Adjacent Channel Interference Text
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Note that all values in this example are for demonstration purposes only. You should determine appropriate settings for your application.
The “Details” output of the Adjacent Channel Interference study is shown below. Click each link to see a description of the information:
Task 0003633 20111129 1307 ACI Study
Adjacent Channel Interference Study
Task 0003623 20111129 1105 LR TIL CasRck Test D
DEMO Castle Rock Test Facility 100MHz
Undesired [Interfering] Signal(s)
Task 0003624 20111129 1105 LR TIL Chytn Test U1
DEMO Cheyenne Mountain Test Facility 107MHz
Task 0003625 20111129 1105 LR TIL Centennial Test U2
TRAINING Centennial Site 131MHz
0003624 -7.03 20111129 1105 LR TIL Chytn Test U1 INTERFERER
0003625 -11.62 20111129 1105 LR TIL Centennial Test U2 INTERFERER
0003624 20111129 1105 LR TIL Chytn Test U1
Azim toward Desired: 44.97 (22771.32m)
Azim toward Undesired: 164.29 (61877.91m)
Undesired is 4.98dB down in the Azimuth pattern
Undesired is 1.87dB down in the Elevation pattern
R0003624 U: -7.03dBu -88.91dBm 1.285E-09mW
0003625 20111129 1105 LR TIL Centennial Test U2
Azim toward Desired: 44.97 (22771.32m)
Azim toward Undesired: 41.23 (39912.65m)
Undesired is 0.00dB down in the Azimuth pattern
Elev toward Desired: -1.30
Elev toward Undesired: -3.67
Undesired is 0.89dB down in the Elevation pattern
R0003625 U: -11.62dBu -87.55dBm 1.759E-09mW
0003623 -44.00dBu 20111129 1105 LR TIL CasRck Test D DESIRED SIGNAL -
Undesired Power sum by freq offset
N+1 1.285E-09mW -88.91dBm (-65.00 D/U)
N+5 1.759E-09mW -87.55dBm (-65.00 D/U)
U (sum): 3.044E-09mW (9.626E-16mW,-150.17dBm)
39 16 57.16 N 105 03 12.87 W (39.28254313 -105.0535761946) -44.0000
Task 0003633 20111129 1307 ACI Study
This is the Task ID and Descriptoin for the Adjacent Channel Interference study
Desired Signal
Task 0003623 20111129 1105 LR TIL CasRck Test D
DEMO Castle Rock Test Facility 100MHz
This is the Area Coverage study (Tile or Target Points) used for the desired signal.
Undesired [Interfering] Signal(s)
Task 0003624 20111129 1105 LR TIL Chytn Test U1
DEMO Cheyenne Mountain Test Facility 107MHz
Task 0003625 20111129 1105 LR TIL Centennial Test U2
TRAINING Centennial Site 131MHz
These are one or more Tasks that are examined for interfereing, or Undesired, signals. The Adjacent Channel Interference Setup program uses the Desired Task specifications and one or more “Undesired” Fixed Facility records to create and compute the Undesired Tasks. You do not need to setup the Undesired Tasks separately. They are created automatically using each of the selected Fixed Facilities and the identical Tile or Target Point Coverage Area defined for the Desired Task.
0003624 -7.03 20111129 1105 LR TIL Chytn Test U1 INTERFERER
0003625 -11.62 20111129 1105 LR TIL Centennial Test U2 INTERFERER
After the header information defining the Desired and Undesired Tasks, each computed point in the Tile or Target Point study is described in detail (assuming the Text Output “Details” option is selected when you set up the Adjacent Channel Interference study).
For each point, the Task ID is shown, followed by the Undesired field strength (in dBu) at the location, and the Task Description of each Undesired study. This information is repeated for each point for convenience of examining points in the study.
0003624 20111129 1105 LR TIL Chytn Test U1
Azim toward Desired: 44.97 (22771.32m)
Azim toward Undesired: 164.29 (61877.91m)
Undesired is 4.98dB down in the Azimuth pattern
Elev toward Desired: -1.30
Elev toward Undesired: -2.37
Undesired is 1.87dB down in the Elevation pattern
R0003624 U: -7.03dBu -88.91dBm 1.285E-09mW
For each Undesired signal at each Tile or Target Point locatoin, the off-axis gain of the receiver location directional antenna (if specified in the Adjacent Channel Interference Setup program) is computed.
If the setup includes a receiver directional antenna, the assumption is that the antenna is correctly aligned in the horizontal (azimuth) and vertical (elevation) planes, with the major lobe pointing from the receiver location toward the Desired signal source. This means that the antenna orientation will be different for every Tile or Target Point location. The program computes the antenna orientation based on the receiver antenna height above ground and the ground location at each location, as well as the transmit antenna height for the Desired study.
Then for each of the Undesired signals, the azimuth and elevation angles from the receiver location to the Undesired source are computed and the gain reduction from the major lobe gain on that off-axis direction is computed. The Undesired field strength is reduced by that amount (computed individually for each Undesired signal).
R0003624 U: -7.03dBu -88.91dBm 1.285E-09mW
The field strength (in dBu, which has been adjusted for the receiver antenna orientation) for each Undesired signal is computed to a receiver power input (in dBm) and the corresponding power level. The conversion from field to power includes the effect of the frequency of the Undesired signal.
The current version does NOT include an adjustment for the fact that receiver transmission line losses may be different for different frequencies of the Undesired signals.
0003623 -44.00dBu 20111129 1105 LR TIL CasRck Test D DESIRED SIGNAL -
-84.00dBm (Min)
The Task ID, received field strength (in dBu), and the Task Descriptoin (with the added tag of “DESIRED SIGNAL” is listed for the Desired signal at the location.
The Desired field strength is converted to the receiver input power level in dBm. The receiver directional antenna (if any) is assumed to be correctly aligned toward the Desired study Fixed Facility. The Mobile Facility record used to setup the Desired Task in HDCoverage should include the major lobe gain of the antenna.
Undesired Power sum by freq offset
N+1 1.285E-09mW -88.91dBm (-65.00 D/U)
N+5 1.759E-09mW -87.55dBm (-65.00 D/U)
For each of the Receiver Rejection specification offset values, all signals in that offset range are summed together. The dBm value for each Undesired signal is converted to a power value (in mW) to be added together, then the sum of the power for each frequency offset is added together. The sum of power is then converted back to a dBm value shown in the output, along with the required D/U ratio (Desired to Undesired) in dBm for that offset.
U (sum): 3.044E-09mW (9.626E-16mW,-150.17dBm) [flag]
The cumulative power sum of all the Undesired signals is shown (in mW). This value is computed by simply adding together all the Undesired power levels for all the frequency offset values.
Also shown is an adjusted cumulative power sum, which includes adding the required D/U value for each offset to the sum of powers for that offset, following Obregon, et. al., eq.5. That adjusted cumulative power sum is converted to a dBm value.
That dBm value is compared to the Desired signal dBm value at the location. If the Desired signal is greater than the adjusted cumulative power sum, then the location is considered to have service. If the Desired signal is less than the adjusted cumulative power sum, the Undesired interfering signal(s) make the Desired signal unusable.
If the adjusted cumulative power sum exceeds the Desired signal level at the location, the [flag] value will be shown as “ (below specified D/U). ” For locations where the Desired signal exceeds the adjusted cumulative power sum, no flag is printed.
39 16 57.16 N 105 03 12.87 W (39.28254313 -105.0535761946) -44.0000
The coordinates for each location are written to the file, along with the resulting value of the field strength at the location. This is also the value written to the Results Database file (Rxxxxxxx.DBF) for the Adjacent Channel Interference study Task.
If the adjusted cumulative power sum exceeds the Desired signal level at the location, the value is shown as –32000, a value recognized in HDMapper as an unusable location. For locations where the Desired signal exceeds the adjusted cumulative power sum, the value will be the field strength (in dBu) of the Desired signal at that location. HDMapper can be used to plot the values of field strength just as with other TAP Area Coverage studies.
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