BPR-4 — Application Procedures and Rules for Television Broadcasting Undertakings
Section C: Technical Requirements for the Establishment of TV Broadcasting Stations Using Primary Allotments
This section pertains to the technical requirements for the allotment and protection of VHF and UHF channels and for the prediction of coverage for TV broadcasting stations in Canada.
The International Telecommunication Union (ITU) uses the word 'allocation' in reference to the provision of a band of frequencies for a particular purpose or service.
An 'allotment' is the provision of a specific channel for a particular community. A list of current Canadian allotments is published by the Department.
An 'assignment' is the authorized use of an allotment by a TV station.
C-1.1.4 Primary Assignment
A primary assignment is a protected station assignment authorized or operating on an allotment.
C-1.1.5 Secondary Assignment
A secondary assignment is an unprotected assignment authorized or operating on a channel in accordance with Section E or G, i.e. LPTV or VLPTV.
C-1.1.6 Effective Radiated Power (ERP)
The effective radiated power (ERP) is the product of the transmitter output power, the transmission line (and combiner) efficiency and the total power gain of the antenna relative to a half-wave dipole.
C-1.1.7 Effective Height of the Antenna above Average Terrain (EHAAT)
The effective height of the antenna above average terrain (EHAAT) is the average of the antenna heights above the average terrain (HAATs) for eight radials spaced every 45 degrees of azimuth starting with true north. The height of the antenna above average terrain (HAAT) is the height of the centre of radiation of the antenna above the average elevation of the terrain between 3 to 16 km from the antenna for each radial.
C-1.1.8 Television Channels
The frequencies allocated to broadcasting are designated by a channel number with each channel having 6 MHz bandwidth as follows:
|Band||Channels||Frequencies (in MHz)|
|VHF||2 to 4 inclusive||54 - 72|
|VHF||5 and 6||76 - 88|
|VHF||7 to 13 inclusive||174 - 216|
|UHF||14 to 69 inclusive||470 - 806|
Frequency band 608-614 MHz, channel 37, is allocated to the Radio Astronomy Service, and is not available for broadcasting.
Maximum ERP values and the associated EHAATs permitted on an allotted channel are as follows:
|VHF CHANNELS 2-6||VHF CHANNELS 7-13||UHF CLASS A||UHF CLASS B||UHF CLASS C|
Note: The maximum ERP is calculated from the maximum value of radiation from the antenna in the plane of maximum radiation or in the direction of maximum radiation for directional antennas.
For UHF stations, the maximum ERP values shall normally be reduced in accordance with the graph in Figure 7 of Appendix 1 when the EHAAT is in excess of the maximum value. As a special case, on class C allotments, super parameter stations are permitted an ERP of up to 5000 kW and an EHAAT in excess of 300 m (refer to Section C-1.7 and Table 1, Appendix 8).
For VHF stations, the maximum ERP value shall not be exceeded. Higher EHAAT values may be accepted for VHF and super parameter UHF stations, provided that the appropriate F(50,10) interfering signal levels at the protected contour of co-channel allotments do not exceed those provided in Section C-1.4. In any event where the EHAAT exceeds 600 m, the ERP for an unlimited allotment or assignment shall be reduced so that the distance to the F(50,10) interfering contour (46 dBu) is equal to that resulting from the maximum permitted ERP for the channel proposed and an EHAAT of 600 metres.
C-1.1.10 Minimum Operating Parameters for UHF
The minimum operating parameters of a class of UHF assignments are the lower limits of the operating parameters or their equivalents2 allowed for that class, and they are as follows:
|CLASS A||CLASS B||CLASS C|
For directional antenna patterns, the ERP values above relate to the maximum value of the pattern.
C-1.1.11 Limited Allotment
A limited allotment is a channel on which a TV station, for purposes of protection, is required to operate with less than maximum parameters. A limitation may apply in one or more directions.
C-1.1.12 Unlimited Allotment
An unlimited allotment is a channel on which a station may operate with maximum parameters. Any allotment, on which a station could operate with maximum parameters by virtue of spacing, may qualify as an unlimited allotment and may be coordinated as such.
C-1.1.13 Antenna Pattern
For horizontal non-directional patterns, variations in the radiation shall be contained within a ± 2 dB limit from the average value (perfect circle). If these limits are exceeded, the pattern is considered directional.
C-1.1.14 Antenna Beam Tilt (Electrical and Mechanical)
Antenna beam tilt is the inclination in degrees of the horizontal radiation pattern of the antenna which causes the maximum radiation to occur at an angle below the horizontal plane. The beam tilt may be achieved by mechanical or electrical means. The maximum permissible ERP, as defined in Section C-1.1.9 shall not be exceeded in either the horizontal or tilt planes.
The Grade A corresponds to a specific value of ambient median field strength existing 9.1 metres above ground. This signal level is deemed to be sufficiently strong, in the absence of interference from other stations and with due consideration given to man-made noise typical of urban environment, to provide a picture which the median observer would classify as of adequate quality, assuming a receiving installation (antenna, transmission line and receiver) typical of suburban or not too distant areas. This signal level is strong enough to provide an adequate quality of picture at least 90% of the time, at the best 70% of receiving locations. The Grade A contour is the geographic limit within which the median field strength equals or exceeds the Grade A value.
The Grade B corresponds to a specific value of ambient median field strength existing 9.1 metres above ground. This signal level is deemed to be adequate, in the absence of man-made noise or interference from other stations, to provide a picture which the median observer would classify as of satisfactory quality, assuming a receiving installation (antenna, transmission line and receiver) considered to be typical of outlying or near-fringe areas. This signal level is strong enough to provide a satisfactory quality of picture at least 90% of the time, at the best 50% of receiving locations. The Grade B contour is the geographic limit within which the median field strength equals or exceeds the Grade B value.
C-1.1.17 Service Contours
The service contours of a TV station are the Grade A and Grade B contours. The Grade A and Grade B contours are the boundaries or contours at which the field strength of a TV station, as determined using the appropriate F(50,50) propagation curves, are as follows:
|Channels||Grade A||Grade B|
|VHF 2 - 6||68 dBu||47 dbu|
|VHF 7 - 13||71 dBu||56 dBu|
|UHF 14 - 69||74 dBu||64 dBu|
The Grade A and Grade B contour values include the adjustments made with respect to different percentages of time (from 90% to 50%) and receiving location (from 70% to 50%) values indicated in Sections C-1.1.15 and C-1.1.16.
The dBu is the field strength in dB above one microvolt per metre (1 μV/m).
C-1.1.18 Operating Parameters
The operating parameters are the approved values of the ERP and EHAAT at which a TV station operates.
(a) For VHF: The protected contour is the Grade B contour but not exceeding a distance of 89 and 82 km for channels 2-6 and 7-13 respectively. The distance to the Grade B contour is determined using F(50,50) curves in Figures 1 and 3 of Appendix 1 and Section C-3.
(b) For UHF: The protected contour is the Grade B contour but not exceeding a distance of 25, 45 and 70 km for class A, B and C channels respectively. The distance to the Grade B contour is determined using the F(50,50) curves in Figure 5 of Appendix 1 and Section C-3.
The interfering contour is the signal level permitted at the protected contour of other allotments and assignments. The distance to the interference contour for co-channel stations is determined using the F(50,10) curves in Figures 2, 4 and 6 of Appendix 1. For all other relationships refer to Table 1, 2 or 3 of Appendix 8. For distances less than 15 km the F(50,50) curves in Figures 1, 3 and 5 of Appendix 1 shall be used.
Note that when antenna beam tilt is proposed, the ERP in the plane of tilt shall be used.
The polarization of the radiated signal is the orientation of the electric component of the electromagnetic field as radiated from the transmitting antenna.
For the purposes of international agreement, Canada is divided into two zones. A description and map of Zones 1 and 2 for Canada and the U.S.A. are shown in Appendix 10.
To reduce the effect of interference between co-channel stations, TV stations are assigned a frequency which is offset by 0, -10 kHz or +10 kHz from the nominal visual carrier frequency of the channel. The nominal frequency offset for each allotment is shown in the Canadian Television Channel Allotment Plan.
TV stations may also use precision frequency offset in accordance with Section C-1.3, where the visual carrier frequency is controlled by phase-locking or frequency stabilization at precise frequency offset of 10,010 Hz or 20,020 Hz with respect to another co-channel station.
C-1.1.24 Distances to Various Contours
In this Procedure, the distances to various contours, including service, interfering or equivalence contours, can be calculated with the F(50,50) and F(50,10) curves of Appendix 1 or with the F50M software. However, if there is a disagreement between the two methods, the results obtained with the F50M software will prevail.
C-1.2.1 Subject to the provisions listed below, TV allotments and assignments are protected to their Grade B contour, unless otherwise indicated. The Grade B contour is determined using F(50,50) propagation curves together with the ERP and HAAT for each of the eight radials. However, for irregular terrain, the local topography may be taken into account in calculating the location of the protected contour. The interfering signal is defined as in Section C-1.1.20 and the permissible co-channel interfering signal levels are listed in Section C-1.4. In determining the interfering signal towards the protected contour of a domestic allotment, the HAAT and the ERP for the pertinent azimuth(s) between the two allotments shall be used.
C-1.2.2 The Grade B contour is only protected to a maximum distance of 89 km for channels 2-6 or 82 km for channels 7-13. For channels 14-69, it is protected to a maximum distance of 25 km for class A channels, 45 km for class B channels and 70 km for class C channels.
C-1.2.3 The protected contour of an unoccupied limited allotment is determined using the limited parameters in all directions or in the direction(s) of limitation where applicable. Protection should be provided on the basis of a practical directional antenna meeting the limitation(s).
C-1.2.4 Where the protected contour extends beyond the boundary of the country in which the allotment is located, protection will be provided only to land areas, including islands, lying within that country. In this case, overlap of the interfering and the protected service contours may be acceptable provided that the interference zone does not fall within these areas. Appendix 6 describes the procedure to determine the interference zone.
To maintain the precise frequency difference, as outlined in Section C-1.1.23, both stations require frequency stabilization within ± 2 Hz. The applicant of the incoming station is responsible for any arrangements with the licensee of the affected station. A proposal for a precise offset frequency shall include a summary of the arrangements made or the discussions undertaken with the affected station. In addition, the applicant shall send a copy of the engineering brief with a covering letter to the affected station licensee preferably at the date of filing the application or immediately after the CRTC has issued a Notice of Public Hearing3. A copy of this letter and the postal or messenger receipt, as proof of delivery, shall be sent to the Department. The letter shall advise the licensee of the arrangements or the discussions undertaken and shall emphasize that any representations that the licensee might wish to make to the Department shall be submitted no later than thirty days after receipt of the engineering brief. Where the affected licensee offers an objection, the application may not be accepted by the Department. However, the Department reserves the right to make an independent decision concerning the disposition of the application. If no reply is received within the specified period, it will be assumed that there is no objection.
C-1.4.1 For a domestic allotment, the maximum permissible interfering signal at the protected contour of another co-channel VHF or UHF domestic allotment, shall not exceed that shown in the following table using F(50,10) curves:
|Interference Signal Level (in dBu)|
|Channels||No Freq. Offset||Freq. Offset||Precise Freq. Offset|
C-1.4.2 An interfering signal exceeding the values of the above table may be permitted by mutual agreement. In addition, any limitation to the service area of the channel applied for, shall not extend into areas where service is intended.
For separation requirements to U.S.A. allotments and assignments, refer to Section C-1.8.
For unlimited allotments, the minimum distance to an adjacent channel unlimited allotment is 96 km. For domestic limited allotments, the minimum distance to either a limited or unlimited adjacent channel allotment, shall be such that the permissible interfering signal at the adjacent channel's protected contour does not exceed the limits established in Table 2 in Appendix 8. However, an interfering signal exceeding the values in Table 2 may be permitted by mutual agreement. In addition, any limitation to the service area of the channel applied for, shall not extend into areas where service is intended.
For separation requirements to U.S.A. allotments and assignments, refer to C-1.8.
The protection afforded domestic UHF allotments is based on the standard separation distances to other co-channel and technically related channel allotments. The standard separation distances are shown in Table 3 in Appendix 8 for class A, B and C stations taken at maximum parameters using a nominal zero and 10 or 20 kHz frequency offset. UHF channel allotments normally shall not be made at separation distances less than those shown in the table. However, a limited class A, B or C channel may be allotted at less than the standard separations providing that the desired to undesired field strength ratios, as shown in Table 3, are not exceeded. In addition, any limitation to the service area of the channel applied for, shall not extend into areas where service is intended.
For separation requirements to U.S.A. allotments and assignments, refer to Section C-1.8.
C-1.7.1 Class C allotments may have operating parameters in excess of the maximum parameters, i.e. 1000 kW ERP at 300 m EHAAT, providing the ERP does not exceed 5000 kW and the maximum level of the co-channel interfering signal, at the protected Grade B contour of another co-channel allotment, does not exceed the applicable values listed in Section C-1.4. In addition, the protection requirements listed in Table 1 of Appendix 8 shall be met. For EHAATs greater than 600 m refer to Section C-1.1.9.
Super parameter stations are not protected beyond a radial distance of 70 km.
C-1.8.1 No VHF allotment in Canada may normally be made with respect to a U.S.A. allotment, at separation distances less than those shown in the table below using a nominal visual carrier frequency offset of 10 or 20 kHz:
|Frequency Relationship||Zone in Canada||Separation|
|Co-channel||1 or 2||275 km to allotments in USA Zone 1|
|Co-channel||2||305 km to allotments in USA Zone 2|
|Co-channel||1||275 km to allotments in USA Zone 2|
|First Adjacent Channel||1 or 2||95 km to allotments in USA Zone 1 or 2|
The Zones for Canada and the U.S.A. are shown in Appendix 10.
The maximum permitted interfering signal to the protected contour of VHF allotments in the U.S.A. is contained in the Canada-U.S.A. Working Arrangement.
C-1.8.2 No UHF allotment in Canada may normally be made with respect to a U.S.A. allotment, at separation distances less than those shown in the table below using a nominal visual carrier frequency offset of 10 or 20 kHz. These separation distances are based on a maximum ERP of 1000 kW and EHAAT of 300 metres.
|Frequency Relationship||Zone in Canada||Separation|
|Co-channel||1 or 2||250 km to allotments in USA Zone 1|
|Co-channel||2||280 km to allotments in USA Zone 2|
|Co-channel||1||250 km to allotments in USA Zone 2|
|First Adjacent (N=±1)||1 or 2||90 km to allotments in USA Zone 1 or 2|
|Intermod. (N=±2,3,4,5)||1 or 2||30 km to allotments in USA Zone 1 or 2|
|Local Oscillator (N=±7)||1 or 2||95 km to allotments in USA Zone 1 or 2|
|Intermed. Freq. Beat (N=±8)||1 or 2||30 km to allotments in USA Zone 1 or 2|
|Sound Image (N=±14)||1 or 2||95 km to allotments in USA Zone 1 or 2|
|Picture Image (N=±15)||1 or 2||120 km to allotments in USA Zone 1 or 2|
Where "N" is the number of the reference channel.
The maximum permitted interfering signal to the protected contour of UHF allotments in the USA is contained in the Canada-U.S.A. Working Arrangement.top of page
When a television service is being contemplated for a particular area and the Canadian Television Channel Allotment Plan does not contain a suitable unoccupied allotment, changes to the allotment plan may be proposed by an applicant.
The following types of changes are envisaged, separately or in combination concerning the addition or upgrading of allotments:
- adding or changing an allotment without affecting any other allotment;
- adding or changing an allotment at the expense of limiting an existing allotment or assignment. Where an assignment is concerned, the licensee's comments on the proposed limitation shall be sought, as required in C-2.4.3. The proposed limitation shall not be greater than that permissible under Section C-2.3.1 for VHF and under Section C-2.3.2 for UHF. For existing allotments refer to Section C-2.3.3;
- adding or changing a UHF allotment at the expense of reclassifying an existing allotment or assignment. This will occur when the parameters of the existing assignment are less than the maximum equivalent with the next lower class. Where reclassification of an assignment is proposed, the licensee's comments on the proposed reclassification shall be sought as required in Section C-2.4.3;
- adding or changing an allotment at the expense of changing the channel of an allotment or an assignment. In the latter case, the licensee's agreement shall be obtained (refer to Section C-2.4.3);
- adding or changing an allotment at the expense of changing the offset of an assignment or requiring the use of precision frequency control (refer to Section C-2.4);
- moving an allotment to an area and replacing the shifted allotment with a suitable replacement; and
- adding or changing an allotment at the expense of deleting an existing allotment.
It is noted that some of the changes in C-2.1 may have a positive impact on the allotment plan in one area but a negative impact in another area. If the Department accepts the changes it would report to the CRTC on the technical aspects of the changes and their impact on the provisions of the Plan provided the proposal is based on a complete application. These changes would be considered conditionally technically acceptable pending a decision by the CRTC. Any changes to the Plan that may be required as the result of such applications would not be made until the Department declares them technically acceptable and the CRTC approves the application.
A proposal to add a channel which is predicated on limiting an unlimited assignment shall be supported by a technical submission, and the licensee shall be informed as required in Section C-2.4.3. The proposal shall protect the station's Grade B contour which shall be determined using the station's operating ERP and an EHAAT of 150 metres. However, where the station's EHAAT exceeds 150 metres, the protected contour shall be the Grade B contour as calculated using the operating parameters but not exceeding the distances designated in Section C-1.1.19. Proposals to add a channel which will further limit a limited assignment shall be supported by a technical submission and the licensee shall be informed as required in Section C-2.4.3. The proposal shall protect the station's Grade B contour as calculated using the station's operating parameters.
A proposal to add a channel which is predicated on limiting an unlimited assignment shall be supported by a technical submission and the licensee shall be informed as required in Section C-2.4.3 The proposal shall protect the station's Grade B contour which shall be determined using the station's operating ERP and using an EHAAT of 100, 150 or 300 metres respectively for the class A, B or C stations. When the station's EHAAT exceeds that for the class the protected contour shall be the Grade B contour as calculated using its operating parameters but not exceeding the distances in C-1.1.19. Proposals to add a channel which will further limit a limited assignment shall be supported by a technical submission and the licensee shall be informed as required in Section C-2.4.3. The proposal shall protect the station's Grade B contour as calculated using the station's operating parameters.
A proposal to limit an unoccupied unlimited allotment to a limited allotment or to reduce further an unoccupied limited allotment shall be supported by technical submission demonstrating that the change would provide an improved channel utilization.
C-2.4.1 When an application for a new television undertaking requires modifications to the Plan, the applicant may consult with the Department regarding these modifications prior to the formal filing of the application. Where pertinent, the study shall show that the coverage objective of the proposal cannot be achieved by less drastic measures such as through the use of a limited allotment and/or directional antenna, etc.
C-2.4.2 Any application proposing to change the channel of an assignment will be found to be incomplete unless it is accompanied by proof that the station affected agrees to the change.
C-2.4.3 Applicants proposing to limit, reclassify, change the offset or implement precision frequency control of the channel occupied by an assignment shall send a copy of the engineering brief, with a covering letter, to the licensee of the affected station, preferably at the date of filing the application or immediately after the CRTC has issued a Notice of Public Hearing4. A copy of this letter and the postal or messenger receipt, as proof of delivery, shall be sent to the Department. The letter shall advise the licensee of the proposed change and shall emphasize that any representations the licensee may wish to make to the Department shall be submitted no later than thirty days after receipt of the engineering brief. Where the affected licensee offers an objection, the application may be returned by the Department. However, the Department reserves the right to make an independent decision concerning the disposition of the application. If no reply is received within the specified period, it will be assumed that there is no objection. Applicants proposing changes involving the offset or precision frequency control which result in additional capital and operating cost for existing stations, will be expected to cover these expenses. Both parties shall agree to maintain the offset or precision frequency control.
C-2.4.4 An applicant may accept interference within its Grade B contour from an existing assignment or from a future assignment on an existing allotment, provided that the engineering brief states that the applicant does not intend to serve the affected area. The extent of the interference area shall be calculated in accordance with Appendix 6 and shall be shown as a hatched area on the proposed station's coverage map.
In all of the cases described in C-2.1, problems can arise when changes to the Plan proposed by one applicant are not compatible with changes proposed by another applicant. It should be noted that incompatibilities can occur even when the proposed service areas are geographically well separated. The Department encourages applicants to cooperate in the search for an early solution to problems of incompatibility. In this regard, the Department will, without divulging the details of the proposed changes, make any incompatibility known to each of the applicants involved, urging their resolution prior to consideration of the applications by the CRTC.
C-2.6.1 Applications for the addition or for modifications to the Canadian Television Channel Allotment Plan may be made with, or independently from an application for an assignment. In either case, documentation in respect of the allotment change(s) shall be submitted.
C-2.6.2 A UHF assignment does not convey a right, real or implied, to a station licensee for continued protection of the licensee's class of station if the operating parameters fall into a lower class. In such cases, the assignment may be reduced to a lower class to facilitate additional allotments and assignments.
C-2.6.3 The Department may make changes to the Canadian Television Channel Allotment Plan which are independent of any application received. It will also take independent decisions, based on technical considerations, in its role as spectrum manager.top of page
All applications for new stations or for changes to an existing antenna or transmitter are required to show the service contours. For determining the service area of a broadcast station, two field strength contours are required. These are Grade A and Grade B contours which indicate the approximate extent of coverage over average terrain in the absence of interference from other television stations. Under actual conditions, the true coverage may vary greatly from these estimates because the terrain over any specific path is expected to be different from the average terrain on which the propagation curves are based.
C-3.2.1 Details of calculations and pertinent data for determining the field strength contours are to be presented in the engineering brief as follows:
- the calculation of the ERP;
- the sources of information (such as maps) for arriving at the HAATs;
- if in unique circumstances, such as locations in mountainous terrain, a method other than that outlined herein is used for determining the service area contours, detailed analysis with profile data should be included;
- a table shall be included as illustrated in the following example:
|Radial No.||Azimuth (deg.)||Depression angle||ERP (kW)||HAAT (metres)||Distance to Grade A Contour (kW)||Distance to Grade B Contour (km)|
Note: Depression angle values shall only be provided for UHF transmitting antennas.
C-3.2.2 The table should be based on eight radials taken at 45 intervals from true north to determine the HAATs and the EHAAT. For each radial, a profile graph shall be drawn extending outward from the proposed site for a distance of 16 km, even if the radial extends beyond the international border. The eight graphs should be plotted separately, on rectangular coordinate paper with the distance in kilometres as the abscissa and the elevation in metres above mean sea level as the ordinate. The graph should reflect the topography of the profile accurately.
C-3.2.3 The average elevation above sea level of the 13 km distance between 3 and 16 kilometres from the antenna site should be determined. This may be obtained by using a planimeter, by obtaining the median elevation (that exceeded for 50% of the distance) in sectors and averaging those values or by averaging a large number of equally spaced points. The number of points required and their spacing should allow an adequate representation of the terrain. Conflict situations will be resolved by the Department using the "point-to-point" prediction method.
C-3.2.4 The HAAT is defined as the height of the antenna centre of radiation above sea level minus the average terrain elevation calculated above.
C-3.2.5 Additional radials shall be included relative to the principal centre(s) to be served where desirable, and particularly, in cases of rough terrain. This is done even if the centre under consideration is more than 16 km from the antenna site. However, the additional radials should not be included in the determination of the station's EHAAT.
C-3.2.6 The following data is to be indicated for each radial graph:
- radial number and azimuth,
- height of antenna above sea level,
- average elevation of terrain for the particular radials,
- HAAT for the radial.
C-3.2.7 In predicting the distances to the field strength contours, the F(50,50) curves of Appendix 1 should be used. The F(50,50) curves represent the field strength at 9.1 m above ground which is exceeded for 50% of the time at 50% of the locations as measured in decibels above one microvolt per metre. The curves are based on an effective power of one kilowatt radiated from a half-wave dipole in free space, which produces an unattenuated field strength at one kilometre of about 107 dB above one microvolt per metre (221.8 millivolts per metre). To use the curves for other powers, the sliding scale associated with the curves should be used as the ordinate scale. This sliding scale is placed on the curves with the appropriate gradation for power on the horizontal 40 dB line. The right edge of this scale is placed in line with the appropriate antenna height gradations, the curves then become direct reading (in μV/m and in dB above 1 μV/m) for the selected ERP and HAAT. Where the intersecting point falls between the curves of equidistant points, linear interpolation shall be used.
C-3.3.1 Depression Angle
The depression angle is based on the difference in elevation of the antenna centre of radiation above the average terrain (HAAT) and the radio horizon. Assuming a smooth spherical earth with a radius of 8500 km, this depression angle can be determined by the following equation:
A = 0.0278 √H
where: A is the depression angle in degrees;
H is the height in metres of the transmitting antenna radiation centre above average terrain of the 3 to 16 km sector of the pertinent radial (HAAT).
C-3.3.2 Beam Tilt
High elevation antennas may be designed with beam tilt of the vertical radiation pattern, to ensure the coverage for the major communities near the antennas.
C-3.3.3 Grade A and Grade B Contours
The distances to the Grade A and Grade B contours shall be predicted by using the ERP in the plane of maximum radiation, the HAATs in the direction of the eight standard radials and the F(50,50) propagation curves. In the case of directional antennas, the ERP value in the direction of the eight standard radials should be used. The antenna vertical plane radiation pattern shall include the beam tilt.
For UHF transmitting antenna systems, the ERP at the depression angle (radio horizon) shall be used. However, in cases where the relative vertical pattern radiation value at the depression angle determined by the above formula in C-3.3.1 exceeds 90% of the maximum value of the radiation pattern in the vertical plane containing the pertinent radial, the maximum radiation shall be used.top of page
C-4.1 Where transmitter sites have been established, the actual coordinates of the transmitter sites shall be used as reference points. If a transmitter site has not been established, the community's reference coordinates (the coordinates of the centre of the city) shall be used unless the coordinates have been specified in the Allotment Plan.
C-4.2 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:
- 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
- determine the number of km per degree of latitude difference for the actual middle
latitude in (a) above;
LATK = 111.108 - 0.566cos (2LATM)
- determine the number of km per degree of longitude difference for the actual middle
latitude in (a) above;
LONG = 111.391 cos (LATM) - 0.095cos (3LATM)
determine the north-south distance in km;
LAT = LATK (LAT1 - LAT2)
determine the east-west distance in km;
LONG = LONGK (LONG1 - LONG2)
determine the distance between the reference points by the square root of the sum of the squares of the distances obtained,
LAT1 & LONG1 = co-ordinates of the first location in decimal degrees,
LAT2 & LONG2 = co-ordinates of the second location in decimal degrees,
LATM = middle latitude between points,
LATK = km per degree of latitude difference,
LONGK = km per degree of longitude difference,
LAT = north-south distance in km,
LONG = east-west distance in km, and
DIST = distance between two reference points in km.
In computing the above, sufficient decimal figures shall be used to determine the distance to the nearest km. The method for computing distances provides adequate accuracy for determining distances less than 350 km.
C-4.3 The azimuth or the bearing between true north and the radial connecting one reference point to the other, shall be calculated as follows:
- convert latitude and longitude into degrees and decimal parts of a degree;
- determine the arc length in degrees between the two reference locations;
d = arccos [sin (LAT2) sin (LAT1) + cos (LAT2) cos (LAT1) cos (LONG1 - LONG2)
calculate the bearing (if the second location is west of the initial location, subtract the result from 360; i.e., 360 - BEAR),
LAT1, LAT2, LONG1 & LONG2 are as specified in Section C-4.2;
d = arc length between locations in decimal degrees;
BEAR = angle between true north (0 degrees) and the connecting radial in decimal degrees.
In computing the above, sufficient decimal figures shall be used to determine the bearing to the nearest degree.top of page
Service requirements and constraints related to the siting of TV broadcasting stations may result in high signal strength levels in populated areas. Under these conditions, TV receivers are susceptible to interference from strong adjacent TV signals. Also, broadcast receivers are susceptible to immunity-type interference, and non-radio frequency equipment (radio-sensitive equipment) may be affected as well. To avoid or to minimize such problems, applicants are encouraged to locate their transmitters away from populated areas. Where this is unavoidable, it is necessary to assess the potential for interference.
The purpose of this subsection is to:
- identify the analysis required from applicants in determining interference potential,
- define the responsibilities of broadcasters in response to interference complaints,
- identify non-valid complaints of interference.
The requirements of this subsection apply to all applications for the issue or amendment of broadcasting certificates for TV broadcasting stations using primary frequency assignments.
In addition to the departmental requirements contained in Section B-2 pertaining to the engineering brief, interference analyses as per Sections C-5.3.1, C-5.3.2. C-5.3.3 and C-5.3.4 are required. In specific cases, the Department may accept a common assessment for co-located stations, multiplexed or otherwise.
For strong adjacent TV signal interference, applicants for a new station or for changes to an existing station shall submit an estimate of the population within the 120 dBu contour for channels 2 to 6 inclusive, or the 115 dBu contour for channels 7 to 69 inclusive.
The location of these contours shall be determined using the appropriate F(50,50) field strength curves and shown on a suitable map. For distances of less than 1.5 km, the free space formula should be utilized (refer to Section C-5.4.2).
Every attempt shall be made to keep the population within the above contours to a minimum. The Department reserves the right to request changes to the antenna site, to the antenna height, to the antenna itself, or to the radiated power to reduce the population within these high field strength contours.
C-5.3.2 If there is any population within the high field strength contours in C-5.3.1 above, determine if any part of the above contours would be located between the Grade A and Grade B contours of any Canadian stations, assigned or allotted, on the first and second adjacent channels for the VHF band, or on the first through fifth adjacent channels for the UHF band. For allotted but unassigned channels, maximum permissible parameters are to be assumed.
C-5.3.3 If there is any population within the overlap areas identified in C-5.3.2 above, then the possibility of interference exists and a list of the Canadian assignments and allotments identified in C-5.3.2 above shall be submitted to Industry Canada:
Broadcast receivers and their associated equipment, as well as non-radio equipment (radio-sensitive devices), are expected to operate properly within field strengths lower that those indicated in the Department's Electromagnetic Compatibility Advisory Bulletin 2 (EMCAB-2). The Department uses EMCAB-2 to make determinations on interference or immunity cases.
C-5.4.1 The antenna radiation patterns, vertical and horizontal (if antenna is directional), are normally supplied by the antenna manufacturer. In predicting high field strength contours, the ERP should be based on the appropriate antenna vertical plane radiation pattern for the azimuthal direction concerned.
F = 137 + 10log(ERP) - 20log(d)
F: is the field strength in dBu (dB above one microvolt per metre);
ERP: is the effective radiated power in Watts at the pertinent depression angle;
d: is the slant distance (in metres) between the centre of radiation of the antenna and the receiving location.
C-5.4.3 For distances between 1.5 and 4 kilometres, the field strength should be determined from the F(50,50) curves. Use the height of the antenna radiation centre with respect to the location under consideration.
C-5.4.4 For distances beyond 4 kilometres, the field strength should be determined from the F(50,50) curves using the pertinent HAAT.
C-5.4.5 Whenever F(50,50) curves are being used, the antenna height and the distance from the tower should be used to determine the depression angle from Figure 3 of Appendix 1. The ERP for that direction shall be determined by the depression angle and the vertical pattern information of the antenna. For the horizontal directional pattern, the power shall also be adjusted according to the azimuth selected.
C-5.4.6 Close-in field strength prediction may involve nulls in the vertical radiation pattern which shall be taken into consideration. The distances (di) along the ground where the field strength due to a vertical pattern null is at minimum, can be calculated by the following relationship:
A and Θi are the beam tilt angle and the angles corresponding to the different nulls in the vertical pattern respectively (both in degrees).
H = height (in metres) to radiation centre of antenna;
di = distances in metres along ground.
For values of Θi + A = 10°:
This general relationship is plotted for various antenna heights as shown in Figure 3 of Appendix 1.
The broadcaster will accept responsibility to:
(A) In the case of strong adjacent channel interference
- remedy valid complaints of interference to TV receivers within the 120 dBu contour (channels 2-6 inclusive) or the 115 dBu contour (channels 7-69 inclusive) of the station (refer to Section C-5.6 for list of complaints judged not valid by the Department), and
- provide technical advice to complainants, located between the 120 dBu contour (channels 2-6 inclusive) or the 115 dBu contour (channels 7-69 inclusive) and the service contours of the station, concerning appropriate action to resolve interference problems attributed to the station, and
- keep the appropriate district office of the Department fully informed of all complaints received and action taken.
(B) In the case of immunity-type interference
The broadcasters will be responsible of solving immunity-type interference when applicable, i.e. for valid complaints.
The guidelines on resolving immunity issues relating to radio-sensitive equipment, are outlined in Industry Canada's Client Procedures Circular 3-14-01, Determinations of Harmful Interference with respect to Radio-Sensitive Equipment. This CPC can also be used as a guide for resolving immunity-related interference to broadcast receivers and associated equipment.
The following is the list of complaints judged not valid by the Department and for which the broadcaster is not responsible for remedial action:
- where the complaint is attributed to the use of a malfunctioning or mistuned receiver or an improperly installed or defective antenna system;
- where the complaint is attributed to the desired signal being received at a location outside the coverage area of the station;
- where the complaint is attributed to the desired signal not being favourably received because of adverse local propagation conditions or building penetration losses;
- where the complaint involves the reception of signals originating from outside of Canada;
- where the complaint involves a high gain receiving antenna and/or an antenna booster amplifier intended for reception of distant stations which, as a consequence, overloads the receiver or creates intermodulation in the amplifier output;
- where the complaint is attributed to the reception of a first-adjacent TV channel station which, under normal allotment criteria, is not fully protected from interference;
- where the complaint is attributed to the reception of a second-adjacent TV channel station which has less than Grade A signal strength, providing the applicant's site has been chosen to minimize this problem (typical receivers cannot reject a strong local signal when tuned to receive a weak adjacent channel station);
- where the complaint is attributed to immunity-type interference to broadcast receivers and associated equipment located in an area where the measured field strength does not exceed the 125 dBμV/m;
- where the complaint is attributed to immunity-type interference to radio sensitive equipment (RSE) that is located in an area where the measured field strength does not exceed the 130 dBμV/m;
- any other complaint which, in the judgement of the Department, is considered not valid.
C-6. Radio Frequency (RF) Exposure, Land-Use and Public Consultations, Immunity-Related Interference, Environmental Assessment and Transport/NAVCANADA Safety-Related Issuestop of page
C-7.1.1 The assignment of a frequency that is harmonically related to the frequency of an existing station in the same area, is very involved from the standpoint of protecting the station on the higher frequency, particularly where different powers and radiation patterns have to be taken into account. Another complicating factor relating to the adequacy of protection of the higher frequency station is the possibility of the internal generation of this type of interference within receivers.
C-7.1.2 Where possible, assignments of harmonically related frequencies in the protected coverage area of an existing station should be avoided. However, if such assignments are required, an analysis shall be submitted in the engineering brief showing that a particular operation is feasible.top of page
The transmitter site for a TV station shall be selected to provide an adequate signal to the immediate and surrounding areas. This often results in a site located in close proximity to other antenna towers and metallic structures. As part of the site selection process, a prediction of the degree of impairment of the television signal due to ghost images resulting from such structures shall be made. In addition, where an antenna tower is proposed in close proximity to an existing TV station, a prediction of the degree of impairment to that existing station is also required.
The purpose of this section is to establish acceptable picture grades (minimum standard of picture quality) in the presence of ghosts for the various types of TV services. These standards were developed from a study on subjective impairment of television signals due to ghosting interference.
A report entitled Report on Predicting Television Ghosting Interference and Picture Quality (TB-5), has been prepared by Industry Canada.
The method has been developed for both triangular and square section towers and is valid for specific frequency ranges and delay ranges. Use of the method of computation developed by the Department is recommended. The use by consultants of another method may be accepted by the Department, but justification for its choice shall be provided.
This procedure shall apply to primary and secondary television stations.
A station shall provide the required grade of service in all directions where there are populated areas including the areas where there may be imminent urban development. Exceptions may be made for stations where the ghosting occurs in mountainous terrain or over water.
C-8.4.2 Ghost Interference Analysis
All antenna towers and other metallic structures, situated within a radius of 500 metres from the proposed transmitter site, from which ghosting interference to the service area could result, should be analyzed. If the reflecting structure is substantially higher than the antenna's radiation centre and the separation distance is greater than 500 metres, it is advisable that a study be carried out. When a non-directional antenna is used by a station, worst case reflecting structures are those that are located directly in line with the principal service area and behind the transmitting antenna; accordingly, locations for the analysis should be selected in that direction.
The above-mentioned 500 metres separation distance is only a guideline and should be applied logically according to the actual situation.
In a case where the consultants for a proposed and for an existing station disagree over the level of potential ghost interference in a common service area, they will be asked to submit their calculations to Industry Canada. If this question has not been resolved, the Department will not approve the incoming station without a commitment, in writing, that the construction of the tower would be monitored jointly by the Department and the applicant and, if objectionable ghosting is created, the tower height will be reduced to permit the existing stations to maintain the picture grade required in Section C-7.6 below.
The Figure of Appendix 7 shows the relationship of ghost delay to ghost level for given picture impairment grades based on a 'typical' sample of TV viewers.
The subjective effects of very short time delayed ghosts appear to be more severe than the curves would indicate in the range 0-500 nano-seconds. Brief tests and theoretical calculations indicate that significant colour saturation and hue changes can be anticipated where the ghost delay is approximately one half period, plus an integer number of periods of the colour subcarrier frequency. Delays in this range result in phase and amplitude modulation of the colour burst and chrominance signal. This aspect of ghost impairment is not covered under this procedure.
The 5-point scale system used in CCIR Recommendation 500-1 is selected as the basic scale to provide an adequate assessment of picture quality.
C-8.6.1 Television Stations on Allotted Channels
Minimum Standard: - Grade 4.0 or better for population within the service contours.
C-8.6.2 Low-Power Television Stations
Recommended Minimum Standard: - Grade 3.5 or better for population within the service contour.top of page
It shall be the standard to employ horizontal polarization. However, circular or elliptical polarization may be employed if desired, in which case clockwise (right hand) rotation, as defined in the IEEE Standard Definition 42A65-3E2, and transmission of the horizontal and vertical components in time and space quadrature shall be used. For either non-directional or directional antennas, the licensed effective radiated power of the vertically polarized component may not exceed the licensed effective radiated power of the horizontally polarized component. For directional antennas, the maximum effective radiated power of the vertically polarized component shall not exceed the maximum effective radiated power of the horizontally polarized component in any specified horizontal or vertical direction. Slant polarization may not be used.
C-9.2.1 Directional antennas may be used by stations operating on unlimited allotments, but their use shall not prevent future increases up to the maximum parameters for VHF and UHF channels. Directional antennas may also be used by stations occupying or proposing the use of limited allotments to render protection to co-channel and adjacent channel stations.
C-9.2.2 For protection purposes, the ratio of maximum to minimum fields of directional antenna system shall not be greater than 20 dB except where signal reflections due to local terrain will present a reception problem or where other circumstances such as a large body of water exist. The radiation from a directional antenna shall not vary from the notified radiation pattern by more than ± 2 dB. Where limitations are involved, the radiation in the direction(s) of protection shall not exceed the limitation. For antenna patterns not meeting this tolerance, the radiation shall be reduced accordingly.
C-9.2.3 Antennas designed with beam tilt of the vertical radiation characteristic, for the purpose of meeting protection requirements, will not be approved. However, the Department would be prepared to consider as special cases, proposals involving beam tilt designed to improve television service close to the antenna, provided that such proposals are supported in the engineering brief by a technical justification.
C-9.2.4 For stations using high gain UHF-TV antennas, it should be noted that the physical rigidity of the antenna and supporting structure becomes a factor in maintaining a reliable signal to the service areas. For antennas with a vertical power gain in excess of 25, particular attention shall be given to the mechanical stability of the antenna installation, and to the location of the vertical pattern minima in relation to the service area.top of page
C-10.1 The signal analysis for a television rebroadcasting station using off-air pick-up or a combination of off-air pick-up and microwave link is to include the following:
- detailed information on the expected field strength of the master station at the proposed receiving location for the rebroadcasting station. This should consist of the measurement data, including copies of charts of actual field strengths recorded over a period of at least thirty days. However, if such measurements are not practicable, the adequacy of the received signal at the point of reception shall be established by calculation. The method used in the analysis shall be outlined in detail;
- results of measurements (which shall be conducted at the proposed receiving location) to determine the presence and levels of extraneous noise, such as interference from electrical equipment, power lines, etc. In this connection, an interference-free condition should not be assumed on the basis of the remoteness of the pick-up station from the usual interference sources. Moreover, the possibility of co-channel interference at the pick-up antenna site shall be considered in the analysis; and
- an undertaking that, in the event the off-air received signal proves to be inadequate in practice, the applicant would provide for microwave, or appropriate alternate facilities, at the applicant's own expense, to overcome the deficiency.
C-10.2 In some cases, the new channel assignment is technically related to the channel used for the off-air reception program feed of an existing rebroadcasting station. When such an assignment precludes the continued use of the off-air reception program feed, an alternate method of program feed shall be provided. The costs of any change that is required to accomplish this objective shall be borne by the licensee of the existing rebroadcasting station that has in the previous years benefited from the direct off-air reception.top of page
C-11.1 TV station transmitters shall be so located to serve the principal centre to which the channel is assigned and to ensure the overall effectiveness of the Allotment Plan. A minimum field strength that corresponds to the Grade A contour is required for satisfactory service to principal target centres5. In secondary target centres, where the reception is achieved by an outdoor receiving antenna, a minimum field strength corresponding to the Grade B contour shall be provided.top of page
Frequency bands 150-174 MHz, 450-470 MHz and 806-890 MHz are allocated to land mobile (LM) services. These are adjacent to VHF and UHF channels 7 (174-180 MHz), 14 (470-476 MHz) and 69 (800-806 MHz). Television assignments with relatively high power on the above channels may cause interference6 to land mobile (LM) base receivers which operate on frequencies near the edge of the television allocations. Conversely, land mobile transmitters on assigned frequencies near the edge of the channel and within the service contour of the television undertaking may cause interference to TV reception.
Consequently, any application proposing the use of TV Channels 7, 14, or 69 may require special analysis and negotiations as part of the technical submission. Appendix 11 provides guidelines outlining the technical criteria that should be applied to minimize or eliminate mutual interference between television and adjacent-band land-mobile services.
The data on LM assignments is available from Industry Canada on a case-by-case basis.
Case of certain Channel 14 Allotments
Concerning the protection of LM base stations operating in the bands adjacent to TV channel 14, when the allotments at Ottawa, Ontario and Sherbrooke, Quebec are assigned, these allotments necessitate the use of the extra filtering of spurious television emissions. Conversely, these two allotments must be protected by the LM base stations.
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