Form 442 Question 6 Revision 4 point 1

0133-EX-CN-2016 Text Documents

Astro Digital US, Incorporated

2016-10-10ELS_182994

                   Form 442, Technical Question 6 Response

   Corvus-BC Mission Experimental Program - Spectrum Utilization Details

                                  (Revision 4.1)


6a. Description of Research Project: The Corvus-BC-4-7 spacecraft mission is a
continuation of the research program intended to demonstrate that operational
quality (17 m GSD resolution) remote sensing data can be collected, processed and
successfully downlinked by 4 very small 6U CubeSat space vehicles and that this
data can be routinely transmitted to the Earth using Ka-Band transmitters utilizing
the DVB-S2 data system standard. For the Corvus-BC-4 through Corvus-BC-7
segment of our constellation, the spacecraft will fly in a LEO circular orbit, at a
circular altitude of 500 km (apogee = perigee = 500 km) and with an inclination of
approximately 97.4°. The spacecraft will each carry three cameras, each with a focal
plane array containing more than 70 megapixels. Each of the three cameras on all
four spacecraft will operate in a different spectral band (GREEN, RED and NEAR
INFRA-RED). Hence each composite (G+R+NIR) image (or scene) will contain more
than 210 million pixels where each pixel is represented by 12 bits. Lossless
compression is used to reduce the total data stored in spacecraft memory and on the
downlink data path by nearly a factor of 2. The Corvus-BC-4 through BC-7
spacecraft will join with the Corvus-BC-1 and BC-2 spacecraft to begin the formation
of the Astro Digital Landmapper Constellation, which will ultimately consist of 30
spacecraft (10 will carry the 3 camera X 20 m (±4 m) GSD resolution configuration
and 20 will carry a 1 camera X 2.5 m (± 0.5 m) resolution configuration. This latter
spacecraft will be approximately three times larger in volume. The Corvus-BC-4
through BC-7 spacecraft will be the first to demonstrate reduced revisit times for
agricultural imagery around the world, an important element of a new concept of
enhanced data delivery in the commercial remote sensing industry. Once these
spacecraft have demonstrated this capability they will be commercially re-licensed
as the first elements of the Land mapper commercial constellation.

High-speed data transmission of the 17m GSD data will occur using a millimeter
wave (Ka-Band) transmitter operating in EESS spectrum at a frequency of 26.800
GHz. Data rates using the DVB-S2 data system standard will range from 35.3 Mbps
to 320.6 Mbps. The emission bandwidth of the Ka-Band transmitter is constant
(independent of modulation and coding) at 86.4.00 MHz (this corresponds to a fixed
symbol rate of 72 Msps). Spectral efficiencies range from 0.49 bits/Hz to 4.53
bits/Hz. The Ka-Band transmitters, while operating here under an experimental
license, will be re-licensed under a commercial license using the same selected
frequency band at some point in the near future. Part 25 license applications are in
process, however, we believe a Part 5 Experimental License is still appropriate for
these four spacecraft as various experimental procedures as well as market
demonstrations need to be carried out using them before they will be ready for
commercial service.


TLM and CMD data transmission from/to the spacecraft are proposed at UHF
frequencies. The CMD and TLM links utilize a transceiver system, which operates in
half-duplex mode (but, not on a common transmit/receive frequency –as per our
filing).


The TLM downlink, while operating under a proposed experimental license, could
operate on these frequencies, once a commercial license has been applied for, as the
proposed spectrum is already allocated to the SRS in all three ITU Regions. The
telemetry downlink data rate for which we are applying is 38,400 bps. The occupied
bandwidth of the radio system is 40.0 kHz (at -3 dBc) and employs a very steep
skirted bandpass filter to limit its output bandwidth. GFSK modulation is employed
on the downlink. This system may also be operated at 19,200 and 9600 bps as
alternative data rates, selected by telecommand. At lower data rates, the spectrum
occupied is correspondingly lower.

The CMD uplink, could also be used under a future commercial license as it utilizes
EESS spectrum (Earth-to-space) in accordance with ITU Table of Frequency
Allocations - within the band 402.0 to 403.0 MHz. While we do not comply with US
Footnote 384 (as we are not transmitting to a US Gov. spacecraft) we have been
mindful of the utilization made by the NOAA GOES DCS system and have avoided the
use of those uplink frequencies. We are currently using this uplink frequency under
experimental license WH2XCA (File No. 0139-EX-RR-2015) as a command uplink to
our Perseus-M1 and –M2 spacecraft and have received no notice of interference to
other systems or services. The command uplink data rate for which we are applying
is 38,400 bps. The occupied bandwidth of the radio system is 40.0 kHz (at -3 dBc)
and employs a very steep skirted bandpass filter. GFSK modulation is employed on
the command uplink. Lower command data rates of 19,200 bps and 9,600 bps are
also possible.




                              Corvus-BC Spacecraft


In addition to the above links, a back-up TLM and CMD relay link will be tested on an
experimental basis. These links will make use of the commercial Globalstar satellite
system. This demonstration will take place using satellite-to-satellite
communications between the Corvous-BC spacecraft and the Globalstar MSS system.
In this instance the cross-linking capability will demonstrate the ability to operate
with multiple spacecraft, thus demonstrating two constellations interacting with
one another. We believe this is another space first. The Command Relay Link will
use the Globalstar transmission frequency band from 2483.5 – 2500 MHz. The TLM
Relya Link will make use of a portion of the Globalstar mobile uplink band from
1616.5 to 1626.5 MHz. It is anticipated that a specific frequency assignment will be
made in both of these broader frequency bands used by the Globalstar system. This
frequency selection process will be made closer to the launch date. As these links
are operating in the Intersatellite Service, this application must consider that
circumstance. Protection to the Radio Astronomy Service is assured by operating
our satellite transmitting modem in the higher band segment above the Co-Primary
allocation to MSS and RAS. The data rates to be used in both link directions (CMD
and TLM) are 9600 bps gross and 8550 bps after removal of system overhead bits.


6b. Specific Objectives of the Research Project:

The research objectives of this project are:

    a) To investigate the image quality, of our system under constant altitude
       conditions, yielding images with a 17 m GSD resolution and to determine the
       commercial implications of improved image site revisitation rates. Corvus-
       BC-4 through BC-7 will add four new spacecraft to a growing constellation, so
       that imagery can be routinely obtained using a small constellation of low cost
       space imaging satellites (these four additional spacecraft, with slightly
       different orbital characteristics will be added to two additional spacecraft,
       Corvus-BC-1 & 2). 1 Corvus-BC-3 (to be launched first, despite the
       numbering of the satellites) will be used to demonstrate a variety of new
       technologies of the space platform as well as to investigate the processing of
       images at different resolution (varying between 16.5 m and 26.4 m GSD). The
       objective of the three-color bands selected is to observe changes in the
       agricultural land areas over the entire Earth with time. The specific
       objective, in this case, is to verify that between 10-14 passes per day of data
       can be downloaded from each of seven spacecraft. This amounts to >150
       GBytes of image data transmitted to the Earth each day from each spacecraft
       and more than 1 TByte/day for the constellation of seven satellites, if this

1 We have also applied for and received an Experimental License for the Corvus-BC-
1 & -2 spacecraft under a previously submitted Form 442. That Part 5 license has
been granted under call sign WH2XXT. The Part 5 license for Corvus-BC-3 has been
granted under call sign WI2XCP.


       passes-per-day objective can be met. We believe this is a significant amount
       of data for such small space systems.

   b) To demonstrate that EESS spectrum in the band 25.5 to 27.0 GHz is suitable
      for operational remote sensing missions, particularly as carried out by small,
      low cost space systems. A specific objective is to utilize the DVB-S2 data
      system standard (at first in VCM mode and ultimately in ACM mode) to allow
      for adaptation of our Ka-Band link to a variety of meteorological conditions
      encountered during downlink data transfers. Using this technology we will
      verify the operational capability of this radio spectrum to produce the
      highest average data rate possible. In other words, we hope to demonstrate
      a technology that has the highest spectral efficiency possible at the lowest
      cost, using the 25.5 to 27.0 GHz frequency band.

   c) To demonstrate that small satellite systems, such as this remote sensing
      mission, can reliably use satellite-to-satellite relay for Command and
      Telemetry support of such a mission and that connection to the space
      segment can be made more frequently and over a broader area of coverage
      than would be possible with one to several ground-based stations. We also
      wish to demonstrate this process can be semi-automated using the seven
      satellites in the emerging Landmapper constellation. This is also an
      experimental objective. Further, we expect to demonstrate that, eventually,
      small space systems could operate using an MSS system like Globalstar as an
      alternative to a UHF SRS assignment. If this can be demonstrated and if the
      arrangement remains cost effective we will have been able to demonstrate,
      as with our mmW activities, that alternative spectrum choices to those
      currently in use (e.g., UHF SRS or Amateur Radio assignments) are possible
      and practical. A further objective in this case is to demonstrate that we do
      not cause harmful interference to any Radio Astronomy operations.

We note that none of these objectives would be possible using currently existing
commercial ground stations, particularly because they do not employ low cost
telecommunications equipment. Therefore, the utilization of a Part 5, Experimental
License is appropriate and this project is in the public interest, even as we progress
into the initiation of the constellation phase of our system deployment.

6c. How will the program of experimentation demonstrate a reasonable promise of
contributing to the development, expansion or utilization of the radio art, or is along a
research line not already investigated?

Astro Digital has developed what we believe is state-of-the-art transmitter
technology that will allow the following extensions of the radio arts and sciences, at
least so far as spaceflight communications are concerned:

   a) It is well known that transmitters operating in the mmW portion of the radio
      spectrum (in this case, within the range 20 to 30 GHz) are subject to excess


   path losses caused by atmospheric absorption and meteorological effects,
   including precipitation and cloud cover. We will demonstrate that the radio
   frequency band at 25.5-27 GHz can be used for routine high-speed data links
   from LEO spacecraft, despite these effects, even using very low cost radio
   equipment carried on-board very small space vehicles. We have developed a
   very small transmitter system that contains a DVB-S2 standard
   modulator/coder, which allows us to adjust the modulation and coding of the
   transmitter over 28 different options of modulation and coding (“MODCOD”),
   thus demonstrating that data rates can be adapted to the radio link over a
   range of spectral efficiency from 0.5 to 4.5 bits/Hz. This also corresponds to
   a data rate agility of from 35.3 to 320.6 Mbps. Initially, we will utilize the
   system in what is known as VCM (variable coding and modulation mode).
   This allows the MODCOD setting to be changed “manually” over 28 steps of
   MODCOD by ground command. Once this has been demonstrated the system
   will then be placed into ACM (adaptive coding and modulation mode). In this
   second case the ground station measures the downlink Eb/No performance
   continuously and then commands the spacecraft to automatically adjust its
   MODCOD setting to produce the highest possible data rate for which the link
   will close. This feedback loop is closed using the CMD uplink to the
   spacecraft as the return path. The loop created can operate with a closed
   loop rate of up to one adjustment per 2 seconds. So far as Astro Digital is
   aware, this technology has not yet been demonstrated at mmW frequencies
   by any commercial company or even the by the US Government (so far as the
   civil sector is concerned).
b) In addition to the adaptability of the transmitter to changing meteorological
   conditions, the system also will produce the highest spectral efficiency
   possible, consistent with the prevailing link meteorological and orbit
   conditions. With the equipment described herein we intend to demonstrate
   spectral efficiencies up to 4.5 bits/Hz. The baseband filter of the transmitter
   has a very steep skirted FIR filter that maintains the output bandwidth to
   exactly 86.4 MHz, independent of data rate. We now contemplate the use of
   the new and emerging DVB-S2X standard that will allow spectral efficiencies
   greater than 7 bits/Hz and with even better Nyquist Roll-Off characteristics.
c) The Ka-Band transmitter operating in these four satellites use built-in high
   gain horn antennas. Operating with a -3 dB beamwidth of 10.2° the space
   segment is designed to communicate with a 2.8 m parabolic dish antenna at
   the Earth station, which has a beamwidth of ≤ 0.26°. The spacecraft and the
   ground station track each other throughout the satellite pass. Hence, by
   using antennas with narrow beamwidths on both ends of the link, we will be
   able to demonstrate that such systems have a very high degree of spatial
   frequency reuse. Using such systems, hundreds of NGSO spacecraft can
   share the same frequency assignment and downlink data to multiple
   ground station locations within view of one another.

d) While the Globalstar MSS system has been used experimentally by other
   small satellite missions, this system demonstration will be the first to fully


   quantify how it might be used in an operational mode to control a
   constellation of LEO spacecraft situated at an altitude well below the
   Globalstar constellation altitude. The evaluation will test the limitations of
   the satellite-to-satellite relay function as the Globalstar system design was
   not originally intended to offer beams whose coverage is optimized for MSS
   stations in LEO orbit (operating below the altitude of Globalstar space
   stations). Our simulations to date, demonstrate that the percent coverage
   increase for CMD & TLM support is well worth the inclusion of a Globalstar
   modem on-board our Corvus-BC spacecraft. We expect to demonstrate that
   the in-orbit performance is actually better than our static link simulations
   indicate. This is simply because the link analysis carries significant margin.

By granting this experimental license, we will demonstrate technology, which
will extend the current state-of-the-radio-arts-and-sciences. The experiments
are expected to demonstrate improvements in both spectral efficiency and
spatial frequency reuse as well as demonstrate these benefits in a constellation
configuration. We believe this demonstration is definitely in the best interest of
the pubic sector.

The bands Astro Digital are using to carrying out the objectives of this
experimental program are also shared by government licensees. We have been
in discussion with several US government agencies who are now using these
bands (or plan to use these bands in the near future) and we believe that our
technologies would also benefit many government licensees as the technology to
be demonstrated is lower in cost and meets higher performance standards than
are being achieved even by large government space systems. We therefore
believe that even government interests are served by allowing such experiments
to be carried out in shared bands. We anticipate that the results of these radio
frequency demonstrations will be published in the literature and that similar
equipment will soon become available in the marketplace.



Document Created: 0730-05-20 00:00:00
Document Modified: 0730-05-20 00:00:00

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