Author Topic: Starlink : New FCC and ITU Filings  (Read 226470 times)

Offline TheRadicalModerate

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Re: Starlink : New FCC and ITU Filings
« Reply #520 on: 12/03/2022 05:07 am »
I wonder what would be the response after 5 years has passed and the number of operational failed failed time on orbit was still lower than the threshold. It would produce a valid trigger value for each constellation based on that constellation's size.

Also how would the orbital operational altitude be calculated in?

It would certainly be a precedent, wouldn't it?

The nice thing about the "object-years" standard is that it automatically incorporates the altitude, and provides a natural trade space for the engineers.  For whatever the standard settles out to be:

1) Design your constellation to stay in VLEO, allow more failures (low object-years before demise), but also incur more frequent replacement costs.

2) You can engineer your birds to incorporate the costs to be reliable enough to have fewer uncontrolled failures in a higher orbit (high object-years before demise).

I think I like this as policy.  It's clearly a shot across SpaceX's bow that the FCC will probably treat them fairly, but reserves the right to screw them if it's politically expedient in the next few years, but it is a pretty clever way to provide incentives not to make crappy satellites--and they have plausible deniability that they're not implicitly threatening SpaceX.

However, this is the FCC becoming the de facto satellite police.  If they're not careful, they'll incentivize the bottom-feeders not to emit at all in spectrum under their jurisdiction, using laser inter-satellite links to aggregators for comm, and then somebody will have to regulate the whole mess again.  Unintended consequences!

I hate to say it, but if you want to avoid yet another agency in the mix, this should really be done by the FAA as part of the launch license.  But then the FAA will have to be able to associate operators with launch providers, so they know when to deny a launch license for an operator that's exceeded their object-years budget.

There's gonna be some growing pains in the industry.

Offline vsatman

no E band for Gen2 - very bad for StarLink
« Reply #521 on: 12/03/2022 10:51 am »
[quote ]
Pending further review and coordination with Federal users, we defer acting on SpaceXís request to use the E-Band as well as any action regarding SpaceXís described use of the emergency beacons.
[/quote]

In my opinion, this is a very heavy blow to SpaceX. Now the main problem of space X is the lack of satellite bandwidth, which is determined by the fact that the transmission of information to the satellite is limited to the 2000 MHz in  Ka band (total 4000 Mhz in 2 polarisation)  Therefore, the most important change in Gen2 was the addition of the E band where 5000 MHz can be used, while in the SpaceX application the frequency channels in the E band were repeated in such a way that the total band available for transmission from the Earth to the satellite was almost  8 times more than that of the first generation satellite .
And precisely because the same frequency range had to be used several times (as far as I remember up to 4 ) - that is, the satellite had to have 4 antennas aimed at different gateways, satellites of the second generation and had to be much heavier and larger in sizes than generation 1. Of course, now they can be designed to use only the Ka band, and then only 4 x 2000 x 2 polarizations of 8000 MHz will be available to StarLink. instead of the planned 5000  x 4 + 2000 x 2 x 4 = 28000 MHz

that is, less than 30% of the planned, respectively, and the Ku band antennas (from Sat to User terminal) can only be used by 30%, and therefore you donít need so much energy for satellite, and such large solar panels and batteries are not needed on board too...
« Last Edit: 12/03/2022 12:02 pm by vsatman »

Offline RedLineTrain

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Re: no E band for Gen2 - very bad for StarLink
« Reply #522 on: 12/03/2022 03:31 pm »
Quote
Pending further review and coordination with Federal users, we defer acting on SpaceXís request to use the E-Band as well as any action regarding SpaceXís described use of the emergency beacons.

In my opinion, this is a very heavy blow to SpaceX. Now the main problem of space X is the lack of satellite bandwidth, which is determined by the fact that the transmission of information to the satellite is limited to the 2000 MHz in  Ka band (total 4000 Mhz in 2 polarisation)  Therefore, the most important change in Gen2 was the addition of the E band where 5000 MHz can be used, while in the SpaceX application the frequency channels in the E band were repeated in such a way that the total band available for transmission from the Earth to the satellite was almost  8 times more than that of the first generation satellite .
And precisely because the same frequency range had to be used several times (as far as I remember up to 4 ) - that is, the satellite had to have 4 antennas aimed at different gateways, satellites of the second generation and had to be much heavier and larger in sizes than generation 1. Of course, now they can be designed to use only the Ka band, and then only 4 x 2000 x 2 polarizations of 8000 MHz will be available to StarLink. instead of the planned 5000  x 4 + 2000 x 2 x 4 = 28000 MHz

that is, less than 30% of the planned, respectively, and the Ku band antennas (from Sat to User terminal) can only be used by 30%, and therefore you donít need so much energy for satellite, and such large solar panels and batteries are not needed on board too...

This is a temporary setback, considering that V-band frequencies will be requested for Gen2 shortly.  I suspect that SpaceX wasn't ready with equipment for the E-band frequencies quite yet anyway.

To recap, the V-band frequencies were 5 GHz up and 5 GHz down, both for user terminals and gateways.

Online gongora

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Re: Starlink : New FCC and ITU Filings
« Reply #523 on: 12/03/2022 03:57 pm »
I'd guess V-band would just be used for gateway comms on these sats (unless maybe they make a V-band aero terminal eventually).

Offline russianhalo117

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Re: Starlink : New FCC and ITU Filings
« Reply #524 on: 12/03/2022 04:07 pm »
Quote
Pending further review and coordination with Federal users, we defer acting on SpaceX’s request to use the E-Band as well as any action regarding SpaceX’s described use of the emergency beacons.

In my opinion, this is a very heavy blow to SpaceX. Now the main problem of space X is the lack of satellite bandwidth, which is determined by the fact that the transmission of information to the satellite is limited to the 2000 MHz in  Ka band (total 4000 Mhz in 2 polarisation)  Therefore, the most important change in Gen2 was the addition of the E band where 5000 MHz can be used, while in the SpaceX application the frequency channels in the E band were repeated in such a way that the total band available for transmission from the Earth to the satellite was almost  8 times more than that of the first generation satellite .
And precisely because the same frequency range had to be used several times (as far as I remember up to 4 ) - that is, the satellite had to have 4 antennas aimed at different gateways, satellites of the second generation and had to be much heavier and larger in sizes than generation 1. Of course, now they can be designed to use only the Ka band, and then only 4 x 2000 x 2 polarizations of 8000 MHz will be available to StarLink. instead of the planned 5000  x 4 + 2000 x 2 x 4 = 28000 MHz

that is, less than 30% of the planned, respectively, and the Ku band antennas (from Sat to User terminal) can only be used by 30%, and therefore you don’t need so much energy for satellite, and such large solar panels and batteries are not needed on board too...
The deferment was without prejudice which means that they can resubmit at a later date. This has happened before for many companies so not a big deal. Just a temporary setback since V-Band rollout is their priority anyways at the moment.
« Last Edit: 12/03/2022 04:10 pm by russianhalo117 »

Online gongora

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Re: Starlink : New FCC and ITU Filings
« Reply #525 on: 12/03/2022 04:35 pm »
I haven't really seen anything saying V-band is a priority

Offline waveney

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Re: Starlink : New FCC and ITU Filings
« Reply #526 on: 12/03/2022 06:39 pm »
I am an amateur astronomer and student of astronomy. Astronomy can deal with this.

These actions by the regulators are about monkey wrenching SpaceX while paying lip service to astronomers and fans of the night sky. US over regulation in this area will cede the industry to other nations.

Here Here.

I too am an amateur astronomer.  (With my name on several Galaxy Zoo papers)

I don't think any Astronomers use the old film and plates with long exposures.  Everyone and everything these days stacks many short exposure images in some way or another  (even Hubble and JWST) If you provide accurate info on when and when they will be observed then the images can be processed to take the effects of a passing sat.  There are far worse problems to worry about, loss of radio spectrum, loss of dark skies for example.

Offline TheRadicalModerate

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Re: Starlink : New FCC and ITU Filings
« Reply #527 on: 12/03/2022 09:20 pm »
I am an amateur astronomer and student of astronomy. Astronomy can deal with this.

These actions by the regulators are about monkey wrenching SpaceX while paying lip service to astronomers and fans of the night sky. US over regulation in this area will cede the industry to other nations.

Here Here.

I too am an amateur astronomer.  (With my name on several Galaxy Zoo papers)

I don't think any Astronomers use the old film and plates with long exposures.  Everyone and everything these days stacks many short exposure images in some way or another  (even Hubble and JWST) If you provide accurate info on when and when they will be observed then the images can be processed to take the effects of a passing sat.  There are far worse problems to worry about, loss of radio spectrum, loss of dark skies for example.

I am no longer an amateur astronomer, but I got interested in this problem enough to learn about CCDs.  Bottom line: you can't just stack exposures on top of each other for photometry applications.

CCDs are not bit-addressable.  You expose the CCD array to your target light source, and every photon causes the pixel it strikes to accumulate a bit more charge.  Then, when the exposure is over, you shift each pixel in the array, line-by-line and then pixel-by-pixel, through the same A/D converter to develop the digitized image.  It's a bucket brigade architecture.  The pixels in the last line in the array are shifted through all the pixels at the same address in all of the preceding lines.

The problem is that the CCD is calibrated to accumulate a certain number of maximum photons.  If you exceed that maximum, three things happen:

1) You no longer have a good photometrically-calibrated value for that pixel, because it's now essentially clipping.

2) The pixel overflows into surrounding pixels, invalidating them as well.

3) As you're shifting the pixel's line through the bucket brigade, over to the edge of the device, for reading through the ADC, the overflow leaves a trail of charge behind it, which will contaminate all the pixels at the same position, in all the succeeding lines, as they shift through the trail.

The problem with bright satellites is that they cause overflows, and usually they cause overflows in at least a couple of pixels in most lines, which means that your photometry across a large amount of the image is extremely noisy.  If you add together a bunch of images like that post-exposure, your photometry is all messed up.

One solution that you might think would work is simply to stop the exposure before the satellite goes over, read out the image, and then re-expose after the satellite has left the field of view.  But photometric-grade CCDs need to be cleared and re-calibrated for noise between exposures.  How this usually works is that the mechanical shutter closes, the CCD is read, then cleared (how it's cleared I don't understand), and then the blank CCD usually takes a picture of the closed shutter to get a noise calibration.  Only then is it ready for a new live exposure with the shutter open.

That takes... a while.  It's not minutes, but it's probably seconds.  And in a dense enough satellite environment, with a wide enough field of view (like Vera Rubin, which is the poster child for this problem), there are enough satellites crossing the FoV that you're consuming a sizable fraction of observing time.

What you need is a pixel that has all the nice noise properties of a CCD, but which is individually addressable, as well as readable and clearable on the fly, during an exposure.  Then you read it before the satellite crosses it, clear it after it's gone, and continue with the exposure.  You've messed up your photometry a little bit, but you never clipped the signal, you never overflowed into other pixels, and the noise you've added is less than you'd have when a wisp of cloud went over part of the FoV.

CMOS can do that.  However:

1) CMOS is a lot noisier than CCD.  It's getting better, but it's not there yet.

2) If you read a CMOS pixel, you have to read it into its own ADC (or an ADC assigned to a small group of pixels), and it turns out that calibrating a bunch of ADCs so they all consistently convert the same amount of charge to the same digital value is extremely difficult.

So, right now, there isn't a detector technology that works.  However, I suspect the answer is to work on some pixel-addressable technology until the noise and ADC calibration problems are no longer an issue.

So it's a real problem, but it's a problem that likely has a technological workaround if you throw enough semiconductor geeks at it.  Then you still have the problem that good wide-field photometric detectors are heavily integrated into their telescopes, and swapping one out isn't easy or cheap.  But, again, that's a technological and financial problem, with a much cheaper solution than "don't put up any more satellites".
« Last Edit: 12/03/2022 09:22 pm by TheRadicalModerate »

Online gongora

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Re: Starlink : New FCC and ITU Filings
« Reply #528 on: 12/03/2022 09:25 pm »
The astronomy conversations need to move to the astronomy & megaconstellations thread.

Offline RedLineTrain

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Re: Starlink : New FCC and ITU Filings
« Reply #529 on: 12/06/2022 03:33 pm »
Here's vaporcobra's article regarding this partial approval.  He is downbeat on the conditions that the FCC imposed.  I share this view at least with regard to the FCC's intent, but believe that over time SpaceX could turn this around using an incremental approach.

In any event, it will take a while to ramp Starship launches and to integrate the V-band frequencies into Gen2.  And we will see fairly shortly how well the dialectic stickers work.  If those need some iteration, this partial approval gives SpaceX time to do that.  Lastly, there could be some benefit to SpaceX in that the partial approval is a bit more lawsuit-proof.

https://www.teslarati.com/spacex-starlink-gen2-constellation-fcc-license-partial-grant/

Offline Reynold

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Re: Starlink : New FCC and ITU Filings
« Reply #530 on: 12/07/2022 07:27 pm »
There is also the interesting point that SpaceX may be able to meet some of these conditions more easily than their competitors, who may eventually regret asking for such restrictions when they have to meet them too. 

Offline deadman1204

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Re: Starlink : New FCC and ITU Filings
« Reply #531 on: 12/07/2022 07:57 pm »
There is also the interesting point that SpaceX may be able to meet some of these conditions more easily than their competitors, who may eventually regret asking for such restrictions when they have to meet them too.
Companies generally ask for restrictions that they know they can already meet.

Online gongora

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Re: Starlink : New FCC and ITU Filings
« Reply #532 on: 12/07/2022 08:14 pm »
https://twitter.com/thesheetztweetz/status/1600595289995345920

https://fcc.report/IBFS/SAT-PPL-20221206-00170
SAT-PPL-20221206-00170
Quote
Description: SpaceX requests U.S. market access for its German-licensed direct-to-cellular payload to communicate on an unprotected, non-interference basis in the 1910-1915 MHz uplink E-s and 1990-1995 MHz downlink s-E bands PCS G Block with off-the-shelf cellular mob

Offline TheRadicalModerate

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Re: Starlink : New FCC and ITU Filings
« Reply #533 on: 12/07/2022 10:29 pm »
And we will see fairly shortly how well the dialectic stickers work.

The typo in this sentence makes me imagine a Starlink bird covered in Stalinist-era Soviet propaganda posters.

Offline su27k

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Re: Starlink : New FCC and ITU Filings
« Reply #534 on: 12/08/2022 03:18 am »
There is also the interesting point that SpaceX may be able to meet some of these conditions more easily than their competitors, who may eventually regret asking for such restrictions when they have to meet them too.

That would require FCC applies the same conditions on their competitors, so far we're not seeing it. For example the object-year thing should be established via rule making instead of being applied to Starlink specifically.

Also a lot of Starlink's competitors registered their constellation in foreign countries, so they don't need FCC authorization, just need market access/landing right which is much more lax and doesn't have the same conditions.

Online Robotbeat

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Re: Starlink : New FCC and ITU Filings
« Reply #535 on: 12/21/2022 01:02 am »
I missed this filing from October with the proposed Gen 2 satellite dimensions for Starship and F9 versions.
https://licensing.fcc.gov/myibfs/download.do?attachment_key=17429628
Did anybody actually download this and attach it to a post? I can't get it to load.
Chris  Whoever loves correction loves knowledge, but he who hates reproof is stupid.

To the maximum extent practicable, the Federal Government shall plan missions to accommodate the space transportation services capabilities of United States commercial providers. US law http://goo.gl/YZYNt0

Online Robotbeat

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Re: Starlink : New FCC and ITU Filings
« Reply #536 on: 12/21/2022 01:03 am »
There is also the interesting point that SpaceX may be able to meet some of these conditions more easily than their competitors, who may eventually regret asking for such restrictions when they have to meet them too.

That would require FCC applies the same conditions on their competitors, so far we're not seeing it. For example the object-year thing should be established via rule making instead of being applied to Starlink specifically.
...
FCC could be sued if they don't apply the conditions in a fair manner. So I'm fully confident this will happen.
Chris  Whoever loves correction loves knowledge, but he who hates reproof is stupid.

To the maximum extent practicable, the Federal Government shall plan missions to accommodate the space transportation services capabilities of United States commercial providers. US law http://goo.gl/YZYNt0

Online gongora

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Re: Starlink : New FCC and ITU Filings
« Reply #537 on: 12/21/2022 02:34 am »
I missed this filing from October with the proposed Gen 2 satellite dimensions for Starship and F9 versions.
https://licensing.fcc.gov/myibfs/download.do?attachment_key=17429628
Did anybody actually download this and attach it to a post? I can't get it to load.

You may have to click it twice.  It's a feature of the FCC web site.


Offline raptorx2

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Re: Starlink : New FCC and ITU Filings
« Reply #539 on: 12/22/2022 08:52 pm »
I missed this filing from October with the proposed Gen 2 satellite dimensions for Starship and F9 versions.
https://licensing.fcc.gov/myibfs/download.do?attachment_key=17429628
Did anybody actually download this and attach it to a post? I can't get it to load.

You may have to click it twice.  It's a feature of the FCC web site.

Or you can find here.  https://www.dropbox.com/s/dhjubtpzkl03z39/SpaceX.pdf?dl=0

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