Author Topic: SpaceX New FCC Filings for Starlink  (Read 9730 times)

Offline lukelol

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SpaceX New FCC Filings for Starlink
« on: 11/08/2018 10:00 pm »
Filing: https://fcc.report/IBFS/SAT-MOD-20181108-00083
Link on FCC site

This includes some really great attachments describing Starlink and their recent changes with this filing:

Attachment Frequency Bands Requ - list of planned operating frequencies

Attachment Waiver Requests - Request for fcc to grant the changes

Attachment Organizational Info -Details on Owners/Directors/Offers of Space Exploration Holdings, LLC

Attachment Legal Narrative
   -Legal narrative detailing 3 main points:
    -Lower Orbit
    -No change in spectral interference.
    -Faster Development

Attachment Technical Informatio -
   -relocate 1,584 satellites previously authorized to operate at an altitude of 1,150 km to an altitude of 550 km
   -details of plan to avoid space junk, avoid wireless interference
   -
 -benefits of the lower orbit:
   -Rapid, passive disposal in the unlikely event of a failed spacecraft
   -Self-cleaning debris environment in general
   -Reduced fuel requirements and thruster wear
   -Benign ionizing radiation environment
   -Fewer NGSO operators affected by the SpaceX constellation
   -84 total pages of spacex/starlink info

Attachment Sched S Tech Report - 64 Pages documenting 116 Satellites in 2 non-geostationary orbits [66 @ 53.0 degrees, 550 km altitude and 50 @ 53.8 degrees, 1110 km altitude]

Attachment technical_parameters - Microsoft Database File Containing Info on Individual Satellites,
   - zip of the same data in CSV format http://rehmann.co/blog/wp-content/uploads/2018/11/fcc-starlink-result.zip

Attachment README - Description of technical parameters file

Feel free to add anything I missed!
« Last Edit: 11/09/2018 12:03 am by gongora »

Offline RedLineTrain

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Re: SpaceX New FCC Filings for Starlink
« Reply #1 on: 11/08/2018 10:27 pm »
Nice find.  Musk now owns 50.5% of the company, down from ~54% two years ago.

Offline biosehnsucht

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Re: SpaceX New FCC Filings for Starlink
« Reply #2 on: 11/08/2018 10:50 pm »
So in terms of the original plan of LEO and VLEO, is this splitting the LEO portion into LEO and something sort of VLEO but not as low as the original VLEO plans ? At least, it looks like they're still listing some for the old altitude ... ?

If they have to get half the satellites launched, can they then launch just these 550km~ satellites, which would be easier (more payload margins for F9 or whatever they're using, and/or more mass budget for the earlier satellites) ?

I see a bunch of "beams" listed, with variations of steerable and shapable, steerable, and fixed - looks like fixed are all for TT&C. While receiving fixed beams seems sensible, does sending fixed beams mean the TT&C links are using a dedicated antenna/dish? Or just that they'll not steer it at all when using the phased array for TT&C?

Looks like every channel is given 50MHz, even TT&C.

Offline speedevil

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Re: SpaceX New FCC Filings for Starlink
« Reply #3 on: 11/08/2018 11:10 pm »
"In an extreme worst case scenario, where the satellite fails... solar activity at a minimum... longest decay time is 5 years, with it more likely to be 1-3 years" (P6, waiver requests).
Further to the above noted 50% ownership, "Musk...and has voting control of 78.7%" (Ownership - P1)

"In fact, SpaceX intends to launch the first batch of satellites to begin populating the orbital shell before the end of 2019" (P8 Legal)
"By operating closer to earth, SpaceX would also reduce the latency of its communication signals to as low as 15ms"(P14
Simplified Ku band only satellites first (P16)
"Fewer satellites in view, due to the lower altitude", "Lower radiated power of satellites and ground terminals" (P17)
"Importantly, earliest generations will still use advanced beamforming..."(P18)


"Two configurations of the satellite will be deployed" - P46

Comparing the DCA table on page 46 with the prior one, the maximum number of silicon carbide LASER dishes has dropped from 5 to 4.
« Last Edit: 11/08/2018 11:22 pm by speedevil »

Online gongora

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Re: SpaceX New FCC Filings for Starlink
« Reply #4 on: 11/08/2018 11:35 pm »

Offline RedLineTrain

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Re: SpaceX New FCC Filings for Starlink
« Reply #5 on: 11/08/2018 11:38 pm »
So no inter-satellite links on the first version of the satellites -- doing the same as OneWeb.

Offline speedevil

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Re: SpaceX New FCC Filings for Starlink
« Reply #6 on: 11/08/2018 11:50 pm »
So no inter-satellite links on the first version of the satellites -- doing the same as OneWeb.

This is unclear.
They say they may swap out components, and there is a maximum of 4 mirrors to do LASER comms.
Going to 5 for the later version does not mean that this version is not doing inter-satellite LASER comms, or most of the initial fleet will have none.

It clearly means the mix has changed.
And of course, inter-satellite radio is still possible.
« Last Edit: 11/09/2018 12:05 am by speedevil »

Offline Mark K

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Re: SpaceX New FCC Filings for Starlink
« Reply #7 on: 11/08/2018 11:51 pm »
So no inter-satellite links on the first version of the satellites -- doing the same as OneWeb.

How do you get that? It says what band the inter satellite links are in the documents shown above?

Online gongora

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Re: SpaceX New FCC Filings for Starlink
« Reply #8 on: 11/08/2018 11:59 pm »

Offline RedLineTrain

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Re: SpaceX New FCC Filings for Starlink
« Reply #9 on: 11/09/2018 12:09 am »
So no inter-satellite links on the first version of the satellites -- doing the same as OneWeb.

This is unclear.
They say they may swap out components, and there is a maximum of 4 mirrors to do LASER comms.
Going to 5 for the later version does not mean that this version is not doing inter-satellite LASER comms, or most of the initial fleet will have none.

It clearly means the mix has changed.
And of course, inter-satellite radio is still possible.

I agree that inter-satellite radio is possible.  Good point.  Are Microsat A & B using radio links?  Regarding the LASERs, read on and it becomes clear that not all three components are going to be on the first version.  The reaction wheels and thruster are going to be there, meaning that the silicon carbide (LASER) components are not.

Edit:  Tintin A and B have optical links.  Hmmm...

https://apps.fcc.gov/els/GetAtt.html?id=185534&x=.
« Last Edit: 11/09/2018 12:14 am by RedLineTrain »

Online gongora

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Re: SpaceX New FCC Filings for Starlink
« Reply #10 on: 11/09/2018 12:14 am »
I agree that inter-satellite radio is possible.  Good point.  Are Microsat A & B using radio links?  Regarding the LASERs, read on and it becomes clear that not all three components are going to be on the first version.  The reaction wheels and thruster are going to be there, meaning that the silicon carbide (LASER) components are not.

If they had changed from laser ISL then the frequencies would have been listed (and it would be a major revision to their application).

Offline Ludus

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Re: SpaceX New FCC Filings for Starlink
« Reply #11 on: 11/09/2018 12:23 am »
I agree that inter-satellite radio is possible.  Good point.  Are Microsat A & B using radio links?  Regarding the LASERs, read on and it becomes clear that not all three components are going to be on the first version.  The reaction wheels and thruster are going to be there, meaning that the silicon carbide (LASER) components are not.

If they had changed from laser ISL then the frequencies would have been listed (and it would be a major revision to their application).

Where does it say or imply they’re dropping laser ISL?

Online gongora

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Re: SpaceX New FCC Filings for Starlink
« Reply #12 on: 11/09/2018 12:29 am »
Where does it say or imply they’re dropping laser ISL?

Not dropping long term, but maybe not including in the first generation satellites.  The silicon carbide bits mentioned in the reentry debris assessment are assumed to be part of the laser terminals.

Online gongora

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Re: SpaceX New FCC Filings for Starlink
« Reply #13 on: 11/09/2018 12:30 am »
Edit:  Tintin A and B have optical links.  Hmmm...

https://apps.fcc.gov/els/GetAtt.html?id=185534&x=.

I've never seen it verified that they actually launched with them (or that they're working if they were included.)

Offline Cheapchips

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Re: SpaceX New FCC Filings for Starlink
« Reply #14 on: 11/09/2018 12:56 pm »

This presumably explains why the Tintins haven't increase their altitude as originally planned. 

Offline Ludus

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Re: SpaceX New FCC Filings for Starlink
« Reply #15 on: 11/10/2018 05:23 am »
If the laser links aren’t there, Mark Handley’s analysis doesn’t apply anymore, at least for the early version. If they are there, cutting the altitude in half would drop latency even further below the best fiber can even theoretically do and double down on the high frequency trading/financial data biz as a license to print money.

https://forum.nasaspaceflight.com/index.php?topic=36552.2340
« Last Edit: 11/10/2018 05:33 am by Ludus »

Offline speedevil

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Re: SpaceX New FCC Filings for Starlink
« Reply #16 on: 11/10/2018 02:38 pm »
If the laser links aren’t there, Mark Handley’s analysis doesn’t apply anymore, at least for the early version. If they are there, cutting the altitude in half would drop latency even further below the best fiber can even theoretically do and double down on the high frequency trading/financial data biz as a license to print money.

https://forum.nasaspaceflight.com/index.php?topic=36552.2340
'theoretical' is not meaningful if it assumes that the limit is the speed of light in glass, because 'air-core' fibers exist, which have nearly the same transmission speed as in vacuum.

Offline Ludus

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Re: SpaceX New FCC Filings for Starlink
« Reply #17 on: 11/10/2018 03:26 pm »
If the laser links aren’t there, Mark Handley’s analysis doesn’t apply anymore, at least for the early version. If they are there, cutting the altitude in half would drop latency even further below the best fiber can even theoretically do and double down on the high frequency trading/financial data biz as a license to print money.

https://forum.nasaspaceflight.com/index.php?topic=36552.2340
'theoretical' is not meaningful if it assumes that the limit is the speed of light in glass, because 'air-core' fibers exist, which have nearly the same transmission speed as in vacuum.

I think Handley is just considering routes for fiber, not future variations in the basic technology. Theoretical in this case just meaning that even with a direct optimal “great circle” connection, though significantly faster than current fiber routes, wouldn’t be as fast as quite a few potential paths on Starlink.

He didn’t consider advances in fiber or the later lower orbit and denser mesh phases of Starlink.

Offline cuddihy

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Re: SpaceX New FCC Filings for Starlink
« Reply #18 on: 11/11/2018 07:30 am »
If the laser links aren’t there, Mark Handley’s analysis doesn’t apply anymore, at least for the early version. If they are there, cutting the altitude in half would drop latency even further below the best fiber can even theoretically do and double down on the high frequency trading/financial data biz as a license to print money.

https://forum.nasaspaceflight.com/index.php?topic=36552.2340
'theoretical' is not meaningful if it assumes that the limit is the speed of light in glass, because 'air-core' fibers exist, which have nearly the same transmission speed as in vacuum.

I think Handley is just considering routes for fiber, not future variations in the basic technology. Theoretical in this case just meaning that even with a direct optimal “great circle” connection, though significantly faster than current fiber routes, wouldn’t be as fast as quite a few potential paths on Starlink.

He didn’t consider advances in fiber or the later lower orbit and denser mesh phases of Starlink.

“Advances in fiber” won’t affect Handley’s analysis WRT great circle minimums, because he is only considering the physical speed of light in glass vs speed of links in air/vacuum.

Altitude and circuit latency on the satellites will have greater impact than any future improvements in fiber.

Offline speedevil

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Re: SpaceX New FCC Filings for Starlink
« Reply #19 on: 11/11/2018 11:16 am »
“Advances in fiber” won’t affect Handley’s analysis WRT great circle minimums, because he is only considering the physical speed of light in glass vs speed of links in air/vacuum.

Altitude and circuit latency on the satellites will have greater impact than any future improvements in fiber.
Hollow glass fiber exists, with the signal propagating in the hollow.
One variant described here.
It is very expensive, ridiculously so compared to fiber at current and has high loss.
(1.7dB/km was the best figure I saw).

This gets around the speed of glass argument, at least in principle, if the above were to be commercialised for long distance links.
Considerable technical challenges remain in practically achieving signal speed of the speed of light, even if your fiber goes that fast.
Losses would need to be greatly reduced to make the number of repeaters tractable for long distance links, even with optical amplifiers the signal is going to be regenerated quite often non-optically compared to current fiber, so achieving that delay is problematic.
« Last Edit: 11/11/2018 11:24 am by speedevil »

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