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Federal Register / Vol. 86, No. 19 / Monday, February 1, 2021 / Proposed Rules
axis angular gain and PFD data.48
Sections 25.264a and b of our rules specify the set of angular ranges over which antenna off-axis gain data and associated PFD calculations must be provided to demonstrate whether the coordination trigger will be exceeded at planned or existing DBS satellite locations.49 SES proposes that transmitting FSS space stations be required to maintain this same minimum longitudinal separation of 0.2 from adjacent DBS satellites, and would extend to them the same limits on orbital inclination and eccentricity. It further proposes extending to transmitting FSS space stations, the requirement to provide antenna off-axis gain and PFD information over the same angular and frequency measurement ranges contained in our rules for 17/24
GHz BSS transmitting space stations.
The required angular measurement ranges and associated orbital parameters including longitudinal separation, inclination and eccentricity, are interdependent values. Accordingly, the offaxis angle occurring between two geostationary satellites will vary as a result of changes in these interdependent orbital parameters. The offaxis measurement ranges specified in our rules for 17/24 GHz BSS satellites are intended to encompass the angular range arising between DBS and 17/24
GHz BSS satellites with longitudinal separations as small as 0.1 degrees,50
while simultaneously accommodating operation of such space stations within typically observed orbital eccentricity and inclination values. At the time the current values for these parameters were chosen, the Commission sought to 48 47 CFR 25.264h and i. Orbital inclination is limited to less than 0.075 and orbital altitude may not exceed 35,806 km or fall below 35,766 km above the Earths surface. Although a DBS space station may exceed these bounds, it may not claim protection from any additional space path interference arising as a result of its excessively inclined or eccentric operations and may only claim protection as if it were operating within the defined bounds. See also, 17/24 GHz Space Path Report and Order at 894547, paragraphs 3941.
49 47 CFR 25.264a. Specifically, measurements must be made over a range of 30 from the X axis in the XZ plane, and over a range of 60 in planes rotated about the Z axis. This rule section also defines the X and Z axes using a cartesian coordinate system wherein the X axis is tangent to the geostationary orbital arc with the positive direction pointing east, i.e., in the direction of travel of the satellite; the Y axis is parallel to a line passing through the geographic north and south poles of the Earth, with the positive direction pointing south; and the Z axis passes through the satellite and the center of the Earth, with the positive direction pointing toward the Earth. See also, 17/24 GHz Space Path Report and Order at 894142, paragraphs 3031.
50 Taking the station keeping requirements of 0.05 into account, the required nominal separation between the two space stations is 0.2.

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provide 17/24 GHz BSS operators with the flexibility to locate at the small orbital separations they then sought, while simultaneously requiring the antenna off-axis gain measurement data to be made within ranges considered to be reasonable by commenters. We note however, that no 17/24 GHz BSS
operator has yet provided service from a location separated from a U.S.licensed DBS satellite by as little as 0.2
degrees.51 Moreover, in more recent instances, 17/24 GHz BSS applicants have sought waivers of our off-axis antenna gain measurement requirements, citing difficulties making measurements over the required angular ranges and or specified frequencies.
In its Petition, SES proposes FSS use in space-to-Earth direction for gateway earth stations, not direct-to-home consumer services. For such use, FSS
operators will not have the same economic incentives to locate space stations at such small longitudinal separations from DBS satellites i.e., to make use of a single subscriber receiving antenna. Thus, we believe that the minimum longitudinal separation from DBS satellites that FSS
space stations must maintain could be increased, resulting in more limited angular ranges over which antenna gain data must be measured.52 Requiring a minimum orbital separation between DBS and downlinking 17.317.8 GHz satellites of 0.5 degrees 53 would reduce the required angular measurement range in planes rotated about the Z axis to as little as 20 degrees. The corresponding reduction in measurement range in the XZ pane would reduce from 30
degrees to approximately 6 degrees.
51 Following adoption of minimum orbital separation requirements in the 17/24 GHz Second Report and Order, Spectrum Five LLC sought to operate from an orbital location of 119.25 W.L.
Spectrum Five LLCs application was granted although the grant later declared null and void. See Petition for Declaratory Ruling Regarding 17/24
GHz Broadcasting-Satellite Service to the U.S.
Market from the 119.25 W.L. Orbital Location, 33
FCC Rcd 153 IB, Sat. Div. 2012 declaring null and void Spectrum Five LLCs grant of access to the U.S.
market for a GSO satellite to be located at the 119.25 W.L. orbital location operating in the 17/24 BSS satellite.
52 One approach that might permit relaxation of the required angular measurement range for off-axis antenna gain and calculated PFD performance would be to increase the minimum orbital separation requirement between transmitting 17.3
17.8 GHz space stations and DBS receiving space stations from 0.2 degrees to a somewhat larger value. Similarly, further restricting the limits placed on orbital inclination and eccentricity could accomplish this, although this would seem somewhat impractical.
53 Taking an east/west station keeping allowance of 0.05 degrees into account a nominal orbital separation of 0.5 degrees results in an actual minimum orbital separation of 0.4 degrees.

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We propose to amend 25.264g of our rules to apply 0.5 degrees as the minimum orbital longitude separation that transmitting FSS space stations must maintain relative to DBS space stations, and to amend 25.264a to reflect the corresponding off-axis measurement angles, i.e., 10 degrees in the XZ plane and 20 degrees in planes rotated about the Z axis.54 We propose to retain our current requirements for orbital inclination and eccentricity, and propose to amend 25.264h to extend these values to FSS space stations. We seek comment on these proposals, and we ask whether 0.2 degrees or some different orbital separation value, or other orbital parameters would be more appropriate. Further, we tentatively conclude that this same change in the required minimum orbital separation value and corresponding antenna measurement angles could be extended to 17/24 GHz BSS space stations transmitting in the 17.317.8 GHz band.
We propose to similarly amend 25.264a and g with respect to 17/24
GHz BSS space stations, and we seek comment on these options, and on alternatives that might be appropriate.
Measurement Frequencies. To account for the frequency-dependent nature of antenna gain, our current rules require off-axis angular measurements to be made at a minimum of three measurement frequencies determined with respect to the entire portion of the 17.317.8 GHz band over which the space station is designed to transmit.55
Although we propose no changes in this requirement, we seek comment on whether our rules should be revised to permit increased flexibility in the measurement frequencies. If so, commenters should be specific regarding how such a rule should be restructured. Comments should address how many measurement frequencies should be required, over what range, and at what separation from each other.
Two-Part Data Submission Process. At present our rules require a two-part submission process for antenna off-axis gain data and associated PFD
calculations to demonstrate conformance with the off-axis PFD
coordination trigger.56 Under this 54 Smaller orbital separations would still be possible if a coordination agreement is achieved between the FSS and DBS operators.
55 47 CFR 25.264a4 and 5. Specifically, these are: 1 Five megahertz above the lower edge of the band; 2 at the band center frequency; and 3 five megahertz below the upper edge of the band. A
greater angular measurement range may be used, if necessary, to account for any planned spacecraft orientation bias or change in operating orientation relative to the reference coordinate system.
56 Initially the Commissions rules required analytical data to be included at the time of
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