Been in the news a lot lately. I’ve always assumed it just overloads an area with some sort of signal, but I know nothing about this kind of stuff so it’s a wild speculation.
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There are different strategies. Some employ overwhelming tactics by flooding the area w like return signals. Others look to scatter Doppler waves and return interference.
Police radar guns work by basically shooting out a laser beam and reading the color it comes back in. If you’re moving towards the radar gun, the light coming back will be shifted blue (higher frequency/shorter wavelength). The amount it’s shifted depends precisely on how fast you’re going
Radar jammers basically send a bunch of light at many different frequencies to blind the gun so it cant see the reflected beam
Well, it overloads and area with noise, in order to obfuscate or destroy any signals. Basically it works by sending out a signal and waiting for a response. To “jam” that signal you provide it with too much input so it can’t distinguish the return signal from all the other noise.
Radar signal is a radio wave, which acts very much like waves on water.
Imagine a perfectly still pool (e.g. indoor one, and you are the first person there). If you drop a ball on one side, you will see waves spread out in pretty circles, and then you will see them bounce off the sides, and some of them will return to the point where you dropped the ball.
Radar picks up those returns and uses them to figure out what’s out there. Unlike the pool, radar can only “see” waves it its actual spot. Think of it as looking at a rubber ducky bobbing up and down in the waves.
Now imagine that your pool had a bunch of kids jump in and start splashing around. Even if they are on the opposite side of the pool, they will make a lot of waves in entire pool, and small waves from your dropped ball will be impossible to see. This is how “signal overloading” works.
“interference” means dropping a second ball into a different part of the pool, to create more waves that aim to confuse whoever is trying to observe the waves from the first ball.
They overload an area with signal, but modern communication systems are really good at selecting signal from noise. Think about a crowded city and how many people are using cell phones, each phone knows how to “listen” for a specific set of signals and ignore all the others. In order to effectively jam signals, these systems have to “listen” to what frequencies are in use, and rapidly create noise before the system switches to another frequency. If the noise is similar to digital signal, it is most effective.
**ELI5**
Radar is like you yelling into a cave and listening for the echo. Imagine doing it. You yell “Echo! Echo!” And you listen for the echo.
And if you’re clever, you realize that the time it takes for you to hear the echo, is related to how deep the cave goes. A longer echo means that the sound traveled further before bouncing back to you.
So you become really good at yelling “Echo” and figuring out just how far the sound went before bouncing.
That’s an ELI5 explanation of how radar works. It sends out signals, and it waits for the echo, and from the echo, it can tell where the bounce came from, how far it is, etc.
So you’re getting really good at this! So you go into a big warehouse, and you want to try out your new ability. You yell “Echo!” and you wait for the echo to come back, so you can guess how big the warehouse is.
But it’s noisy in the warehouse. Too noisy. It’s so noisy that you can’t hear your own echo!
And your buddy who plays pranks on you, he’s next to you playing music on his phone, loudly, and that also makes it difficult for you to hear your echo. If he’d stop playing that loud sound, you might have a chance to hear your own echo.
So “radar jamming” is like that. An adversary emits some kind of signal that makes the radar equipment unable to hear its own echo.
Easiest way to think about it is that radar and all radio/microwave communications are light.. they are light beyond what we can but it is light none the less. There is little to no radio/microwave light in the atmosphere naturally (there is natural radio but its very weak/dim). This light needs a special eye to see it and can be broadcast by the same eye in most cases.. this is the antenna/tower/dish. At the ELI5 level what is happening is that they flash the light and look for images in what is bouncing off of it for radar.. and for communications its like a pattern of blinking light and using light of different colors to send messages.
Jammers work by blasting the area with a brighter light.. so bright that you cant see anything else. Patterns of light/light color that overwhelm the “eyes” (antenna/tower/dish). You blast light to the point that any other light in the area cannot be distinguished. Kinda like looking with a flashlight in the dark and then someone turns on a super powerful strobe light. Your eyes are blinded by the flash and keep changing to fast for your eyes to adapt and see what your flashlight was lighting up.
In it’s simplest form, to jam a signal (be it radar or communications) all you have to do is have a more powerful signal than the one they’re using. A receiver is only going to hear the most powerful signal on whatever frequency or frequencies they are using. It’s not hard *at all* to jam a particular frequency. The challenge comes from systems that use a range of frequencies. Depending on the type of radar, the frequencies can scale up and down at random to prevent speccific jamming. Some communicaiton systems have a frequency list that allows them to change to a different channel/frequency in the event of interference, while others “hop” from one frequency to the next, seemingingly at random (it isn’t random, but good luck figuring out the hop sequence without a supercomputer) and spending less than a second on each frequency. For that, you need a broad-spectrum jammer the wipes out a several megahertz worth of the frequency range.
But in the end it’s just one signal transmitting at a higher power than the one you’re trying to jam.
Imagine that you and your friend are sitting in class on opposite ends of the room. You’re supposed to be quiet, but you and your friend can get away with whispering back and forth to each other since the teacher has stepped out of the room. Since the rest of the room is quiet, you can clearly hear each other and carry on a conversation. Now imagine in the middle of your conversation, some guy stands up in the middle of the room and starts singing “baby shark” at the top of his lungs. You and your friend are both still whispering back and forth to each other, but neither can hear what the other is saying because of the guy screaming the words to “baby shark”. That’s pretty much how a jammer works, but with radio waves instead of sound.
Think of it like this:
You can hear a pin drop in an empty, quiet room.
“Jamming” would be as if you started a party in that room. Hearing that pin drop is virtually impossible.
Good jamming will be similar in results.
Current technology is designed to combat background noise. So to still “jam” it you need to broadcast at a high enough power to over whelm the equipment trying to clean the signal. The technical aspects are practically ignorable if you use enough power at the correct frequencies. But that amount of power might also cook people…
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