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?).
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").
> 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.)
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.
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.
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.
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.
>now if the control station can switch one receiver off to a dummy load, instead of to an antenna that might be useful.
That wouldn't do anything, would it? A phased array antenna is relatively small enough that a jamming signal from the ground would jam all antennas, not just one or a few.
Wouldn't such equipment attract anti-radiation weaponry very quickly? Combat practice with anti-aircraft battery is to light radar up for 30 seconds at most and then relocate immediately, because anything more will attract counter-battery fire.
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.
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.
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.
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]
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.
Jammers are only illegal in the civilian legal context. I'm not aware of anything that makes jammers inherently illegal by broader law of armed conflict. Necessity and proportionality comes into play. Targeted jamming of military communications would certainly be allowed. Jamming of dual-use satellites becomes more nuanced.
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.
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.
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
no they are not
thats dumb
but what is most assuredly happening, useing the most correct military protocols,is that Russia is hosting military attaché's from China and many others ,ie non combatant oficers who can watch
and learn how to combat western weapons and tactics
and as its turned into drone war 1,everybody has to recalibrate,with the brick's block(heh heh) all realy realy glad it isnt them getting droned to bits
Russia is training some north Korean troops,but its likely going to be realy basic stuff fof joint
border patrols and all in all a pr stick in the eye for the collective west
https://archive.is/0fjW1
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?).
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").
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
> 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/article/2...
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)
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.
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.
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.
>now if the control station can switch one receiver off to a dummy load, instead of to an antenna that might be useful.
That wouldn't do anything, would it? A phased array antenna is relatively small enough that a jamming signal from the ground would jam all antennas, not just one or a few.
depends on the arrangement of the antennas. When it comes to phased arrays you can basically use any arrangement you want within reason
I bet it would jam synthetic aperture radars
Wouldn't such equipment attract anti-radiation weaponry very quickly? Combat practice with anti-aircraft battery is to light radar up for 30 seconds at most and then relocate immediately, because anything more will attract counter-battery fire.
What mechanism is this using?
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.
https://en.wikipedia.org/wiki/Klystron
Early 1900s electronic devices/components have the best names.
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.
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.
> 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.
> 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...
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.
Jammers are only illegal in the civilian legal context. I'm not aware of anything that makes jammers inherently illegal by broader law of armed conflict. Necessity and proportionality comes into play. Targeted jamming of military communications would certainly be allowed. Jamming of dual-use satellites becomes more nuanced.
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.
> shot down just causing more debris
Yes, wars create debris. In this case, on the ground.
> 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.
The current slate of Russian GPS jamming is not being done by satellites.
Same with this system. It is terestrial with wheels.
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.
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
You can’t wait for escalation? Are you pro-war???
They're currently shipping North Korean soldiers in to assist their invasion of Ukraine. That's a rather significant "escalation".
no they are not thats dumb but what is most assuredly happening, useing the most correct military protocols,is that Russia is hosting military attaché's from China and many others ,ie non combatant oficers who can watch and learn how to combat western weapons and tactics and as its turned into drone war 1,everybody has to recalibrate,with the brick's block(heh heh) all realy realy glad it isnt them getting droned to bits Russia is training some north Korean troops,but its likely going to be realy basic stuff fof joint border patrols and all in all a pr stick in the eye for the collective west
In English, it's a convention to use a space after a comma.
Unless you believe in Ukrainian propaganda.
Are you pro-capitulation to authoritarian states?