US satellite jammer is set for delivery as flaws are fixed
22 comments
·October 25, 2024echoangle
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?).
moandcompany
Communication satellites generally need to have multiple antennas to provide focused coverage over geographic areas, some of which may be phased array antennas; such antennas and their associated coverage "beams" are generally steerable to some degree. 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 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 (i.e. jamming), 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.
sidewndr46
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
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
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.
fasteddie31003
I bet it would jam synthetic aperture radars
amelius
What mechanism is this using?
darquomiahw
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
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.
sharpshadow
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.
Etheryte
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.
ceejayoz
> 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.
JumpCrisscross
> shot down just causing more debris
Yes, wars create debris. In this case, on the ground.
tullianus
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.
petre
> 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.
https://archive.is/0fjW1