It seems US didn't coordinate Starshield's unusual spectrum use with other countries.
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US spy satellites built by SpaceX send signals in the “wrong direction”
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so much about adhering to international rules or whatever BS they usually spout. Of course there are many more unrecorded US satellites out there doing worse things.
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TFA doesn’t give Tilley’s antenna gain (or G/T) just cites SNR. Considering it’s easy to receive a 2W S-band transmitter into an omni with a 3 meter dish at WAY higher than 20 dB SNR, it certainly doesn’t require a gain antenna on the spacecraft.
Quick link budget:
1000 km range, 2 GHz = Free space loss is 32 + 20log10(1000) + 20log10(2000) =158 dB
Radiate +33 dBm - so you’d get 33-158=-125 dBm into an isotropic antenna (0dBi, aka omni).
Assume 1 MHz BW and 4 dB Noise figure (which is kind of crummy) - you get noise is -110 dBm.
3m antenna at S-band is about 33 dBi gain, so your -125 dBm is now -92 dBm, which is about 18 dB SNR..
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Not high power - a few watts into an omni is easily detectable above the noise floor from LEO with even a modest antenna. All those cubesats using S-band downlinks have omni antennas.
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Perhaps this is intentional? Could one of star shields capabilities be "global interference" or perhaps even targeted interference with certain satellites at any moment, such as at the outbreak of a war?
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His paper provides all the calibration details via reference 8. Zenodo dot org record 17373141
He provides an analysis of the carrier levels and references the relative SNR of wide band data.
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Reading this I instantly thought, "not a mistake." When you look at all the benefits of testing out sending signals on reserved bands, it is not a mistake. It's like trying out a scheme for robbing banks without any consequences for getting caught.
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The spacecraft are not sending signals in the wrong direction. That's a seriously terrible was to describe what is going on. The spacecraft are sending signals precisely where they're intended, just using an unapproved frequency. Come on Ars, you can do better than that.
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The constellation started operating under the previous government.
This is disingenuous nonsense.
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Not really relevant to your main point, but 2 GHz is low enough that modern digital receivers can sample it directly. No mixer required.
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No, the question is that any law-abiding enterprise should be able to count on the spectrum being used according to the published rules.
And not having some undefined future negotiations with the US government along the lines of "please stop violating the spectrum use for your hundreds of satellites".
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I don't get the problem. They are using a band reserved exactly for what they are doing, and no one has reported interference. If they are doing satellite to satellite, obviously the signal is going to be in the "wrong" direction compared to ground-to-sat.
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A very good reminder, thanks! All my background in heterodyning is at optical wavelengths. We're a wee bit away from sampling that directly!
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sure - see the link budget in my other post - Don’t need a very big antenna on the ground to overcome ~160 dB free space loss (isotrope to isotrope). 3 meters is 33 dBi gain at 2 GHz.
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i don't know if someone else already postulated that maybe this was intended? seems like the article talks a lot about it possibly interfering in earth to space and space to space communication. isn't this what they would call radio jamming? seems like something a military would want to do to their adversaries tech.
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Mistakenly sending signals in the wrong direction? Not likely. I would bet on sending active scanning signal in the intended direction.
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I am so disappointed that they're actually intending to blast us with radiation (yes, I know, not that kind of radiation, but shouldn't 5g conspiracy theorists get all up in arms over this? Oh, I forgot, Smoothie King and Robot Boy can do no wrong, so this signal probably cures cancer and gayness) and the satellites aren't literally upside-down blasting signals away from Earth due to some incompetent bungle. That would be so much more fun 
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Or it's an honest mistake because the article gives no indication of when these satellites were launched, so I assumed recency? Have a pleasant day.
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Exactly. They're operating in the "no harm, no foul" rules and are mostly fine according to a strict understanding of the treaties. The point of it is to show that there's not really anyone coordinating it.
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If he was Russian, his lame attempts at humour would be much drier though equally as bad I expect.
As a Guardian opinion piece put it recently - no amount of money will ever make him funny.
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You need something that can convert from 2100Mhz down to UHF frequency band (the U.S standard for television).
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So I didn't need to read the rest of the article given this. This isn't SpaceX doing something wrong this is the NRO saying "go ahead" to SpaceX. I didn't bother reading the article further. It's obvious this is another anti-SpaceX Jon Brodkin special with a lot of text padding to mean nothing.
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Is this good to detect sub-pyramidian voids? Asking for a friend
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W9MPH/AE here
I'm not weighing in on the international communications law issues, but ... given what is known about the radio infrastructure on Starlink satellites, and thus, likely, the Starshield satellites, signals from Starshield to the ground are very likely highly directional. So not so likely to cause problems for other satellites on orbit.
I'm not weighing in on the international communications law issues, but ... given what is known about the radio infrastructure on Starlink satellites, and thus, likely, the Starshield satellites, signals from Starshield to the ground are very likely highly directional. So not so likely to cause problems for other satellites on orbit.
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It has always struck me that the inter-satellite links ( like Starlink’s) were a key technology a spy satellite in low earth orbit would need to pass the intelligence from above its target to friendly territory not able to see the satellite directly. Will be interesting to hear if these transmissions are being received in other parts of the world although in truth much of that could have US assets set up to receive the data.
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SpaceX is not involved in any way. The satellites are completely controlled by the government, and even their communications systems are military-grade and not made by SpaceX.
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I'd like to know how his receive antennas were pointed. In particular: if the antennas were at a very low elevation, the signals may have been pointed at another satellite near the opposite horizon. In fact, he could estimate the satellite's beamwidth by measuring how the signal strength changes as the satellite passes overhead. I'd also be interested in whether the signal seems to be pointed forward or backward (i.e. at a satellite in the same orbital plane), or to the side. (IIRC, the early optical links between Starlink satellites were forward and backward, with links between planes planned for later.)
Strong signals with broad beams pointed toward the ground to the left and right, but not along the flight path would suggest SAR.
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Am I the only person whose first thought was that the "wrong direction" was toward an antenna farm outside Moscow?
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Obvious spear job on SpaceX. Way down deep in the article, it is revealed that SpaceX probably isn't at fault.
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Responsible adults can also move fast and break things when they are testing in a hardware-rich environment. There's much more information retrieved from something breaking than when something works the first time.
When something breaks, you learn the limits of a specific design. When something works first time, you only know a specific design works in a specific environment - you don't learn where things will break in the design.
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Counterpoint, moderm Windows.
Cybertruck.
The Social Media Formerly know as Twitter.
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We've been seeing s-band interference in our weather satellites for months! We've not been able to locate where it's coming from. Is it only in the 2025-2100 range? Who do I contact?
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I am pleading with Mr Putin to please Kessler Syndrome this shit ASAP. The American pedophile billionaires either stay here and die with the rest of us, or they get to infect the rest of the universe with their disease. Let's all do the right thing for once.
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