ViaSat Aero Ex Parte

Ex PARTE PRESENTATION NOTIFICATION LETTER submitted by ViaSat, Inc.

Ex Parte and Erratum

2013-02-15

This document pretains to SES-LIC-20120427-00404 for License on a Satellite Earth Station filing.

IBFS_SESLIC2012042700404_986264

                                                                 555 Eleventh Street, N.W., Suite 1000
                                                                 Washington, D.C. 20004-1304
                                                                 Tel: +1.202.637.2200 Fax: +1.202.637.2201
                                                                 www.lw.com

                                                                 FIRM / AFFILIATE OFFICES
                                                                 Abu Dhabi       Moscow
                                                                 Barcelona       Munich
                                                                 Beijing         New Jersey
                                                                 Boston          New York
                                                                 Brussels        Orange County
February 15, 2013                                                Chicago         Paris
                                                                 Doha            Riyadh
                                                                 Dubai           Rome
VIA ELECTRONIC FILING                                            Frankfurt       San Diego
                                                                 Hamburg         San Francisco
                                                                 Hong Kong       Shanghai

Ms. Marlene H. Dortch                                            Houston         Silicon Valley
                                                                 London          Singapore
Secretary                                                        Los Angeles     Tokyo
Federal Communications Commission                                Madrid          Washington, D.C.
445 Twelfth Street, SW                                           Milan

Washington, DC 20554


               Re:    Ex Parte Submission and Erratum; IBFS File Nos. SES-LIC-20120427-
                      00404; SES-STA-20120815-00751, Call Sign E120075

Dear Ms. Dortch:

       ViaSat, Inc. (“ViaSat”) submits this ex parte to supplement the record in the above-
captioned application proceedings. Enclosed are:

       (i) A supplement to Telesat’s coordination confirmation letter, further confirming that
Telesat has taken into account its existing coordination agreements in evaluating ViaSat’s
proposed operations, and that it will include those parameters in future coordinations; and

       (ii) An erratum to two pages of the ViaSat Technical Response filed on January 24, 2013,
which corrects a math error that occurred in converting ViaSat’s statements about 4.5 sigma and
4.9 sigma probability events into percentage equivalents. Notably, that correction has no
material bearing on ViaSat’s Technical Response or the statements in the Response of ViaSat.

       If you have any questions regarding this submission, please do not hesitate to contact the
undersigned.



                                             Respectfully submitted,

                                                    /s/

                                             John P. Janka
                                             Elizabeth R. Park

Enclosures



DC\2430015.1


Ms. Marlene H. Dortch
February 15, 2013
Page 2




cc:       Robert Nelson
          Andrea Kelly
          Stephen Duall
          William Bell
          Howard Griboff
          Paul Blais
          Joseph Hill
          Byung K. Yi
          Alyssa Roberts
          Kathyrn Medley
          Kal Krautkramer
          Cindy Spiers
          Hsing Liu
          David Keir, Counsel to Row 44, Inc.




DC\2430015.1


    Telesat
1601 Telesat Court                                                 EN2013-002
Ottawa, Ontario K1B 5P4                                            12 February 2013




Federal Communications Commission
445 12lh Street, SW
Washington, DC 0554

Attention: International Bureau

Re: Supplement to Engineering Certification of Telesat Regarding IBFS File No. SES-
    LIC-20120427-000404.SES-STA-20120815-00751

Telesat provides this update to its Engineering Certification dated December 18, 2012
regarding the coordination of ViaSat's proposed Ka band aeronautical earth stations,
which will operate over the Teles at-licensed WildBlue-1 and Anik-F2 networks at
ni.rwx.
Telesat has taken its existing coordination agreements for the WildBlue-1 and Anik-F2
networks into account in evaluating the parameters of ViaSat's proposed AES operations,
and confirms that it will take those ViaSat parameters into account in its future
coordination agreements with respect to WildBlue-1 and Anik-F2.



Respectfully submitted,




E. A. Neasmith, CD, M.Sc. (Eng), P.Eng
Manager ITU and Coordination
Office of CTO
Telesat




           Tel: 613-748-8700 • Fax:613-748-8712 • Information: http://www.telesat.com


ERRATUM
February 15, 2013

In addition, as the AES must be operating at specific locations in order for energy from the
sidelobes and grating lobes to fall in the vicinity of a victim satellite, ViaSat developed a detailed
geospatial model that considers among other things, the actual antenna pattern, the AES location,
the target satellite, and the victim satellite. The output of this model was shared with satellite
operators during discussions and depicts the areas in which an AES must operate to cause a
given rise over thermal noise (ΔT/T) level. In many cases the aircraft must be operating outside
the service coverage area in order to produce a meaningful increase in noise. However, as that
theoretically could occur only outside the coverage area of the service satellite, no potential for
interference actually exists because the transmitter would be disabled in those instances.

Row 44’s pointing error projections rely on incorrect statistical analyses.

ViaSat actively monitors both azimuth and elevation pointing errors and will inhibit
transmissions when the declared pointing error limit is exceeded on either axis independently of
the other. ViaSat has a long history of making antennas for dynamic antenna pointing
applications, including mobile platforms. The antenna control unit (“ACU”) that ViaSat will use
in this case is based on the same technology used in ViaSat’s existing Ku band mobile systems
and will ensure compliance with the antenna pointing accuracy limits stated in ViaSat’s
application.

Row 44 presents what purports to be a formula to project the pointing error along the GSO. Row
44 uses this formula to produce the table on page 6 of its Technical Appendix and claims that the
results in the table represent the 1-sigma or 3-sigma likelihood of the maximum pointing angle
for the indicated skew angle. Row 44’s application of the formula and presentation of the data in
the table are wrong in two ways.

First, the joint probability of two 1-sigma or two 3-sigma events is not itself a 1-sigma or 3-
sigma event.

The joint probability of two independent 3-sigma events is given as follows:

       P(az = 3-sigma ∩ el = 3-sigma) = (1 – 99.73) x (1 – 99.73)

       0.0027 x 0.0027 = 7.29 x 10-6 ≈ 4.5 sigma, or 7.3 x 10-410-8%

Thus the azimuth error and the elevation error both reach a 3-sigma value simultaneously only
0.000000073% of the time – if they are independent events. However, they are not completely
independent.

In the case of the Mantarray antenna, the azimuth and elevation errors are actually inversely
correlated to a degree in that the worst case azimuth and elevation error each actually occur when
the other axis is least likely to experience significant error. This inverse correlation is a function
of the elevation angles at which the peak velocities for azimuth and elevation occur.
Specifically, azimuth pointing errors have the greatest chance of occurring when the AES is
pointing at high elevation angles (e.g., near the equator), and elevation pointing errors have the
greatest chance of occurring when the AES is pointing at low elevation angles (e.g., operating at


                                                  2


ERRATUM
February 15, 2013


higher latitudes). This reduces the actual likelihood of a simultaneous dual axis 3-sigma event
even more.

Second, while Row 44 includes the ± sign for the azimuth and elevation error in its table, Row
44 only includes the results for cases where both axes have the same error sign, i.e. both positive,
or, both negative values. This characterization of the error scenario for the maximum pointing
error across GSO as a 1 or 3-sigma event is wrong. In fact, because half of the time the azimuth
or elevation error will have a negative sign, the probability of dual axis 3-sigma events along the
GSO would more correctly be:

       (0.5 x 0.0027) x (0.5 x 0.0027) = 1.28 x 10-6 ≈ 4.9 sigma or 1.28 x 10-410-8%

That is, only 0.0000000128% of the time would both antenna axis experience simultaneous 3-
sigma error events where the error direction is additive.

In any case, the pointing error performance of the Mantarray has been disclosed and coordinated
with other potentially affected satellite networks.

Row 44 mischaracterizes ViaSat’s antenna design and manufacturing process.

In describing alleged deficiencies in ViaSat’s antenna construction, Row 44 makes incorrect
assumptions about the Mantarray antenna’s design and assembly. Row 44 claims that
manufacturing tolerances will not be precise enough to produce horn spacings that are uniform or
repeatable, and thus, the grating lobe pattern will vary among units. Row 44 also claims that the
effects of aging and varying environmental conditions could change the antenna performance.

The Mantarray antenna design is composed of three parts: 1) a thin uniform fiber reinforced
dielectric window or aperture closeout for environmental protection, 2) a single grid plate with a
number of waveguide openings or apertures that is a multiple of the number of horns, and 3) a
single horn plate with a number of individual waveguide openings or apertures. Items 2 and 3
control the grating lobe characteristics by careful layout and choice of the interleaving of horn
and grid openings.

The grid plate and horn plate are precision milled from single pieces of aircraft grade (6061-T6)
aluminum stock to very high tolerances in a temperature controlled environment. Finished parts
are 100% dimensionally inspected using a state-of-the-art computer controlled coordinate
measuring machine. Locating pin features are used to insure proper mating between the grid and
horn plates and the two components are bonded into a single assembly in a temperature
controlled environment using the precise machine locating features. Finally, each unit is 100%
RF tested in a state-of-the-art antenna measurement facility during production prior to integration
with the positioner, and no antenna will be deployed that does not meet its performance
requirements regarding grating lobes.

These manufacturing and testing processes ensure the uniformity and repeatability of antenna
construction. In addition, the performance of the Mantarray antenna is not expected to change


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Document Created: 2013-02-15 13:22:05
Document Modified: 2013-02-15 13:22:05

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