181–190 of 469 posts
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> Basically this happens just before sunrise, and just after sunset. I've seen plenty of satellites in the middle of the night, from very dark areas (wilderness). They look like stars, only they move more quickly. These observations go back a decade, at least.
That doesn't seem right, why would they be bright?
My understanding of the state of the art of inter-satellite optical links is that they have only been used between satellites that are basically in the same orbital plane and in more or less the same orbit. That is, the angle from one satellite to the other changes very very slowly, so that the optics don't have to do much tracking -- and consequently satellites can only form an optical link with other satellites tha…
Take a look at the slides from the presentation, I think the geometry clearly shows cross-plane links in the mesh. Having worked on these types of systems, I've had more difficulty with the lookahead angles (rx from where the target was, tx to where it will be due to speed of light) than the tracking -- fine tracking performance was required for all modes, and it largely became a GNC and acquisition time issue (since…
Is there rough pointing, followed by some rastering, until the sensor gets a hit? Maybe with some slight beam widening first? My assumption is that you would want exactly one laser, one sensor module, and probably a fixed lens on each? Is the sensor something like a 2x2 array, or pie with three pieces, to allow alignment? Or is it one big sensor that uses perturb and observe type approach to find the middle?
Also, is there anything special about the wavelengths selected? Are the lasers fit to one of the Fraunhofer lines? 760nm seems like a good choice?
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That's actually a somewhat useful visual.
Not really unless you're using 1 GB flash drives from fifteen years ago. 256 GB is now common, which would make that petabyte less than 1 football field. (It's only 4096 such drives.)
1GB flash drives are still 1GB today.
>256 GB is now common, which would make that petabyte less than 1 football field. (It's only 4096 such drives.)
If we're completely changing what we're using for scale, you can fit a petabyte on ~10 100TB drives, which is like 3% the length of an olympic swimming pool.
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I'm immensely interested in people commenting how they are disinterested in X thing. Please go on! I'd love to know the motivation of posting, it makes no sense to me. Seems to be a self-fulfilled prophecy.
I guess I just wish the HN timeline wasn't so full of his garbage.
I've ridden in Teslas. Some likes, but holy shit that drivetrain. Not garbage.
You however, have been consuming garbage media. Hint: if every other day (ahem Gawker sites) there is an outrageous anti-Musk headline or "crazy thing Musk said" headline, your media source is total garbage.
Is he a "good guy"? No. Is he "the worse thing ever?" No. What does it matter what he says or does? Nothing. Yet he is living in seemingly millions of people's brains as the sum factor of dozens of PR and advertising campaigns, in addition to the general anti-intellectualism of America.
Anyway, Starlink is a transformative data provider service that blankets virtually the entire world in broadband class connectivity, including massive amounts of third world countries and other areas.
Calling it garbage is dumb.
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> Basically this happens just before sunrise, and just after sunset. I've seen plenty of satellites in the middle of the night, from very dark areas (wilderness). They look like stars, only they move more quickly. These observations go back a decade, at least.
That doesn't seem right, why would they be bright?
I would guess, reflected moonlight (moon over the horizon) would be enough to light up the dot well enough to see unaided.
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I think they are still tiny. Also don't networking systems routinely deal with temporary link disruption?
What does that have to do with the odds of rocket induced dropped packets?
Lets not forget about clouds, birds, airplanes, hot hair balloons and tons of other things that separate the ground from space.
We have protocols and networks already designed today that deal with this exact problem.
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Take a look at the slides from the presentation, I think the geometry clearly shows cross-plane links in the mesh. Having worked on these types of systems, I've had more difficulty with the lookahead angles (rx from where the target was, tx to where it will be due to speed of light) than the tracking -- fine tracking performance was required for all modes, and it largely became a GNC and acquisition time issue (since…
In general , how is the initial alignment performed? Is there rough pointing, followed by some rastering, until the sensor gets a hit? Maybe with some slight beam widening first? My assumption is that you would want exactly one laser, one sensor module, and probably a fixed lens on each? Is the sensor something like a 2x2 array, or pie with three pieces, to allow alignment? Or is it one big sensor that uses perturb a…
Earlier quoted context omitted.
Take a look at the slides from the presentation, I think the geometry clearly shows cross-plane links in the mesh. Having worked on these types of systems, I've had more difficulty with the lookahead angles (rx from where the target was, tx to where it will be due to speed of light) than the tracking -- fine tracking performance was required for all modes, and it largely became a GNC and acquisition time issue (since…
In general , how is the initial alignment performed? Is there rough pointing, followed by some rastering, until the sensor gets a hit? Maybe with some slight beam widening first? My assumption is that you would want exactly one laser, one sensor module, and probably a fixed lens on each? Is the sensor something like a 2x2 array, or pie with three pieces, to allow alignment? Or is it one big sensor that uses perturb a…
On wavelengths, if you're trying to hit 100gbit+, you're probably having to use coherent optics, and there aren't many technology options or wavelengths on the market.