1Introduction - popovsociety.com Meeting 3/US… · Web viewAll three pfds are now below the Study 2 pfd curve required to protect the FS with an FS antenna gain of 37 dBi and below

US Radiocommunications SectorFact Sheet

Working Party: WP 5B Document No: USWP5B20-12_Second Draft

Ref: Annex 26, 5B/411 Date: 7th March 2018

Document Title:

WORKING DOCUMENT TOWARDS A PRELIMINARY DRAFT NEW REPORT ITU-R S.[UA_pfd] FOR RESOLUTION 155 (WRC-15)

Author(s)/Contributors(s):

Don NellisFederal Aviation Administration800 Independence Ave., S.W.Washington, DC 20591

Michael NealeACES Corporation for the FAA

Phone/Email:

Phone: (202) 267-9779e-mail: [email protected]

Phone: (858) 705-8978e-mail: [email protected]

Purpose/Objective: The purpose of this contribution is to re-present the contribution that was carried over from the November 2017 meeting (Annex 26 of 5B/411) of WP 5B. The attached is the WP 5B chairman’s merge of all of the contributions to this report that were not discussed in November. No changes are proposed to the US contribution (Study 2#) other than to remove the reference to highlighting on the first page.

Abstract: This contribution discusses the pfd required to protect the FS from emissions from the CNPC link transmitter located on the UA. It is required to address resolves 14, 15 and 16 in Resolution 155 (WRC-15) by WRC-19.

/TT/FILE_CONVERT/5E1ED432C0E9B078743DC7C1/DOCUMENT.DOCX 02/03/2018 05:10:00 PM 04/12/2017 09:04:00 AM

mailto:[email protected]

- 2 -5B/411 (Annex 26)-E

[Note: This document is a merger of contribution made to this meeting of WP 5B and Annex 27 of the last chairman’s report. The meeting has not reviewed the content of this document and hence it cannot be considered as if any agreement has been reached with respect to the text. Additionally, completion of this document needs to be consistent with the “Draft Working Party 5B guideline for the implementation of Resolution 155 (WRC-15)” see appendix XX to this chairman’s report]

In reviewing Resolution 155 (WRC-15) Working Party 5B notes that the Power Flux Density approach contained in Article 21 of the Radio Regulations is used for the protection of terrestrial services where coordination between Earth station and terrestrial station assignments is governed by Article 9 of the Radio Regulations namely RR No. 9.17 and RR No. 9.18.

To date there is no established mechanism or procedure to carry out the required coordination between Earth station(s) on board aircraft and terrestrial station(s) assignments.

Moreover, the applicability of the Power Flux Density for the protection of the terrestrial service (and not the protection of the assignment) needs to be carefully examined to verify its validity for such protection due to the moving feature of the Earth stations on board the aircraft. Consequently, for the protection of terrestrial stations and their assignments the non-interference conditions should be applied.

However, the Power Flux Density approach, once validated, could be used to facilitate discussion (bilateral or multilateral) among the concerned parties involved in the matter.

Blue highlighting indicates proposed revisions from France

Green highlighting indicates proposed revisions from USA

This document contains two different studies on fixed protection for Resolution 155 (WRC-15) in the two following annexes.


Radiocommunication Study Groups

Source: Document 5B/TEMP/176

Subject: Merged contributions to ITU-R M.[UA_PFD]

Annex 26 to Document 5B/411-E4 December 2017English only

Annex 26 to the Working Party 5B Chairman’s Report

WORKING DOCUMENT TOWARDS A PRELIMINARY DRAFT NEW REPORT ITU-R S.[UA_PFD]

Power flux-density limits to protect terrestrial services from Earth stations on board Unmanned Aircraft in the frequency

band 14.0-14.47 GHz

- 3 -5B/411 (Annex 26)-E

ANNEX 1

Study #1

In Resolution 155 (WRC-15), World Radiocommunication Conference resolves:

“

1 that assignments to stations of geostationary FSS satellite networks operating in the frequency bands 10.95-11.2 GHz (space-to-Earth), 11.45-11.7 GHz (space-to-Earth), 11.7-12.2 GHz (space-to-Earth) in Region 2, 12.2-12.5 GHz (space-to-Earth) in Region 3, 12.5-12.75 GHz (space-to-Earth) in Regions 1 and 3 and 19.7-20.2 GHz (space-to-Earth), and in the frequency bands 14-14.47 GHz (Earth-to-space) and 29.5-30.0 GHz (Earth-to-space), may be used for UAS CNPC links in non-segregated airspace*, provided that the conditions specified in resolves below are met;

[..]

14 that, unless otherwise agreed between the administrations concerned, UA CNPC earth stations shall not cause harmful interference to terrestrial services of other administrations (see also Annex 2);

15 that, in order to implement resolves 14 above, power flux-density hard limits need to be developed for UAS CNPC links; one possible example of such provisional limits to protect the fixed service is provided in Annex 2; subject to agreement between the administrations concerned,

that annex may be used for the implementation of this resolution;

16 that the power flux-density hard limits provided in Annex 2 shall be reviewed and, if

necessary, revised by the next conference;

[…]

“

The details of the proposal are provided in Appendix 1.


- 4 -5B/411 (Annex 26)-E

APPENDIX 1

Study #2 [F 5B/XXX]

Method A ProposalsTo ensure protection of the fixed service from an emission of a UAV communicating with a satellite, the proposals consist in requiring compliance with the following technical arrangements in the identified frequency band for UAV which is also used by the fixed service on a co-primary basis with FSS.

The following technical arrangements are based on the proposal for revision of Recommendation ITU-R F.758 provided by France at WP 5C considering these parameters of fixed service stations applicable in the frequency band 14.25-14.4 GHz.

France is of the view that the same methodology could be applied for the frequency band 14-14.25 GHz with relevant value of fixed service stations parameters.

In the frequency band 14.25-14.47 GHz used by FS networks, within line-of-sight of the territory of an administration where FS networks are operating in this band, the maximum pfd produced at the surface of the Earth by emissions from a single station on board a UAV and operating in the FSS should not exceed:

–124122 dB(W/(m2 · MHz)) for θ ≤ 5°–124131+ 01.5 8 * *( θ – 5)2 dB(W/(m2 · MHz)) for 5° < θ ≤ 1025°–122+ 28.5*log10(θ – 5) dB(W/(m2 · MHz)) for 10° < θ ≤ 50°

–7586 dB(W/(m2 · MHz)) for 5025° < θ ≤ 90°

where θ is the angle of arrival of the radio-frequency wave.


- 5 -5B/411 (Annex 26)-E

ANNEX OF APPENDIX 1

Description of the methodology and simulation results

1 IntroductionThis annex describes the studies carried out to determine the proposed pfd mask to ensure protection of FS stations in the frequency band 14.25-14.4 GHz based on the proposal for revision of Recommendation ITU-R F.758 provided by France at WP 5C. The same methodology should be applied for the frequency band 14-14.25 GHz with relevant value of fixed service stations parameters.

2 Methodologya) PrincipleThe scenario consists in determining whether the protection criteria for an FS station are respected with non-stop co-channel line-of sight operation during a period of one month of a single UAV.

The UAV's flight plan is defined randomly on great-circle trajectories at constant altitude and speed.

b) ProcessThe figure below shows the stages of the methodology adopted.


- 6 -5B/411 (Annex 26)-E

c) Geometryi) Principle

According to WGS84 definitions:

Semi-major axis: a = 6 378 137 m

Flattening coefficient: f = 1/298.257223563

The following parameters are inferred:

Semi-minor axis: b = a(1-f) = 6 356 752.3142 m

First excentricity: e = √2 f − f 2 = 8.1819190842622*10^-2

Second excentricity: e’ = √ f 2−f(1−f )2 = 8.2094437949696*10^-2

Mean radius of the semi-axes: R1 = 6 371 008.7714 m

The different references used are the following:– ECEF (Earth-Centered, Earth-Fixed)– WGS84 (World Geodetic System 84)– ENU (East, North, Up).

They are presented in the figure below, where the angles φ and λ represent respectively the WGS84 latitude et la longitude.


Determine ENU coordinates of the circle according to aircraft altitude and radio station height

If we consider two points A and B on the sphere, of latitudes A and B and longitudes λA and λB , then the angular distance in radians SA-B between A and B is given by the fundamental spherical trigonometry relation, using dλ = λ B – λ A:

SA – B = arc cos (sin A sin B + cos A cos B

cos dλ)

The distance S in metres is obtained by

multiplying SA-B by the average radius of the Earth .

Draw two random angles to define ENU start and end points

Determine ECEF coordinates for two points of line-of-sight circle

Determine WGS84 coordinates of the two points

Calculate the great-circle distance between the two points of the radio station circumference

Determine the number of points according to the speed of the aircraft for a 1 second increment

Determine the path points with 1 second increments in WGS84

Determine the path points with 1 second increments in ECEF and the radio station – UAV vectors in ENU

Calculate the off-axis gain values and apply the emission mask

Calculate the level of interference received by the radio station

At end of path, check 1 month has elapsed, otherwise restart

Test the interference level (short- and long-term I/N and FDP for Ku)

Vary the radio station height, radio station gain, UAV altitude - > different pfd masks

WGS84 location of radio station

Radio station WGS84 > ECEF

- 7 -5B/411 (Annex 26)-E

ii) Receiver: Fixed-service station

The position of the FS station is randomly defined:– Latitude, 0° – Longitude, 0°

The antenna height of the station used for the study is 30 m and pointing in North direction.

iii) Transmitter: Station on board the UAV

The UAV’s trajectory is defined by an entry point and an exit point randomly selected on the radio station’s line-of-sight circle, then by the points linearly distributed on the major axisgreat circle trajectory between those two points (see figure below for an example with a flight path over the radio station).

The following altitudes have been considered: 1 000 m, 4 000 m, 7 000 m, 10 000 m, 13 000 m and 16 000 m. Several aircraft speeds were used in the simulation and it was found that the results were not dependent on this parameter. The results presented in this study were generated for an aircraft speed of 200 kt (370 km/h). The gap between two intermediary points is the distance equivalent to one second trajectory at a given fixed speed.


- 8 -5B/411 (Annex 26)-E

FIGURE 1

Example of a flight path over an FS station


- 9 -5B/411 (Annex 26)-E

The figure below shows the parameters used to define the line-of-sight circle:

∝1=arcos ( RR+H 1

)

∝2=arcos ( RR+H 2

)

PtCirconferenceENU (θ)={( R+H 2 )∗sin (∝1+∝2 )∗cos(θ)(R+ H 2 )∗sin (∝1+∝2 )∗sin(θ)−R+( R+H 2 )∗cos (∝1+∝2 )

In this study, two scenarios have been considered.

Scenario 1:In the scenario 1, the entry and exit points are both chosen randomly on the line of sight circle of the FH station.

Scenario 2:In the scenario 2, the entry points are chosen randomly on the line of sight circle of the FH station but the exit points are forced to be at 180° of their corresponding entry point.

3 Analysis in the band 14/10 GHza) Characteristics of the emission

i) PFD masks

Various masks in the band considered were analysed before being able to provide a proposed PFD mask.

The following figure presents a comparison between the current limitations in the Resolution 155 (WRC-15) based on Recommendation ITU-R M.1643 and the mask proposed to ensure the FS protection.


- 10 -5B/411 (Annex 26)-E

FIGURE

Power flux density limits comparison

0 10 20 30 40 50 60 70 80 90

angle (°)

-135

-130

-125

-120

-115

-110

-105

-100

-95

-90

-85

PFD

(dB

W/m

²/MH

z)

ITU-R M.1643 pfd limitsProposed pfd limits

The proposed mask in Annex 1 corresponds to the mask UAV_Option4_Ku.


PFD mask as a function of angle above horizon

- 11 -5B/411 (Annex 26)-E

b) Receiver characteristics

i) Receiver antenna gain

The maximum antenna gain used for the studies is selected, respectively, as 49, 45, 35, 28 or 18 dBi.

The antenna pattern is based on Recommendation ITU-R F.1245 for point-to-point (P-P) links.

For point-to-multipoint (P-MP) links, the antenna pattern to be used would be that in Recommendation ITU-R F.1336.

ii) Receiver antenna elevation

For the receiver elevation, the following values are taken into account: 0°, 1°, 2°, 3°, 4° and 5°.

iii) Analysis of FS protection criteria

1) Interference levelThe interference level is obtained by applying the following formula:

I=PFD+GRec−10∗log 10¿)

with: f in Hz

c in m/s

Thus: I=PFD+GRec−44 at 14 GHz.

2) Noise levelThe noise level considered for 14 MHz was set at –126124.5 dBW and for 1 MHz is set at –138 136 dBW, and obtained from the following equations, with a noise figure of 6 8 dB:

Receiver_Noise_dBm = –114 + 10.*log10(BANDWIDTH_MHz) + Noise_Figure_dB

Receiver_Noise_dBW = Receiver_Noise_dBm – 30;


ITU-R

- 12 -5B/411 (Annex 26)-E

3) Protection criteriaRecommendation ITU-R F.758 describes the principle and also levels for protection criteria in terms of I/N for both long-term and short-term time percentages, and in terms of fractional degradation in performance (FDP).WP 5C (5B/308) provides the protection criteria of the fixed service to take into account in the current study.

The long-term criterion consists in not exceeding an I/N level of –10 dB for more than 20% of the time in the case of co-primary services.

In this case, the FDP must also respect a threshold of 10% according to the methodology set out in in Recommendation ITU-R F.1108.

Recommendation ITU-R F.1494 proposes a methodology for determining the short-term FS protection criterion.

The worst case corresponds to an I/N of 19 dB with a time percentage of 92.752.10E-04%.

DescriptionThe total fade margin is taken at 37 dB for a bit error rate (BER) of 10-3 and automatic transmission power control (ATPC) of 13 dB. The fade margin for the severely errored second (SES) ratio is 1 dB less and 5 dB less for the errored second (ES) ratio. The short-term I/N criterion is selected such that the net calculated margin is positive.

The performance degradation is linked to the time percentage p by the following equation:

DP ( % )= DstEPO (%) . EPO(% )100

= p(%). A(%)100

The time percentage associated with the I/N threshold is calculated with the following equation:

p(% )= DP(%)A (% )

100

where: EPO: error performance objective (%)

Error performance objective (EPO) is substituted by the parameters errored second ratio (ESR) and severely errored second ratio (SESR) (Rec. ITU-R F.1565). DstEPO: standard EPO degradation (10% included in the calculations in the tables). DP (%): performance degradation due to interference (cf. Rec. ITU-R F.1565;

= ESR(%) or SESR(%) as appropriate). p: percentage of time during which the short-term I/N ratio may be exceeded

(%). A: percentage of time during which the adopted fade margin may be exceeded

(%) (see Recommendation ITU-R P.530).


http://www.itu.int/rec/R-REC-P.530/en

- 13 -5B/411 (Annex 26)-E

Time percentage for the severely errored second (SES) ratio of an FS station participating in an international network

Parameters Value SourceFM for BER 10-3 (dB) 37 Rec. ITU-R F.1494

FM for SES (dB) 36 Rec. ITU-R F.1494ATPC (dB) 13

Short-term I/N (dB) 20 Adopted valueNet FM for SES (dB) 3

SESR (%) 0.0002 Rec. ITU-R F.1565 Table 1a – 500 km Probability of exceeding FM (%) 3.3 Rec. ITU-R P.530

Short-term protection criterion time percentage (%) 6.06E-03

Time percentage for the errored second (ES) ratio of an FS station participating in an international network

Parameters Value SourceFM for BER 10-3 (dB) 37 Rec. ITU-R F.1494FM for ES (dB) 32 Rec. ITU-R F.1494

ATPC (dB) 13Short-term I/N (dB) 19 Adopted value

Net FM for ES (dB) 0 ESR (%) 0.001 Rec. ITU-R F.1565 Table 1a – 500 km

Probability of exceeding FM (%) 63 Rec. ITU-R P.530 Short-term protection criterion time percentage (%) 1.59E-03

Time percentage for the severely errored second (SES) ratio of an FS station participating in a national long-distance network

Parameters Value SourceFM for BER 10-3 (dB) 37 Rec. ITU-R F.1494FM for SES (dB) 36 Rec. ITU-R F.1494

ATPC (dB) 13Short-term I/N (dB) 20 Adopted value

Net FM for SES (dB) 3 SESR (%) 0.00012 Rec. ITU-R F.1565 Table 3a – 50 km

Probability of exceeding FM (%) 3.3 Rec. ITU-R P.530 Short-term protection criterion time percentage (%) 3.64E-03


- 14 -5B/411 (Annex 26)-E

Time percentage for the errored second (ES) ratio of an FS station participating in a national long-distance network


FM for ES (dB) 32 Rec. ITU-R F.1494ATPC (dB) 13

Short-term I/N (dB) 19 Adopted valueNet FM for ES (dB) 0

ESR (%) 0.0006 Rec. ITU-R F.1565 Table 3a – 50 kmProbability of exceeding FM (%) 63 Rec. ITU-R P.530


Time percentage for the severely errored second (SES) ratio of an FS station participating in a national short-distance network


FM for SES (dB) 36 Rec. ITU-R F.1494ATPC (dB) 13

Short-term I/N (dB) 20 Adopted valueNet FM for SES (dB) 3

SESR (%) 0.0015 Rec. ITU-R F.1565 Table 5aProbability of exceeding FM (%) 3.3 Rec. ITU-R P.530


Time percentage for the errored second (ES) ratio of an FS station participating in a national short-distance network


FM for ES (dB) 32 Rec. ITU-R F.1494ATPC (dB) 13

Short-term I/N (dB) 19 Adopted valueNet FM for ES (dB) 0

ESR (%) 0.0075 Rec. ITU-R F.1565 Tables 4a and 5aProbability of exceeding FM (%) 63 Rec. ITU-R P.530



- 15 -5B/411 (Annex 26)-E

c) Examples of I/N ratio cumulative distribution function for scenario 1The following two figures correspond to a FS station with maximum antenna gain of 49 dBi with elevation angles of 0° and 5°, respectively.

-40 -30 -20 -10 0 10 20I/N in dB

10-4

10-3

10-2

10-1

100

101

102

cdf i

n %

Cumulative distribution of I/N at 14GHz

FDP(%) = 0.47096

FDP(%) = 0.89463

FDP(%) = 0.75325

FDP(%) = 0.64136

Scenario_10000m_0°_49dBi_M1643Scenario_1000m_0°_49dBi_M1643Scenario_3000m_0°_49dBi_M1643Scenario_6000m_0°_49dBi_M1643

-40 -30 -20 -10 0 10 20I/N in dB

10-4

10-3

10-2

10-1

100

101

102

cdf i

n %


FDP(%) = 0.0070954

FDP(%) = 0.02589

FDP(%) = 0.028112

FDP(%) = 0.097521


The following two figures correspond to a FS station with maximum antenna gain of 37 dBi with elevation angles of 0° and 5°, respectively.


- 16 -5B/411 (Annex 26)-E

-40 -30 -20 -10 0 10 20I/N in dB

10-4

10-3

10-2

10-1

100

101

102

cdf i

n %


FDP(%) = 0.32881

FDP(%) = 0.33878

FDP(%) = 0.26207

FDP(%) = 0.25977


-40 -30 -20 -10 0 10 20I/N in dB

10-4

10-3

10-2

10-1

100

101

102

cdf i

n %


FDP(%) = 0.014475

FDP(%) = 0.025429

FDP(%) = 0.024908

FDP(%) = 0.034391



- 17 -5B/411 (Annex 26)-E


- 18 -5B/411 (Annex 26)-E


- 19 -5B/411 (Annex 26)-E


- 20 -5B/411 (Annex 26)-E


- 21 -5B/411 (Annex 26)-E


- 22 -5B/411 (Annex 26)-E


- 23 -5B/411 (Annex 26)-E

d) Examples of I/N ratio cumulative distribution function for scenario 2The following two figures correspond to a FS station with maximum antenna gain of 49 dBi with elevation angles of 0° and 5°, respectively.


- 24 -5B/411 (Annex 26)-E

-40 -30 -20 -10 0 10 20I/N in dB

10-4

10-3

10-2

10-1

100

101

102

cdf i

n %


FDP(%) = 3.24 (1000 m), 5.17 (4000 m), 4.15 (7000 m), 4.48 (10000m), 3.72 (13000m), 3.42 (16000m)

Scenario_1000m_0°_49dBi_UAV_Option7_200kt_Ku_10100Scenario_4000m_0°_49dBi_UAV_Option7_200kt_Ku_10130Scenario_7000m_0°_49dBi_UAV_Option7_200kt_Ku_10160Scenario_10000m_0°_49dBi_UAV_Option7_200kt_Ku_10190Scenario_13000m_0°_49dBi_UAV_Option7_200kt_Ku_10220Scenario_16000m_0°_49dBi_UAV_Option7_200kt_Ku_10250

-40 -30 -20 -10 0 10 20I/N in dB

10-4

10-3

10-2

10-1

100

101

102

cdf i

n %


FDP(%) = 0.66 (1000 m), 1.53 (4000 m), 1.79 (7000 m), 2.31 (10000m), 2.9 (13000m), 3.06 (16000m)


The following two figures correspond to a FS station with maximum antenna gain of 35 dBi with elevation angles of 0° and 5°, respectively.


- 25 -5B/411 (Annex 26)-E

-40 -30 -20 -10 0 10 20I/N in dB

10-3

10-2

10-1

100

101

102

cdf i

n %


FDP(%) = 5.08 (16000m), 4.50 (13000m), 3.93 (10000m), 3.70 (7000m), 3.67 (4000m), 3.17 (1000m)


-40 -30 -20 -10 0 10 20I/N in dB

10-3

10-2

10-1

100

101

102

cdf i

n %


FDP(%) = 5.537 (16000m), 4.87 (13000m), 3.87 (10000m), 3.61 (7000m), 2.77 (4000m), 1.33 (1000m)



- 26 -5B/411 (Annex 26)-E

Study #2

[Editor’s note: to discuss considering the update of the proposed pfd mask in study #1]

In Resolution 155 (WRC-15), World Radiocommunication Conference resolves:

“

1 that assignments to stations of geostationary FSS satellite networks operating in the frequency bands 10.95-11.2 GHz (space-to-Earth), 11.45-11.7 GHz (space-to-Earth), 11.7-12.2 GHz (space-to-Earth) in Region 2, 12.2-12.5 GHz (space-to-Earth) in Region 3, 12.5-12.75 GHz (space-to-Earth) in Regions 1 and 3 and 19.7-20.2 GHz (space-to-Earth), and in the frequency bands 14-14.47 GHz (Earth-to-space) and 29.5-30.0 GHz (Earth-to-space), may be used for UAS CNPC links in non-segregated airspace*, provided that the conditions specified in resolves below are met;

[..]

14 that, unless otherwise agreed between the administrations concerned, UA CNPC Link Earth stations shall not cause harmful interference to terrestrial services of other administrations (see also Annex 2);

15 that, in order to implement resolves 14 above, power flux-density hard limits need to be developed for UAS CNPC links; one possible example of such provisional limits to protect the fixed service is provided in Annex 2; subject to agreement between the administrations concerned,

that annex may be used for the implementation of this resolution;

16 that the power flux-density hard limits provided in Annex 2 shall be reviewed and, if

necessary, revised by the next conference;

[…]

“

The Annex 2 limits proposed in Resolution 155 (WRC-15) are in essence equivalent to those in ITU-R M.1643 namely:“An Earth station on board UA in the frequency band 14.0-14.47 GHz shall comply with provisional power flux-density (pfd) limits described below:

−132 + 0.5 · θ dB(W/(m2 · MHz)) for θ ≤ 40°−112 dB(W/(m2 · MHz)) for 40 < θ ≤ 90°

where θ is the angle of arrival of the radio-frequency wave (degrees above the horizontal).NOTE – The aforementioned limits relate to the pfd and angles of arrival that would be obtained under free-space propagation conditions.

“

However, the limits in ITU-R M.1643 (and consequently those in Resolution 155 (WRC-15)) were developed to protect the incumbent primary services from the introduction of a new secondary service that was not intended to provide safety-of-flight communications. In the case being considered in Resolution 155 it is a new application of a current service (CNPC use of the FSS) that is being considered not the introduction of a new service. Additionally, that service (FSS) already has well defined power flux-density limits for its current applications that adequately protect the


- 27 -5B/411 (Annex 26)-E

other incumbent services, however in the case being considered here the source of interference is a moving Earth station on an aircraft and not a stationary one on the ground.

Study 2 in Annex 2 discusses a non-statistical approach to the analysis of the sharing of the new application of the FSS (CNPC Link) with incumbent services and the response to Resolution 155 (WRC-15) to develop power flux-density hard limits for UAS CNPC links.

Two power flux-densities (pfd) need to be considered.• The pfd required to protect the incumbent services (FSS and FS)• The pfd caused by the new application (CNPC) of the FSS

If the pfd caused by the new application exceeds the pfd required to protect the incumbent services, then sharing will not be possible. Conversely if the pfd caused by the new application of the FSS does not exceed the pfd required to protect the incumbent services, then sharing is possible.

Appendix 2-1 of Annex 2 considers the pfd required to protect the incumbent services. Since compliance with ITU-R S.728 is a prerequisite of the approach then that pfd will ensure protection of the FSS. Consequently, Study 2 only considers interference into the FS.

Appendix 2-2 of Annex 2 considers the pfd caused by the new application of the FSS, namely the CNPC Link Earth station transmitter located on the UA.

Appendix 2-4 of Annex 2 considers the temporal characteristics of the PFD caused by the UA at the location of the FS.

Summary of ResultsAppendix 2-3 to Annex 2 provides comparisons of the pfd caused by the UA CNPC Link Earth station transmitter at the FS locations with the pfd required to protect the FS.

The analysis shows that with the aircraft at lower latitudes and/or higher altitudes then the pfd caused by the CNPC Link Earth station transmitter on the UA, at the location of the FS, is lower than when the UA is operating at higher latitudes and/or lower UA altitudes.

Under the assumptions of the FS parameters in Study 2:• when using a UA antenna comparable to those currently in use in segregated airspace

(Bessel)• when the UA e.i.r.p. density complies with ITU-R S.728 (which is equivalent to ETSI

EN 302 186 and 8 dB higher than FCC 25.227)• when the FS antenna elevation is at its worst at +5 degrees

The pfd caused by the UA will not exceed that required to protect the FS if the UA is flying at less than 50 degrees’ latitude and higher than 20 kft altitude:• or when the FS antenna elevation is at a more typical +2 degrees’ elevation

The pfd caused by the UA will not exceed that required to protect the FS if the UA is flying at less than 65 degrees’ latitude and higher than 20 kft altitude.

Annex 2-4 adds the dimensions of both time and misalignment of FS and UA antenna beams to the above analysis. Although the pfd required to protect the FS can be exceeded by the UA at high latitudes when the UA is flying at less than 20 kft altitude the amount of time this occurs is limited to only a few minutes and if the UA is located only 1-2 degrees off of the centre of the FS antenna beam then the pfd caused by the UA never exceeds that required to protect the FS at latitudes as high as 70 degrees, even using the higher 49 dBi FS antenna gain. Because of the latency associated with GSO satellite based CNPC links it is not anticipated that UA will fly at altitudes below approximately 20 kft when operating using them. This is because the latency would make the


- 28 -5B/411 (Annex 26)-E

UA too slow to respond in terrain or other aircraft avoidance situations so the altitudes of 20 kft in the above results overview would not be operationally restrictive.

The geometry used in Study 2 is the absolute worst case (UA Earth station, FSS space station and FS on same longitude with antennas aligned) because it captures the shortest interference path length with antennas aligned. When this condition does not exist the pfd caused by the UA at the location of the FS will be less. In fact, this condition as well as the condition where the satellite, UA and FS are not at the same longitude (and consequently the interference path is not the shortest) with the antennas aligned, will occur very rarely. So, in the majority of cases the interference will be significantly less than that predicted by Study 2.

To support this conjecture Annex 2-5 examines the percentages of locations for the UA, when it is within radio line-of-sight of the FS antenna, at which the pfd caused by the UA will exceed the pfd required to protect the FS. It demonstrates that even at the highest latitude and lowest altitude that is anticipated for UA operation that there are only a very small percentage (0.06-0.22%) of geographic locations, within radio line-of-sight of the FS, where the pfd caused by the UA will exceed the pfd required to protect the FS. Higher gain FS antennas reduce this percentage because of their narrower bandwidths.

Additionally, as recognized in ITU-R F.1494, ITU-R F.1108 etc. for harmful interference to occur the aligned UA interferer condition must happen at the same time as the FS to FS link experiences a fade. It is only under that condition that the 19 dB I/N caused by the UA can impact the error performance of the FS to FS link which under normal/unfaded conditions has a 37-47 dB C/N (reference ITU-R 1494/5) which would not be materially impacted by the 19 dB I/N caused by the UA.

Further, since the highest pfd created by the UA occurs when the range and altitude of the UA locates it directly aligned with the centre of the FS antenna beam then any fading on the FS to FS path will occur equally on the UA to FS path because both the wanted signal and the signal from the UA are travelling over exactly the same path.


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APPENDIX 2-1

The PFD Required to Protect the FS

Three elements determine the pfd at the Earth’s surface required to protect the FS:1) The noise power density of the FS receiver, No dB(W/MHz).2) The required I/N at the FS receiver input, I/N dB.3) The on-axis and off-axis gain of the FS antenna, GOFS dBi, where OFS is the off-axis

angle from the on-axis boresight of the FS antenna.

pfd to protect FS = No + I/N - GOFS + 44.7 dB(W/(m2 . MHz)) §1)

The factor of 44.7dB (10 log 4π(d/λ)2), where d = 1 m and λ = 0.0207 m (14.47 GHz), converts e.i.r.p. density to flux-density.

The off-axis pfd levels to protect the FS will increase (i.e. the FS will be less sensitive to interference) from the on-axis value based on the FS antenna gain (reduction) GOFS versus off-axis angle OFS degrees. Study 2 uses the off-axis antenna gain profile based on ITU-R F.1245 as recommended by WP 5C in 5B/308.

Following WP 5C’s 8 June 2017 liaison to WP 5B (5B/308) Study 2 uses values extracted from ITU-R F.758 for:1) The noise power density of the FS receiver, No = -136 dB(W/MHz).2) The acceptable short-term I/N at the FS receiver input, I/N = 19 dB.3) The on-axis and off-axis gain of the FS antenna, GOFS = 37 dBi (14.0-14.25 GHz) and

49dBi (14.25-14.47 GHz), where OFS = 0 and whose off-axis gain changes in accordance with the gain shown in ITU-R F.1245.


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FIGURE A2-1

Comparison of PFDs required to protect the FS

Figure A2-1 shows a comparison of the pfds required to protect the FS based on ITU-R M.1643 (equivalent to that in Annex 2 of Resolution 155 (WRC-15)), and FS antenna gains of 37 dBi and 49 dBi.

The curves use a maximum antenna elevation angle for the FS of 5 degrees so the pfd required to protect the FS is constant up to 5 degrees and then increases in accordance with the off-axis gain reduction of the FS antenna.

curves are higher than that for the ITU-R M.1643 curve since they use a higher I/N. As noted above the I/N used in ITU-R M.1643 was chosen based of the service under consideration being secondary.

Since the UA is continuously moving then it is anticipated that any interference from the UA into the FS will be short-term in nature, the statistical analysis in Study 1 is the more appropriate approach to analyse the exact temporal nature of this interference. Study 2 is more focussed on the interference caused by the UA under various of its operating conditions so these short-term curves are used only as a reference for this analysis and not as a means to determine the pfd mask to protect the FS that is required by Resolution 155 (WRC-15). However, it is anticipated that Study 1 will not lower the pfd levels near the main beam of the FS antenna, which are associated with infrequent events, but only adjust the pfd levels for larger FS antenna off-axis angles since the UA will spend much more of its time in these off-axis locations and consequently the long-term protection criteria will dominate the pfd mask required to protect the FS.


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APPENDIX 2-2

The PFD Caused by the CNPC Link

Four elements determine the pfd at the Earth’s surface caused by the CNPC Link Earth station transmitter on the UA.1) The off-axis e.i.r.p. density from the CNPC Link antenna on the UA, EOUA dB(W/MHz),

where OUA is the off-axis angle from the on-axis boresight of the UA antenna.2) The spreading path loss from the UA to the FS, S dB.3) Any additional losses on the propagations path, P dB.4) Any attenuation caused by the UA’s airframe, A dB.

pfd caused by CNPC transmitter at the FS = EOUA – S – P – A dB(W/(m2 . MHz)) §2

To calculate the on-axis pfd, the UA CNPC Link transmitter e.i.r.p. spectral density (eirpd) must be adjusted so that, with the antenna off-axis profile used, the off-axis eirpd is never higher than the eirpd regulations allow; at any off-axis angle.

FIGURE A2-3

Off-Axis EIRPDs

Figure A2-3 plots various off-axis e.i.r.p. density regulations. ITU-R S.524 allows the highest off-axis (and consequently on-axis) eirpd, however with the smaller size antennas used for UAS applications ITU-R S.728 is more appropriate.

The levels of ITU-R S.728 are identical with those allowed in Europe (ETSI EN 302 186) and some 8 dB higher than those allowed in the USA (FCC 25.227). Note 1 in ITU-R S.728 indicates that the levels in ITU-R S.728 may need to be lowered by 8 dB where satellite spacing’s are only 2 degrees


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(such as over the USA) compared to the 3-degree spacing envisaged in ITU-R S.728 and which is more typical over Europe.

Since FS systems do not use the 14 GHz band in the USA Study 2 will use the off-axis eirpd levels from ITU-R S.728 that are representative of the levels that will occur over Europe.

Using the formula for off-axis gain for antennas with D/λ <= 100 from ITU-R S.465 Note 4, the following on axis eirpds were calculated by adjusting the UA CNPC link transmitter eirpd so as to ensure the off-axis eirpds never exceeded the levels in ITU-R S.728. A bandwidth of 1 MHz has been used to allow direct comparison with Annex B-1, Appendix A (Study 1) and Appendix 2 of Resolution 155 (WRC 15).– Small Antenna - 0.45m diameter, 42.3 dBW in 1 MHz.– Medium Antenna - 0.8m diameter, 49.9 dBW in 1 MHz.– Large Antenna - 1.2m diameter, 55.1 dBW in 1 MHz.

These eirpds are maximized to enable the highest performance links to be achieved (as required by a safety-of-flight application) consistent with compliance with ITU-R S.728.

FIGURE A2-4

EIRPDs caused by CNPC at the UA location

Figure A2-4 plots the off-axis eirpds, at the location of the UA, for the three sizes of antenna identified above and shows how they comply with ITU-R S.728 (they just touch at the 2 degrees off-axis point on the graph and are well below the ITU-R S.728 curve at all other off-axis angles). Figure A2-4 also shows an antenna profile (Bessel) that is closer to that currently used by certain UA operating in segregated airspace.

Figure A2-5 depicts the vertical geometry used in Study 2. It shows a UA flying at a certain latitude and altitude and its antenna angles to the FSS space station. It also shows the FS and its antenna angles. It should be noted that the vertical off-axis angles will also depend on the relative longitudes


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of the FS, FSS space station and UA Earth station. In the analysis used in Study 2 the longitudes are assumed to be the same. This vertical geometry is used in Study 2 as it will cause the highest pfd at the FS due to the CNPC Link Earth station transmitter on the UA since the interference path is the shortest possible. Although (for visual clarity) Figure A2-5 depicts a flat Earth the actual calculations performed assume a spherical Earth with a 6 378 km radius.

In Study 2 the UA latitude is adjusted to various values between 0 degrees (equator) and 70 degrees (nominal FSS GSO coverage limit), this sets the UA antenna elevation (see Figure A2-5) to the FSS space station. The altitude of the UA is also varied and this determines the UA antenna (OUA) and the FS antenna (OFS) off-axis angles and consequently the distance from the UA to the FS. Finally, the FS antenna elevation is varied from 0 degrees to 5 degrees although it is clear from Figure A2-5 that 5 degrees represents the worst-case interference condition.

FIGURE A2-5

Vertical Interference Geometry

The interference path experiences a distance squared attenuation due to the spreading of the signal as it radiates from the UA (Study 2 uses ITU-R P.525 to evaluate this parameter). The interference path will also experience gaseous attention (Study 2 uses ITU-R P.676 to model this parameter) and attenuation due to the UA airframe. Airframe attenuation is modelled in Study 2 by curve fitting the attenuation that has been under development for the last few years. That attenuation versus angle below horizontal at the UA (UA Fuselage Angle) is reproduced here in Figure A2-6. No attenuation occurs up to 20 degrees below horizontal to ensure the signal path to the space station is not impacted as the aircraft manoeuvres. Directly below the aircraft the airframe causes a maximum of 35 dB of attenuation.


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FIGURE A2-6

UA Fuselage Attenuation


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APPENDIX A2-3

Comparison of the PFD Caused by the CNPC Link andthe PFD Required to protect the FS

The eirpd caused by the UA at the UA location, the interference path attenuation and the fuselage attenuation from Annex A2-2 were combined using formula §2 (from Annex A2-2) to calculate the pfd caused by the UA at the location of the FS for various UA latitudes and altitudes. The results of this analysis appear in Annex A2-3 as a number of graphs depicting the pfd caused by the UA CNPC Link Earth station transmitter versus the pfd required to protect the FS over a range of angles of arrival of the radio-frequency wave at the FS in degrees above the horizontal.

FIGURE A2-7

PFDs at a UA Latitude of 45 Degrees and Altitude of 19 kft

Figure A2-7 shows the pfd required to protect the FS (same as Figure A2-1) overlaid with the pfds caused by the UA at the FS location when the UA is flying at 45 degrees’ latitude and 19 kft altitude - ICAO scenario 2 from 14 May 2013 (5B/269).

It shows that the pfd caused by the UA, when using the Bessel antenna, is lower than that required to protect the FS Study 2 curve with an FS antenna gain of 37 dBi.


https://www.itu.int/md/R15-WP5B-C-0269/en

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FIGURE A2-8


Figure A2-8 shows the UA at the same 45-degree latitude but now at an altitude of 45 kft - ICAO scenario 1 from 14 May 2013 (5B/269). All three pfds are now below the Study 2 pfd curve required to protect the FS with an FS antenna gain of 37 dBi and below the 49 dBi FS antenna gain pfd curve at angles of arrival of less than approximately 2 degrees for the ITU-R S.728, ITU-R S.465 and Bessel antenna curves. The Bessel antenna curve is also lower than the ITU-R M.1643 curve by 5 dB at an angle of arrival at the FS of 0 degrees.


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FIGURE A2-9


Figure A2-9 shows the pfds for an aircraft altitude of 66 kft (the maximum from ICAO scenario 1 from 14 May 2013 (5B/269)). In this figure, all UA pfds are lower than the Study 2 37 dBi FS antenna curve and the 49 dBi FS antenna gain pfd curves (at angles of arrival below about 3-5 degrees) required to protect the FS. All caused pfds are below the ITU-R M.1643 required protection curve at angles of arrival at the FS of between 0.5 and 2 degrees.

FIGURE A2-10

PFDs at a UA Latitudes of 0 and 70 Degrees and Altitude of 30 kft

Figure A2-10 shows the pfds caused by the UA when it is flying at an altitude of 30 kft and 0 degrees’ latitude (left-hand side) as well as 70 degrees’ latitude (right-hand side). It is clear that at


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0 degrees’ latitude the pfds caused by the UA are lower than when the UA is operating at 70-degree latitude.

At 70 degrees’ latitude, the pfds caused by the UA are above the pfd curves (except at low angles of arrival) required to protect the FS that are being considered. As the UA altitude is lowered the first point at which the pfd caused by the UA exceeds the pfd required to protect the FS is, as expected, at the 5-degree arrival angle point on the FS required protection curves. As can be seen from all of the Figures A2-7 through A2-10 at lower angles of arrival at the FS the pfds caused by the UA are always lower than at the 5-degree angle of arrival point. Consequently, FS with lower antenna elevations will always be protected if the 5-degree angle of arrival case is met.

The above analysis was used to develop the minimum UA altitude versus UA latitude required to protect the FS at various FS antenna elevation angles, which are equivalent to the of angles of arrival of the radio-frequency wave at the FS in degrees above the horizontal.

Figure A2-11 plots the minimum UA altitude required to protect the FS at the 5-degree FS antenna elevation point versus UA latitude for the various antenna patterns and the 37 dBi FS antenna gain FS required pfd protection curve.

Figure A2-11 shows that with the anticipated range of UA operating altitudes (ICAO scenarios 1 through 5 from 14 May 2013 (5B/269) indicate altitudes from 19 kft - 60 kft) then the pfd caused by the UA will not exceed that required to protect the FS with a 37 dBi antenna gain at latitudes less than approximately 60 degrees; depending on the antenna pattern.

FIGURE A2-11

Minimum UA altitude required to protect FS with 37 dBi FS Antenna Gainand 5 degrees Elevation


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FIGURE A2-12

Minimum UA altitude required to protect FS with 49 dBi FS Antenna Gainand 5 degrees Elevation

Figure A2-12 shows that with the anticipated range of UA operating altitudes (ICAO scenarios 1 through 5 from 14 May 2013 (5B/269) indicate altitudes from 19 kft - 60 kft) then the pfd caused by the UA will not exceed that required to protect the FS with a 49 dBi antenna gain at latitudes less than approximately 40 degrees; using the Bessel antenna pattern.


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FIGURE A2-13

Minimum UA altitude required to protect FS with 49 dBi FS Antenna Gain and 2 degrees

Figure A2-13 shows that with the anticipated range of UA operating altitudes (ICAO scenarios 1 through 5 from 14 May 2013 (5B/269) indicate altitudes from 19 kft - 60 kft) then the pfd caused by the UA will not exceed that required to protect the FS with a 37 dBi antenna gain at FS antenna elevation angles of less than 2 degrees at latitudes less than approximately 65 degrees; depending on the antenna pattern.


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FIGURE A2-14

Minimum UA altitude required to protect FS with 49 dBi FS Antenna Gain and 2 degrees Elevation

Figure A2-14 shows that with the anticipated range of UA operating altitudes (ICAO scenarios 1 through 5 from 14 May 2013 (5B/269) indicate altitudes from 19 kft - 60 kft) then the pfd caused by the UA will not exceed that required to protect the FS with a 49 dBi antenna gain at FS antenna elevation angles of less than 2 degrees at latitudes less than approximately 55 degrees; using the Bessel antenna pattern.


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APPENDIX A2-4

Temporal Characteristics of PFD Caused by the CNPC Link and

the PFD Required to protect the FS

Annex A2-4 uses the same geometric model as depicted in Figure A2-5 as well as the same UA and FS parameters as used in the previous Annex’s of this Study 2 but now considers the temporal characteristics of the pfd caused by the UA Earth station at the location of the FS.

Figure A2-15, 16 and 17 show, versus time, by how much the pfd caused (PFDC) by the UA Earth station exceeds the pfd required (PFDR) to protect the FS at the FS location with an FS antenna gain of 37 dBi. The graphs are limited to show only the time when the UA is within radio line-of -sight of the FS (using a k of 4/3). The UA is flying at a constant 19 kft altitude (ICAO scenario 2 from 14 May 2013 5B/269) on a path directly towards the FS antenna’s maximum gain. Negative times are as the UA approaches the FS, positive times are as the UA fly’s away from the FS after passing overhead of the FS antenna. Speeds of 100 knots, 250 knots and 500 knots were used, which are speeds representative of those that are anticipated. The UA antenna is pointing at a space station located on the same longitude at the FS antenna and the FS antenna elevation is 5 degrees, which represents the worst-case condition for interference.

FIGURE A2-15

PFDC-PFDR for a UA altitude of 19kft and speeds of 100 knots, 250 knots and 500 knots

As determined in Appendix 2-3 of this Annex the pfd caused by the UA only exceeds the pfd required to protect the FS when the UA is operating at high latitudes and low altitudes (which is


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why the lowest altitude in the relevant ICAO scenarios is used in this section of the analysis). As can been seen in Figure A2-15, when the UA is flying at 70 degrees’ latitude, the pfd caused by the UA exceeds the pfd required to protect the FS by approximately 11 dB worst-case (independent of UA speed). These periods of positive PFDC-PFDR range in time from 1 518 seconds (25.3 minutes) to 303 seconds (5.1 minutes) for UA speeds of 100 and 500 knots respectively.

Figure A2-16 and 17 show similar characteristics but at these latitudes (45 degrees and 0 degrees) the pfd caused by the UA never exceeds the pfd required to protect the FS.

FIGURE A2-16

PFDC-PFDR for a UA altitude of 19kft and speeds of 100 knots, 250 knots and 500 knots


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FIGURE A2-18

PFDC-PFDR for a UA altitude of 19kft and speeds of 100 knots, 250 knots and 500 knots using

an FS antenna gain of 49 dBi

Figure A2-18 shows the value of PFDC-PFDR when the FS antenna gain is 49 dBi and the UA is again flying at 19 kft altitude and with a range of speeds from 100 to 500 knots. The pfd caused by the UA Earth station exceeds the pfd required to protect the FS by a maximum of approximately 13 dB for times ranging from 283 seconds (4.7 min) to 56 seconds (0.95 min) with speeds of 100 knots and 500 knots respectively.

Figure A2-19 shows how the PFDC-PFDR reduces very rapidly as the angle between the path of the UA and the direction of maximum gain of the FS antenna changes. The graph shows that with an approximately 3-degree bearing offset the PFDC-PFDR has reduced by 11 dB and is now below the level where the pfd caused by the UA Earth station exceeds that required to protect the FS even at 70 degrees’ latitude. The rapid change of PFDC-PFDR is not only due to the narrow FS beam width (3dB +/- 1.1 degrees) but also because the UA is moving further way from the main beam of the FS while the UA antenna has still to be pointed at the space station location.


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FIGURE A2-19

PFDC-PFDR for a UA altitude of 19kft and a speed of 250 knots versus offset angle between the UA path and the main beam direction of the FS

Consequently, even at 70-degree latitude there is only a small set of UA geographic locations where the pfd caused by the UA will exceed the pfd required to protect the FS when the UA is flying at or above 19 kft altitude, confirming the validity of using the short-term I/N in this study.

Figure A2-20 shows the same situation but now using the 49 dBi FS antenna gain. Again, there is a very rapid reduction in the pfd caused by the UA Earth station as the angle between the main beam of the FS and the UA location diverges from 0 degrees. This reduction is even higher than for the previous graph because the 49 dBi gain FS antenna only has a 3 dB beam width of +/- 0.28 degrees. Only a 2-degree offset produces an approximately 27 dB reduction in the pfd caused by the UA at the location of the FS. This reduction is adequate to protect the FS even at the highest latitude (70 degrees) being considered in these Studies and again confirms the validity of using the short-term I/N in this study.


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FIGURE A2-20

PFDC-PFDR for a UA altitude of 19 kft and a speed of 250 knots versus offset angle between

the UA path and the main beam direction of the FS


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APPENDIX A2-5

Percentage of locations where the PFD Caused by the UA exceeds the PFD Required to protect the FS

Because of the geometry involved with the main beam coupling into the FS antenna there are only a very few UA locations at which the pfd caused by the UA will exceed the pfd required to protect the FS.

An analysis was performed to examine approximately 22,000 (using a 10 km range by 1 degree azimuth grid) UA locations within radio line-of-sight of the FS antenna which was located 100 ft. above local ground level. Figure A-21 depicts the horizontal geometry used in that analysis. It shows a UA flying at a certain latitude and its antenna angles to the FSS space station and FS. It also shows the FS and its antenna angles. It should be noted that the horizontal off-axis angles will depend on the relative longitudes of the FS, FSS space station and UA Earth station. In the analysis used in Study 2 the longitudes are assumed to be the same. This horizontal geometry is used in Study 2 as it will cause the highest pfd at the FS due to the CNPC Link Earth station transmitter on the UA since the interference path is the shortest possible. Although (for visual clarity) Figure A2-21 depicts a flat Earth the actual calculations performed assume a spherical Earth with a 6 378 km radius.

Figure A2-22 shows that with the FS antenna gain of 37 dBi and all of the other characteristics used in Study 2 when even at 70 degrees’ latitude and 19 kft altitude (the worst location for the UA) then the pfd caused by the UA will exceed the pfd required to protect the FS only at 0.22% of all possible UA locations within radio line-of-sight of the FS antenna.

Figure A2-22 also shows that with the FS antenna gain increased to 49 dBi this percentage drops to 0.06% at 70 degrees’ latitude because of the narrower beam width of the higher gain antenna used in Study 1.

At lower latitudes, for both studies, the percentage of locations drops to zero for those latitudes where the pfd caused by the UA does not exceed the pfd required to protect the FS.


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FIGURE A2-21

Horizontal geometry used to determine the Percentage of locations versus latitude where PFDC exceeds PFDR for a UA altitude of 19 kft using Study 1 and Study 2

characteristics

FIGURE A2-22

Percentage of locations versus latitude where PFDC exceeds PFDR for a UA altitude of 19kft using Study 1

and Study 2 characteristics


Documents

1Introduction - popovsociety.com Meeting 3/US… · Web viewAll three pfds are now below the Study 2 pfd curve required to protect the FS with an FS antenna gain of 37 dBi and below