• circuscritic
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    41 year ago

    Anti-radiation missles targett the high output of the RF spectrum used by radars, not those used by satellite navigation.

    • @ForgotAboutDre
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      41 year ago

      A jammer will be a high output RF. The jammers just shout louder than the signals they want to jam to drown them out. This is wideband high gain noise that degrades the signal to noise ratio of the target signals.

      • circuscritic
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        1 year ago

        Close, but you’re missing the part that RF spectrum is more than just wideband. There’s X band, UHF, UWB, and many many more.

        Jammers pick a portion, or portions, of the RF spectrum, and blast it with noise, yes.

        But they don’t magically deny every bit all at once.

        And radar is different still, especially when you’re talking about SEAD, or radar hunting missiles.

        • @Buddahriffic
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          11 year ago

          I think the main point is that it’s technically possible to target jammers of any sort based on following the jamming signal itself, but the question is if there are any weapons that do that for arbitrary frequency ranges or if that is currently limited to radar frequencies.

          The unsettling part is it doesn’t have to be a jamming signal that is targeted. It’s possible to have a missile target areas with higher 3G activity or even follow a wifi signal to a device, though it would need another method of getting within range. But targeting a signal is easier than communicating with that signal, plus a missile could have a much better receiver than your phone or router.

    • @Aceticon
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      11 year ago

      But can those things not be adjusted to target a different part of the spectrum?!

      I mean, in terms of just Electronics a band filter can be changed to have a different center frequency, although there probably are other considerations beyond merelly the frequencies being taken in by the missile controller when switching for targetting radars to targetting jammers.

      I was just wondering if the Ukranians (who definitelly seem to have lots of knowhow when it comes to weapon manufaturing) haven’t altered a missile to operate similarly to a HAARM but for other frequencies rather than just the ones used by radars or even if there isn’t already an anti-jammer mode (with a selectable frequency) for existing missiles.

      • circuscritic
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        1 year ago

        Warning: This is speculation based on my existing knowledge, mostly because I don’t feel like Googling for 5-30min to confirm. But if anything is wrong, please show me a source so I can correct

        The AGM-88 HARM isn’t like a cc1111 or some infinite band SDR IC that you can just switch the frequencies on. It literally targets radiation.

        SAM Radars pump out shitloads of specific radiation, like cook your steaks and go sterile levels, if you’re too close.

        Different radar bands are used for tracking vs targeting, and maybe the HARM has to be toggled between those, or maybe it always tracks both, I don’t know.

        Regardless, it’s not designed to just “pick any RF and go boom”. It’s sensor track the high levels of radiation that are specifically emitted by SAM Radars, because it’s designed for SEAD (Suppression Enemy Air Defense).

        Maybe newer SEAD missiles have that flexibility, but the HARM is originally 70s era, and that’s what Ukraine has been provided - at least publicly.

        Edit: additionally, the HARM has to be mission programmed prior to launch because of the SU retrofits. Unlike on say, an F-16, where it’s fully controllable from within the cockpit to run a variety of missions, make changes mid-sorty, etc.

        • @Aceticon
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          1 year ago

          With the exception of things like Alpha and Beta Radiation (which are respectivelly high energy atoms and neutrons, if I remember it correctly), all “radiation” (from to longwave radio waves, through infrared, visible light, ultraviolet, x-rays and into Gamma radiation) are ust photons with different energy levels hence different frequencies.

          So the radiation from radars is just photons within a certain range of frequencies, which is even within what’s considered the radio waves spectrum, same as a normal radio but of different frequencies hence different energy.

          Radiation in this case is just used as a technical terminology (because they’re radio waves that radiate from an emitter), same as one might say “microwave radiation” (which, by the way, is also just photon in a different part of the spectrum), rather than implying that it’s the specific radiation from radioactivity.

          There are indeed consideration in things like antenna design for different radio frequencies and you can’t just design something that will work equally well for any of the entire range of frequencies. I was actually not thinking that HARMs could be “tuned” to different frequencies but rather than guidance module add-ons could be designed for more generic missiles in order to home in on specific frequencies for targetting jammers, as a jammer needs not be anywhere as complex as a radar and can be little more than a very strong emitter in a specific frequency or narrow range of frequencies which is emitting white noise.

          (The idea of a GPS-guided missile with a terminal guidance module that just homes in on the strongest emitter in a certain radiowave frequency range is just delicious. I believe the Ukranians have used things like mobile phone emissions to locate and target Russian troops so they’re at the very least manually doing triangulation of radio emissions)

          From my naive knowledge from the side of Electronics it seems it would be reasonably simple to design a directional radiowave detector for what is the equivalent of “a guy shouting really loud to drown all conversation”.

          PS: But yeah, beyond all this, your point about specifically the HARM still makes absolute sense.

          • circuscritic
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            1 year ago

            Let’s try a little thought experiment, or practical if you have the time and money:

            First step:

            Go buy a Commodore 64 and an RTX-4800

            Next step:

            Make them work together

            Last step:

            Find a Soviet 70s/80s era computer (probably a mainframe style) and network it with your Commodore 64 that has an RTX-4800.

            You’re suggestion boils down to:

            Science says it’s possible, why don’t they just redesign the entire missle?

            But, I am just spitballing here. If you are that convinced that this is doable, or even has been done, go do some research.

            • @Aceticon
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              -21 year ago

              Your example in highly artificial and uses constraints that are not applicable here: an RTX-4800 interfaces with a computer via a complex protocol called PCI-Express (now in version 4) which is very complex because it had to be designed to pass a lot of data really fast (Gigabits per second) as that was required for the main use case of that board: rendering millions of vertices worth of textured 3D models into a 2D output at least 25 times per seconds (though many people nowadays expect 100 times per second or more).

              Something that provides a direction in a 3D space, on the other hand, has to send all of 12 bytes a couple of times per second (if you’re using a double-precision floating point value for each coordinate), so the design of the interface hasn’t been constrained by the need for ultra-high throughtput and can be very simple.

              As it so happens, the second part of your example (getting a Soviet 70s/80s era computer to talk with a Commodor 64) is quite likely possible using the Serial protocol.

              In fact a more correct version of that example would be to get a Soviet 70s/80s computer to talk to a modern microcontroller - because for any system designed now to interface with older systems one of the sides would always be modern - and that absolutelly is possible as long as that computer has any kind of comms protocol, as even if it doesn’t have Serial (which would be strange, but possible) you can always program a modern microcontroller to bit-bang any protocol that’s not high throughput. (In fact there are tons of projects out there were people interface modern microcontrollers with ancient hardware).

              Also we’re talking about something that already receives GSM data from a GSM module, and my experience of working with that kind of electronics (civilian) is that it’s simple digital data via something like Serial.

              I agree that are for sure be constraints I am entirelly unware of here (as I have no experience with designing military hardware), but your idea of were they are is, from my own experience desiging electronic systems, not at all in the right area.

              • circuscritic
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                1 year ago

                Are you just using ChatGPT, or another LLM, to string words and concepts together?

                Kinda sounds like you are, at least for significant sections of your responses.

                Some parts are just confusing as to why even include them, unless you actually have no idea what they mean, or why they’re not contextually relevant, for example:

                GSM? Nope, not a factor…

                PCIE - why specify v4?

                But, whatever, I’m not a Raytheon engineer. Doesn’t matter if you convice me (you haven’t, but doesn’t matter).

                Edit: also, FWIW, Those constraints aren’t artificial. They’re each specific to what you’re suggesting.

                Old American tech, retrofitted and repurposed with brand new tech, and then integrated with, and fired from, old Soviet tech.

                There is a reason that NATO was only able to integrate fire control to the HARM for the SU’s, and not all of its cockpit control features and capabilities. Which is why they have to preprogrammed for each sortie…

                • @Aceticon
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                  -11 year ago

                  It makes sense that somebody who thinks radar “radiation” is different from radiowaves can’t follow point-by-point electronics engineering explanations and design engineering considerations so thinks they must be the product of ChatGPT.

                  Should’ve dropped this conversation after the comment where you explained radar “radiation” as special.

                  Thanks for the lesson.

                  • circuscritic
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                    1 year ago

                    Not special, just a lot more power being fed through it vs other battlefield RF.

                    I followed, but it was just dumb. Way too many words to explain, or justify, a functionally unsound idea: converting HARM into a new missle, with a different purpose (Counter-EW vs SEAD).

                    But okay, you’re cleary an ubermensch, go to Raytheon, or start a new company. I’m sure you’ll get boatloads of investors.