[HN Gopher] US satellite jammer is set for delivery as flaws are...
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US satellite jammer is set for delivery as flaws are fixed
Author : JumpCrisscross
Score : 42 points
Date : 2024-10-25 16:54 UTC (6 hours ago)
(HTM) web link (www.bloomberg.com)
(TXT) w3m dump (www.bloomberg.com)
| maples37 wrote:
| https://archive.is/0fjW1
| echoangle wrote:
| Is there some more info on what exactly this system is jamming?
| Radar satellites? It probably can't prevent optical images and
| downlinking of collected data to enemy ground stations.
|
| Edit: according to this (
| https://www.dailymail.co.uk/sciencetech/article-14001079/amp...
| ), it jams enemy communication which is relayed over satellites.
| I imagine this only works if the receiving antenna on the
| satellite isn't highly directional enough to only pick up signals
| where enemy troops are known to be. If the satellite has a phased
| array, the origin of the signal could be filtered very fine
| grained as far as I know and this kind of jamming could be
| removed (unless it is so strong that it completely saturates the
| amplifiers of the receiver?).
| fasteddie31003 wrote:
| I bet it would jam synthetic aperture radars
| sidewndr46 wrote:
| A phased array can have its phase altered to be steerable. That
| doesn't work if you overwhelm the receiver to the point it
| becomes a non-linear device.
| MegaDeKay wrote:
| Yeah, but it does take a lot more power as you point out.
| Just like you can use the phased array to form a beam toward
| a particular location of a particular size, you can also do
| the opposite and create deliberately low gain toward the
| jammer. So then you need enough jammer power to overwhelm the
| LNAs on the individual elements, each of which have
| relatively low gain.
| sidewndr46 wrote:
| no, it doesn't work that way at all. The receive side of a
| communication satellite would be multiple antennas each
| connected to its own receivers. The receiver all use a
| common clock source to perform demodulation (which is a
| bunch of steps usually, but whatever). The result of each
| receiver is summed, the result signal is transmitted by
| another transmitter connected to a different antenna on a
| different frequency. Phase difference between the receivers
| is used to steer the array. How the phase difference is
| created varies. But if you overwhelm just one receiver it
| basically just injects noise into the entire process. So
| you wind up summing noise with all the other signals, which
| destroys the signal to noise ratio of the transmitted
| signal
|
| now if the control station can switch one receiver off to a
| dummy load, instead of to an antenna that might be useful.
| Whether or not military comm satellites can do that is most
| definitely classified.
| moandcompany wrote:
| Communication satellites generally need to have multiple
| antennas to provide spanning coverage over large geographic
| areas, which are divided up into coverage cells; some of the
| antennas may be phased array antennas; antennas and their
| associated coverage "beams" are generally steerable to some
| degree, electronically for phased array, and/or mechanically
| via physical gimbal mechanisms. In some or most cases,
| communication signals are non-viable without focused coverage
| because the signal strength would otherwise be insufficient.
|
| Received signal strength, from the point of view of a
| terrestrial satellite communications terminal on the
| ground/airborne/maritime can also vary based on where the
| terminal is located within the footprint of a communication
| satellite's coverage beam; it's typically strongest at the
| center of a beam.
|
| The most primitive conceptual model for a communications
| satellite is often described as a "bent pipe," where signals
| transmitted up to a satellite from the ground are relayed as-
| received by the satellite back down to terrestrial receivers.
| In the linked article, the diagram reflects a concept such
| that: if a "jammer" can interfere with the transmitted signal
| to the satellite in a manner that the satellite cannot discern
| the true signal from noise contributed by the "jammer," what is
| relayed back down to terrestrial receivers by the satellite is
| "drowned out" because the relayed signal is now a combination
| of the true signal and sufficiently more noise contributed by
| the jammer rendering the communications channel and any signals
| over that channel non-viable (i.e. "jammed").
| 2OEH8eoCRo0 wrote:
| Noob antenna question: in a phased array is most transmit
| energy lost to destructive interference?
|
| I thought that the beam was just the region where the waves
| didn't destructively interfere
| JumpCrisscross wrote:
| > _in a phased array is most transmit energy lost to
| destructive interference?_
|
| No. Phased-array antennae can be up to 90% efficient [1].
| You aren't losing energy to destructive interference so
| much as channeling it to the constructive modes. (Totally
| physically inaccurate, but I think analogously correct.)
|
| [1] https://www.mwrf.com/technologies/embedded/systems/arti
| cle/2...
| grayfaced wrote:
| Low gain where there is destructive interference and high
| gain where there is constructive interference. That is the
| feature. Same amount of energy is radiated, it is just
| amplified in the high-gain main lobe.
|
| A low gain direction is not the same as no signal though.
| With enough power you can overpower the main lobe signal.
|
| https://en.wikipedia.org/wiki/Gain_(antenna)
| amelius wrote:
| What mechanism is this using?
| darquomiahw wrote:
| I'd imagine a parabolic dish that points at the satellite,
| driven by something powerful like a klystron. With a highly
| directional antenna and high power one should be able to
| saturate the satellite receiver.
| Jtsummers wrote:
| That's what L3's published images look like. A dish on a
| trailer that can be moved to wherever it's needed. It's an
| antenna that's producing (mostly) high-powered noise while
| pointed at a target satellite. Probably configurable like an
| ordinary antenna to make it mission specific and take
| advantage of known weaknesses in the target system.
| lysace wrote:
| https://en.wikipedia.org/wiki/Klystron
|
| Early 1900s electronic devices/components have the best
| names.
| sharpshadow wrote:
| Uhm are they serious!? Jammers are forbidden by most countries
| and they find it okay to put that into space as a satellite.
| Honestly if the scenario they describe when it comes to use it
| will be a target immediately and shot down just causing more
| debris. Space should be kept weapon free for the sake of
| humanity.
| ceejayoz wrote:
| > Jammers are forbidden by most countries and they find it okay
| to put that into space as a satellite.
|
| You'll find such forbidding tends to exempt the countries
| themselves. Every military on the planet uses jammers.
|
| I can't collect taxes, but they can. I can't put someone in
| jail, but they can. I can't negotiate with foreign powers, but
| they can.
| Brybry wrote:
| > I can't negotiate with foreign powers
|
| As an aside, I think this one is a maybe (in the US). Weirdly
| in over 200 years there's only been two indictments under the
| Logan Act and no convictions. [1]
|
| [1] https://www.reuters.com/article/us-usa-trump-russia-
| un/flynn...
| JumpCrisscross wrote:
| > _shot down just causing more debris_
|
| Yes, wars create debris. In this case, on the ground.
| Etheryte wrote:
| Shooting other people is also forbidden in most countries, but
| militaries of said countries are still allowed to do it e.g.
| when they're at war. This is the same, but for satellite
| communications.
| petre wrote:
| > Jammers are forbidden by most countries
|
| Russia is jamming their Western neighbours' GPS. I can't wait
| for US microwave weapons that fry their satellites.
| Afforess wrote:
| You can't wait for escalation? Are you pro-war???
| dralley wrote:
| They're currently shipping North Korean soldiers in to
| assist their invasion of Ukraine. That's a rather
| significant "escalation".
| MaxPock wrote:
| Unless you believe in Ukrainian propaganda.
| tullianus wrote:
| The current slate of Russian GPS jamming is not being done by
| satellites.
| krisoft wrote:
| Same with this system. It is terestrial with wheels.
| petre wrote:
| They have satellites of their own. Since it's more
| expensive to launch, put them into orbit and operate them,
| I'm sure they'll reach some sort of "mutually beneficial"
| agreement, like we promise not to screw with yours if you
| won't mess with ours.
| anonymous8888 wrote:
| tit-for-tat means targeting ground equipment
|
| attacking satellites is an escalation, and if they
| retaliate in-kind, we'll get mutually assured destruction
| of satellites and Kessler syndrome, and the size of the
| US economy means there's a lot more to lose in MAD
| compared to them
| tullianus wrote:
| The jammer under discussion is not a satellite. It is a ground-
| based system that jams satellites. Did you read the article?
| There's even a photo of the system right at the top.
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