Comments of Garmin I

COMMENT submitted by Garmin International, Inc.

Garmin International, Inc. Comments

2018-07-09

This document pretains to SAT-AMD-20180531-00044 for Amended Filing on a Satellite Space Stations filing.

IBFS_SATAMD2018053100044_1452143

                                    Before the
                      FEDERAL COMMUNICATIONS COMMISSION
                                  Washington, DC 20554

In the Matter of                            )     1B DocketNo. 12340
                                            N
LightSquared Request to Modify Its ATC      )     IBFS Bile Nos, SAT—MOD—20120528—
Authorization                               )     00160; SAT—MOD.2012002%.00161;
                                            )     SaT—MOD—20101118—00239; SEs—MoOp—
                                            )     20121001—00872; SAT—AMD—20r80531—
                                            )     00044;SAT—AMD—20180531—00045
                                            )
                                            )
                                            )
LightSquared Technical Working Group        )     18 DocketNo 11—109
Report                                      )




                                         GARMIN INTERNATIONAL, INC.
                                                M. Anne Swanson
                                                      of

                                                Wilkinson Barker Knaver, LLP
                                                1800 M Street, NW, Suite 800N
                                                Washington, DC 20036
                                                2023833342

                                                Its Atomeys

Dated: July 9, 2018


                           TABLE OF CONTENTS

SUMMARY.
1.    INTRODUCTION
IL    TiE LIGADO MODIFICATION APPLICATIONS, AS AMENDED, DoNOT FULLY
      ADDRESS IMPORTANT CONSIDERATIONS AND RECOMMENDATIONS RAISED
      BY EXPERT AVIATION REGULATORY BODIES AND AVIATION PARTTES    3
TL    CONCERNS ABOUT HARMPUL INTERFERENCE TO HELICOPTER USE OF
      CERTIFIED AVIATION DEVICES, ALREADY DOCUMENTED IN THE RECORD
      REMAIN UNADDRESSED .       —                                 6
IV.   THE UNIVERSALLY RECOGNIZED 1 dB STANDARD IS THE PROPEX METRIC
      FOR ASSESSING INTERFERENCE..................
      CONCLUSION....


                                           stmmany
       Garmin does not oppose the Ligado Modifieation Applications and recently filed

Amendment, consistent with its setlement agreement with Ligndo.
       "The aviation—zelated changes in the Amendment represent a positive advence on these
jssues. Ligudo‘s proposed adoption ofa 9.8 dBW power level, as suggested recently by the U.S.
Department of Transportation, is a first step toward protecting certified aviation GPS devices. The

proposal, however, does need to be accompanied with consideration and commitments regurding
corollazy restrictions on the spacing of towers/transmitters, as well as regarding cortain antenna
parameters —such as height, downtlt, and polarization.

       Deereasing the power of individal ancillary terrestrial component base stations is only
effective in lowering aggregate power levels if site spacing or tower density remains consistent
with assumptions made in the original analysis, Antenna height, downtit, and polarization are
also critical variables in any power calculation. Variations from the Department of
Transportation‘s assurmptions must be considered in evaluation ofa power level proposal.
Without consideration and commitments regarding these issues, protection of Garmin‘s certified

aviation GPS devices is not assured.

       The effect of Ligado‘s proposals also needs to be considered with respect to helicopter
operators‘ reliance on certified aviation GPS devices. Maximizing public availabilty of
information about Ligedo‘s proposed "standoffeylinders" is paramount to ensure safe
implementation with respect to certfied aviation GPS devices.

       Garmin respects the FAA‘s jurisdiction and expertise regarding certified aviation issues,
and grant of Ligado‘s Modified Applications and Amendment should be preceded by explicit


FAA determination and acknowledgement that operation of the proposed network is compatible

with cortified aviation devices.

       Finally, Garmin remaina strong supporter of applicationof a 1 dB decrease in a GPS
device‘s carrier—to—noise density ratio (°CNy") (the "1 dB Standard®) as a threshold determinant
of harmful interference to the deviee‘s operations. Use ofany alternative measure based on only
user experience will fail to cousider the vast number of devices, uses, and environments in which

GPS devices are deployed. ‘The 1 dB Standard is very relevant and appropriate to this
proceeding because the design changes ongoing at Garmin in connection with the settlement
agreement itselfe based on ensuring that ts GPS products are not degraded by more than 1 dB
C/N; in the presence of Ligado signals. Garmin agreed not to oppose the Ligado Modification

Applications precisely because, speaking anly for Gazmin‘s devices, the technical parameters to
which it agteed in the Settlement Agreement were basod on its own testing using the 1 dB
Standard

        The 1 dB Standard is also relevant to Gazmin‘s certified aviation devices. As discussed

in these comments, the receiver‘s CMNo link budget, used in the Radio Frequency Interference

analysis that underpins roceiver performance standards, t times has less than 1 dB ofmargin
As also discussed, these considerations are relevant as woll to ensuring certiied avistion devices®

abilityto process informationfrom GPS avgmentation systems.

       GPS manufacturers in the U.S. need a consistent, universal, and quantifiable metric to

incorporate into their product designs and testing.. Absent that, future product development,
innovation, and the country‘s GPS and GNSS technology lead will be adverselyaffected. The
1 dB Standard is vital o ensure such continued development and to ensure U.S. devices are

internationally compatible and competitive.


                                           Before the
                      FEDERAL COMMUNICATIONS COMMISSION
                                     Washington, DC 20554

in the Matter of                                 )
                                                 )
LighiSquared Request to Modify Its ATC           )      1B DocketNo. 12340
Authorization                                    )
                                                 )      TBPS File Nos. SAT—MOD—20120028—
                                                 )      00160; SAT—MOD—20120928—00161;
                                                 )      SAT—MOD—20t01112—00230; sEg—MOD—
                                                 )      20121001—00872; SAT—AMD—20180531—
                                                 )      doors; SAT—AMD—20180531—00048
                                                 )
LightSquared Technical Working Group             )      1B DocketNo. 11—109
Report                                           )




         Garmin International, Inc. ("Garmin®)files these comments in response to Ligado
Networks L1.C‘s (*Ligado‘s") amended applications for modification of ts Mobile Setellite
Service (°MSS®) licenses.‘. As discussed in detail below, Garmin submits these comments to
supplement the record on two points: i) consideration of recommendations from aviation
regulatory partics and aviation stakeholders related to continued safe operation of Garmin‘s
certified avistion products; and (i) use of a 1 dB decroase in the Carrier—to—Noisc Power Density
Ratio (°C/N,°) as a metric t measure interference to an affeeted GPS receiver (the "1 dB
Standard"). In processing the Modification Applications and Amendment,it is important that the
FCC take both points into account.
‘ See Applications of LightSquared Subsidiary LLC, Narrative, IBFS File Nos. SAT—MOD—
20151231—00090, SAT—MOD—20151231—00091, and SES—MOD—20151231—0081
(‘Modification Applications"); Ligado Networks LLC Amendiment License Modification
Applications, IBES File Nos. SAT—AMD—20180531—00044 and SAT—AMD—20180531—00045
("Amendment®). See also FC , Satellite Policy Branch Information, Spuce Station Applications
Accepted for Filing, Public Notice, Report No. SAT—01321, at1 (tel. June 8, 2018). in these
comments, Garmin uses the term "Ligado" to refer to Ligada‘s predecessors


L      INTRODUCTION

       Garmin, along with ts affiliates, is a leading, worldwide provider ofnavigation
equipment, committed to making superior products for automotive, avietion, marine, outdoor,
fitness, and sports uses that are an esseatial part of ts customers‘ lives. Garmin has a long
history of innovation and of working with the Pederal Communications Commission (°PCC"or
"Commission‘), other agencies, and communications and navigation stakholders on vita issues
concerning spectrum use.
       Since its founding almost 30 years ago, Garmin has evolved into a leading, worldwide
provider of certified avistion devices, almost all of which ere enzbled by Global Positioning

System ("GPS") technology. Garmin‘s broad, overall product portfolio serves a wide range of
customers and brings critical safety—0f—life applications to the global marketplace.
       Gasmin has long supported the development ofnew broadband services in this country; t
believes, however, that broadband deployment generally should not come at the expense of harm
to the nation‘s well—functioning, innovative, and economically important GPS service. With

respect to the particular service pat forward by Ligado, Garmin entered into a settloment
agreement with Ligedo in which Garmin agreed not to object to Ligndo‘s proposals regarding
Garmin‘s non—certified aviation and general location/ravigation lines of business as long as

certain technical parameters were met." At the same time, Garmin reserved the right to comment

onissues related to certified avietion devices." In addition, Garmin and Ligedo did not reach an

agreement about whether the 1 dB Standard was an appropriate metricto use to evaltate
* See Settlement Agreement and Releases, by and between Gazmin Internetional, Inc. and New
LightSquared LLC and LightSquared Subsidiary LLC, at Paragraphs 9(2)& 10(a) (dated Dec.
16, 2015) ("Settiement Agrocment"), attached to Letter from Gerard J. Waldron to Marlene H.
Dortch, IB Docket Nos. 12—340 eral. (filed Dec. 17, 2015).
" Settlement Agreement at Pamgraphs 7(d) & 9(a).


interference, and Garmin continues to participate actively in discussions ofthe issue.* Finally,
the parties to the settlement agreed that Garmin‘s exccution of the agreement did not constitute
an endorsement byGarmin of Ligado‘s proposal, and Ligado agroed not to make any statement
or represcntationto that effect." Garmin‘s agreement with Ligado addresses its own GPS
devices and does not speak to protection for all GPS devices.
11.    THE LIGADO MODIFICATION APPLICATIONS, AS AMENDED, Do NOT
       FULLY ADDRESS IMPORTANT CONSIDERATIONS AND
       RECOMMENDATIONS RAISED BY EXPERT AVIATION REGULATORY
       BODTES AND AVIATION PArrhes
       ‘The avistion industry overall has been one ofthe primary beneficiaries of the
development ofGPS, andthe ECCmust vigilantly continue to consider concerns regarding the
potential impact ofLigade‘s proposed service on certiied aviation devices. Given the
essentiality of GPS for aviation, where safety—of—life is of paramount concem, ccrtified aviation
devices must continue to operate on an interference—free basis. As Ligado has recognized,
evaluation of anyinterference must be based upon tochnical determinations byavistion safety
experts at the Federal Aviation Administration (*FAA") and RTCA, Inc. Their expertise will
help ensure interference—free operation.
       Ligedo‘s latest filing proposes several aviation—related changesto its proposals and
represcats a positive advance on these issues.* Specifically, Ligadosuggeststhe following three
changes: () lowering the power level of ts ancillary terrestrial component (*ATC®) base stations
operating in the 1526—1536 MHz band to 9.8 dBW(10 W) with a +/~ 45 degree cross—polarized



* ui Paragraph 6(h).
* Ad at Paragraph 12.
* See Leter from Gerard J. Waldron er al. to Marlene H. Dortch, IB Docket No. 11—109 er al,
(Aled May 31, 2018), with attached Ameadment.


base station antenns; (i) probibiting any Tigado ATC base station antenna in this band from
operating ata locationless than 250 feet laterallyor less than 30 fect below an obstacle clearance
surface established bythe EAA; and (ii} requiring Tigadoto comply with reporting, notification,
and monitoring obligetions discussed in the Amendment."

       Ligado‘s proposed adoption of the 9.8 dBW power limit follows a recent
recommendationto thateffect put forward bythe U.S. Department of Transportation in its "Final

Report"issued after a multi—year "OPS Adjacent Rand Compatibility Assessment."* This
decrease in power is a firsstep toward protecting certifed aviation receivers; however, such a
step by itself absent consideration and commitments regarding coroilary restretions on the
spacing oftowers and transmitters — inter—site distances ("ISD‘s") between such locations — is
insulficient to protect Garmin‘s certified aviation receivers. Similerly, without consideration and
commitments regarding antenna parameters —such as height, downtil, and polarization ~
protection of Garmin‘s cerified aviation receivers is not assured."
       First, decreasing the power ofindividual ATC base stations, us Ligedo has proposed, is
only effective in lowering aggregate power levels if site spacing or tower density remains
consistent with assurnptions made in the original analysis."" Changes in cellste density
necessitate compensating adjustments in power levels. For instance, if tower density were to
" 14 at 1—2 & Amendment
* U.S. Department ofTransportation, Global Positioning System (GPS) Adjacent Band
Comparibility Assessment, Final Report,at VI, 149 (Apr. 2018) (DOT/ABC Final Report"),
hilpsofwwwstransportation.sov sites‘dotgovlles/docs/subdoc/1 86/dot—zps—adjacent—band—final—
reportapril2018pdfo
* As the DOTABC Final Report notes, the 9.8 dBW power level it recommended is highly
deperdent upon and sensitive to these anterna parametrs. /. at 148.
‘° DOTassumed ATC base stations arrangedin a hexagonal grid formation with 433 meter and
693 meter ISDs. 1d.at Tables 5—5 & 5—9; 152—153.


inerease beyond the leve! assumed in the DOT/ABC Final Report without anycompensating
adjustment to the power level, certified aviation devices would likely experience harmful
interference,
        Second, antenna height and antenna downtiltare critical variables in any power
calculation, and variations from DOTFAA assumptions must be considered in evaluation of:
power level restrction. Ligado‘s publicly discussed proposals for its network include providing
communications and data connectivity for unmanned aerial vehicles ("UAVs") or drones."
Tikting or turning antennas skyward to provide such connectivity for UAVs would likely cause
harmful interference to eertified avietion devices, without compensating changes, and must be
taken into account in evaluating the Modification Applications and Amendment. Accordingly,
PAA—sanctioned limits should be captured explicitly in FCC processing ofthe Modification
Applications and Amendment.
        In like manner, the polarization of transmitted signals must be explicitly addressed in
evaluation ofproposed power levels. Ligado‘s Amendment is insufficiently specific with respect
to the issue of polarization. Por instance, fits ATC base stations will only be cross—polarized at
the degreo specified in the Ameadment, it needs to commit to that on the record. The 9.8 dBW
power level recommended bythe DOT/ABC Final Report only pertains to an analysis utlizing
eross—polarized signals."*: Becouse of the greater sensitivityof certified aviation devices to


"" John Crof, LighiSquared Successor Fuses Space and Grownd Networksfor UAS, Aviation
Week (Apr. 18, 2017),hitp:/avietionwoek.com/cornected—nerospacelihtsqusred—successor—
fuses—space—and—ground—networks—uss; see also Press Release, Ligedo Networks, Remarks af
Ligado Networks CEO Doug Smith at Politico Live "SpectrumImovation, and Infrastructure in
the Trimp Era." (June 15, 2017), hitps:/igadocom/oress/remarks—ligado—networks—ceo—loug—
sithe

7 DOT/ABC Final Report at 149. As the DOT/ABC Final Report itsolf recommends, "a
requirement for cross—polarization emissions from the base stations must be captured in any
                                                  5


vertical polarization, Ligado needs to be explicit aboutitsplans with respect to polarization, so
power levels can be assessed accurately.
T1t.   CONCERNS ABOUT HARMPUL INTERFERENCE TO HELICOPTER USE OF
       CERTIFIED AVIATION DEVICES, ALREADY DOCUMENTED IN THE
       RECORD, REMAIN UNADDRESSED

       Various parties have raised concers,in particular, sbout the effect of Ligedo‘s proposed
ATC base stations on the safety of helicopter operations that rely upon certiied aviation devices
for navigational guidance."" In the Amendmont, Ligndo assumes aireraft will be 250 feet from
one of its ATC base stations —a "standoff eylinder" of thatradius."* Yet, helicopter operators

have raised concerns about their sbilty, when operating near such proposed stardoif cylinders,
to relyon GPS—based navigation and GPS—enabled capabilities for obstacle/errain avoidanco and
position reporting with other air bound operations."



Hicense application or issuance. A vertical polarization (only) based limit must be significantly
lower than 9.8 dBW." 14.
"" See, e., Letter from Capt. Tim Cunoil, President, Air Line Pilots Associstion, Intemnational
("ALPA®), eral., to Daniel K. Elwell, TB Docket Nos. 12—340 er al, at 2 (filed Jume 18, 2018)
("Aviation Parties‘ June 2018 Letter®) (The letter was filed on behalf ofALPA, Airbomne Public
Safety Association, Airerat Owners and Pilots Association, Airlines for America, Association of
Air Medical Serviees, Helicopter Association Interational, Helicopter Safety Advisory
Conference, National Agricultural Aviation Association, Nationa! Business Aviation
Association, National EMS Pilots Associstion, and Professional Helicopter Pilots Association));
Letterfrom Edward A. Yorkgitis I., Counsel for Aviation Spectrum Resources, Inc. ("ASRTY),
to Marlone H. Dortch, 1B Docket Nos, 12—340 ef al, at 2—3 & Attachment B (filed June 20, 2017)
(ASRI June 20, 2017 Letter®) (The letter reflected participation also by Airlines for America,
Helicoprer Association Interational, and Aerospace Industries Association.)
!* Amendment at 1—3.
‘* Aviation Parties‘ June 2018 Letter at 2; RTCA, Tnc. "Operetional Review of Ligado Networks
Proposal for Standoff Cylinders (Approved by the Tactical Operztion Committec December
2016)," Dec. 2016 ("RTCA TOC Report‘), at S,available at bitp:/fprod—ha.rtoa.ore373elwb,
 Meckmesh,com/sites/de(aultiles e        dec_2016 summary;pdf("Artachment 4");ASRI June 20,
2017 Letter at2—3.


       These concems about aviation safety wrise for a number of reasons, Pirst, there currently
is no codified aviation prohibition on rotorwing airerall entering such standorf eylinders.!"
Second, contrary to support forthe eoncopt in RTCA participants‘ review ofLigndo‘s proposals,
there is no indication that information on the location of Ligado‘s ATC base station towers and
their related standoff cylinders wl be made publicly available."" As aviation partics have
recommended,        such information is provided in a database to the operational community, and
the obstacle data was [sic] incorporated into equipment performing TAWS/HTAWS function.
this would begin to help ensure safety."®. Without publicly uvailable information,a large
question remains as to how helicopter pilats using ccrtified aviction equipment will know
whether or not they are operating within a standoP eylinder.""
       On the other hand, making standof eylinders part of the FAA‘s Digital Obstacle File
database or other publicly available sources would go a long wayto support compliance with
flight planning requirements, help operators avoid standofeylinders, and reduce the potential for
inadvertent flights across or into eylinders with the attendant possibility of fight acidents*


* See, eg., 14 C.F.R § 91.119, setting forth a helicopter exemption related to minimum safe
altitudes, which relies on publicly available FAA information and parametens in the rule, but
makes no reference to standards akin to Ligado‘s proposul.
!" Exhibit 1 to the Ameadment provides for base station data to be submitted to the ECC and
FAA with public availability ofthe information allowed only through the FCC‘s codified
confidentiality procedures, which permit very limited access to contidentia information.
* RTCA TOC Report at 6.
"" *Operators remain concerned that 10000 ~20,000 Standoff Cylinders may be in the [National
Airspace SystemJ and pilots may not know where they are. ‘here is interest in understanding
how operators may know where these cylinders are, and operators should be engaged to provide
input into howthis information would be made available toaviation stakeholders."1.
* See FAA, Digital Obstacle File (DOF) https:/Arwsw fan gov/nir_traffic/light info/aeronay=
{digital_products/dof/ (ast visited July 9, 2018), which includes the following description: ("The
Digital Obstacle File (updated every 56 days) describes all known obstacles of intorest to
                                                  7


Maximizing publicly evailable information is peremount because, as the DOT/ABC Final Report
noted, avietion community concems include the possibility that, even with full public access,
"pilot workload, conflision, or errar could lead to aireraft inadvertcntly entering an assessment
zane [or Standoff Cylinder] and losing needed GPS functionality."*"
       The FCC, working closely with the FAA, needs to focus on, and exhaustively review,
theso safety—related concerns. Not only did the DOT/ABC Final Report catalog them, but, as
recently as several weeks ago, a large number ofavistion industry stakeholders, having had an
opportunity to reviewthe DODABC Final Report and Ligndo‘s latest fling, concluded that "the
concemns and safety issues of e industry have NOT been addressed.""". Similarly, the

DOT/ABC Fina! Report itselfacknowledged thet "[t}he FAA hes not completed an exhaustive
evaluation ofthe operational scenarios in developing the assessment zone(s]" or standoff
eylinders." In addition, the Report noted that "the cxrrent analyses do not include an operational

aviation users in the United States, with limited coverage ofthe Pacific, the Caribbcan, Canada,
and Mexico....")

        FAA helicopter air ambulance fight planning regulations require consideration of terrain
and obstacies, and simailar steps could be taken with regard to this information to ensure aviation
sufety. See 14 C.F.R § 135.615(a), which with respect to visual fight rales("VFR") flight
planning provides for a number ofrequirements, including the following: "Prior to conducting
VER operations, the pilot in command must (1) Determine the minimum safe eruise altitude by
evalusting the terrain and obstacles along the planned route offlight; (2) Identify and document
(he highest obstacle along the planned route of flight."
* DOT/ABC Final Report at VIL. The DOT/ABC Fina! Report summerized the following
additional concems regarding standoff eylinders: "technical and human factors issues associated
with re—initialization ofGPS after loss of the signal or when the signal reception is intermittont;
workload and buman factors impacts on pilots to monitor and (rack assessment zone locations;
... ind impacts to onboard and ground systems that are dependent upon GPS, such as Automatic
Dependent Surveillance (ADS) Broadcast‘Contract (3/C), or fixed—wing and helicopter terrain
awareness warting system including obstecle alerting."" Ad.
* Aviation Parties‘ June 2018 Letter at 2.
" DOTABC Final Report at VIL


assessment ofthe impact of the assessment zone[s} in densely populaled areas, which may
present additional variables, including the risk posed to people and property for operations such
as UAS using certified avionics which may be required to operate within the assessment zone.""*
       Garmin respects the FAA‘s jurisdiction and expertise regerding certified aviation issues
and related safety concerns and reiterates that grant of Ligado‘s Modified Applications and
Amendment should be preceded by explicit FAA determination and acknowledgement that
operation of the propased network is compatible with certified aviation devices

Iv.    THE UNIVERSALLY RECOGNIZED 1 dB STANDARD IS THE PROPER
       METRIC FOR   AsS  iG   RFEREN

       In its Amendment, Ligado again criticizes the use of a standard metrie—a 1 dB decrease
in a GPS device‘s carrier—to—noise—density ratio (°C/Ng®) (the "I dB Standard") —as a threshold
determinunt of harmful interference to a GPS receiver‘s operation.""

       Ligado‘s position overlooks the eriica! differences between navigation and
communication systems and the underlying engineering concepts that govern their operation. As
Garmin has documented extensivelyin the record, the 1 dB Standard is the long—established and
appropriate determinant ofharmfil interference to GPS and other Radio Navigation Satellie
Service (‘RNSS®) receivers. As Garmin lso recently highlighted, this is the case whether the
1 dB Standard is applied to out—of—band emissions (*OOBE") that emanate from services in
adjacent bands but fall within the RNSS band or overload interference that emenates from
services in adjocent bands and overpowers receivers in the RNSS band."" This metric is the

"g
** Amendment at n.9.
** Letter from M. Anne Swanson to Marlene H. Dortch, TB Docket Nos. 11—109 eral. at 2—5 (filed
May16, 2018) (‘Garmin May 2018 Letter"), eiting U.S. Air Foree, SMC/GP (GPS Directorace},
Background Paper on Use of1—dB decrease in C/Np as GPS Interference Protection Criterion, at
                                                 9


appropriate standard for evaluating harmful interference from adjacent band services because it
successfully apgregates increases in the noise floorfrom OOBE alongside degradation from
overload interference, and it does so in a manner even more generous than some existing
recommendations cited by the Air Force analysis endorsing use of the 1 dB Standard."" As
Garmin has noted, a holistic approach is a more effective and reasonsble regulstory approach to
resolving this issue than a piecemeal regime, which focuses separately on diffecent types of
interference affecting the same devices."*

       As noted above, Garmin‘s Settlement Agreement with Ligado specifically provides that
the parties did not reach an agreement sbout whether the 1 dB Standard was an appropriate
metric to use to evaluate interference, That agreement also provides for spocifiedtemporal
periods during which Ligndo will operate its network at reduced power levels to permit time for
the design and development of hardened receivers that will be able to tolerate interference at the
levels specified in the Settlement Agroement. The 1 dB Stundard is veryrelevent and
appropriate to this proceoding because that design change, which is ongoing at Garmin, is itsclf
based on ensuring that its GBS productsare not degraded bymore than 1 dB C/Niin the presenco
ofLigado signals. Garmin agreed not to oppose the Ligado Modification Applications precisely
because, speaking onlyfor Garmin‘s devices, the technical parameters to whichit agreed in the
Settlcment Agreement were based on its own testing using the 1 dB Standard


2, 6—9 (June 2017), wwwaps.gouspectrum/ABC/ dB—background—paper.pdf. and also citing
HeaaRTy & Karcan Rs., Understanding GPS, Principles and Applications, Section 5.111
(Artech House, Boston, 2nd Ed. 2006).

* Garmin May 2018 Letter at 4.
* Id; see also Letter from F. Michael Swiek to Marlene H. Dortch, IB Docket Nos, 12—340 er a.,
at 2—11 (fled July 13, 2017); Comments of Garmin International, Inc., TB Docket Nos. 12—340 er
al. at 8—19 (filed May 23, 2016)

                                                 10


        Without use of the universal and objective 1 dB Stundard Garmin‘s testing to ensure
compliance with the Sertlement Agreement would devolve into an administratively unproductive
and ineffective exercise. The same is true fortesting interference to GPS deviees in other
contexts: without use of the 1 dB Standard. individual and unique test scenarios would need to be
developed for thousands ofuse cases — whether in automotive, aviation, marine, outdoor, fitness,
or sports applications. The extensive volume of festing required across a host ofsubjective
measurements of user—cxperienced "accuraey," when multiplied bythe plethora of test scenarios,
would yield a vast amount ofdata that would simplybe administratively staggering — and
unlikely to demonstrate any universal trend or establishment of anyother reliable metric
Regulators who reject use of the 1 dB Standard would face a daunting task and likely one that
would prove inconclusive and unproductive in the end.
       Indeed, the volume ofdata accumulated in the NASCTN testing ofjusta select few
devices, which relied on an approach other than the 1 dB Standard, was extensive."" As Garmin
has previously discussed, these results actually provide direct and indirect support for use of the
1 dB metrie: "direct" support because the NASCTN test data showed a direct correlation
between a 1 dB drop in C/Ns anddegradation of the key performance indicators that were
analy7ed: "indirect"support by highlighting the extreme complexity ofan approach like
NASCTN‘, which focused only on measuring the effect of interfering signals on selected key
performance indicatorsof the GPS devices under test""
® William F. Young, er al, LTE /mpacts on GPS Final Test Report, National Advanced
Spoctrumand Communications Test Network ("NASCTN®) (Feb. 15, 2017), htps: nclpubs«
1nist.gov nistpubs/TechnicalNotes/NIST.     N. 1952.pdf
  Garmin May 2018 Letter at 4—5.
                                                 1


       The 1 dB Stendard is also relevant to Garmin‘s certified aiation devices, and Ligndo‘s
jmplication to the contrary in its Amendment is overly simplistic. There are numerous instances

in which use of the 1 dB Standard is very relevant to designing and assessing the performance of
Garmin‘s certified avistion devicos.
       ‘The 1 dB Standard is relevant to certified aviation devices precisely because the
receiver‘s CNo link budget is used in the Radio Frequency Interference analysis that underpins
the receiver performance standerds considered by RTCA und the FAA."! For instance,in the

Wide Area Augmentation System ("WAAS"), there is less than a 1 dB of mergin available for
sdditional interference beyond that which was envisioned in the existing standard."" With
WAAS, "oven small changes in the C/No link margin can have significant adverse consequences
on receiver and ultimately navigation system performance."".As litle as "a 0.4 to 0.6 dB
difference in link mazgin, under certain seenarios, can change the WAAS word error rate by an
order of magnitude, Loss of continuity probabilityis closely tied tthis and certain other key




*‘ The link budgot is a foundational equation amalgamating all system gains and losses
(including interference) from the GPS satellite tothe receiver. The link budget allows system
designers to ensure sufficient link margin (and safety margin) exists to accommodate the known
losses the system will encounter (e.¢.. path loss, interference, otc.).
* WAAS is a regional space—based augmentation system operated by the FAA to provide
extremely accurate navigation information for civil aireraft operating throughout North America.
See PAA, Satellite Navigation — Wide Area Augmentation System (WAAS), hitps:/wwnfuo—
«golabouoffice orghesdquarters offices/ato/service_units/techops/nayservices/gnsswans (last
visited July 9, 2018); see also GPS, Augmentation Systems... Wide Area Augmentation System
(WAAS), hupsswwow, ops.gow/systems/augmentations (last visited July 9, 2018). (Although
WAAS is "designed primarily for aviation users, WAAS is widely available in receivers used by
other positioning, navigation, and timing communities.").
* RTCA, nc., Assessment ofRadio Frequency Interference Relevant to the GNSS L1 Frequency
Band, RTCA/DO—235B, prepared byRTCA SC—150, Mar. 13, 2008 at §2.6.3, at 23.
                                                12


receiver performance measures (e.2. carrier phase error).""" Contrary to Ligedo‘s contention, the
1 d3 Standard is relevant tocertified aviation safety concerns as well.
       GPS menuficturersin the U.S. need a consistent, universal, and quantifiable metric to
incorporate into their product designs and testing. Without that, fature product development,
innovation, and the U.S. lead in GPS and other Global Navigation Satellite System ("GNSS®)
technologies will be adversely affected. The | dB Standurd is vital to ensure such continued
development and to ensure U.S. devices are intemationallycompatible and comperitive,
¥.     CONCLUsION
       Garmin does not object to the Modification Applications and Amendment, consistent
with the terms ofNits Settlement Agreement, which permit it to make comments on issuesrelated
to certified avistion devices and the 1 dB Standard. Garmin respectfully requests that these
comments be taken into nccount as the FCC reviews the Modification Applications and
Amendment.
                                              Respectfully submitted,
                                              GARMIN INTERNATIONAL, INC.
                                              ny. 4O AJ——
                                                  M. Anne Swanson
                                                        of
                                                  Wilkinson Barker Knauer, LLP
                                                  1800 M Street, NW, Suite 800N
                                                  Washington, DC 20036
                                                  2023033342
                                                      Its Attomeys
Dated: Joly 9, 2018
"r
                                                 13



Document Created: 2018-07-09 16:52:12
Document Modified: 2018-07-09 16:52:12

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