Exhibit C Interference Analysis

0158-EX-CN-2019 Text Documents

Swarm Technologies, Inc.

2019-03-08

                                                                                  Swarm Technologies Inc.
                                                                                 Exhibit C to FCC Form 442
                                                                                              March 8, 2019
                                    Exhibit C - Interference Study


Interference and Electromagnetic Compatibility Study

        The experimental Swarm satellite network, which includes 3 satellites and 2 US
earth stations1, employs the 137-138 MHz band for space to earth and earth to space
links, consistent with the US and International table of frequency allocations. To
demonstrate compliance with an experimental systems obligation to operate on a non-
interference basis with other authorized operators in the bands, this report provides a
three part electromagnetic compatibility study with the existing authorized users.
Specifically, the report includes: 1) a study of compatibility with terrestrial services,
2) a study of compatibility with other satellite systems, and 3) a study of compatibility
with radio astronomy services.


Statement for Terrestrial and Aeronautical Mobile System Compatibility

       ITU Radio Regulations impose power flux density (PFD) limits that trigger
coordination for certain terrestrial (fixed and mobile) and aeronautical mobile systems
                                                                2
in the 137-138 MHz band and adjacent 138-143.6 MHz band . In summary the PFD
thresholds that trigger coordination are as follows:

      ● Terrestrial Services: -125 dBW/m​2​/4KHz
      ● Aeronautical Mobile (R): -125 dBW/m​2​/4KHz
      ● Aeronautical Mobile (OR): -140 dBW/m​2​/4KHz

     Figure 1 shows a plot of the expected PFD at Earth’s surface for all angles of
arrival at the operational orbit altitude. Note that due to the antenna gain pattern, the
PFD at ​Earth’s surface diminishes significantly as the satellite elevation increases
towards 90 degrees. The gain pattern is optimal for communications at elevations 10 to
60 degrees where the majority of ground access time occurs.




1
 The three satellites for which an authorization is sought will transmit only when within line of sight of two
US earth stations, one in Los Altos CA, and one in Atlanta GA, when commanded by the ground
station. No other earth stations will transmit to the three satellites.
2
    ITU RR Appendix 5, Annex 1, article 1.1.1 and 1.1.2


                                                                  Swarm Technologies Inc.
                                                                 Exhibit C to FCC Form 442
                                                                              March 8, 2019




     Figure 1. PFD at Earth’s surface produced by a satellite transmission

         In summary, the power flux density (PFD) at the Earth’s surface produced by the
Swarm satellites will not exceed -145 dB(W/m²) in any 4 kHz band at any angle of
arrival, which is under the threshold for coordination with both terrestrial services and
aeronautical mobile (R or OR) and therefore​ does not trigger a coordination requirement.



Statement of Satellite ServiceSystem Compatibility

        From the ITU Space Network Systems Online (SNS), a list of satellite systems
using the 137-138 MHz band was collected and shown in Table 1. For each satellite
system, the table indicates the administrative jurisdiction, service areas, frequency
overlaps, and ultimately a disposition for a coordination requirement. Most satellites
have either no frequency overlap with Swarm satellites, have no area coverage overlap,
or have no apparent earth stations in the USA. In addition, a search of the FCC IBFS for
the 137-138 MHz band show that only Orbcomm is licensed for a space system using
these space services links within the United states. In summary, only Orbcomm
Satellites, and NOAA N require some form of coordination for operations in the USA.
Swarm will seek consent from both the NTIA and Orbcomm regarding those systems.


                                                                                Swarm Technologies Inc.
                                                                               Exhibit C to FCC Form 442
                                                                                            March 8, 2019

        The Interference Protection Criteria (IPC) for meteorological satellites3 in the
137-138 MHz band is -136 dBW per 150 kHz. This IPC is applicable for the NOAA N and
NOAA KLM satellites. There is no frequency overlap with NOAA KLM and therefore no
interference is expected. The NOAA N earth stations may have an isotropic gain as high
as 10 dBi4 and in this case the signal power from a Swarm satellite into a NOAA N ground
receiver could reach -132.8 dBW exceeding the IPC. This however will be a rare situation
where a Swarm satellite is transmitting at the same time the NOAA N earth station is
pointed in the direction of the Swarm satellite (given a 10 dBi antenna has some
directionality). In fact, potential interference conjunctions above -136 dBW/150 kHz IPC is
estimated to occur less than 0.00037% of the time which meets the IPC limit of less than
0.0063% of the time (as specified by the previously referenced ITU recommendation.)
This is estimated as follows5: The Swarm transmissions will occur less than 0.069% of the
time daily over each ground station. The NOAA N satellite may transmit up to 3.3% of the
time daily in the same area. A 10 dBi earth station antenna has a 6 dB beamwidth of
approximately 72 degrees, which is about 16% sky coverage. This results in a potential
interference conjunction exceeding -136 dBW into the earth station receiver no more than
0.00037% of the time. Therefore the experimental Swarm satellite system meets the IPC
for NOAA N and coordination should not actually be required. Note that this estimate
assumes the worst case scenario that the satellites share a similar orbit and equatorial
crossing time and anything otherwise would yield a smaller conjunction percentage.


       There are two other satellite systems shown in the tables below deserving
additional attention, IMDC and SI-SAT-BILIKIKI. In each of these two cases
there is potential frequency overlap and the USA is a designated coverage area in the
ITU notices. However, none of these systems have launched yet, and no US licenses
or applications were submitted to the FCC as of December 2017. The IMDC system is a
single satellite by the company Innovative Solutions In Space in the Netherlands. It
appears there will only be an earth station in the Netherlands. The SI-SAT-BILIKIKI is a
planned large Mobile Satellite Service constellation by Pangea Networks LLC. Pangea
Networks is a US based company but filed their satellite system notification through
the Solomon Islands administration. the status of their launch authorization licensing
and construction progress is unknown by Swarm, and Pangea has no space system
licensing within the United States.




3
 ITU R-REC-SA.1027-5, Table 1, Sharing Criteria at 137-138 MHz, Interfering signal power (dBW) should
not exceed –136 dBW per 150 kHz more than 0.0063% of the time.
4
    ​The ITU SNS for NOAA N shows receive antenna type ND with up to 10 dBi isotropic gain.
5
     Swarm transmissions: 2 second duration * 10 contacts * 3 satellites / 1440 minutes/day = 0.069%,
NOAA transmissions: 12 minute duration * 4 contacts * 1 satellite / 1440 minutes/day = 3.3%,
NOAA earth station antenna sky coverage: PI*(72 deg beamwidth / 2)^2 / PI*(90 deg)^2 = 16%


                                                                             Swarm Technologies Inc.
                                                                            Exhibit C to FCC Form 442
                                                                                         March 8, 2019


        In these tables, red-colored boxes indicate frequency overlap between the
 respective system in the row and the Swarm satellites. Green rows indicate some
 level of coordination or additional consideration is required for the system.



Table 1: List of Satellite Systems in the ITU SNS, transmitting 137-138 MHz
Satellite          Country   Service Area     Freq Overlap   Coordination   Notes
                                              (max freq      requirement
                                              shown)
AGILE              Italy     XVE              138            None           Equatorial NGSO,
                             Kenya ES                                       no orbital access to USA.
ATS-5              USA       GEO              ...137.365     None           GEO, no frequency overlap
                             NC ES
EUTELSAT-48E       France    GEO              ...137.230     None           GEO, no frequency overlap
                             Belgium ES
IMDC               Nether    XAA,             137.9-138      None           Not launched yet?
                   lands     Netherland ES    E-S, S-E                      No US license/stations
                                                                            Innovative Solutions In Space
IMP-J              USA       AK, NC ES        ...137.995     None           Inactive, 1970’s
LEOTELCOM-1        USA       XAX              ...137.325     Orbcomm        No frequency overlap
                             (world)                         Consent
LEOTELCOM-2        USA       XAX              ...137.928     Orbcomm        To be coordinated with
                                                             Consent        Orbcomm
LEOTELCOM-5        USA       XAA              ...137.655     Orbcomm        No frequency overlap
                                                             Consent
MCSCS              China     XAA (world)      ...137.525     None           No frequency overlap
METEOR-3M          Russia    XAA              ...137.975     None           deactivated March 2006
METOP              France    XAA              ...137.1       None           No frequency overlap

NOAA N             USA       XAA              ...137.932     NTIA consent   To be coordinated w/ NTIA
                                                             IPC met        IPC met
NOAA-KLM           USA       XAA              ...137.793     None           No frequency overlap
RS-D2              India     IND (India)      ...137.550     None           No area or frequency overlap
SAUDISAT-1C        Saudi     ARS              ...137.525     None           No area or frequency overlap
                   Arabia    (Saudi Arabia)
SAUDISAT-2         Saudi     ARS              ...137.513     None           No area or frequency overlap
                   Arabia
SEO                India     IND              ...137.990     None           No area overlap, 1980’s
BHASKARA-1
SEO                India     IND              ...137.990     None           No area overlap, 1980’s
BHASKARA-2
SI-SAT-BILIKIK     Solomon   XAA              137-138        None           Not launched yet
I                  Island                     (1 MHz)                       No US license/stations
(300 satellites)                                                            Pangea Networks
SROSS-1            India     IND              ...137.690     None           No area or frequency overlap
                                                                            1990’s


                                                                                Swarm Technologies Inc.
                                                                               Exhibit C to FCC Form 442
                                                                                            March 8, 2019

Radio AstronomyService Protection

        Pursuant to the ITU Radio Regulations 5.208A, Swarm's satellites meet the ITU
recommendations6 to avoid interference with the nearby Radio Astronomy Service
(RAS) band (150.05-153 MHz). The satellites transmit only in the 137-138 MHz band
and out of band emissions are minimized by digital modulation techniques and filtering
with at least 85 dB spectral roll-off 7 at 150 MHz resulting in a power flux density (pfd) at
Earth’s surface not exceeding -265 dB(W/(m​2​ · Hz)) thereby meeting the RAS protection
criteria of -259 dB(W/(m​2​ · Hz))8.
      The experimental ground stations share the same frequency and out of band
suppression characteristics. Ground stations will be positioned at a distance or
otherwise obstructed such to prevent line-of-sight observations by a Radio Astronomy
site using the 150.05-153 MHz band9 and resulting in a signal attenuation that meets
the RAS interference protection criteria. In addition, the frequency of transmissions
from the Swarm earth stations is much less than 2% of the time10 which also meets the
RAS protection criteria11.



Conclusion

         The experimental satellites and US earth stations pose no risk of creating harmful
    interference with any known system with the exception of Orbcomm. As represented
    above, Swarm satellite transmissions are compliant with the frequency allocation
    tables and meet PFD based protection criteria for terrestrial systems and RAS as well
    as meteorological satellite systems. Swarm will seek specific consent from Orbcomm
    to mitigate any potential for interference with their system.




6
  ​ITU Radio Regulations, Resolution 739 (Rev. WRC-15) and Recommendation ITU-R M.1583.
7
  Measured performance at 150 Mhz is -86 dBc within the limits of the test equipment and likely exceeds
this performance in the RAS bands. -80 dBc occurs at 3 Mhz from the carrier.
8
  ​As specified in ITU-R M.1583, the protection criteria is -238 dB(W/m​2​) in a 2.95 MHz reference
bandwidth and as recommended in ITU-R RA.769-2 Table 1, the threshold for harmful interference is
-259 dB(W/(m​2​ · Hz)) at a center frequency 151.525 MHz.
9
 Recommendation ITU-R RA.769-1 specifies “above about 40 MHz sharing may be practicable with
services in which the transmitters are not in direct line-of-sight of the observatories”.
10
  The experimental transmissions are at a maximum of 2 second durations 30 times per day
(~0.069% of the time). This accounts for 3 satellites with up to 10 contacts each per day.
11
     ITU RR 2016, Resolution 739, article g, and ITU-R RA.1513-2, article 2.



Document Created: 2019-03-07 14:05:06
Document Modified: 2019-03-07 14:05:06

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