How do signals get jammed?

00:00:07
Speaker 1: A common trope in science fiction is the strategic move of signal jamming, interfering with your enemy's ability to communicate. My personal favorite example of this is not from Star Wars or from Star Trek, but Space Balls. When their communications fail, they realize they've been jammed because literal raspberry jam drips across the screen. But is that really how jamming technology works or is it more like noise canceling headphones or something else. Today we'll dig into the physics of signal jamming, including the bleeps, the sweeps, and the creeps. Welcome to Daniel and Kelly's Extraordinary Universe.

00:01:02
Speaker 2: Hello, I'm Kelly Winer Smith. I study parasites and space.

00:01:06
Speaker 1: Hi, I'm Daniel. I'm a particle physicist and I'm a big fan of jam.

00:01:11
Speaker 2: Oh, but not the kind that we're talking about today. Were you in a band or anything in high school?

00:01:16
Speaker 1: Oh? I played the clarinet in a marching band and you could totally not hear anything. And I played the saxophone in a jazz band, so not a very cool kind of band. But yeah, I've been in bands. How about you? You were goth as a teenager, so you're either listening to or performing music. Yeah, I'm guessing. Yeah.

00:01:34
Speaker 2: I played the electric guitar in some grundrock bands. Pretty awesome.

00:01:40
Speaker 1: And you were recently invited by a listener to be on their hip hop track.

00:01:44
Speaker 2: Yeah, we'll see where that goes. They said I needed singing experience, so I'm guessing that's going to disqualify because singing in the car probably doesn't count.

00:01:53
Speaker 1: I don't know that's experienced showers and cars.

00:01:56
Speaker 2: I guess we'll see, all right. So my question for you today is we're talking about like, you know, equipment and when it doesn't work, whether it's you know, because someone's being malicious or not, that's really frustrating. So what piece of equipment in your life has been the most frustrating to you? Oh?

00:02:13
Speaker 1: Wow? I think the thing I'm most often frustrated by are the things I use most to, like a phone or a computer. But in reality, these things are amazing. Like I use my computer for hours every single day. It's always there, it's almost always works exactly as I expect it to, so my frustration there is really unfair. I think the frustration that's most fairly targeted is to the dishwasher, because like it's got a simple job. It does one thing and it just doesn't work a lot of the times. You know, like, why can't we just invent the dishwasher where you put the dishes in and they get washed.

00:02:45
Speaker 2: It does a lot of things though, it like it senses how dirty the dishes are, it washes them. It dries them also, that's another thing it does. It does at least two things.

00:02:54
Speaker 1: Wow, look at you standing up for dishwashers.

00:02:57
Speaker 2: I mean, they are kind of incredible. They save you a lot of time.

00:03:00
Speaker 1: When they become AI empowered and take over the world, they're going to listen to this podcast and they're going to know you're one of them.

00:03:05
Speaker 2: I'm hedge in my bets man.

00:03:10
Speaker 1: Well as a person who's done a lot of home improvement projects. Kelly, which piece of equipment in your life have you been most frustrated by?

00:03:17
Speaker 2: Oh, you know, I think I love all of my power tools equally. I think I think the thing. So I had a piece of equipment I worked with that gave me really big highs and really big lows. And that was the electro fishing boat that I used in grad school. So I was doing a largemouth bass survey in the Sacramento San Joaquin Delta and we were trying to catch largemouth bass. And I loved driving this boat. It was so much fun. I loved operating the boat. And when nobody was around at like four am, when we were putting the boat, you know, like down the ramp and into the delta, that was amazing. But at busy times of day, when I had to like use our giant truck and back the boat down the ramp, that was the most frustrating because inevitably, some incredibly well meaning guy would see, oh, a woman is trying to back the boat down the ramp. And they never were helping the guys. It was only when I was trying. And again they were trying to be very nice, right, and I appreciated their help, but it wasn't really helping because I did a great job on my own. But when they were trying to tell me, I would get really flustered because you know, you turn the you know, the wheel in one direction, the bocos in the opposite direction, and when somebody is trying to tell you, like go that way, it gets more confusing. I was doing flying on my own, but whenever somebody would try to help me. That's when I would mess it up. I just wanted to like leave my window rolled up and be like, no, I'm not listening to you, but then that would have been rude. And so anyway, that was my most frustrating equipment experience was trying to get the boat down the ramp when people were around. And again I wasn't mad at them. They were trying to help. That was nice.

00:04:55
Speaker 1: And you're not even mad at the equipment, right.

00:04:57
Speaker 2: No, I'm not even mad at the equipment. It was just like, it's just a very frustrating experience. Every time I'd pull up to the boat ramp, I'd get like anxious if there was anybody else there. But that's why I really liked being on the crew that would start at like four am, because usually there was no one else there and I could just whoop in one like fell swoop, get it down and then we'd be in the water and we'd go out when collect our fish.

00:05:20
Speaker 1: Well, we aren't all out on the water at four am to collect fish. But almost everybody lives a life that's dominated by machines electronic devices that enable your life and make it easier or more complicated or just more fun. And sometimes they don't work just because they're busted or it's user error, but sometimes it's malicious. That's right, somebody out there is interfering with your use of your devices. And today we're going to talk about one of those modes of interference, signal jamming, which appears all over the place in popular media and science fiction. And a bunch of people wrote in and said, hey, can you explain what is signal jamming?

00:05:56
Speaker 2: And I'm glad that they did because I love hearing stuff like this explo by Daniel. You'll get the clearest explanation when Daniel's the one explaining it. But let's go ahead and ask our extraordinaries, you know, the ones who didn't write in to ask for a better explanation. How does a signal jammer work? And here's what they had to say.

00:06:15
Speaker 1: You have a wave that's getting canceled out by another wave.

00:06:21
Speaker 2: They probably emit electromagnetic waves. It's just the right frequency to be perfectly deconstructive to other waves.

00:06:27
Speaker 3: By inserting destructive interference essentially the inverse waves of any intended communication, thus making it be unintelligible. Kind of how noise canceling headphones insert anti noise to negate out any undesirable outside noise. I have no idea how signal jamma works.

00:06:48
Speaker 2: My best guess would be that it uses photons in some.

00:06:53
Speaker 3: Way scrambling the radio waves. I don't know, some sort of powder way disrupting the others, but it needs to be a superior powderway. Can you hit a particle way with another particle.

00:07:06
Speaker 2: Way by sending a bunch of random data of the same signal type that screws up the receiver so it doesn't know what data is real and what's stake.

00:07:15
Speaker 1: All right. I love the idea of superior particles that you can like zap one kind of particle another kind of particle and it'll be dominated nice.

00:07:24
Speaker 2: Yes, that is pretty epic.

00:07:26
Speaker 1: The way you say nice reminds me that this weekend I was hanging out with a two year old and she's in this phase of just like picking up words, and something happened she like dropped a marble right under her mom's eye, and I said nice. And then every time she did something mischievous the whole evening, she went nice, and I laughed my head off. Anyway, these are very nice responses and the theme that emerges for me is that a lot of people think it's destructive interference. They think it's this fancy wave canceling stuff, like the thing happening with your noise cancelation headphones. So I think it's great that we're going to dig into the actual mechanics of how signal jamming works, because hint, hint, it's not destructive interference.

00:08:12
Speaker 2: What all right, So how our message is actually sent?

00:08:15
Speaker 1: Yeah, So to understand how signals are jammed, we have to understand the physics of signals. And for this conversation, we're going to ignore quantum mechanics because you mostly can. And as a reminder, you know, anytime we do physics, we're always using a simplified description of the universe. We can't bring all of our knowledge to bear all at once because tomorrow and we don't need to and number two then we'd get nothing done ever, because we'd be solving Einstein's equations in impossible ways. So we're always just like choosing what aspects of physics to use and neglecting some little bits. And for this conversation, we can treat this like classical and electromagnetism. So we have electric fields and magnetic fields and oscillations within them, and we can ignore like quantum pulses and fussiness and all that kind of stuff.

00:08:59
Speaker 2: Okay, okay, well, you know, and we only have an hour. And when we talk about messages, are we talking about like radio messages cell phone messages or are those all kind of the same thing.

00:09:12
Speaker 1: Those are all kind of the same thing. Everything here is a signal that's transmitted wirelessly, which means it's a pulse in the electromagnetic field, right, And so we're going to talk about messages encoded as pulses in the electromagnetic field, which basically means you're sending light invisible light or visible light of various frequencies. Right. And so when you listen to your radio, for example, you're getting radio waves. Radio waves are oscillations in the electromagnetic field that are picked up by your radio. When you listen to your cell phone, you're getting cellular information that's oscillations of the electromagnetic field, just at a different frequency. When you used to watch TV with antennas, you are picking up signals over the air, which are just oscillations in the electromagnetic field. When you tap your credit card on something to pay for it. There's a little bit of electromagnetic information being passed back and forth. So all of these things are electromagnetic, right, So all these messages are electromagnetic. They're just oscillations in the electromagnetic field, okay, And the way that you send them is an antenna. Right, So let's think about what is the physics of an antenna. It's like a long cylinder of metal. It's got a bunch of electrons in there, right, and you apply some current the electrons to move one way and the electrons to move the other way. Now, electrons have an electric charge, right, and so they make an electric field. So if an antenna is just sitting there, it has an electric field. And if you pull on the electrons to move them, the electric field changes because you're moving the electrons. The electric field moves with the electrons. Right. That makes sense. So if you have one electron, for example, and you wiggle it, what happens, Well, instead of having the same electric field through time, Now that electric field is changing. I move the electron, electric field moves with it. Right. All cool? But if I move my electron here in California, can Kelly tell immediately that I've moved my electron. No, she can only tell when the new electric field gets to her, so there's a time delay. If I wiggle my electron up and down, then I create a wiggling electric field through time that eventually gets to Kelly and she can pick it up with her electric field measuring device. Does that make sense?

00:11:22
Speaker 2: That does? Okay, It's kind of amazing that wiggling electric fields can give you like music and complicated.

00:11:29
Speaker 1: I know, crazy, yeah, And so all of this information is just encoded in wiggling electric fields, which create magnetic fields. And that's what light is, right. Light is a coupled oscillation between electric fields and magnetic fields. They're very tightly linked, and changing electric fields make magnetic fields, changing magnetic fields make electric fields. So it's this incredible physical phenomena that you can send information through the universe if they're in these fields. And as you say, it's really cool that you can use those wiggles to represent almost any kind of information. Right. You can like encode my voice, you can send data. You know, you can send anything essentially if you just come up with some way to encode it. You say, this kind of wiggle means that this other kind of wiggle means something else, and then you can use that to transmit information. And so the basic physical setup is you have an antenna where you are controlling the electrons, which means you control the wiggles and somebody else the receiver. Kelly has an antenna, and when the electric field arrives at Kelly, how does she know that it's changed. Well, her antenna's electrons get wiggled by the electric field for the same reason that wiggling my electrons makes a wiggling electric field. That wiggling electric field when it arrives at Kelly's antenna, it wiggles her electrons. Then she has electronics to pick up those wiggles as current and that's her signal. So effectively, I send a signal in my electronics to a signal in Kelly's electronics. That's how message transmission works.

00:12:57
Speaker 2: Okay, And this works because like so, these messages need to pass through like buildings and forests and stuff like that. And does some of it get lost as it passes through that? Or no, because electrons and their fields just go through stuff.

00:13:14
Speaker 1: Or do yeah, yeah, great question. The answer is yes and no. It depends on the frequency So for example, if you're doing radio, then your frequencies are like kill a hertz or megahertz. Right, when you're listening to like rock one o seven point nine, one oh seven point nine means one hundred and seven point nine megaherts is the frequency of that signal. When you're using Wi Fi, then it's like two point four or five gigahertz, right, those are hurts. Those are frequencies. It tells you how many times the signal oscillates per second. Five gigaherts is five billion oscillations per second.

00:13:49
Speaker 2: Wow.

00:13:50
Speaker 1: Cell phones use like six hundred megaherts to like fifty gigaherts. So each one has a different frequency range and different frequencies behave differently just the same with it, like different frequencies of light are either visible or invisible, and different stuff is transparent or opaque. Like X rays pass right through your soft muscle tissue, but they don't pass through bone and light visible light doesn't pass through soft muscle tissue, right, So different things are transparent to different frequencies. In general, shorter frequency stuff like cell phones and Wi Fi has shorter ranges than longer frequency stuff like radio. There's less atmospheric absorption. Like the atmosphere is more transparent to radio than it is to Wi Fi and cell towers, so it doesn't fizzle out as much, and radio is less sensitive to like small obstacles. Radio can also bounce off the atmosphere sometimes depending on the frequency, and so it's easier to pick up radio for miles and miles away or you know, like ham radio operators can talk to people from around the world using those frequencies, whereas you can never do that with like cell phone towers. But cell phone towers are designed to only cover like the region that you're in. You don't want to hear from other cell phone towers.

00:15:03
Speaker 2: Okay, I feel like I remember when we had a conversation about space based solar we were talking about frequencies, like what frequency would you pick so that you could get your message down to Earth so it wasn't getting caught in the clouds and stuff like that. And this is a similar, yeah, exactly idea.

00:15:19
Speaker 1: Right exactly, And the greenhouse effect is of an effect just for this reason that like light passes mostly through the atmosphere, but then the Earth absorbs it changes a frequency, glows at a lower frequency to which greenhouse gases are opaque, right, And so that's why the light can pass in but not out because the greenhouse gases are transparent to the light coming in and opaque to the light coming out. Right, So like the same gases are opaque or transparent to different frequencies. Another major issue for interfering is metals. Right, any kind of conductor, just like your antenna is going to receive the message, it's going to wiggle the electrons in your antenna. If you're inside a metal cage with your antenna, you're not going to get the signal because the metal cage is gonna wiggle its electrons, and it wiggles and its electrons in exactly the way to counter that field. That's what an antenna does. So the metal cage basically eats the signal. And that's why in an elevator or anything we call a Faraday cage just a metal box, you basically can't get electromagnetic signals or send them. This is why people put tinfoil hats on their head. There's like actual physical basis.

00:16:24
Speaker 2: That's great. Okay, wow, I never knew they were so smart.

00:16:30
Speaker 1: I'm not saying the CA is trying to control you, but if they were a tinfoil hat really would protect you.

00:16:35
Speaker 2: Wow, okay, great, maybe I'm gonna start lining my winter hats with tinfoil just in case. Amazing. All right, we're gonna take a break, so run to your kitchens, grab some tinfoil, and we'll be right back. And we're back to Daniel and Kelly's Extraordinary Universe. So we were talking about how the frequency of waves can determine what things might like get in the way of the signal. Are there other things that can like get in the way or generate noise or basically mess up the signal in some way?

00:17:27
Speaker 1: Yeah, noise is a big issue because your intent is not the only thing broadcasting, Like, the universe is variously loud at various frequencies because there's other stuff generating electromagnetic radiation, and so you want to pick a channel where the universe tends to be quieter. Like one of the reasons that astronomers look for messages from aliens at one particular frequency they call it the watering hole, is because that's the one where the universe is pretty quiet, And so if you were going to broadcast, that's a good place to do it. And so your goal is you want to send a message from Californative Virginia, is to either find a quiet band where nobody else is broadcasting, or to be louder than the noise so that the antenna can pick it up above the noise. That's crucial. Nice, I can always count on you for two year old humor. Thank you.

00:18:20
Speaker 2: Yeah, that's right, that's that's the level I've risen to.

00:18:23
Speaker 1: Nice. Think a two year old say that?

00:18:25
Speaker 2: Oh boy.

00:18:26
Speaker 1: Anyway, So the idea of a signal jammer is actually quite simple. It's make a bunch of noise, makes so much noise that the person who's trying to receive the signal can't hear it over the noise. It's like if your sibling is trying to spoil the end of a movie and you go l L L. You can't hear them. You are jamming their signal. You can't hear their signal over the noise that you are making, in this case, probably trying to prevent somebody else from getting a signal. So you just make a bunch of noise at the same frequency where they're trying to hear it, and maybe you're closer to the than the original sender is, so you can create a bunch of loud noise to make it hard for them to hear.

00:19:05
Speaker 2: Okay, so you need to make sure that it's the same wavelength so that it's it's not interfering, it's just overlapping and making noise exactly.

00:19:15
Speaker 1: And let's pull those two things apart, because a lot of the listeners suggested that signal jamming could use destructive interference. So let's dig into that for a minute and remind ourselves what is destructive interference? While we're thinking about electromagnetic signals as waves, waves are complicated and they can interfere. Right, you have the double slit experiment. You have also some weird optical effects you have like in your living room when you're listening to the TV, there's like spots where it's louder and quieter at the same distance from the TV. What is going on? Remember that waves can add and they can subtract. So waves go up and down. Right, if you slap on the surface of your bathtub, you make waves that are up and down in the surface of the water. If you slap with the other hand, then those waves overlap with each other. And if one wave is going down the same time the other waves going up. Then they cancel out. Up plus down equals nothing. So this is a destructive interference. It's not like you have two waves that are in the same place at the same time and you can detect both of them. They literally add up to zero, and so they cancel each other out. That's destructive interference.

00:20:16
Speaker 2: I miss being a kid. I can't remember the last time I took a bath. That was like a thing I did when I was eight, But it sounds like fun to smack on the surface of a bath and play with the waves.

00:20:27
Speaker 1: It's fun. You're doing physics experiments, that's right, But this is hard to do. In order for this to happen, you have to have two waves that are exactly the same height and the same frequency and out of phase by one hundred and eighty degrees, which means that like one of them is shifted so that it's going down when the other one is going up. Otherwise they'll constructively interfere. Right, two waves that are both going up at the same time will add up to a double wave. Right, And so this is hard to arrange. And it's amazing that like your noise canceling headphones can do this. What they do is they have a little microphone inside them, so they detect the sound that's about to hit your ear, and then they generate exactly the waves needed to cancel out that sound. So the two play on top of each other and literally cancel out.

00:21:12
Speaker 2: Okay, So I have a question. So I'm imagining our podcast being transmitted and for some crazy, unimaginable reason, someone's trying to jam us. Someone doesn't want our message to get through, right, Okay, So the wave that's carrying our podcast, is it like as we speak, the waves are getting generated, so you know, like when I see our audio files on like Audacity, are they being generated like that? Or is it like there's constant waves being created as the message gets sent out across you know, the sky, and like at the top of one wave is our cannibalism joke and the bottom of the next wave is our white chocolate joke. And could I guess what I'm wondering is, could you generate a wave to destructively interfere or would you need to know what somebody was going to say to generate the wave? Like how how complicated would it be? Does that question make sense.

00:22:14
Speaker 1: Yeah, great question. It is complicated, especially because our podcast and almost all audio comes at multiple frequencies. Like I speak at a range of frequencies. You speak at a different range of frequencies. Like my voice would sound very different if I only spoke at one frequency. Right, It's a whole range. That's what contributes to it sounding like me and somebody else sounding like somebody else. That's why, like violins sound different from pianos, even if they play the same note, right, they have a different like mixture of frequencies. So that's the number one that makes it complicated. But you're asking, like, do you need to know the signal in advance to destructively interfere? And also we're not talking about jamming right now. We're talking about destructive interference, right, just to clarify what that is. So the best way to destructive the interferre is yes, to know exactly what the signal is in advance, and to play the diversion of it, right, the one that wiggles down instead of up, and then it would perfectly cancel out. Usually you know as canceling headphones don't know that, right, but they have a microphone they listen to the sound, and then they calculate what you would need to do to counteract it and generate that on the fly.

00:23:15
Speaker 2: That sounds really complicated.

00:23:17
Speaker 1: It's very cool. Yeah, yes, it's incredible, but it only works when those two waves overlap very locally. Right. They generate that noise so that in your ear the two waves go the opposite directions, But those two waves don't go the opposite directions everywhere. Right. They generate it so that those two waves are out of phase right in your ear, but they're not out of phase somewhere else, just like you know how when you walk around your living room, sometimes the sound constructively interferes, and it's loud, sometimes it's quiet, right. That's because phase depends on distance. Right where you are in the wiggle or you up or down depends on how far you are from the source. So you can do destructive interference, and that's an excellent way to cancel out somebody signal, but you can only do it one place. So if you're the Soviet Union and you want to jam like broadcast of Voice of America across Europe, there's no way to do that with destructive interference, unless you're like buying everybody noise canceling headphones and putting them on their head. Each one would have to generate a different cancelation signal based on where that person is, right, use no way to cancel it broadly all over Europe or even over like a two meter span. It's very very sensitive and very very localized. So destructive interference very cool, very powerful, very amazing technology, but not the basis of signal jamming, because you can't do it over a broad.

00:24:39
Speaker 2: Area, all right, So destructive interference out not nice.

00:24:45
Speaker 1: Instead, signal jamming is much cruder. It's just your annoying siblings shouting in your ear right and so you're right. You have to target the right frequency. If Kelly is expecting to get a signal from Daniel at a certain frequency, then to jam that signal, you just make a bump bunch of noise at the same frequency. And you want to make it like unpleasant, or you want to make it like really loud and uninteresting, you know, to drown out the interesting stuff. And so like early jambers from the Soviet Union, for example, it used to be powered by a diesel engine. So like a diesel engine generating the electricity, you needed to generate the signal, and they were like, well, what signal are we going to send? And they decided just to send the sound of that diesel engine as the gamming signal at that frequency, So.

00:25:27
Speaker 2: You know, it happened to be the right frequency or they adjusted it. They adjusted were down to be the right fork.

00:25:34
Speaker 1: They adjusted it, but has like a little bit of natural variation which makes it harder to filter out, you know, so it's like, yeah, I know. Or other classic choices are bagpipes, which I think is just like, you know, choosing to weaponize Scottish culture. I mean, you can't send haggis over the airwaves, so this is like the second best thing.

00:25:56
Speaker 2: Yeah good, Yeah, can you find a third way to isolate our Scottish listener, l.

00:26:03
Speaker 1: I'm just speaking to the power of their culture, you know, I see, Yeah to be I'm wait, I'm a big fan of Scott's I've hired several Scottish post docs. I have recently been to Scotland were killed at a great time. Love Scotland for the record, Do.

00:26:16
Speaker 2: You love Hagison bagpipes? Daniel, Let's move on, Daniel. Where does the phrase jamming come from? Because I don't usually think of jamming as meaning like make a lot of noise to drown out something else. I think of jamming as like, you know, putting a wrench in something to stop it all together.

00:26:38
Speaker 1: I mean, this is a really fun question because jam has so many meanings, right, Like there's a strawberry jam you make at the end of the summer. And I used to think that that was the connection with signal jamming, that like you're throwing a pot of jam onto somebody's radar dish or okay, but it's not. It's more like a log jam, you know how you can like have a traffic jam, things get clogged up, and so signal jamming is like clogging up signals. Not making starberry jam, or not hanging out and playing the electric guitar with your goth friends in the garage in the afternoon, which is also another kind of jamming.

00:27:14
Speaker 2: Not or weeby jam. I'm not gonna do anymore singing to and I don't want to alienate any other groups of people.

00:27:20
Speaker 1: Will move on alienate you're getting invitations. Somebody out there was like, that's the voice I need on my hip hop album.

00:27:26
Speaker 2: Well, but then I went and sort of almost saying, so they're gonna send that invitation immediately. So uh, all right, moving moving on.

00:27:35
Speaker 1: But the basic idea is you create a signal that's hard to filter. If you're trying to interfere with me sending messages to Kelly, for example, and you create noise at just one particular frequency, Kelly could just delete that from what she's hearing and listen on another frequency. Or I can shift my frequency a little bit so it's not on the noise frequency.

00:27:54
Speaker 2: And you're gonna talk to me like this instead.

00:28:01
Speaker 1: And so you know, to be effective at jamming, you want to do it broadly over a few frequencies, and you want to send something that's harder to remove. Like we know that noise can be removed. Our amazing audio wizard Matt removes noise from these tracks all the time. But the hardest noise to remove is like variable noise, unpredictable noise. So if you want to be hard to remove, you've got to generate unpredictable noise. And that's why like bagpipes or diesel engines are better than just like a single piercing note.

00:28:30
Speaker 2: Okay, all right, are there other ways to jam?

00:28:33
Speaker 1: Yeah, it's like an arms race of cleverness here some people do things like capture the real signal and then modify it and tree transmit a deceptive version of it. So you know, you're like taking Daniel's message and you're adding a bunch of quantum woo to it, and then you're sending that to Kelly and she's getting very confused because it sounds like Daniel, but it's full of nonsense, you know. And so this is like more powerful, more subtle signal jamming. But basically all these things are loud radio shouters. You know, just be really really loud. And the idea is to have your jammer close to the receiver. So like you're trying to interfere with the signals sent from California to Virginia. See you set up near Kelly's farm. You create one of these jammers. You're not gonna interfere with my signals going to Hawaii or whatever, but you're gonna interfere with Kelly getting the signal because you can be louder for Kelly than I am, because you're closer to her. These jammers, when they're effective, typically fairly localized.

00:29:29
Speaker 2: Why can't a jammer that's sending like a diesel engine sound or whatever, be just as effective as the original message. If it's sent out as strongly as the original method.

00:29:42
Speaker 1: It can absolutely if you have that much power to send out a really loud jamming message, then yes, and we can talk about some examples of that. But typically the range depends on the power and the proximity. Like you can buy a cheap handhold cellphone jammer that works, you know, like thirty to fifty meters, so you can walk around in a way that nobody can get a phone call or nobody can send you a phone call. The military has more powerful jammers that work like, you know, hundreds of meters away. But I should note, for I talk about these things, these things are totally illegal.

00:30:14
Speaker 2: Oh okay, I was going to ask why more people haven't messed with their exes using these things, but okay, totally illegal.

00:30:19
Speaker 1: Yeah, totally legal. And almost every country in the world it's illegal to build one of these things, mostly because they interfere with emergency communications, right, Like it's hard to overcome these things, and if somebody needs to make a phone call, a nine one one call or something, you know, it could be bad, like there's a guy in two thousand and two in France who installed a jammer because he was frustrated by his kid's use of phones late at night, and he knocked out service for the whole town for like hours and hours. And yeah, that guy got in a lot of trouble. So, you know, parenting gone high tech wrong.

00:30:56
Speaker 2: So how did he get a jammer? Or was he like super he made his own jammer because he, you know, just kind of knew what he was doing.

00:31:04
Speaker 1: Well, these things are totally legal, but you can buy them. People are out there building them and selling them, and so yeah, for sure they exist, and you could probably even buy one online. It's not that hard. But anybody out there who's listening should know these things are totally illegal. And so when you get caught, don't say Daniel told me how this works and I decided to do it.

00:31:24
Speaker 2: Yeah, no, we're we're talking jail time finds rights. Don't blame DK. We told you so.

00:31:32
Speaker 1: Exactly. And these things just get more and more sophisticated. Our description of messages was essentially how analog messages work. You're encoding it somehow directly into the waveform. But modern communication is mostly digital right, we're transforming the waves somehow into digital signals zeros and ones, which involves some sort of binning. Right, so you have thresholds et cetera, et cetera. And these digital signals also use complex modulation technique, so like you're shifting the phase. There's all sorts of back and forth between like the receiver and the transmitter. Do they recognize each other? You know, okay, I'm ready send the signal. Now, okay, I got it. This check sums back and forth. It's not as simple as just like I'm broadcasting in the clear for anybody to listen to. And so more complicated digital signal jammers can be really subtle. They can like send a fake handshake to say hey, I'm the sender, and they can keep doing that, and it like traps the receiver in an infinite loop. It's sort of like almost more like hacking than like jamming. You're just confusing the receiver so it can't actually hear the real.

00:32:36
Speaker 2: Message oh wow. And so you can't like change the channel at that point or.

00:32:41
Speaker 1: And so the response is to like shift the channel constantly.

00:32:45
Speaker 3: You know.

00:32:45
Speaker 1: Defense mechanis will get into that in a minute. There are approaches to avoid this, But there are other technologies that are easier to jam, like Bluetooth and Wi Fi. Like if you have many devices, they avoid talking over each other. Before your phone transmits via bluetooth, listens be a Bluetooth to hear is anybody else transmitting and so I'll just wait. So they avoid colliding with each other. And so if you just are constantly shouting at that frequency, you basically block all Bluetooth. So you can block Wi Fi and Bluetooth more easily because they're very polite technologies, right, They're avoiding colliding with you. And so if you're just really really rude and loud all the time, then a continuous transmission like that can effectively block signals.

00:33:26
Speaker 2: No good, We're becoming more vulnerable over time. Lovely, All right, well, let's take a break and when we come back, let's take a bit of a stroll through jamming history and see times that this has been used in the past. All right, welcome back to Daniel and Kelly's Extraordinary Universe. And now that we're all experts on the science of jamming, let's take a little stroll through the history of jamming, and Daniel will tell us about when jamming has been used in the past.

00:34:12
Speaker 1: Yeah, so you know, we developed electronic transmissions in the early nineteen hundred, so you know, radio and all this kind of stuff, and then it was very very important. In World War Two, the radio and radar became very important. And radar is just you know, sending out more electromagnetic pulses and seeing how they bounce back and using that to detect like, you know, jets, et cetera. And so radar jamming became very important. You didn't want to be spotted when you're zooming in for your bombing sortie, and so airplanes could like send out false radar signals, right, you send out pulses that make it sound like you got bounced back from something else or et cetera. Then you could jam radar. If you're just like constantly sending pulses at somebody's radar, then they can't hear anything. If your planes are coming in but you have another device it's like shooting a huge amount of radar specifically at that listener, then they can't use their radar to detect your planes.

00:35:04
Speaker 2: I guess, as someone who's more of a fish person than a bird person, I was thinking of the submarines. Were they jamming the submarine radars too?

00:35:12
Speaker 1: Yeah, exactly the same kind of thing happens for submarines. You can also jam radio, like the BBC broadcast over the continent, and the Nazis were not big fans of the BBC. They thought it was you know, left leaning media bias, as we often hear, and so they tried to jam that radio essentially just broadcast at the same frequency as loudly as possible so that you just can't hear the BBC.

00:35:37
Speaker 2: Wow.

00:35:37
Speaker 1: And then there's hilarious stories like Russians left minds all over Finland, but these were radio activated minds, so it could be like remotely detonated. And so the Finns figured out what frequency it was, and they played polka music continuously for like five months at that same frequency, so the Russians couldn't activate their minds, and then by that point the battle reason the minds had died.

00:36:01
Speaker 2: That's amazing.

00:36:02
Speaker 1: I know, I love the polka defense.

00:36:05
Speaker 2: Does polka music come from Finland?

00:36:08
Speaker 1: I don't think so. I thought it was more Truman I associated more with like Octoberfest, But so I don't know why they chose poka music.

00:36:16
Speaker 2: I mean, they must have liked it, right, because they were gonna have to listen to it for a long time, all right. So after World War Two came the Cold War, I'm guessing jamming was important then too.

00:36:27
Speaker 1: Yes, exactly. So the BBC and the Voice of America tried to broadcast into the Soviet Union, and the Soviets didn't like that, and so they tried to jam those signals. Same way they just like create loud broadcasts at the same frequency to interfere. Okay, But it's interesting because you know, how well you pick up a distant radio station depends a lot on the atmosphere conditions. You know, is there a lot of wind between you and there, which changes like the density patterns in the air, which creates like refractions and reflections. It's sort of like optics. And so as the day goes on, you might like hear the BBC louder or quieter, or the jam or louder or quieter. So you might be able to pick up the BBC during some parts of the day during certain weather conditions. You know, the jamming is not one hundred percent effective. You can also as a defense mechanism use like directional antennas the simple model of antenna we talked about before, which just like you have a tower, it picks up electrons, but you can also build them have a more complex structure, so they're better at picking up signals in certain directions. Like for example, this microphone I'm talking to. Our audio guide tells me that it's a directional microphone. If I speak at the front of it, then it picks me up better than if I'm speaking at the side of it. And that's just because the structure of the electronics inside of it that resonates better with a signal from one direction. And so if you want to only pick up signals from the UK and not from Moscow, you don't want to use a general antenna. You want a directional antenna helps you overcome the signal jamming a.

00:37:54
Speaker 2: Little bit, except the Soviets would want to pick up the message from Moscow and not from the UKA. But yeah, I see your point exactly. Well, let's let's go to one of the best states in the United States. Let's hear about jammers in New Jersey. I was born in New Jersey, so I do I do so love New Jersey.

00:38:13
Speaker 1: So as a reminder, jamming is totally illegal. But there was a guy in twenty thirteen in New Jersey who wanted to evade company tracking. Like he was driving a work truck and the company had a GPS tracker on it, and he didn't want them to know when he, like you know, went in and out or took a nap in the side of the turnpike for two hours or whatever. So he bought a cheap GPS jammer and he put it on his work truck and it worked, but it also jammed all the systems at Newark Airport, causing huge chaos for airport traffic. And yeah, so he was fined tens of thousands of dollars for creating that hassle. So again, these things totally illegal, Do not use them.

00:38:53
Speaker 2: I mean, he's lucky, like planes didn't crash into each other and a bunch of people died. He's lucky he didn't go to jail or something. But yes, totally illegal, friends, exactly.

00:39:04
Speaker 1: And jamming extends not just on the surface of the Earth. You can also interfere with communications into space. Right. A lot of our communications these days goes via satellite, and satellites require sending messages up to the satellite and then receiving messages back down from the satellite. So that's two opportunities to interfere with the signals. It's uplink jamming and down link jamming.

00:39:27
Speaker 2: Are satellites do you think they're like any more or less susceptible because they have like do they have specific places where messages are received where that you could like sneak up to and jam or everything has that, and so that doesn't make them any more susceptible.

00:39:42
Speaker 1: Now they are more and less susceptible. Like on one hand, they're less susceptible because they're far away and so like if you want to interfere with uplink jamming, then you need to really send a powerful signal to get to the satellite. Like if you want to interfere with that signal from the ground, you send a signal at the same frequency, and that's powerful because you could like disrupt everybody who's using that satellite if you overwhelm the satellite with some signal. But you need a really powerful signal to do that to get to the satellite. On the other hand, satellites can broadcast over a huge range on the surface of the Earth, right, And so if you want to mimic satellite transmissions, that's much much harder because you'd need to like access where everybody is. And so to make it harder for ground receivers to receive those messages from satellites is pretty tricky because they have such a broad range.

00:40:31
Speaker 2: I thought you said it was going to be easier and harder, but it just sounds like it's harder and harder.

00:40:36
Speaker 1: Okay, well, the easier bit actually is. Unfortunately, this is pretty easy to do, like if not expensive or complicated to interfere with satellite communications. There's a fairly low threshold, like technical competency you need to do this, which is why we see like interference with satellite communications from lots of countries around the world. Indonesia, Cuba, Ethiopia, Libya, Syria, all these places have like for military reasons, you know, and so does the US of course, you know, technology to interfere with satellites. And again this is totally illegal in US law and also violates International Telecommunications Union. But if you want to buy one, they're like the size of a hockey puck, So it's not expensive, it's not complicated, it's not even very big, and this is a potentially very large issue. The United Nations put out of warning calling for urgent protection of radio navigation satellite service to support accurate and global navigation and timekeeping. So it's definitely a big issue, and it's actually happened, like satellites have definitely been jammed.

00:41:41
Speaker 2: Tell us stories, because this kind of stuff keeps me up at night, Like if something happens to all of our satellites, I mean one, I've been living in Charlottesville, Virginia for six years now. I still use my GPS. I would be toasted if satellites were you know, out of commission tomorrow and I couldn't use GPS anymore.

00:42:03
Speaker 1: Well, I read this hilarious interview with General John Heighten, who's head of the Air Force Space Command, and somebody asked him if there had been actual instances of satellite jamming, and he said that in twenty fifteen there were two hundred and sixty one cases where they had been jammed from getting information from their satellites down to the ground segment. And then the interviewer asked them how many of those cases were from like adversaries, you know, bad actors or enemies or other governments, and he says zero. Where are they coming from? He says, these are almost always self jamming. You know, people broadcast. The military is broadcasting constantly in all sorts of frequencies, and so they just like are not organized enough to not jam themselves. And so he thinks that like two hundred times in that one year they unwittingly interfered with their own signals because the M spectrum is very, very complicated, and like a small mistake can create like huge strategic impacts. So this is definitely an issue.

00:43:04
Speaker 2: Okay, But presumably Okay, so I don't remember hearing in twenty fifteen that we jammed ourselves in something absolutely catastrophic happened, So presumably these are mostly minor things that we do that happened.

00:43:17
Speaker 1: Exactly a small delay, we can't hear from the satellite, We lost the connection of the satellite. What's going on? Reboot the machine, Okay, now it's working. That kind of situation is what I'm imagining. But there are times in conflict zones when this has definitely happened, like Libya in two thousand and six jammed a mobile satellite provider called Theraa and a long investigation concluded that jamming came from Libya, so they decided they were like jam this whole provider of mobile satellite communications and.

00:43:44
Speaker 2: Is Therayah a Libyan company? Where they like trying to was it a company that the Libyan government didn't like or was it some other countries.

00:43:53
Speaker 1: It's not clear. It came from Libya, and the government of Libya is one of the shareholders of this company, so it's not even really clear exact exactly what the motivation was.

00:44:02
Speaker 2: Huh.

00:44:03
Speaker 1: All right, and then in Iran in two thousand and two, there's another case of jamming, and of course in conflict zones right now, like Russia has been accused of jamming GPS signals to interfere with the Ukraine military. And also Russia was accused of affecting flights over eastern Europe by jamming GPS signals. There was a time when the European Commission president her plane was forced to land because signals were jammed. She was forced to land in Bulgaria. Wow, and they suspected interference by Russia.

00:44:36
Speaker 2: Yikes. For a lot of these things, I wonder how hard it is to figure out who did the jamming because if you like remove the if you turn off the jam or you remove the device. Yeah, it's probably hard to know, like did a country jam our stuff or did we self jam? And to be clear, I'm not trying to be like, well, do we really know it's Russia. I'm not trying to exonerate Russia in this particular instance or anything. I'm just saying the this kind of stuff is hard, which I wonder could make it used in war situations more often, just because it's the kind of thing that you can, like, you know, say oh we didn't do it, prove it, prove it if you think we did.

00:45:11
Speaker 1: Yeah, because these signals can go really far distances, it's hard to tell exactly where they're coming from. And then even if you figure out where they were coming from, the jammer is not necessarily there anymore. And so yeah, it's pretty effective and pretty easy to hide. But there are other things you can do to defend yourself. You can increase the power of your signal just be louder than the noise. You can use a directional antenna like we mentioned earlier, or you can change frequencies, like instead of just broadcasting on one frequency, you can have a plan with a person listening to your signal of how you're going to change frequencies, Like we can agree on a schedule and we'll switch will hop between frequencies. That makes it harder.

00:45:50
Speaker 2: To jam, does mean? I mean with satellites you have to apply for frequencies through the International Telecommunications Union. So I wonder if that makes it hard to have secrets for like which frequencies you're going to bounce between, because you need to register for the frequencies you're going to be using.

00:46:08
Speaker 1: Yeah, but usually you register for a range, and so if you move within that range and a specific pattern, then it can work. And in fact, this was an invention of Hollywood actress Hidie Lamar. She coinvented frequency hopping technology back in nineteen forty two to help prevent the Nazis from jamming radio guided torpedoes. Yeah, very cool. She's a Hollywood actress and a radio frequency genius. And that technology is used like now in modern Wi Fi and GPS and all sorts of stuff.

00:46:37
Speaker 2: That's awesome, cool way to go.

00:46:39
Speaker 1: And advanced drones also do this to avoid being jammed. I mean, if somebody's controlling a drone, they're doing it using signals, and if you can jam those signals, they can lose control of their drone. Right, So the higher end drones have this sort of technology where the controller and the drone agree on the frequency schedule, essentially to avoid being jammed or to be less susceptible. Interesting, but really the best defense against being jammed is to find the jammer and turn off the jammer. You know, in some way, that's really the best thing you can do.

00:47:09
Speaker 2: When you say turn off the jammer, I guess when I think of the jammer, I think of the person who's doing the jamming. And I was like, well, Daniel, that sounds very intense, but yes, I guess, turn off the equipment. But all right, Well, I had fun jamming with you today, Daniel, and I learned a lot.

00:47:24
Speaker 1: So that is how signal jamming works. And I hope that understanding the physics of this technology gives you more insight into how everything around you is working, how they're all talking to each other, and how mostly it works seamlessly. Even if we get frustrated at our.

00:47:38
Speaker 2: Dishwashers and are electro fishing boats, and.

00:47:43
Speaker 1: If my dishwasher is sentient and is tapped into the podcast Network and is listening to this. I'm not apologizing.

00:47:50
Speaker 2: Message to my bosh, you're doing a great job. I appreciate you. Thank you for your hard work.

00:47:58
Speaker 1: All right, and you all are doing a great job of expanding your minds in this extraordinary universe.

00:48:03
Speaker 2: Thanks everyone, until next time.

00:48:12
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00:48:20
Speaker 2: Daniel and Kelly's Extraordinary Universe is edited by the amazing Matt Kesselman.

00:48:24
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00:48:34
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00:48:40
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00:48:51
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