Author Topic: Starlink : General Discussion - Thread 3  (Read 335059 times)

Online Galactic Penguin SST

Re: Starlink : General Discussion - Thread 3
« Reply #40 on: 03/05/2022 04:16 am »
https://twitter.com/elonmusk/status/1499972826828259328?s=21

This IMHO is more of a partial trolling on Roscosmos, which has just declared themselves and the Russian space program to “shift emphasis to building satellites by themselves for national defense purposes”: https://twitter.com/roscosmos/status/1499335245635764224?s=21

I definitely can see SpaceX themselves trying to fit more jamming resistance features to Starlink though - in fact I would not be surprised if the US military or even NATO offers a contract for that.
Astronomy & spaceflight geek penguin. In a relationship w/ Space Shuttle Discovery. Current Priority: Chasing the Chinese Spaceflight Wonder Egg & A Certain Chinese Mars Rover

Offline kevinof

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Re: Starlink : General Discussion - Thread 3
« Reply #41 on: 03/05/2022 07:34 am »
"Some Starlink terminals near conflict areas were being jammed for several hours at a time. Our latest software update bypasses the jamming.

Am curious to see what’s next!"


And in a reply Elon says…

“In a way, this is free QA haha”

https://twitter.com/elonmusk/status/1500026380704178178
« Last Edit: 03/05/2022 07:50 am by kevinof »

Offline drzerg

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Re: Starlink : General Discussion - Thread 3
« Reply #42 on: 03/05/2022 09:24 pm »
Do you know what bad weather actually means? Check names for the russian MRL and other missile weapons systems: град, ураган, смерч, солнцепек...

Offline jak Kennedy

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Re: Starlink : General Discussion - Thread 3
« Reply #43 on: 03/05/2022 09:54 pm »
snip

Quote
Katya Pavlushchenko: Dmitry @Rogozin to Russia Today: "When Russia implements its highest national interests on the territory of Ukraine, @elonmusk appears with his Starlink which was previously declared as purely civilian. Here is this mud (мурло) opened himself..."



Elon Musk: Ukraine civilian Internet was experiencing strange outages – bad weather perhaps? – so SpaceX is helping fix it

When was Starlnk ever described by Elon as purely civilian? If so I missed it but I have always believed the DoD was interested. It would be crazy not to be used by the military and with eventually many thousands in orbit hard to any of them all down.

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Online Comga

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Re: Starlink : General Discussion - Thread 3
« Reply #44 on: 03/05/2022 09:55 pm »
Do you know what bad weather actually means?
Check names for the russian MRL and other missile weapons systems: град, ураган, смерч, солнцепек...
"castle, hurricane, spruce, sunshine ..." :)
"multiple rocket launcher system (MRLS)"
One might complain about drzerg being cryptic, but check out his profile location: Kyiv!
Good luck, drzeng!  Best wishes for you and your family.
What kind of wastrels would dump a perfectly good booster in the ocean after just one use?

Offline Mongo62

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Offline schaban

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Re: Starlink : General Discussion - Thread 3
« Reply #46 on: 03/06/2022 12:31 am »
Do you know what bad weather actually means?
Check names for the russian MRL and other missile weapons systems: град, ураган, смерч, солнцепек...
"castle, hurricane, spruce, sunshine ..." :)
"multiple rocket launcher system (MRLS)"
One might complain about drzerg being cryptic, but check out his profile location: Kyiv!
Good luck, drzeng!  Best wishes for you and your family.
Correct translation are Hail, hurricane, tornado/twister, heatwave

Offline Nomadd

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Re: Starlink : General Discussion - Thread 3
« Reply #47 on: 03/06/2022 12:49 am »
 I wonder how you prevent jamming with software. Enable frequency hopping? Disable automatic disconnect for noisy signals? More power for better SNR? Lower minimum elevation to enable more available satellites? Lower data rate?
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Online DanClemmensen

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Re: Starlink : General Discussion - Thread 3
« Reply #48 on: 03/06/2022 01:20 am »
I wonder how you prevent jamming with software. Enable frequency hopping? Disable automatic disconnect for noisy signals? More power for better SNR? Lower minimum elevation to enable more available satellites? Lower data rate?
I wrote a long answer, but then decided not to post it. I urge you to think about this.

Offline Joseph Peterson

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Re: Starlink : General Discussion - Thread 3
« Reply #49 on: 03/06/2022 01:41 am »
https://twitter.com/KyivIndependent/status/1500264314875359238?s=20&t=9Xk3C4FWA24Xtp_usW7A2g

Quote
Zelensky: Additional Starlink satellite tech to arrive in Ukraine next week.

Zelensky announced that he spoke with Elon Musk, who will provide more Starlink satellite systems for Ukraine’s war-torn cities.

They also discussed possible space projects for after the war.

I love that Zelensky is thinking about Ukraine's space industry after the war.

Offline Joseph Peterson

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Offline 1

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Re: Starlink : General Discussion - Thread 3
« Reply #51 on: 03/06/2022 03:09 am »
I wonder how you prevent jamming with software. Enable frequency hopping? Disable automatic disconnect for noisy signals? More power for better SNR? Lower minimum elevation to enable more available satellites? Lower data rate?
I wrote a long answer, but then decided not to post it. I urge you to think about this.

Perhaps a PM might be appropriate? I won't fault anyone for an abundance of caution, but unless any particular poster has actual experience with electronic warfare, I very much doubt any sugestion here would not have already been thought about, analyzed, and already either improved upon or discarded. That said, Nomadd's questions appear to stem from one particular assumption which is perfectly safe to address.

It is public knowledge that dishy uses a phased array antenna. When most folks hear that phrase, they think of beam steering; but that's only one result of the greater effort of beam-forming. By sending more power in one direction, you send less power in other directions.

However, there is a principle in antenna design known as the reciprocity theorm. It essentially says that an antenna that transmits more strongly in a particular direction must also recieve more sensitively in that same direction. Thus, if dishy detects a hostile signal from a particular direction, the beam can be reformed such that the array has poor reception in that direction. This will likely come as a net loss to main lobe directivity, but could result in an overall improvement to SNR. This would be implemented at the software/algorithm side of things.

Just a basic example based on known information.

Online waveney

Re: Starlink : General Discussion - Thread 3
« Reply #52 on: 03/06/2022 06:25 am »
I wonder how you prevent jamming with software. Enable frequency hopping? Disable automatic disconnect for noisy signals? More power for better SNR? Lower minimum elevation to enable more available satellites? Lower data rate?

At least any of these:

* Wide spread spectrum transmissions - difficult to jam every frequency

* Heavy duty error correction - Can recover from signal levels lower than noise!

* By keeping the signal bandwidth down and trading that for a large used operational bandwidth its amazing what can be achieved.  Even getting messages through the what appears to be white noise.   (Once worked a way to send a low speed message upstream on a shared downstream fibre - just by carefully induced patterns of errors in the medium)



Offline OTV Booster

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Re: Starlink : General Discussion - Thread 3
« Reply #53 on: 03/06/2022 02:15 pm »
Maybe implement the fix in the jammers software? ;D
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Offline niwax

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Re: Starlink : General Discussion - Thread 3
« Reply #54 on: 03/06/2022 02:49 pm »
I wonder how you prevent jamming with software. Enable frequency hopping? Disable automatic disconnect for noisy signals? More power for better SNR? Lower minimum elevation to enable more available satellites? Lower data rate?

At least any of these:

* Wide spread spectrum transmissions - difficult to jam every frequency

* Heavy duty error correction - Can recover from signal levels lower than noise!

* By keeping the signal bandwidth down and trading that for a large used operational bandwidth its amazing what can be achieved.  Even getting messages through the what appears to be white noise.   (Once worked a way to send a low speed message upstream on a shared downstream fibre - just by carefully induced patterns of errors in the medium)

Don't forget about directionality, unless the jamming signal is coming from the same place as the satellite the dish can distinguish between the two.
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Offline dondar

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Re: Starlink : General Discussion - Thread 3
« Reply #55 on: 03/06/2022 07:43 pm »
I wonder how you prevent jamming with software. Enable frequency hopping? Disable automatic disconnect for noisy signals? More power for better SNR? Lower minimum elevation to enable more available satellites? Lower data rate?
they use high bandwidth multi-point to multi-point communication links. Plenty of possibilities. Beside already mentioned approaches they have choice of encoders/modulators. they are programmable nowadays and by choosing specific variants you can win SNR/directionality of the signal by losing some bandwidth. Just polarization encoding already does wonders against white noise jamming. And you can build a proper mix with frequency hopping/spreading if you have good mathematicians.

Because it is all software you  end with automatic software  functions  which just trying and probing different variants until you get a handshake.

Offline Asteroza

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Re: Starlink : General Discussion - Thread 3
« Reply #56 on: 03/06/2022 09:35 pm »
I wonder how you prevent jamming with software. Enable frequency hopping? Disable automatic disconnect for noisy signals? More power for better SNR? Lower minimum elevation to enable more available satellites? Lower data rate?

Musk mentioned reducing dishy power consumption for mobile/generator use, to get it down to cigarette lighter levels, so dishy will potentially have reduced transmit power as a result (which won't help).

One could make the argument that in wartime, the usual transmit power limits imposed by various organizations may be subject to loose interpretation...

On the sat end of things, you're ultimately limited by solar panel (and battery) power budget, not just for transmit antenna but for receive processing as well. Picking out and ignoring jammers is going to be crucial, but gets harder with mobile jammers. Now if someone was supplying location data for jammers, that might make it easier...

Offline su27k

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Re: Starlink : General Discussion - Thread 3
« Reply #57 on: 03/08/2022 02:31 am »
Looks like the mobile roaming feature is enabled for everyone, including those in North America: Starlink Mobile Roaming

Quote from: tuckstruck.net
Elon Tweeted “Mobile roaming enabled, so phased array antenna can maintain signal while on moving vehicle”. Hmmm… interesting! I guess that in context, he probably meant for this to apply to his recent supply of Starlink terminals to the brave souls defending Ukraine. But it got me thinking… if it can work in Ukraine, could it work for a couple of British overlanders touring around North America too? We’re lucky to have roaming enabled on our system, so could I stick our Dish on our RV roof and get Starlink mobile roaming… internet ‘in motion’?

Offline niwax

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Re: Starlink : General Discussion - Thread 3
« Reply #58 on: 03/08/2022 12:14 pm »
Some interesting data I hadn't seen before:

Apparently power on the original dish is now down to about 50W (or 40W when powered directly from DC). The new rectangular dish is supposed to be even lower.
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Offline Nomadd

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Re: Starlink : General Discussion - Thread 3
« Reply #59 on: 03/08/2022 04:17 pm »
Some interesting data I hadn't seen before:

Apparently power on the original dish is now down to about 50W (or 40W when powered directly from DC). The new rectangular dish is supposed to be even lower.
I've seen a new one using around 54W on AC while streaming video. Not sure about standby or low usage.
Those who danced were thought to be quite insane by those who couldn't hear the music.

 

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