notification, to reply thereto. If an objection is raised within this period, the letter shall state, with as much particularity as the circumstances permit, the basis for the objection. The proposing Administration may then have an opportunity to meet the stated objection by suitable amendments to its proposal. If no reply is sent within the 45 day period prescribed, a notified proposal shall be considered approved. In all cases, notification procedures should be completed prior to domestic grant of authorization.

5.1.2 At the end of each calendar quarter, each Administration will forward to the other a recapitulation of all notifications made during that three-month period. Each year both Administrations will exchange, verify, and reconcile the complete data base.

5.2 Notification of Changes to Allotments

5.2.1 Notification of changes to allotments shall contain community name, state or province, reference coordinates (latitude and longitude) and pertinent channel changes.

5.2.2 Proposed allotments which do not conform to the Table of Minimum Distance Separations set out in this Arrangement shall normally be considered acceptable for technical coordination if objectionable interference would not be caused within the protected service contour of existing co-channel and adjacent channel allotments or assignments (except LPFM's). The following standards shall be used to determine the existence of objectionable interference:

5.2.2.1 The distance to the protected service contour of FM allotments and assignments shall be based on maximum allowable parameters and shall be determined from the F(50, 50) curves attached for the appropriate field strength contours listed below.

Class  Field Strength Maximum Distance
A 0.5 mV/m (54 dBu) 33 km
B1 0.5 mV/m (54 dBu) 51 km
B 0.5 mV/m (54 dBu) 65 km
C1 0.5 mV/m (54 dBu) 86 km
C 0.8 mV/m (58 dBu) 97 km

(U.S. Class C2 allotments and assignments shall be considered as Class B allotments and assignments for the purposes of this document. Canadian Class A1 shall be considered as Class A for the purposes of the above table).

5.2.2.2 The interfering field strength contour shall be determined from the F(50,10) propagation curves attached, except when the resultant distance is less than 15 kilometres, in which case the F(50,50) curves will be used.

5.2.2.3 Objectionable interference shall be considered to exist if the following interfering contours of classes A, B, B1 and C1 overlap the protected service contour:

Channel relationship Field strength
Co-channel 0.05 mV/m (34 dBu)
First adjacent 0.25 mV/m (48 dBu)
Second adjacent 5.00 mV/m (74 dBu)
Third adjacent 50.00 mV/m (94 dBu)

Where the interfering contour is from a Class C channel allotment or assignment, the following signal strength contours shall be used:

Channel relationship Field strength
Co-channel 0.08 mV/m (38 dBu)
First adjacent 0.40 mV/m (52 dBu)
Second adjacent 8.00 mV/m (78 dBu)
Third adjacent 80.00 mV/m (98 dBu)

5.2.2.4 Where the protected contour extends beyond the boundary of the country in which the allotment is located, protection shall be provided only to land areas, including islands, lying within that country. In this case, overlap of the interfering and the protected service contours shall be acceptable provided that the interference zone does not fall within these areas. Annex III describes the procedure to determine the interference zone.

5.3 Notification of Assignments

5.3.1 Notification of station assignments or changes in operating parameters of existing stations must set out the actual operating parameters which are to be employed. These may be less than the maxima permitted for the allotted channels. The use of lesser operating parameters initially shall not preclude the later use of assignment is being notified, the antenna height above average terrain for all connecting radials between it and the assignments and allotments to which it is short spaced shall be supplied. Each of these antenna heights is to be calculated by interpolating between the antenna heights above average terrain of the two standard radials that are adjacent to the connecting radial.

5.3.2 Notifications of assignments shall contain the following information:

  • City, State or Province
  • Transmitter location (Latitude and Longitude)
  • Channel Number and Class of Station
  • Channel Frequency
  • Call Sign
  • Antenna
  1. Height of center of radiation above average terrain (3-16 km)
  2. Height of the center of radiation above average terrain of the two adjacent standard radials if limited assignment is proposed.
    • Effective radiated power
  3. Horizontal pattern if a directional antenna is proposed.

5.4 Technical coordination

Technical coordinations concerning allotments and assignments shall normally consist of an exchange of letters between the Department of Communications of Canada and the Federal Communications Commission of the United States of America. In the event that the matter cannot be resolved by correspondence, a meeting shall be arranged.

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Annex I

Frequency/Channel Table

Frequency
(MHz)
Channel
N
88.1 201
88.3 202
88.5 203
88.7 204
88.9 205
89.1 206
89.3 207
89.5 208
89.7 209
89.9 210
90.1 211
90.3 212
90.5 213
90.7 214
90.9 215
91.1 216
91.3 217
91.5 218
91.7 219
91.9 220
92.1 221
92.3 222
92.5 223
92.7 224
92.9 225
93.1 226
93.3 227
93.5 228
93.7 229
93.9 230
94.1 231
94.3 232
94.5 233
94.7 234
94.9 235
95.1 236
95.3 237
95.5 238
95.7 239
95.9 240
96.1 241
96.3 242
96.5 243
96.7 244
96.9 245
97.1 246
97.3 247
97.5 248
97.7 249
97.9 250
98.1 251
98.3 252
98.5 253
98.7 254
98.9 255
99.1 256
99.3 257
99.5 258
99.7 259
99.9 260
100.1 261
100.3 262
100.5 263
100.7 264
100.9 265
101.1 266
101.3 267
101.5 268
101.7 269
101.9 270
102.1 271
102.3 272
102.5 273
102.7 274
102.9 275
103.1 276
103.3 277
103.5 278
103.7 279
103.9 280
104.1 281
104.3 282
104.5 283
104.7 284
104.9 285
105.1 286
105.3 287
105.5 288
105.7 289
105.9 290
106.1 291
106.3 292
106.5 293
106.7 294
106.9 295
107.1 296
107.3 297
107.5 298
107.7 299
107.9 300

Annex II Figures 1 and 2

Annex III

Procedure to Determine Interference Zone

On an appropriately scaled map plot the transmitter sites and do the following:

  1. Plot the protected service contour for the assignment or allotment to be protected based on maximum parameters in accordance with 5.2.2.1. If the assignment or allotment is limited, the agreed upon parameters shall be used instead of maximum parameters.
  2. Plot the interfering contour for the proposed assignment or allotment based on its proposed parameters in accordance with 5.2.2.2 and 5.2.2.3.
  3. Mark the two points where the contours intersect.
  4. Repeat steps 1, 2, and 3 except increase the value of each contour while maintaining the same protection ratio until the protected and interfering contours are tangential.
  5. Draw a line joining the intersection points obtained above. The area contained within this line and the protected service contour drawn in step 1 defines the interference zone.

Example

The following example shows the interference zone between an existing class B station and a proposed class A station which are short-spaced and on second-adjacent channels.

  1. The protected service contour from 5.2.2.1 is 54 dBu which extends to 65 km.
  2. The interfering contour from 5.2.2.3 is 74 dBu. (The extent of this contour will vary depending on the proposed operating facilities).
  3. Mark the two points where the contours intersect.
  4. Plot the 54 dBu service contour and the 74 dBu interfering contour and mark the two points of intersection. Continue to increase the value of the contours, plot them, and mark the intersection points until the contours are tangent.
  5. Draw a line joining the intersection points obtained above. The area contained within this line and the protected service contour drawn in step 1 defines the interference zone. This area is shown cross-hatched in the drawing.
Interference Zone
Example of interference zone

[Description of figure]


Image Descriptions

Figure 1

The Figure 1 is a graphic showing a set of curves which gives in dBµV/m the estimated field strength exceeded at 50% of the potential receiver locations for at least 50% of the time for a receiving antenna height of 9.1 meters and a transmitter ERP of 1 kilowatt in the lower VHF band (channels 2-6 & FM). Each curve corresponds to a distance (between 1.5 km and 300 km). Each of these curves gives, for various Heights Above Average Terrain (HAATs), the corresponding estimated field strength at the given distance of the curve. The vertical axis is the estimated field strength and runs from -20 to +110 dBµV/m. The horizontal axis is the HAAT; its scale is logarithmic and runs from 30 to 1600 meters. There are 35 curves corresponding to the following distances (in km): 1.5, 2, 3, 4, 5, 6, 7, 8, 9, 10, 15, 20, 30, 40, 50, 60, 70, 80, 90, 100, 110, 120, 130, 140, 150, 160, 170, 180, 190, 200, 220, 240, 260, 280, 300.

The table below gives the field strength values corresponding to various HAAT values for each of these curves:

Figure 1: Estimated Field Strength Exceeded at 50% of the Potential Receiver Locations for at least 50% of the Time at a Receiving Antenna Height of 9.1m.
Distance in kmTransmitting Antena Height Above Average Terrain, in Metres
30 40 50 60 70 80 90 100 150 200 300 400 500 600 700 800 900 1000 1600
 Field Strength in dB above 1 µV/m for 1 kW ERP
1.593.0095.5097.6599.0099.80100.40100.80101.10102.00102.40102.80102.90103.00103.00103.00103.00103.00103.00103.00
2.087.8090.3092.3593.9095.1095.9096.5597.0098.4099.1099.80100.10100.25100.35100.40100.45100.50100.60100.70
3.080.8083.2085.2586.9088.1589.2090.0090.7093.1594.6095.8096.3596.6096.7096.7596.8096.9096.9597.15
4.075.7078.2580.3081.9583.3084.4085.3586.1589.1090.9092.6093.4093.8594.0094.1094.2094.3094.3094.30
5.072.0074.3076.3078.0079.5080.6081.6082.5085.8087.8090.0091.0091.5091.7091.8091.9091.9592.0092.15
6.069.0071.0073.0074.7076.2077.4078.5079.4082.8585.0087.5088.8089.5089.9090.1090.3090.4090.5090.70
7.066.3568.4070.4072.1073.5574.7575.8076.8080.2582.6085.4086.9087.6588.1588.5088.7088.8589.0089.40
8.064.0066.2068.2069.8571.2572.4573.5074.4578.0080.3083.6085.2586.1086.7087.1087.4087.6087.8088.15
9.062.0064.2066.2067.8069.2070.3571.4572.4575.8578.3081.6083.4084.5085.2085.7086.1086.4086.6087.15
10.060.0062.4064.3566.0067.3568.5069.6070.5074.0076.4579.8581.8083.0083.8084.3584.8085.1585.4086.25
15.053.0055.3057.2558.9560.3061.5062.5063.4067.0069.5573.0075.3577.2078.6079.6080.3580.9081.2582.50
20.048.0050.1052.1053.7555.2056.3057.3058.3061.8064.4067.9070.3572.3573.9075.2076.1576.8577.4079.65
30.040.5042.7544.7546.5047.9049.0050.0551.0054.5057.0060.6063.2565.3567.1068.6069.7070.6071.5075.30
40.035.0037.2039.1040.6042.0043.1044.2045.1548.7051.2054.9057.5059.7561.8063.5064.7065.7566.6570.50
50.030.1032.3034.2035.8037.2538.4039.4040.3043.8046.3549.9552.7055.2057.3059.0060.3561.5062.4566.00
60.026.6028.3029.7531.1032.4033.5034.5035.4039.0041.6545.2048.1050.9053.0054.6055.9557.0557.9561.60
70.023.3024.6025.9027.1028.2029.2030.2031.1034.6037.1040.9044.0046.9048.9050.4051.7052.8053.7057.50
80.020.3521.4022.5023.5024.5025.4526.3527.2530.5032.9036.6539.7542.8044.8546.4547.7548.8049.7553.50
90.017.7518.5019.3020.0020.8021.5522.3023.0526.2028.6032.3035.3038.3540.5542.2543.6044.7045.6549.35
100.015.5016.0016.6017.2017.8518.4519.0019.6022.4024.7028.3031.2034.3036.6538.5039.9041.0041.9045.30
110.013.3513.9014.4514.9515.4515.9516.4516.9519.2521.3024.6527.3530.5033.0034.9536.4537.5038.4042.00
120.011.4011.9012.3012.7513.2013.6514.1014.5516.5018.2021.2524.0527.0529.5531.4032.8033.8534.7538.35
130.09.509.9010.3010.7011.1011.5011.9512.3514.0015.4018.3021.1523.9526.3028.0529.4030.4031.2035.00
140.07.708.158.558.959.309.7010.1010.4511.9513.3015.7518.5021.0023.1024.8526.1027.1027.9531.80
150.05.906.406.807.207.557.908.258.6010.0011.2513.5016.0018.3020.2021.8023.0024.0024.9029.00
160.04.104.605.105.505.906.256.606.908.209.5011.6013.6015.6017.4018.9020.0021.0022.0026.20
170.02.503.003.503.904.304.655.005.306.607.709.7011.7013.4015.0016.3017.5018.6019.6023.90
180.01.001.502.002.402.753.103.403.704.905.957.909.6511.2512.7514.0015.1516.2017.2021.50
190.0-0.50-0.100.350.751.151.501.802.103.204.306.207.809.2010.6011.8013.0014.0015.0019.50
200.0-2.10-1.60-1.20-0.75-0.40-0.050.300.601.802.804.506.007.358.609.7510.8011.8512.8017.35
210.0-3.50-3.10-2.70-2.35-2.00-1.65-1.35-1.000.201.202.904.305.706.958.059.0510.0511.0515.30
220.0-4.95-4.60-4.30-3.95-3.65-3.30-3.00-2.65-1.40-0.351.402.804.205.356.407.458.459.4513.65
230.0-6.40-6.10-5.75-5.40-5.10-4.75-4.45-4.15-2.85-1.85-0.151.302.553.754.805.856.857.8012.25
240.0-7.80-7.55-7.20-6.85-6.50-6.15-5.80-5.50-4.20-3.25-1.60-0.201.002.153.204.255.206.1510.75
250.0-9.40-9.00-8.65-8.30-7.95-7.60-7.30-7.00-5.75-4.75-3.10-1.75-0.600.551.652.703.754.709.30
260.0-10.95-10.55-10.15-9.75-9.40-9.10-8.75-8.45-7.30-6.30-4.65-3.30-2.10-0.900.201.252.253.257.75
270.0-12.35-11.95-11.60-11.20-10.85-10.50-10.25-9.90-8.80-7.85-6.15-4.80-3.60-2.35-1.25-0.250.751.756.30
280.0-13.70-13.30-13.00-12.65-12.30-11.95-11.65-11.35-10.25-9.30-7.70-6.25-5.00-3.80-2.70-1.65-0.700.254.90
290.0-15.10-14.70-14.35-14.00-13.65-13.35-13.10-12.80-11.65-10.70-9.15-7.75-6.50-5.35-4.25-3.20-2.25-1.303.30
300.0-16.30-16.00-15.65-15.30-15.00-14.70-14.40-14.10-13.00-12.00-10.45-9.15-7.95-6.80-5.70-4.70-3.75-2.851.70

At the right of the graphic, there is a scale for the conversion of the ERP from Watts to dBs above 1 kW. The ERP in dBs above 1 kW is equal to ten times the logarithm of the ERP in kW. The table below shows the reference values from the scale.

ERP Power in dB over 1 kW
1 Watt -30 dB
10 Watts -20 dB
100 Watts -10 dB
1 kilowatts 0 dB
10 kilowatts 10 dB
100 kilowatts 20 dB
1 Megawatts 30 dB
10 Megawatts 40 dB

Back to figure

Figure 2

The Figure 2 is a graphic showing a set of curves which gives in dBµV/m the estimated field strength exceeded at 50% of the potential receiver locations for at least 10% of the time for a receiving antenna height of 9.1 meters and a transmitter ERP of 1 kilowatt in the lower VHF band (channels 2-6). Each curve corresponds to a distance (between 15 km and 500 km). Each of these curves gives, for various Heights Above Average Terrain (HAAT), the corresponding estimated field strength at the given distance of the curve. The vertical axis is the estimated field strength and runs from -40 to +90 dBµV/m. The horizontal axis is the HAAT; its scale is logarithmic and runs from 30 to 1600 meters. There are 35 curves corresponding to the following distances (in km): 15, 20, 30, 40, 50, 60, 70, 80, 90, 100, 110, 120, 130, 140, 150, 160, 170, 180, 190, 200, 220, 240, 260, 280, 300, 320, 340, 360, 380, 400, 420, 440, 460, 480, 500.

Distance in kmTransmitting Antena Height Above Average Terrain, in Metres
30 40 50 60 70 80 90 100 150 200 300 400 500 600 700 800 900 1000 1600
 Field Strength in dB above 1 µV/m for 1 kW ERP
1553.1555.6057.6559.3560.6561.8062.8563.7567.4069.9073.5075.8077.7079.1580.2581.1081.6581.9583.00
2048.6550.8052.7554.4055.8057.0558.1059.1562.6565.2068.6071.1573.0074.6576.0076.9577.7078.2080.25
3042.3544.5546.3547.8549.2550.3551.3552.3555.9558.4562.0064.6066.6568.5069.9571.0572.0572.9076.50
4038.6040.5042.0043.4044.6045.6046.6047.5050.8053.2556.9059.7062.0063.7065.1566.3567.4068.4072.40
5035.9037.5539.0040.2041.1542.0042.8543.6546.8049.1552.7555.7058.3060.0561.4562.6063.6564.6068.80
6033.7035.0036.0037.0037.8538.6039.3040.0043.0045.3049.2052.0054.5056.4057.9059.1060.1061.0065.00
7031.7532.7033.5534.2534.9535.6036.2036.8539.5541.7045.3048.4051.0553.0054.5055.8056.8557.8062.00
8030.0030.7031.3031.8532.4032.9033.4033.9536.4038.5041.9045.1047.8049.8051.4052.7053.8054.8059.00
9027.8528.5029.0029.4529.8530.3030.7531.2533.4035.3038.6041.8044.7546.8048.2549.5050.6051.6056.00
10026.0026.5026.9027.3027.7028.0028.4028.8030.8032.6035.5038.8041.8043.8045.3046.5547.7048.7053.00
11024.0024.5024.9525.3025.7026.1026.4526.8028.5029.9032.5036.0039.0041.0042.5543.8044.9045.8050.00
12022.0022.5023.0023.4023.8024.2024.5524.9026.4027.7530.0533.5036.3038.3039.7040.9542.0042.9047.10
13020.0020.6021.1521.6022.0022.4022.7023.0524.5025.7528.0031.0034.0035.8037.0538.1539.1540.0544.10
14018.2018.8019.3019.7520.2020.5520.8521.2022.6023.8026.0028.8031.2033.0034.2535.3536.2537.1541.40
15016.5017.0017.4517.9018.3018.7019.0519.4020.8021.9523.9026.3528.7530.4531.7532.8033.7534.6538.80
16014.6515.1515.6016.1016.5516.9517.3017.6519.0020.2022.1024.5026.5028.0029.2030.2531.2532.1536.30
17012.8513.3013.8014.3014.7015.1015.5015.8517.3018.5020.3022.3024.0025.5026.8527.9529.0029.9534.10
18011.0011.5012.0012.5012.9013.3013.6514.0015.5516.7018.5020.4022.0023.4024.6525.8026.8027.8032.00
1909.109.7010.2010.7011.1011.5011.8512.2513.7014.8516.6518.5020.0521.4522.7023.8024.9025.9030.10
2007.408.008.559.009.459.8010.1510.5011.9013.0014.9016.7018.2019.6020.8021.9523.0024.0028.10
2105.706.406.957.457.808.208.558.8510.2011.2013.2015.0016.5017.8519.0020.1021.1022.1026.40
2204.004.705.205.706.106.506.807.158.509.6011.5513.3014.8016.1017.2518.4519.5020.5024.80
2302.403.003.504.004.404.755.105.456.807.909.8511.5013.0014.3015.5016.7017.7518.8023.10
2400.801.401.852.302.703.103.403.755.106.208.209.8011.3012.6013.8015.0016.1017.1021.50
250-0.70-0.200.250.701.101.501.802.103.504.506.508.209.7011.0012.2013.4014.5015.5019.90
260-2.30-1.75-1.35-0.90-0.50-0.150.200.501.802.854.806.507.959.3510.5511.7512.8513.8518.40
270-3.75-3.25-2.80-2.40-2.00-1.65-1.25-1.000.151.153.004.706.107.508.8010.0011.1012.1016.80
280-5.10-4.70-4.25-3.85-3.50-3.15-2.80-2.50-1.40-0.351.403.004.405.807.108.309.4010.4515.10
290-6.50-6.10-5.65-5.25-4.85-4.55-4.25-4.00-2.85-1.90-0.201.202.804.205.506.707.758.8013.40
300-7.90-7.45-7.00-6.60-6.30-6.00-5.70-5.40-4.25-3.40-1.70-0.201.202.603.804.956.007.0011.60
310-9.00-8.65-8.25-7.90-7.60-7.30-7.00-6.75-5.70-4.90-3.20-1.70-0.301.002.203.354.405.4010.10
320-10.20-9.80-9.50-9.15-8.85-8.55-8.30-8.05-7.05-6.15-4.70-3.30-1.90-0.550.651.802.853.858.30
330-11.40-11.10-10.75-10.45-10.15-9.90-9.65-9.40-8.40-7.60-6.00-4.70-3.30-2.00-0.800.301.302.306.80
340-12.70-12.40-12.00-11.70-11.40-11.15-10.90-10.70-9.75-8.90-7.30-6.00-4.70-3.50-2.30-1.15-0.150.805.20
350-13.90-13.60-13.25-12.90-12.65-12.40-12.15-11.90-11.00-10.15-8.60-7.35-6.05-4.80-3.70-2.60-1.60-0.603.80
360-15.20-14.85-14.50-14.20-13.90-13.65-13.40-13.15-12.20-11.45-9.90-8.70-7.40-6.20-5.00-4.00-3.10-2.102.10
370-16.50-16.05-15.70-15.40-15.10-14.90-14.65-14.40-13.50-12.70-11.10-9.90-8.80-7.60-6.50-5.50-4.60-3.650.40
380-17.75-17.30-16.90-16.60-16.30-16.10-15.85-15.65-14.80-14.00-12.40-11.20-10.10-9.00-8.00-7.00-6.10-5.15-1.00
390-19.00-18.50-18.10-17.80-17.50-17.25-17.05-16.80-16.00-15.20-13.70-12.50-11.40-10.30-9.40-8.45-7.50-6.60-2.50
400-20.10-19.70-19.30-19.00-18.70-18.45-18.20-18.00-17.20-16.40-14.90-13.70-12.60-11.60-10.65-9.80-8.90-8.05-3.90
410-21.25-20.85-20.50-20.15-19.90-19.65-19.40-19.20-18.40-17.60-16.10-15.00-13.90-12.90-12.00-11.10-10.30-9.40-5.15
420-22.50-22.00-21.65-21.35-21.10-20.85-20.65-20.45-19.60-18.80-17.20-16.20-15.20-14.25-13.30-12.35-11.55-10.70-6.60
430-23.70-23.25-22.90-22.60-22.35-22.15-21.90-21.70-20.70-19.90-18.40-17.30-16.35-15.40-14.50-13.60-12.75-11.90-7.90
440-24.95-24.50-24.10-23.80-23.55-23.35-23.10-22.90-21.90-21.05-19.60-18.50-17.50-16.60-15.70-14.80-13.90-13.10-9.15
450-26.00-25.65-25.30-25.00-24.75-24.50-24.25-24.00-23.05-22.25-20.85-19.70-18.70-17.75-16.85-15.95-15.10-14.30-10.40
460-27.10-26.80-26.50-26.20-25.90-25.65-25.40-25.20-24.20-23.40-22.00-20.90-19.85-18.90-18.00-17.10-16.30-15.50-11.70
470-28.35-28.00-27.70-27.40-27.10-26.85-26.60-26.35-25.30-24.50-23.05-21.95-20.95-20.00-19.15-18.30-17.50-16.70-12.90
480-29.70-29.20-28.90-28.55-28.25-28.00-27.75-27.50-26.40-25.60-24.15-23.00-22.00-21.10-20.25-19.50-18.70-17.95-14.10
490-30.80-30.40-30.10-29.75-29.45-29.10-28.85-28.60-27.50-26.70-25.30-24.10-23.15-22.25-21.40-20.65-19.90-19.15-15.40
500-31.90-31.50-31.20-30.90-30.60-30.30-30.00-29.75-28.70-27.85-26.50-25.30-24.30-23.40-22.60-21.80-21.05-20.25-16.60

At the right of the graphic, there is a scale for the conversion of the ERP from Watts to dBs above 1 kW. The ERP in dBs above 1 kW is equal to ten times the logarithm of the ERP in kW. The table below shows the reference values from the scale:

ERPPower in dB over 1 kW
1 Watt-30 dB
10 Watts-20 dB
100 Watts-10 dB
1 kilowatts0 dB
10 kilowatts10 dB
100 kilowatts20 dB
1 Megawatts30 dB
10 Megawatts40 dB

Back to figure

Interference Zone

This figure is shows how to calculate the interference zone as described in the previous example. The protected station is a class B station on the left and 4 field strength contours are plotted (54, 56, 58 and 60 dBuV/m).

The interfering station is a class A and is plotted on the right. Four interfering field strength contours from this station are plotted (34, 36, 38 and 40 dBuV/m). Each contour from the protected station intersects the contour from the interfering station at two points (top and bottom), except for the 60 dBuV/m from the left and the 40 dBuV/m from the right which are tangent to each other.

The interference zone is shaded and drawn as follows. The right boundary of the interference zone follows the 54 dBuV/m of the protected station between the two intersections of the 34 dBuV/m contour from the interfering station. The left boundary follows the intersections on top and bottom of the 56 dBuV/m contour on the left with the 36 dBuV/m contour on the right then goes through the intersections of the 58 with the 38 dBuV/m. The top and bottom boundary of the interference zone finally joins together at the tangent point of the 60 and 40 dBuV/m contours.
Back to figure