BPR-10 — Application Procedures and Rules for Digital Television (DTV) Undertakings (sf10156)

Annex D – Determination of Protected Area

D1. Introduction

Assessment of the protected area using a terrain-sensitive model is performed only within the noise-limited bounding contour.

D2. Determination of Noise-Limited Bounding Contour

The noise-limited bounding contour is computed using the site location, maximum ERP , Heights Above Average Terrain ( HAATs ) and the horizontal antenna radiation pattern. The distance to the bounding contour is determined, in each of the 360 degree compass directions, by using a combination of actual and linear interpolated HAAT and antenna radiation data. HAAT is determined directly from the terrain elevation database every 10 degrees, starting from true north, and by linear interpolation for radials in between. Directional antenna tabulations provide actual relative field every 10 degrees starting from true north. Linear interpolation is used to derive relative field values in between. Individual relative field values are squared and multiplied by the maximum ERP to find the ERP along a specific azimuth. In predicting the distance to the bounding contours, the F(50,90) statistics should be used to calculate the field strengths (refer to Annex F).

D3. Determination of Protected Area

The location of the noise-limited bounding contour is based on propagation curves in Annex F. The true television service availability may vary from these estimates because the terrain over any specific path is expected to be different from the type of terrain on which the propagation curves are based. Therefore, a terrain-sensitive method, with the appropriate time and location statistics, are to be used to determine the protected area.

D4. Bounding Contour Tables

The bounding contour tables for DTV should contain information as illustrated in the following example:

Table D1: DTV Contour Table
Radial
No.
Azimuth
(degrees)
ERP
(kW)
HAAT
(m)
Distance to
Digital Urban
Contour
( km )@ 61  dBμV/m
Distance to
Noise-limited
Bounding Contour
( km ) @ 41 dBμV/m
1 0 20 190 38 62
2 45 19 207 39 63
3 90 18 232 40 64
4 135 17 335 44 71
5 180 17 281 42 67
6 225 20 200 39 62
7 270 17 311 43 69
8 315 17 296 43 68

Table D1 should be based on eight radials taken at 45 degree intervals from true north to determine the HAATs.

The bounding contour table for LPDTV should contain information as illustrated in the following example:

Table D2: LPDTV Contour Table
Radial
No.
Azimuth
(degrees)
ERP
(W)
HAAT
(m)
Distance to
Noise-limited
Bounding Contour
( km ) @ 51 dBμV/m
1 0 500 28 14
2 90 2000 30 19
3 180 1000 25 17
4 270 800 27 16

Table D2 should be based on four radials taken at 90 degree intervals from true north to determine the HAATs.


Annex E — Interference Analysis

E1. Identification of Potentially Interfering Assignments and Allotments

Assignments and allotments that may be a source of interference are identified as a function of distance and channel relationships. Only those assignments or allotments whose distance from the protected station is less than the value given in Table E1 are considered as potential sources of interference.

Table E1 — Culling of Undesired Assignments or Allotments
Interfering Channel Offset Relative to Desired Channel Maximum Distance from Protected Station to Interfering Station (km)
−1 200
0 450
+1 200

E2. Short-Spacing Determination

Depending on the relative strength of the two stations involved, separation distances are based on the protection of the contour on the near side or on the far side. The required distance between adjacent channels is based on the near side value, whereas the required distance between co-channels may be based either on the near side or on the far side, whichever gives the largest distance. Both cases are calculated at the edge of a circle with radius distP . The value of distP is computed using the propagation statistics F(50,90) given in Annex F, the Desired (D) field strength as specified in Table 1 of Section 2.1, the EHAAT and the maximum ERP of the desired station. Then the Undesired (UNS and UFS) field strengths are computed using the following formulas:

UNS = D – D/Uiv + FB, in the near-side case and,

UFS = D – D/Uiv, in the far-side case.

where:
FB is the front-to-back ratio of the receive antenna in dB , given in Table E2 of Section E3;
 
D/Uiv in dB is the system input voltage protection ratio as given in tables E4 and E5 of Section E4;
 
D is the desired field strength in dB and U is the undesired field strength in dB ;
 
UNS is the undesired field strength in dB for the near-side;
 
UFS is the undesired field strength in dB for the far-side.

 

Once the undesired field strength values are computed ( UNS and UFS ), one can then use the undesired station's ERP and EHAAT , together with the F(50,10) propagation statistics given in Annex F, to calculate the minimum required distances between the undesired station and the edges of the circle ( distUNS and distUFS ).

 

In order to compute the required distance to protect the desired station, the radius of the previously defined circle (distP) is then added to distUNS in the near-side case or subtracted from distUFS in the far-side case:

distREQns = 1.12 ×(distP + distUNS) in the near-side case

distREQfs = 1.12 ×(distUFS – distP) in the far-side case in the far-side case

where:
distP:
is the radius of the circle computed using the propagation statistics F(50,90) given in Annex F; the Desired (D) field strength as specified in Table 1 of Section 2.1; the EHAAT and the maximum ERP of the desired station;
 
distUNS :
is the minimum required distance between the undesired station and the near-side edge of the circle, computed with the F(50,10) propagation statistics; and
 
distUFS :
is the minimum required distance between the undesired station and the far-side edge of the circle, computed with the F(50,10) propagation statistics.

 

Once the far-side distance and the near-side distance values are computed using the equations in this section, one should retain the maximum of the two as the required separation distance to protect the desired station.

 

As the desired station also needs to protect the undesired station from interference, it is also necessary to calculate the required distance in order to protect the undesired station. The same procedure is carried out using the former desired station as the current undesired one and the former undesired station as the current desired one. The final required separation distance is the maximum of the required distance to protect the desired station and the required distance to protect the undesired station.

Two stations are considered to be short-spaced if the distance between the stations is less than the required separation distance calculated. As a result, a more detailed interference analysis is needed to determine the interference using the method in Section E6 of this annex.

E3. Antenna Patterns

E3.1 Receiving Antenna Pattern

The receiving antenna is assumed to have a directional gain pattern, which tends to discriminate against off-axis undesired stations. This pattern is a planning factor affecting interference. The attenuation, in dB, provided by the assumed receiving pattern is:

For θ < 90 degrees:

  • Low VHF: MAX (–10, 20log(cos4(θ)) )
  • High VHF: MAX(–12, 20log(cos4(θ)) )
  • UHF: MAX (–14, 20log(cos4(θ)) )

For θ ≥ 90 degrees, the attenuation is at its maximum value as in Table E2 below.

Where θ is the angle between the lines joining the desired and undesired stations to the reception point.

When the undesired station is far off-axis, the maximum discrimination given by the front-to-back ratio is attained.

Table E2 — Front-to-Back Ratios Assumed for Receiving Antennas
Front-to-Back Ratios (dB)
Low VHF High VHF UHF
10 12 14
Figure E1 — Receiving Antenna Pattern
Figure E1 — Receiving Antenna Pattern
Description of figure E1

The Figure E1 of Annex E is a graphic with three curves showing the receiving antenna pattern for the three frequency bands: Low VHF, High VHF and UHF. The vertical axis is the attenuation in dB and runs from −16 to 0 dB. The horizontal axis is the angle in degrees and runs from 0 to 90 degrees. The curves follow the values in the table below:

Annex E — Figure E1 — Receiving Antenna Pattern
Angle in degrees Attenuation for the Low VHF Band in dB Attenuation for the High VHF Band in dB Attenuation for the UHF Band in dB
0 0 0 0
5 −0.13 −0.13 −0.13
10 −0.53 −0.53 −0.53
15 −1.2 −1.2 −1.2
20 −2.16 −2.16 −2.16
25 −3.42 −3.42 −3.42
30 −5 −5 −5
35 −6.93 −6.93 −6.93
40 −9.26 −9.26 −9.26
41 −9.78 −9.78 −9.78
42 −10 −10.31 −10.31
43 −10 −10.87 −10.87
44 −10 −11.45 −11.45
45 −10 −12 −12.04
46 −10 −12 −12.66
47 −10 −12 −13.3
48 −10 −12 −13.96
49 −10 −12 −14
50 −10 −12 −14
60 −10 −12 −14
70 −10 −12 −14
80 −10 −12 −14
90 −10 −12 −14

E3.2 Transmitting Antenna Pattern

The transmitting antenna is assumed to have a vertical gain pattern as per Table E3. The gain between 90 degrees above the horizontal and 0.75 degrees below the horizontal is 1.00.

Table E3 — Vertical Patterns for Transmitting Antennas
Angle
(degrees)
Gain in Vertical Plane (relative field strength)
Low VHF
Analog and
DTV
High VHF UHF
Analog DTV Analog DTV
0.75 1.000 1.000 1.000 1.000 1.000
1.50 1.000 0.950 0.970 0.740 0.880
2.00 0.990 0.860 0.940 0.520 0.690
2.50 0.980 0.730 0.890 0.330 0.460
3.00 0.970 0.600 0.820 0.220 0.260
3.50 0.950 0.470 0.730 0.170 0.235
4.00 0.930 0.370 0.650 0.150 0.210
5.00 0.880 0.370 0.470 0.130 0.200
6.00 0.820 0.370 0.330 0.110 0.150
7.00 0.740 0.370 0.280 0.110 0.150
8.00 0.637 0.310 0.280 0.110 0.150
9.00 0.570 0.220 0.280 0.110 0.150
10.00 0.480 0.170 0.250 0.110 0.150
Figure E2 — DTV Transmitting Antenna Pattern (Vertical)
DTV Transmitting Antenna Pattern (Vertical)
Description of Figure E2

The second figure of Annex E is a graphic with three curves showing the DTV transmitting antenna vertical pattern for the three frequency bands:  Low VHF, High VHF and UHF. The vertical axis is the relative gain and runs from 0 to 1. The horizontal axis is the angle in degrees and runs from 0 to 10 degrees. The curves follow the values in the table below:

Annex E — Figure E2 — DTV Transmitting Antenna Pattern (Vertical)
Angle (degrees) Vertical gain in the Low VHF band Vertical gain in the High VHF band Vertical gain in the UHF band
0 1 1 1
0.75 1 1 1
1.5 1 0.97 0.88
2 0.99 0.94 0.69
2.5 0.98 0.89 0.46
3 0.97 0.82 0.26
3.5 0.95 0.73 0.235
4 0.93 0.65 0.21
5 0.88 0.47 0.2
6 0.82 0.33 0.15
7 0.74 0.28 0.15
8 0.637 0.28 0.15
9 0.57 0.28 0.15
10 0.48 0.25 0.15

 

Figure E3 — NTSC Transmitting Antenna Pattern (Vertical)
NTSC Transmitting Antenna Pattern (Vertical)
Description of Figure E3

The third figure of Annex E is a graphic with three curves showing the NTSC transmitting antenna vertical pattern for the three frequency bands:  Low VHF, High VHF and UHF. The vertical axis is the relative gain and runs from 0 to 1. The horizontal axis is the angle in degrees and runs from 0 to 10 degrees. The curves follow the values in the table below:

Annex E — Figure E3 — NTSC Transmitting Antenna Pattern (Vertical)
Angle (degrees) Vertical gain in the Low VHF band Vertical gain in the High VHF band Vertical gain in the UHF band
0 1 1 1
0.75 1 1 1
1.5 1 0.95 0.74
2 0.99 0.86 0.52
2.5 0.98 0.73 0.33
3 0.97 0.6 0.22
3.5 0.95 0.47 0.17
4 0.93 0.37 0.15
5 0.88 0.37 0.13
6 0.82 0.37 0.11
7 0.74 0.37 0.11
8 0.637 0.31 0.11
9 0.57 0.22 0.11
10 0.48 0.17 0.11

 

E4. Desired-to-Undesired (D/U) Input Voltage Ratios

E4.1 DTV

Criteria for the ratio of desired-to-undesired input voltage are summarized in the following table.

Table E4: Interference Criteria for Co-channel and Adjacent Channel Assignments and Allotments
Interfering Channel Offset Relative to Protected Channel D/U Ratio (dB)
–1 (Lower Adjacent) –28
0 (Co-Channel) +15*
+1 (Upper Adjacent) –26

*  The D/U ratio for co-channel interference in tables E4 and E5 is only valid at locations where the signal-to-noise (S/N) ratio is 28 dB or greater. At the noise-limited bounding contour, where the S/N ratio is 16 dB, the co-channel D/U ratio is 23 dB. At locations where the S/N ratio is greater than 16 dB, but less than 28 dB, D/U values for co-channel interference are as follows:

D/U = 15 + 10log10[1.0/(1.0–10–x/10)], where x = S/N – 15.19 dB

The quantity “x” is the amount by which the desired S/N ratio exceeds the minimum required for DTV reception.

This adjustment is made to the co-channel D/U ratios to account for degradation due to increased noise when the S/N ratio is near the limiting value for reception.

E4.2 LPDTV

As LPDTV assignments may operate with one of three different emission masks, first-adjacent protection ratios should be adjusted accordingly. These D/U ratios are applied to LPDTV assignments for all their respective first-adjacent protection requirements.

Table E5: Co-channel and First-Adjacent Interference Criteria for LPDTV Assignments
Interfering Channel Offset Relative to Protected Channel D/U Ratio (dB)
–1 (Lower Adjacent)
+1 (Upper Adjacent)
for Simple Mask
–7
–1 (Lower Adjacent)
+1 (Upper Adjacent)
for Stringent Mask
–12
–1 (Lower Adjacent)
+1 (Upper Adjacent)
for Full Mask
-28
-26
0 (Co-Channel)  +15*

* see Table E4

E4.3 DTV and LPDTV

Co-channel and first-adjacent interference criteria for protecting DTV from LPDTV are summarized in the following table.

Table E6:  Interference Criteria for Co-channel and Adjacent Channel Assignments and Allotments
Interfering Channel Offset Relative to Protected Channel D/U Ratio (dB)
–1 (Lower Adjacent)
+1 (Upper Adjacent)
for Simple Mask
–7
–1 (Lower Adjacent)
+1 (Upper Adjacent)
for Stringent Mask
–12
–1 (Lower Adjacent)
+1 (Upper Adjacent)
for Full Mask
-28
-26
0 (Co-Channel)  +15*

* see Table E4

Co-channel and first-adjacent interference criteria for calculating interference from DTV to LPDTV are summarized in the following table.

Table E7: Interference Criteria for Co-channel and Adjacent Channel Assignments and Allotments
Interfering Channel Offset Relative to Protected Channel D/U Ratio (dB)
–1 (Lower Adjacent) –28
0 (Co-Channel) +15*
+1 (Upper Adjacent) –26
* see Table E4

E5. D/U Field Strength Ratio

The desired-to-undesired (D/U) field strength ratio in dB can be derived from the ratio of tables E4 and E5 and from the directional gain pattern (GP) in dB of the receiving antenna as described in Section E3.

D/U (Field Strength) = D/U (Input Voltage) – |GP|

The required D/U field strength ratio at the edge of the noise-limited bounding contour on the near side can be calculated by using the front-to-back (FB) ratio in dB in Table E2 of Section E3.

D/U (Field Strength) = D/U (Input Voltage) – FB

Therefore, the DTV required D/U field strength ratios at the edge of the noise-limited bounding contour on the near side are:

Table E8: DTV Required D/U Field Strength Ratios at the Edge of the Noise-limited Bounding Contour on the Near Side
  Required D/U field strength ratio (dB)
Interfering Channel Offset Relative to Protected Channel Low VHF High VHF UHF
–1 (Lower Adjacent) –38 –40 –42
0 (Co-Channel) 13 11 9
+1 (Upper Adjacent) –36 –38 –40

E6. Interference Calculations

The interference analysis should be based on a terrain-sensitive method, such as the Longley-Rice model, using the appropriate time and location statistics. The area within a station’s noise-limited bounding contour is normally divided into square cells. The coordinates of the census blocks inside each cell are retrieved along with the population of each block. The census blocks should be based on the latest available Statistics Canada census data. From this information, the total population and the coordinates of the cell centroid are determined for each cell. It is suggested that a square cell size of 2 km or less on a side be used.

First, the desired field strength is evaluated for each cell within the noise-limited bounding contour. A radio path between the desired DTV transmitter and the population centroid of each cell is examined using a terrain-sensitive propagation model applied for the median situations for 50% of locations, 90% of the time at a receiver antenna height of 10 m above ground. The interference analysis retains only those population cells that have been determined to have desired field strength above the threshold for reception given in Tables 1 and 2 of Section 2. Radio paths between undesired DTV transmitters and the point representing protected population are examined. For each such radio path, a terrain-sensitive propagation model is applied for median situations for 50% of locations, 10% of the time at a receiver antenna height of 10 m above ground. The terrain elevations data used in the analysis should be based on Canadian Digital Elevation Data (CDED) or United States Geological Survey (USGS). A protected population cell being examined is counted as having interference if the ratio of desired-to-undesired input voltage from each interference source is less than the critical minimum values given in Section E4 of this Annex. It should be noted that the comparison is made after applying the discrimination effect of the receiving antenna.

E7. Calculation of Population Service Loss

The population service loss caused by the new proposal is calculated as:

\[ \%   Population   Service   Loss = \frac{A}{B} × 100\% \]

where:
A = the population within the protected area predicted to receive interference from only the new DTV proposal, and
 
B = the population within the protected area