Aviation Spectrum Re

Ex PARTE PRESENTATION NOTIFICATION LETTER submitted by Aviation Spectrum Resources Inc

Aviation Spectrum Resources, Inc. Written Ex Parte

2018-09-24

This document pretains to SES-AMD-20180531-00856 for Amended Filing on a Satellite Earth Station filing.

IBFS_SESAMD2018053100856_1538000

                                        KELLEY DRYE & WARREN LLP
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                                                September 24, 2018



  Ms. Marlene H. Dortch                                                           vw ECFS
  Secretary
  Federal Communications Commission
  445 12th Street, S.W.
  Washington, D.C. 20554

               Re;         Written Ex Parte Presentation of Aviation Spectrum Resources, Inc.: IB
                           Docket Nos. II-I09,12-340; IBFS File Nos. SES-MOD-20151231-00981,
                           SAT-MOD-2015123I-00090, SAT-MOD-20151231-00091, SES-AMD-
                           20180531-00856

  Dear Ms. Dortch:

          Aviation Spectrum Resources, Inc. (“ASRI”), by its attorney, hereby submits for
  inclusion in the record in the above-referenced matters the attached August 10, 2018, Letter of
  the Positioning, Navigation and Timing (“PNT”) Advisory Board (“PNTAB”)' containing its
  recommendation to the PNT Executive Committee (“EXCOM”) regarding the Ligado License
  Modification Application Amendment of May 31,2018 submitted in the above-referenced
  application IBFS Files (the “Ligado proposal”).^




  '       The PNTAB provides independent advice to the U.S. government on GPS-related policy,
  planning, program management, and funding profiles in relation to the current state of national
  and international satellite navigation services. The PNTAB consists of GPS experts from outside
  the U.S. government, with 25 members representing U.S. industry, academia, and international
  organizations. See https://www.gD$.uov/uovernance/advisory/
  2        Letter of Bradford W. Parkinson, U‘ Vice Chair, PNTAB, to Patrick M. Shanahan,
  Deputy Sec’y of Defense and Jeffrey A. Rosen, Deputy Sec’y of Transportation, dated Aug. 10,
  2018 (the “PNTAB Letter”), appended hereto. The PNTAB Letter can be found online at
  httns://rntfnd.orti/20]8/08/10/ijnt-board-letter-on-liEado-nublished/


      NG-2TSFKRLD 4835-6304-5236vl


                                 KELLEY DRYE & WARREN LLP

Ms. Marlene H. Dorteh
September 24, 2018
Page 2


        The PNTAB Letter stated that to assess potential interferenee from Ligado to GPS devices
“the only tests that met the PNTAB criteria were the DOT’S Adjacent Band Compatihility
[tests].The PNTAB Letter goes on to state that “We strongly support ‘no more than 25% (1
dB) noise degradation’, which is the long accepted international standard for evaluating
interference to GPS and similar systems.” PNTAB Letter at 1."^ In reviewing other testing
available, the PNTAB Letter states that the “[pjroof of ‘assured protection’ ascribed to Ligado-
sponsored tests ... were found inadequate & incomplete by independent review board.”^ The
PNTAB declares further that Ligado’s “suggest[ions] that the major GPS manufacturers have
agreed with their position” are “clearly untrue.” PNTAB Letter at 1.

        The PNTAB Letter quantifies the impact from lOW Ligado transmitters on general
aviation and helicopter (“GAV”) GPS receivers (of the non-certified category). PNTAB
explains that the bounding degradation radius for GAV receivers from a single Ligado tower at
low would be 1040 meters. Id., at 2. The PNTAB Letter also states that the minimum
separation between Ligado 10 W transmitters to protect GAV receivers at maximum 10%
degradation - meaning “avoiding degradation over at least 90% of the region near Ligado
transmitters” - would be almost 6.3 km. Id. The PNTAB Letter notes that even more restrictive
separation criteria may be needed “if Ligado is to operate without unduly interfering in real
world conditions.” Id.

        The PNTAB also addressed the economic arguments that have been submitted into the
record, concluding that the “risk is far too great, and far too many questions remain, for Ligado’s
proposal to be approved.” Id. at 3. The PNTAB Letter observes that, “[wjhile there are many
broadband alternatives (Ligado would be a very small percentage of this national asset), [a]ny
impairment to current and future uses [of GPS] is clearly contrary to the national interest.” Id.
The PNTAB adds that Ligado “[c]ontinues to totally ignore effects on new GPS signals (LIC)
and complementary GNSS systems (e.g. Galileo)'^ Id. (emphasis added). Notably, a recent PNT
study referenced in the PNTAB Letter ascribed that for High Performance GPS receivers alone,
there are over $31 Billion in annua! benefits.^




^      PNTAB Letter, Attachment, at 5, slide 10 (rating “Ligado Sponsored” and other tests for
“compliance with PNTAB criteria”). See also U.S. Department of Transportation, Global
Positioning System (GPS) Adjacent Band Compatibility Assessment (April 2018).
       The PNTAB “explicitly reject[s] Ligado’s critique of this {i.e., the 1 dB] standard.” Id.
5     Id., Attachment, at 2, slide 3 (Summary of the latest Ligado Proposal).
^     Id. at 2, citing The Economic Value of GPS: Preliminary Assessment, June 11, 2015,
found at https://www.tms.ttov/aovernance/advisorv/meetinas/2015-Q6/levesoivpdf


NG-2TSFKRLD 4835-6304-5236vl


                                    KELLEY DRYE & WARREN LLP

Ms. Marlene H. Dorteh
September 24, 2018
Page 3


       The PNTAB Letter concludes with the clear statement that “the technical consensus of the
PNTAB” leads the PNTAB to “strongly recommend [EXCOM’s] opposition to the Ligado
proposal. ” ^ leaving little doubt as to the collective views of the independent OPS experts
formally recognized and appointed by the US government.

     This letter is being filed with the Secretary’s office as required by Section 1.1206 of the
Commission’s Rules, 47 C.F.R. § 1.1206.

                                                      Respectfully submitted.



                                                      Edward A Yorkgitis, Jr.
                                                      Attorney for Aviation Sp<      ^um Resources, Inc.

Attachment

cc:     Rachael Bender, Advisor to Chairman Pai
        Erin McGrath, Advisor to Commissioner O’Rielly
        Umair Javed, Advisor to Commissioner Jessica Rosenworcel
        Will Adams, Advisor to Commissioner Carr
        Julius Knapp, Office of Engineering and Technology
        Ronald Repasi, Office of Engineering and Technology
        Paul Murray, Office of Engineering and Technology
        Michael Ha, Office of Engineering and Technology
        Charles Mathias, Wireless Telecommunications Bureau
        Jose Albuquerque, International Bureau
        Karl Kensinger, International Bureau
        Robert Nelson, International Bureau




’       PNTAB Letter at 3 (bold emphasis in original). The Chair and certain members of the PNTAB recused
themselves from the PNTAB Letter “to avoid any appearance of a conflict of interest.” Id.



NG-2TSFKRLD 4835-6304-5236vl


                               ATTACHMENT
                           August 10, 2018, Letter of
            the Positioning, Navigation and Timing Advisory Board
        containing its recommendation to the PNT Executive Committee
      regarding the Ligado License Modification Application Amendment
                                of May 31, 2018




NG-2TSFKRLD 4835-6304-5236vl


August 10, 2018
Honorable Patrick M. Shanahan, Deputy Secretary of Defense
Honorable Jeffrey A. Rosen, Deputy Secretary of Transportation
Co-Chairs, National Executive Committee for Space-based Positioning, Navigation and Timing
Herbert C. Hoover Building, Room 2518
1401 Constitution Ave., NW
Washington, D.C. 20230


Subject: PNT Advisory Board (PNTAB) Recommendation to PNT Executive Committee (EXCOM) Regarding Latest
Ligado Proposal
Dear EXCOM Chairs and Members,
On the 31st of May 2018, Ligado Networks amended its Federal Communications Commission (FCC) license
modification application. They have proposed reducing initial transmitter power to ~ 10 watts and abandoning use
of the band closest to Global Positioning System (GPS) frequencies. Unfortunately, they have not specified
transmitter spacing nor do they propose a feasible scheme for monitoring their interference levels, expecting the
GPS user to contact them instead.
We recognize the need for efficient spectrum management. At the same time, we believe it is imperative that we
follow the PNT EXCOM stricture to not adversely affect current and future GPS uses. To pursue this purpose, we
strongly support “no more than 25% (1 dB) noise degradation”, which is the long accepted international standard
for evaluating interference to GPS and similar systems.
Ligado has never agreed that this international standard applies to their proposed use of the adjacent band. They
have suggested that the major GPS manufacturers have agreed with their position. This is clearly untrue. Trimble,
Deere, and Garmin have all recently responded with filings that specifically support use of the 25% degradation
standard 1. They explicitly reject Ligado’s critique of this standard and Ligado’s attempts to use other, unconventional
criteria that would not protect all GPS uses.
We believe GPS users should be protected everywhere. But even if the nation decided to apply the 1 dB criterion to
only 90% of the area surrounding Ligado transmitters, their new proposal must be rejected. Their revised ~ 10 watt

1 Comments filed on Ligado’s May 31, 2018 Amended License Modification Application in Docket 11-109:
Comments of Garmin International, Inc. July 9, 2018: “In its Amendment, Ligado again criticizes the use of a standard metric-a
1 dB decrease in a GPS device’s carrier-to-noise-density ratio (“C/No”) (the “1 dB Standard”) – as a threshold determinant of
harmful interference to a GPS receiver’s operation.” “As Garmin has documented extensively in the record, the 1 dB Standard is
the long-established and appropriate determinant of harmful interference to GPS and other Radio Navigation Satellite Service
(RNSS) receivers”
Comments of Trimble Inc. July 9, 2018:“To the extent that, in evaluating the Modification Applications, the Commission
addresses the standard for determining the potential for harmful interference to Global Positioning System (“GPS”) and Global
Navigation Satellite System (“GNSS”) devices and applications, it should dismiss Ligado’s calls for the rejection of the long-
established interference protection criterion for GPS/GNSS receivers of a 1 dB decrease in the Carrier-to-Noise Power Density
Ratio (“C/No”) and the proposed alternative use of key performance indicators (“KPIs”).”
Comments of Deere and Company, July 9, 2018: “Deere nonetheless advises that its position with respect to Ligado’s Amended
Modification Applications must not be interpreted as acquiescence in or, in any way agreement with, Ligado’s continued efforts
to depart from long-accepted practice and establish a new metric for determining potential harm to GPS and other GNSS systems
based on Key Performance Indicators (“KPIs”). Deere does not agree with this approach and reaffirms its staunch support for
application of a one (1) dB decrease in Carrier-to-Noise Power Density (“C/N0”) (the “1 dB Standard”) as the appropriate metric
for determining whether a GPS receiver has experienced harmful interference.”


maximum Effective Isotropic Radiated Power (EIRP) proposal far exceeds the power level that can be tolerated by
the GPS-user community at the previous spacing of ~400 meters by a factor of over 2,500.
We believe avoiding degradation over at least 90% of the region near Ligado transmitters is the absolute minimum
protection for GPS receivers in each class. This would be a hypothetical 90% Protection Evaluation. This is not an
endorsement of this level since of course, all users would prefer 100% protection. The Department of Transportation
(DOT) Adjacent Band Compatibility (ABC) study is the only validated test 2 to verify degradation at various received
power levels.
Those results inform that to insure degradation not exceed 10% of the Region (90% Protection) for High
Performance receivers, either:
    •    Ligado maximum power can be no more than .0036 watts at the 400-meter spacing they had earlier
         planned. Tolerable power would be 3/10ths of 1% of their proposed ~ 10 watts. (see enclosure)
         Or
    •    The closest spacing of Ligado transmitters is 20,000 meters 3 (over 12 miles) for their proposed ~ 10 watt
         power level (see table below for other receiver classes)




While the GPS high performance receivers are the most sensitive to interference, they are also the most valuable.
The most recent PNT EXCOM study ascribed over $31 Billion in annual benefits to this class alone 4.
As restrictive as these criteria are, they may need to be even more so if Ligado is to operate without unduly
interfering in real-world conditions. When performing the calculations to arrive at these criteria, we did not consider
the following points that would impose greater restrictions:
    •    The aggregate noise created by transmissions from multiple towers
    •    Reflections from the ground and buildings which can increase interference by a factor of 10 or more
    •    The impact on PNT uses of newer GNSS signals, such as those from Europe’s Galileo GNSS
    •    Impacts on Military Users



2 National PNT Systems Engineering Forum (NPEF) GAP Analysis, March 5, 2018
3 Separation to insure degradation not exceed 10% for other classes of receivers is in the following Chart (see enclosure for
explanation of ABC data that gives the Bounding Degradation Radius)
4 The Economic Value of GPS: Preliminary Assessment, June 11, 2015.

https://www.gps.gov/governance/advisory/meetings/2015-06/leveson.pdf

                                                             2


In addition, it is not reasonable that one interference source, Ligado, be allowed to use up the whole interference
budget for GPS.
We believe there are further serious concerns about the impact of Ligado’s proposed operations on special, and
scientific users of GPS that should be fully explored, such as:
    •    Unmanned Aerial Vehicles (UAVs)
    •    Weather data and forecast
    •    Space-based receivers
This risk is far too great, and far too many questions remain, for Ligado’s proposal to be approved. While there are
many broadband alternatives (Ligado would be a very small percentage of this national asset), there is only one GPS.
Any impairment to current and future uses is clearly contrary to the national interest.
Therefore, implementation of their recently proposed ~ 10 watt operating scheme will create totally unacceptable
interference for a great number of GPS users in the United States. In fact, despite power limits in their current
amended application, it is probable they could still be allowed to increase this power over time. This would be even
more destructive to GPS users.
This is the technical consensus of the PNTAB. We strongly recommend your opposition to the Ligado proposal.
Data from the DOT’s ABC Study was used to reach these conclusions. This study, the third formal examination of this
issue by the PNT EXCOM, met all scientific criteria for a credible national evaluation. Calculations and graphs used
to support these results are provided in the attachment.
Sincerely,




___________________________________________________
Bradford W. Parkinson, 1st Vice-Chair, on behalf of the PNTAB
(PNTAB Chair and some members recused to avoid any appearance of a conflict of interest)
Enclosure: Supporting calculations and graphs
cc:
− PNT EXCOM Departments and Agencies
− Hon. Jim Bridenstine, NASA Administrator
− Dr. Scott Pace, Executive Secretary, National Space Council (NSpC)
− Hon. David Redl, Assistant Secretary for Communications and Information and Administrator, National
  Telecommunications and Information Administration (NTIA)
− Mr. Julius Knapp, Chief, Office of Engineering and Technology, FCC
− Mr. Harold “Stormy” Martin, Director, PNT National Coordination Office (NCO)




                                                         3


                                      8/9/2018




          Analysis of
   Ligado May 2018 Proposal
        and Assessment
          August 2018

              PNTAB




Bottom Line Up Front

      • The PNTAB strongly
    recommends disapproval of
  Ligado’s amended proposal for
      ~10 watt transmitters
                of
           May 31, 2018

                                  2




                                            1


                                                                                              8/9/2018




           Summary of the latest Ligado Proposal:
1.    Completely abandons terrestrial use of the 1545-55 MHz band
2.    Reduces Power from 1.5kW to ~10 Watts in 1526-36 MHz band
3.    Unspecified distance between Transmitters
4.    Monitoring up to users, who must use a call-in number
5.    Proposal asserts that it resolves all aviation issues (Aviation community filings
      disputes this)
6.    Does not directly address most sensitive receivers – High Performance - but
      say “Ligado’s co-existence agreements with major GPS manufacturers and
      thousands of hours of empirical testing assure protection for all other classes
      of GPS devices”. Note: High-Performance receivers create over $30B per year
      in identified benefits to the US.
      •    Ligado statement is not true. Top three manufacturers support international
           standard of 1 dB degradation, equivalent to a 25% drop in GPS signal power.
      •    “New” Ligado 10W proposal violates noise standard by factors of 2500 or more at
           400m spacing.
7.  Proof of “assured protection” ascribed to Ligado-sponsored tests that were found
    inadequate & incomplete by independent review board. So “proof” is an erroneous
    statement.
8. Completely ignores ABC testing for most categories of receivers, which clearly
    shows proposal is unacceptable.
9. Continues to totally ignore effects on new GPS signals (L1C) and complementary
    GNSS systems (e.g. Galileo)
10. Military receiver impacts – i.e. M-code must be discussed by USAF who apparently
                                                                                  3
    oppose the proposal




     Adjacent band interference concern
                                        “Upper” band is apparently off the
                                             table. Is this forever?




         “Lower” band Power reduced to ~10 Watts. Spacing not specified but
       original was ~400 meters. To meet broadband requirements it is possible
      that this will be less. Perhaps about 100 to 200 meters. Plausibly, perhaps
      Micro or Femtocells. Microcells typically are a watt at 500 Meters coverage
             (~1 km spacing). Femto cells are 100 milliwatts at 30 Meters.

                                       Assured PNT for All                                4




                                                                                                    2


                                                                                                  8/9/2018




    Summary Rationale for Disapproval
• PNTAB believes use of GPS should be protected everywhere and for all current and future
  uses as directed by EXCOM letter in 2011. The “G” in “GPS” should really be Global.
• At “new” ~10 watt power, tower spacing would have to be at least 20.4 kilometers to
  protect High Performance Receivers, even if only protected over 90% of coverage area
• Viewed another way, with 400 meter spacing, Ligado power would have to be further reduced
  from ~10 watts to 0.0036 watts (2500 times lower) to protect tested High Performance
  Receivers, even if only protected over 90% of coverage area.
• Asking the High Performance GPS Users to monitor the interference is totally unrealistic –
  they would not know how to do it, and would have no means to trace the problem to Ligado.
• Ligado continues to ignore emerging use of modernized GPS and GNSS signals. Impacts to
  receivers tracking these wider bandwidth signals could be worse than for current GPS signals
• If Ligado’s current license is approved, their spokesperson implied that over time they would
  expect to be allowed power increases. Temporary power reductions offered only to gain
  regulatory approval must be recognized as such and rejected.
• Proposal is deliberately vague on geometry and spacing of towers. Ligado has repeatedly
  declined to provide these critical technical details to PNTAB to enable full and accurate
  assessment of interference. They have addressed Aviation (433m) and ignored High
  Performance Uses that have been shown to be much more sensitive to degradation.
                                                                                          5




                             The Evidence
      • Definition -Degradation Radius is the distance
        from the transmitter, beyond which the
        international interference standard is not violated.
      • That standard (1 dB degradation) is equivalent to a
          25% drop in GPS signal power
           Conceptually, the radius defines a circle of
          degradation.
                 --------------------------
      • All major GPS manufacturers, the US Air Force,
        DOT, the Aircraft Industry and many others
        strongly support this International standard.
      • The DOT ABC report performed a detailed analysis
        in Appendix I. These scientific results form the
        basis for our analysis
                                                                                          6




                                                                                                        3


                                                                                                          8/9/2018




  Overview: Transmitter Power, Transmitter Tower
  Spacing and Percentage Degradation Area for GPS
                      receivers
• Virtually all receivers will be degraded if they are too
  close to a Ligado Transmitter (overwhelm the “front-end”)
• Consider a hypothetical case, where receivers can be
  degraded up to 10% of their operating area
   • Then degradation radius around each tower must be less than
     0.17 times the spacing This is called the Degradation Limit
     Radius
   • This can be achieved by either reducing power or
     increasing spacing (decreasing tower density)
• Earlier Ligado proposal is that tower spacing should be
  ~400 meters.


                                 Assured PNT for All                                                  7




  A visual Example:
  To insure additional                           90% Area
  interference noise does not                   Protected –
  exceed 25% International                    spacing = 6.0 *
  Standard either:                              Degradation
  • Limit closest Transmitter                   Limit Radius
    Spacing for a given power
        Or                                       50% Area
                                                               Why is Transmitter Spacing Critical?




                                                Protected –
  • Constrain Power for a given
                                              spacing = 2.4 *
    spacing (Reduce Degradation Radius)         Degradation
                                                Limit Radius
  Green – Un-degraded                                          Why is Transmitter Spacing Critical?



                                                20% Area
                                               Protected –
                                              spacing = 2.1*
                                               Degradation
                                               Limit Radius



                                                                                                      8




                                                                                                                4


                                                                                                                       8/9/2018




     Tradeoff – Degradation Radius versus % of Region Degraded –
                                           Relationship defined by simple, directly‐scalable geometry…

                                        Percentage Degraded Area for Various Degradation Radii
    Percentage of Area Degraded   100
                                   90
                                   80             No degradation exceeds 1 dB
                                               beyond 0.17 of Transmitter spacing
                                   70
                                                – or transmitter spacing is 1/0.17
                                   60              times the Degradation Limit
                                   50                        Radius.
                                   40
                                   30
                                   20
                                   10      10%                                    Degradation Limited to
                                                                                       10% of Area
                                    0
                                        0.00        0.10       0.20        0.30         0.40      0.50     0.60
                                               Degradation Radius ‐ Fraction of Transmitter Spacing
                                                                  Assured PNT for All                             9




 Reminder: the only tests that met the PNTAB criteria
     were the DOT’s Adjacent Band Compatibility




                                                                                                 Ligado
Key:                                                                                           Sponsored   “ABC”
Fully Compliant

Non‐Compliant

                                                                  Assured PNT for All                             10




                                                                                                                             5


                                                                                            8/9/2018




     Example of ABC Test Results: Interference “Masks”
 (Tolerable Received Power from Adjacent Band –all receivers in each class)




                                                  Band




  Received
    Power
  should be                     Lower
    below                       Ligado
                                                 GPS
                                 Band
     lines                       1530            1575
                                 MHz             MHz


                                         Assured PNT for All                         11




On the same Scale – Received GPS power is less than 1/10000th
           of the Adjacent band degradation power.
   That is the reason GPS is located next to the MSS band




                                                 GPS
                                                 1575
                                                 MHz
                Interference
               Power should
                  be below
                    lines      Lower
                               Ligado
                                Band
                                             GPSBand
                                                  signal is
                                1530          1/10,000th
                                MHz              Max
        ‐110                                 Interference
                                Lower
                                Ligado
        ‐120                     Band
                                                                   GPS received power at
                                 1530                                  ‐128.5 dBm =
        ‐130
                                 MHz                                 1.41 e‐16 Watts
                                                               0.000000000000000141 Watts
        ‐140
                                         Assured PNT for All                         12




                                                                                                  6


                                                                                    8/9/2018




  Determining Allowable Transmitter
 power from ABC measured acceptable
            GPS Receiver degradation
• The DOT also performed a detailed analysis of
 transmitter antenna patterns and transmitter power
 levels around the proposed transmitters.
• They used the measured receiver Interference Masks to
  calculate allowable transmit power at various ranges
  from the Ligado Transmitters
• Considered Classes of receivers (80 were tested):
   • High Precision and Networks (HPR)
   • General Aviation and Helicopters (non-certified) (GAV)
   • General Location/Navigation including emergency response
     vehicles (GLN)
   • Timing (TIM)
   • Celluar (CEL)
                                                                               13




         From Appendix I -DOT Test and Analysis:
                High Performance Receivers –
    Impacts of single 10W Ligado micro-Urban transmitter.
                       * Degradation Radius is 3.4 Km.
                * Start loosing Low Elevation Satellites at 560m.
                      Start Loosing All Satellites at 170m

                560 m
            Loss of
         lower elevation
              Sats




                                                                    3400 m =
     170 m
                                                                Degradation
     Loss of
                                                                  Radius
     all sats




                                                                               14




                                                                                          7


                                                                                        8/9/2018




   Hypothetical Tower Spacing Example for
        High Performance Receivers
• Assumptions:
    • Ligado Power of 10 Watts
    • Hypothetical protection of only 90% of transmitter region
• What is the closest spacing that would insure GPS
  protection from 25% noise increase?
    • Answer: 6.0 times the degradation radius. Previous example
      showed a 3400 Meter Degradation Radius from ABC Report
      Appendix I
• Therefore: Protection of High Performance Receivers
  would require tower spacing of 20.5 km (12.7 miles), even
  if protected over only 90% of the cell area

10 watt transmitters clearly incompatible with
       use of High Precision Receivers
   (in fact All of Region is degraded at spacing of 5 km)
                                                                                   15




       Using the ABC Degradation Radii ‐Calculation of
  minimum Ligado 10W separation for various Classes of GPS
                        receivers
                                 Bounding       Minimum Separation Between
                            Degradation Radius   Ligado 10 Watt Transmitters
                             for Receiver Class           (Meters)
 Class of GPS Receiver
                           with 10W Transmitter      % Region Protected
                            (from ABC report –
                                Appendix I)     90%        50%        10%
 High Performance/ High
    Productivity (HPR)        3400 meters         20,481       8190         6104
Emergency Vehicles and
General Navigation (GLN)      1045 meters          6295        2815         2098
  General Aviation and
   Helicopters (GAV)          1040 meters          6265        2802         2088
      Timing (TIM)            293 meters           1765         789          588
       Cell (CEL)              9.5 meters           57           26           19
                                 We strongly believe 90% is the minimum Area
                                Protection Criterion (maximum 10% degradation)
                                                                                   16




                                                                                              8


                                                                        8/9/2018




For closer spacing - Maximum allowable Ligado Power
                      to insure:
   GPS Protection for 90% of Transmitter Region .

    High                     Tower Spacing
Performance
 Receivers      1000   400    200                            100
 Protected     Meters meters meters                         meters
   All          .023 W        .0036 W            .00089 W   .00022 W


Based on envelope of quantitative data taken from 40 Different HPRs,
           tested by DOT for Adjacent Band Compatibility




                           Assured PNT for All                     17




It may be worse – not included in analysis…
 • Multiple towers contribute additive noise
 • Reflections from ground and buildings can
   increase normal 1/R2 models by factors of over
   10 (Factors of 15 measured in Las Vegas tests)
 • The newer GNSS signals have wider RF
   bandwidths for greater accuracy and A/J, but
   the receivers also may have greater sensitivity
   to the adjacent band power. In ABC tests, the
   Galileo E1 signal was more sensitive for HPRs.
 • The new military signal deliberately pushes
   energy away from the center frequency, closer
   to Ligado power.
                           Assured PNT for All                     18




                                                                              9


                                                                                 8/9/2018




  Clash – Fundamental Incompatibility
                        Ligado Proposals
  ~ Date     Power       Spacing                      Comments
                                           Original "Thanksgiving" Proposal to
    2010     15.6 kW    400 Meters
                                                          FCC
                                            Quickly dropped power when PNT
    2012     1.56 kW    400 Meters
                                                  community protested
    2015     1.56 kW    400 Meters                   Same as 2012
    2017     19.8 W    Would not say       Verbal only: less than 400 Meters?

    2018      9.8 W    Did not specify     New filing – claimed compatibility

DOT Adjacent Band Compatibility Tests – 90% Protection Evaluation




                             Assured PNT for All                          19




  PNTAB Recommendations
  • Strongly recommend rejecting latest Ligado
    10 watt proposal
      • Does not meet PNT EXCOM January 2012 goal to
        protect “existing and evolving uses of space-
        based PNT services”
      • Not even close
  • Apply DOT Adjacent Band Compatibility
    (ABC) results and methodology to any future
    proposals


                                                                          20




                                                                                      10


                                  8/9/2018




         Backups



                             21




 Instead of constraining
  Minimum transmitter
  separation, consider
 Constraining the Ligado
   Transmitter Power
           and
Still meeting the 90% Area
  Degradation Criterion
                             22




                                       11


                                                                                                                                            8/9/2018




                                                             Example of    Transmitter constraints
                                                                      (Ligado originally requested 1.56 kW)




Max Tolerable Ligado Power ‐ Watts
                                      1
                                                                      Not Tolerable
                                      .1                     > 25% noise increase
                                     .01                                        3.8 milliwatts for 400m transmitter
                                                                                spacing – protection beyond 68m.
                                     .001
                                                                                                                      Tolerable Power at
                                                                                                                           distance
                                      .0001                            68
                                                                       m.
                                                                                      For 90% of Area to be protected, degradation
                                     .00001                                           radius must not exceed 0.17 times transmitter
                                                                                       spacing. With 400 meter tower spacing, that
                                                                                              distance would be 68 meters.

                                      0             100       200     300        400
                                                HighDegradation
                                                     Precision Receiver
                                                                Radius ‐ –Meters
                                                                           Maximum
                                      HighTolerable      Lxxx
                                           Precision Receiver    PowerTolerable
                                                              – Maximum vs Distance
                                                                                Ligado Power vs
                                                                      Distance (all HPR receivers –             Ligado at 1530 MHz)


                                                                                        Assured PNT for All                            23




                                          To achieve Protection over 90% of Region by
                                     Applying a power constraint for various closest Distances
                                                  Between Ligado Transmitters –
                                     At 1 kilometer, Ligado power must be less than 0.023 Watts

                                                                                     Maximum Transmitted Power
                                                                            Degradation limited to 10% of Transmitter Region
                                          Maximum Transmitted Power




                                                                            1



                                                                        0.1
                                                   Watts




                                                                       0.01                                    Protect All HPR…

                                                                                                1 Km Microcell Spacing? Ligado power
                                                                                                    must be less than 0.023 Watts
                                                                      0.001
                                                                               0     1000     2000      3000      4000    5000
                                                                                Distance Between Ligado Transmitters
                                                                                                 (Meters)
                                                                                                                                       24




                                                                                                                                                 12


                                                                                                                           8/9/2018




Three Levels of Adjacent
Band Interference - ABI
           Already Presented
           1. Increase of noise floor by >25% (the “1dB” criterion).
              We have used this level to define the “Degradation
              Radius”
           But there are two more serious levels:
           2. Onset of total loss of Low Elevation Satellites – the
              “Loss of Low Elevation” radius.
           3. Onset of total loss of all satellite signals – the “Total
              Loss” radius
           The calculation of % of regional area with a particular
           ABI effect proceeds in the same way as the 25%
           degradation (#1)


                                                                                                                   25




             High Performance Receiver Loss of GPS signal
            10 Watt transmitter Power (First Low elevation, then all Satellites)
            560 m
             Loss of
           lower Sats



100%                                                               High Perfomance Receivers
                                                                        Percent of Area
     90%
                                                                  Loosing Satellites Completely
                            3040 m > 25%
170 m
                            Noise Increase
Loss of
all sats




     80%                                                       for Spacing 0f 10 Watt Transmitter
                                                                * Loss of Low Elevation Satellites
     70%                                                             * Loss of all Satellites
     60%                                                               Loss of low elevation
                                                                                                   Loss of low elevation
                                                                         satellites exceeds
     50%                                                                50% of Area when
                                                                                                  satellites exceeds 10%
                                                                       spacing is less than       of Area when spacing
     40%                                                                  1.4 kilometers.             is less than 3.4
                                                                                                        kilometers.
     30%
                                              If 10 Watt spacing is
     20%                                     less than 500 meters
                                               HP Receivers begin
     10%                                      to lose all satellites
                                                over 50% of Area
           0%
                        0           1000                         2000                      3000


                                             Transmitter separation – Meters
                                                                                                                    26




                                                                                                                                13


                                                                                                                 8/9/2018




Analysis for all three levels of Interference was performed by DOT ‐
       Examples for various classes of GPS Receivers follow
 Emergency Services and General                      Helicopter and General Aviation Receiver Degradation
 Navigation Receiver Degradation                                              Radii
              Radii                                           102 m 10 Watt transmitter Power
   10 Watt transmitter Power                                    Loss of
                                                                 lower
                                                                  Sats




                                                           41 m
                                                          Loss of                                      1040 m
                                1045 m                    all sats                                      > 25%
                                 > 25%                                                                  Noise
                                 Noise                                                                Increase
                               Increase

      Timing Receiver Degradation Radii
         10 Watt transmitter Power
             87 m
           Begin Loss
               of
           lower elev.
              Sats




   27 m
   Begin
   Loss
     of
                                           293 m
     all                                   > 25%
    sats                                    Noise
                                          Increase
                                                                                                            27




Q. What should the
degradation radius be, such
that no more than 10% of a
given region is degraded?

A. It scales directly with the
separation distance and, for
10% regional degradation, is
0.17 times that separation.
           (At 0.57 times separation, 100% is degraded)

                                                                                                            28




                                                                                                                      14


                                                                               8/9/2018




Max Ligado Transmitter Power and tower density
should be constrained by the % area that is degraded

                                               Geometric problem directly
                                                 scales with spacing of
                                                    transmitters (d)
                                               Furthest point from all is at
                                                1/30.5 times d = 0.57 * d

                                             For Example:
                                              At 0.57 *d, 100% of the area
                                                    would be covered

                                                What degradation
                                              radius would result, if
                                                degradation were
                                              limited to 10% of the
                                                      area?
                       Assured PNT for All                              29




                                     To Protect GPS for 90% of an
                                       area, with transmitters at
                                     spacing d, degradation radius
                                       must be less than 0.17 d.
                                       (i.e. Less than 17 % of the
                                                 spacing)




 Whatever the Ligado spacing, to protect 90% of the Region,
 the degradation radius must not exceed 17% of the Spacing
                   between Transmitters
                       Assured PNT for All                              30




                                                                                    15


                                                           8/9/2018




   Results for other classes of receivers –
 Maximum Tolerable Power at certain sizes of
             Degradation Circle
  From DOT Adjacent Band Compatibility Tests

          Degradation
          Circle Radius




 In fact, using the ABC results and the proposed 10
 Watt Ligado transmissions, 50 % of the 40 tested
HPR receivers would be degraded beyond the 10%
degradation circle at a transmitter spacing of 280
                      Meters
                                                      31




                                                                16



Document Created: 2018-09-24 14:19:09
Document Modified: 2018-09-24 14:19:09

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