How GPS Works

27:11Yeah. Is this where I could come in? Yeah. I was hoping so. Hey, well, I'm not going to tell you that, but how about this? You're 690 miles from Minneapolis. Okay. So that's great. At least they didn't repeat the Boise thing, right? Because if they said that, you'd just be like, man, that didn't help at all. But now you know where you are from Minneapolis, and you can do the same thing with Minneapolis. Using that as the center point of a circle, you draw a circle with a radius of 690 miles around Minneapolis. Now you're really close because what you'll find is the circle around Boise and the circle around Minneapolis, they overlap, right?

27:47Yeah, you get a little football in the middle. Yeah, like a Venn diagram. And if you look at a Venn diagram, where those two circles overlap, there's two points where they intersect, right? Where they cross each other, those lines cross each other. And because you are 625 miles from Boise and 690 miles from Minneapolis, you are somewhere where those two circles overlap at those two points. One of those is right. The other is off by hundreds of miles. So you still need to narrow it down. Right. So you're like, is there one more wiseacre in this town who will tell me by not telling me where I am where I am?

28:30Right. And so you go into this final, the only other gas station in town. And you say, guys, someone told me I was 625 from Boise. Didn't help much. Someone else said 690 from Minneapolis. Please just tell me where I am. They said, oh, oh, you're 650 miles from Tucson, pal. Do you just trash the place at this point? Yeah, you just lay waste. You find the nearest broom, and you just start knocking everything off the shelves. That's awesome. My collector beer steins. All right, so now you've got three circles, though. And this is where I got super tripped up because I was like, oh, cool, let me draw this out.

29:04And I drew it out, and I was like, these don't intersect at a common point. Right. But if you're using exact GPS calculations, distance from a satellite, or in this case, points on a map, then that's – you know exactly where you are because it's going to intersect at only one place at three points. Yeah, all three circles will overlap with one another. So they intersect at two different points. Each circle intersects with the other at two points. But all three of them will only intersect at one single point. And you have just trilateral-related your position. You know where you are. And Marshall said, this is Denver, by the way.

29:43That's where you are is Denver. Because I think if we hadn't have included that, some people would have been really upset. Yeah, but you know you're in Denver because you can't catch your breath and it smells like weed everywhere. That's right. And now you have to figure out what to do even though you're dead. Yeah. And liberals and conservatives are smashed together and everyone's like, what kind of state is this? It is. It's crazy like that, isn't it? Yeah. I love Colorado. I think it's interesting that way. It's like all of the shows we've done in Denver, it's like a wedding, like split down the middle.

30:13The people on one half of the room all have guns out. The other half are all playing hacky sack. Right. It's an interesting place. And one guy goes, hey, you ever try to shoot a hacky sack in midair? Watch this. It's kind of fun. Okay, so that's trilaterolation. That's 2D trilaterolation because what you've done is found your, if you were a flat point and the Earth was flat, which it's not, that's all we would need to do. But the Earth is a sphere. It's round. And so what GPS uses is 3D trilaterolation, which rather than flat circles, it uses spheres. And when the three or four usually, because you use four satellites, where those spheres all intersect, the one point, that's where you are.

30:59Because now you not only know where you are longitudinally, you also know where you are altitudinally. My friend, I hate to break it to you, but you did the old Josh Clark insert and extra consonant thing. Trilateralizational? It's trilateration. I know, and I've been wanting to say trilateralization for so long. Well, you weren't even saying that. I just had to get it off my chest. You were saying trilateralation. Okay. All right. So now that's three ways. So trilateration? Trilateration. That sounds made up like Space Force. I know. All right. Trilateration-ization. Yeah. Oh, wait. Station. So that's it.

31:45That's how you figure. Well, I should say that's how your GPS receiver figures that out. It knows where those three or four satellites are because they tell it where they are. It figures out the distance between you and your receiver for each of those four. And it tells it, oh, here's where I am because here's where all those, that information intersects. Right. And I think you mentioned the spheres while I was obsessing about the extra L, right? Yes, I did. Okay, great. And there's a really pretty image out there. I can't remember what website I found it on. But if you search, like, how GPS trilateration works, it will come up, I'm sure.

32:24But it shows, like, the four spheres created by the satellites, and they're all in four different primary colors, and it's so pretty. I saw that, yeah. I understand that there are three primary colors, but whatever the fourth one is, it's basically a primary color as far as I'm concerned. Okay. Should we take our second break? Yeah, I think so, Chuck. Look, we earned it with that trilateration, explanation, explanation. We'll be right back.

33:06New year, new goals, and in this economy, a better money plan is more necessary than ever. I am Matt. And I'm Joel. We are from the How to Money podcast, and every week we help you to spend smarter, save more, and make sense of what's going on out there. If you want 2026 to be the year you finally feel in control of your money, we're here to give you the tools and advice to help you make it happen. Listen to How to Money on the iHeartRadio app, Apple Podcasts, or wherever you get your podcasts. Hey there, this is Dr. Jesse Mills, director of the men's clinic at UCLA Health and host of the Mailroom podcast.

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35:45Okay, Chuck. So there's one other thing, kind of like a little sidebar I felt like we should talk about. If you've ever tried to figure out where you are and your phone's like, turn on Wi-Fi and we'll get a better reading. I've never understood that until you explained it. So what it's trying to do is it's prompting you to turn on your Wi-Fi based positioning system. And that is based essentially on the same thing that Dr. Getting was getting at, which is you can use information from different sources and comparing those sources to figuring out where you are. And so rather than using satellite information, this uses the, it bases it on the known strengths of different Wi-Fi network towers, antenna.

36:35And so depending on how strong one signal is compared to where you are, in addition to comparing it to another signal and another signal, another signal, it's like, oh, you're in Denver. Right. You don't know how dumb I am? I don't think you're dumb. I know you're not dumb, but let's hear what you have to say. I say this out loud at the risk of losing listeners that might be new listeners. I'm like, I can't listen to this guy. Oh, this is really dumb. And up until yesterday, whenever my phone or my car or something said, you know, turn on your Wi-Fi to improve accuracy of your location. It's like, I'm not near my house.

37:11What is this thing asking me to do? I'm not near my Wi-Fi. You weren't like, you're not the boss of me. No. I was just, that's pretty dumb. I don't, no, it's not. Wi-Fi is everywhere. It doesn't have to be your house Wi-Fi. So, yes, that's one way it does it. And it does it in your house, too, but that's because your router is a big blabbermouth and tells everybody where you are. I'm glad to get it. It's like, they don't know. I'm not near my house. Why is it asking me to turn on my Wi-Fi? This phone is so stupid. Oh, boy. All right. So speaking of the opposite of stupid, your smartphone, how accurate are those things?

37:51When GPS first started, they said, and this was, again, like 95-ish, They said it's going to be accurate to within 100 meters 95 % of the time, which at the time was like, hey, that's not bad at all. Like that gets me in the neighborhood of where I want to be. They've gotten much, much better. Now they say two meters within two meters of 6.6 feet, but it's really closer than that. They did some measuring in 2021, and the global average across all users was about just a little more than two feet. Mm-hmm. And, you know, again, that depends on a lot of things. If it's got tall buildings in the way, space weather, atmospheric conditions, apparently like a really dense like jungle canopy or thick shrubbery can actually degrade the accuracy of that signal.

38:39Yeah. You got a hickory tree? Well, T.S. for you because GPS isn't going to work. Is that a thick tree? Thick canopy? Yeah. I would. Yeah, I think so. I mean, it's a known shade tree. No. Oh, it's a. Yeah. It's a KST. That's right. Put it on the list. If it could broadcast information, it would also be a known point. Yeah, exactly. So there's a couple of other things that can mess with your GPS signal coming from the satellite. Because remember I said that they navigate celestially? Well, if the Earth's position itself relative to the satellite, satellite can know where it is. But if the Earth shifts a little bit, like the magnetic core sloshes around just enough that the Earth kind of wobbles a little bit, or if the sea currents are particularly strong, it can like slow the rotation of the Earth.

39:34Those things, I mean, just the tiniest, tiniest changes can alter the accuracy of the signal that it gets. But that's just the signal that they're like, we're going to get you within six feet. They don't guarantee your receiver, and your receiver typically adds a little bit of inaccuracy. I think five meters is usually what you're going to get from, like, your average dumb GPS receiver. Yeah, and I get, I mean, it's amazing we're here because if you're, like, GPS to just say, this is good. If you're five feet away from the restaurant or your friend and you don't see them, that's on you. Yeah, just look up.

40:16Yeah. So we're getting better, though, you know? Yeah, no, it's getting, I mean, I imagine they're going to have it, I think, March 24, if you're an ideal, if it's clear skies, you're out in the middle of the desert or something, they can be as accurate as 30 centimeters. Which is five AA batteries end-to-end. we're going to get even better than that though chuck because right now there's some really good gps antenna that are starting to pop up in smartphones and those those are a dual band dual a dual band dual frequency receivers one of those two and that uses the l1 the standard civilian gps band that has been around since the beginning but it's gotten better over time And it also uses the new Whizbang L5.

41:05And this is like the next generation of GPS. It's not widespread enough yet. There's not enough satellites out there that are L5 for an antenna to just rely on that. But when you put L1 and L5 together, it gets pretty good. The thing is, is you might ask yourself, like, why would you need to get, like, within centimeters of the restaurant that you're going to? It doesn't make sense. Well, some people use GPS for more than just finding the restaurant that they're going to. Yeah, that's right. And your parents and grandparents might be using their Garmin still. So just have patience with them. I think that Garmin was actually one of the original GPS devices.

41:49Yeah, and it's still being used in certain cars in certain people's families. Are those things even supported any longer? I don't know, man. It's pretty funny, though. It's like looking at a MySpace webpage or something when you look at it. I'll bet it is. But yes, I took us off task. You were talking about other things that this is used for a lot. We talked about landing airplanes. That's pretty important. Accuracy is pretty important, maybe not down to the centimeter. But if you want to track soil moisture, you can do that via GPS. If you want to measure the size of a glacier and whether it's shrinking or moving, you can do that very, very accurately.

42:28And not just sort of ballpark things anymore. Migration patterns. If you want to see where that school of whales is headed and how they know when they get there and how far they are from where they started, you can do that with great accuracy. Yeah. Also, things use it to basically stay in position like modern agricultural equipment like harvesters. They go in a straight line by themselves thanks to really precise GPS. Same with self-driving cars. Oh, sure. Yeah. And then, like, apparently it's just grown so ubiquitous and so reliable that contractors use it. Like digital blueprints will have GPS coordinates for, like, a nail or an electrical outlet or something like that.

43:16So you can know exactly where that thing's going to go, which, I mean, that's got to cut down on construction costs and time dramatically. Yeah. I thought the thing on tunneling was kind of cool. I never really thought about that. But if you're tunneling through two sides of a mountain to ideally meet in the middle and have a one long tunnel that's not one tunnel with a little zigzag in the middle because they were off by a little bit, you can do that down to the centimeter, you know, or 30 centimeters, rather. Yeah. A tunnel that goes through a mountain with like a hairpin turn in the middle.

43:48That sounds great. And if you put all this stuff together, all these different uses for GPS, which again, the American taxpayers give to the world for free, it generated, I think in 2022,$94 billion worth of stuff. Right? All of that receivers that were sold, all of the tunnels that were drilled correctly, like all that stuff came to generate$94 billion. And in the next five years, it's expected to hit almost$300 billion. So it's a big deal. Like we rely on GPS a lot. And so because we rely on something this much and because, like you said, we don't have a backup of GPS in particular, it can be pretty delicate, I guess you could say, to put it delicately, because it can get screwed up pretty bad pretty easily.

44:43And in fact, on a very local level, you or I could go screw up somebody's GPS for fun anytime we wanted. Yeah, that was a little disconcerting to learn. I thought like, oh, well, surely this thing has just some weird, robust government shield that cannot be hacked. Right. And that's not true. In fact, the military, I mean, it's part of military, just regular operations to jam GPS for another country. their planes and drones, or to spoof it is when you send it, you know, jam it and make it nonoperable. But you're like, ooh, here's some fake coordinates that you're going to think are real. Right, yeah.

45:22Like, they do that all the time. Countries do that to us all the time. But like you said, any schmo that's got$300 can get a software-defined radio and figure out how to use it and jam somebody's GPS. And so your neighbor's walking around wondering where that restaurant is. I know. They're like, Fridays. Right. I wanted to go to Binigan's. Yeah, so you were talking about spoofing. Apparently, Iran in 2019, just for kicks, spoofed a British cargo ship's GPS and told that it was in international waters when really they had drifted into Iranian waters. So Iran was like, oh, you're our ship now and you're our crew now.

46:04And they held the whole thing for 10 weeks just by being jerks, apparently. I can't figure out what the point would have been for that other than to flex. Yeah, that is a little odd. I'm sure somebody knows. Or maybe it was a flex. Yeah, and the kids still say that, right? They flex? Oh, you're asking the wrong guy. Okay, well, let's say they do. I mean, Ruby says things I don't understand and I just don't even ask. I know. I know. My niece Mila was schooling us on slang, and I'm like, there's no context for that. It doesn't make any sense. Yeah. I'm trying to think of one example. I know I'm going to get it wrong.

46:42No cap? No. Something like skibbity. Oh, skibbity toilet? Yes. And I understand, yes, it's a web video or whatever, but the videos itself make no sense whatsoever, too. Yeah. Hey, you know, all we did in the 80s was shorten awesome to os and un-os. That was our big contribution. That was just as sophisticated as we got. I don't know about the skibbity stuff. Yeah, and I don't mean to complain. I mean, each generation builds on the last, comes up with its own stuff. I'm happy about that. I just don't understand it. Well, that's the point, I think. You know, I think you're right, actually, and I'm kind of hurt by that.

47:22Yeah, it's, you know, kids and teens come up with their own language, so adults don't know what the heck we're talking about, and they can laugh behind their backs. Yeah. We did the same thing. I didn't. We said, that's very un-oss, and our parents were like, what are they saying? I can't make heads or tails of that. Airlines can get jammed. There was a study that found intentional jamming of airlines was a problem in three regions, only three. More than 70 ,000 flights were jammed between February and August of 2022. And that, you know, once you jam it up, you can't reset it. Like that plane lands and then the unjamming happens.

48:02Yeah, you have to turn the whole thing off and reset everything. You can't just reset the GPS antenna. They need to work out all that stuff, don't you think? They definitely do. But something about those flights being jammed, those are civilian flights being jammed by bad actors and sometimes governments and militaries. So what you're trying to do essentially is to crash a plane full of people. Like that's your shot. It's not like a really dedicated shot at it, but that's pretty much the goal of doing that to an airliner. Yeah. And you have no idea how much I put my hand over my mouth when you said bad actors and I almost shouted out a few names of actors.

48:42Who are you going to name? No, I can't because, you know, you never know. People might listen to this. I'm sensitive to hurting people's feelings now here in my 50s. I think that's great, man. Well, text me some names then. I will. Okay. There's another thing that spoofing, I believe, I think they use spoofing for it, is to cheat at games like Pokemon Go. Yeah. Where you can fake where your own GPS coordinates are to say like, oh, I'm at the, I don't know, Pikachu's lair or something like that. So give me the egg that Pikachu is guarding, which I can turn into like some skee-ball tickets and get a comb.

49:23or a skibbity toilet. I hope that doesn't mean something dirty, right? It means nothing from what Mila's told me. Like, it's just basically a thing you say. Okay. I hope I'm not outing Mila as uncool, though. Well, I'm just glad that you have someone in your life that's down with that kind of stuff because it's pretty vital these days. I don't know if it's vital that I know that skibbity toilet exists. Maybe not that, but skibbity toilet that has its own Wikipedia entry. Oh, I believe it. Have you seen the videos, though, that it's based on? No, but I see a screenshot now. They're mesmerizing.

50:01It doesn't pull me in. You should watch a second or two of it. You don't need to watch much. You get the gist of it really quick, but you'll find that your mouth is open. Not in awe, but just because you're glazed over. Right. So, like you said, the United States is not unaware of the vulnerability. That was what I was saying. It was in a delicate position. It's vulnerable. It's a very vulnerable system. And, you know, like globally and also locally. So they are taking steps to update it. And that is going to come in the form of adding more and more L5 satellites. That's right. But for now, if you want to be a little shocked taking into consideration how dependent we are on GPS, the average age of a GPS, specifically the United States' global positioning system, satellites, is 13 years.

50:59Yeah. That is really old for a satellite. But, Chuck, tell them how old the oldest satellite in the constellation of GPS satellites is. That would be 27 years old. Is that right? Yeah. Yes. That thing has sarcopenia.

51:21I guess that's it for GPS, huh? Yeah, this was more fun than I thought. And you know what? I'm glad we had some fun and had some laughs because that feels like a lighter tribute for Marshall than something else. For sure. Hopefully we made you proud, Marshall. And thanks again for everything. And since we said thanks to Marshall Brain, then I think it's time for listener mail.

51:48I'm going to call this Forget Rice. How about some peace and love? Hey, guys, big fan of the show. I love listening when training for marathons and love the recent marathon episodes. While listening to the history of refrigeration, the rice method for managing a musculoskeletal injury was mentioned. Did you know, guys, that in 2020, the medical world threw out the rice method and transitioned to peace and love? I don't even remember mentioning that, let alone knowing that tidbit. I think I probably did. So for peace and love, we have protection. Avoid activities that cause pain for two to three days.

52:26Elevation. The A is avoid anti-inflammatories because apparently that reduces healing and you should avoid ice too. I have heard that anti-inflammatories are actually not very good for you. I never take those anyway because I don't really need to. But, yeah. Lucky. Some people really need them. I know. I'm sure. Where was it? A. So down to C, compression. E, education, which is avoid unnecessary passive treatments. Your body will heal. So I guess educate yourself. They were like, we really need an E here. Yeah. Yeah. Basically. And then we, and is not spelled out, but love is load. Let your pain be your guide.

53:08optimism, condition your brain, vascularization, pain-free cardio, and exercise, restore mobility through active approach. And Sarah says, this is a lot. I hope people can learn to avoid ice and anti-inflammatories for optimal recovery, but it's having a hard time catching on. I can't imagine why. That is from Sarah, PT bird nerd, Hollingsworth, and she's a bird nerd and loves our bird episodes. That's awesome. Thanks, Sarah. Way to spread the good word. I know there's a lot of good advice and information in there, but it's just going to take months of digesting that information to try to figure out those acronyms.

53:49Yeah. If you want to be like Sarah and put something on our radar that we weren't aware of before, we love that kind of thing. You can send it to us via email, like Sarah did, to stuffpodcasts at iheartradio.com.

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54:32But 2026 is the year for you to get intentional and make real progress. That's right. Each week we break down what's happening with your money, the most important issues to focus on, and the small moves that make a big difference. Kick off the year with confidence. Listen to How to Money on the iHeartRadio app, Apple Podcasts, or wherever you get your podcasts. I'm John Polk. For years, I was the poster boy of the conversion therapy movement. the ex-gay who married an ex-lesbian and traveled the world telling my story of how I changed my sexuality from gay to straight. You might have heard my story, but you've never heard the real story.

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