Speaker 1: Get in text with technology with tex Stuff from how
Speaker 1: stuff Works dot com. Hey there, and welcome to tech Stuff.
Speaker 1: I'm your host, Jonathan Strickland, senior writer for how stuff
Speaker 1: Works dot com and today in the studio, I am
Speaker 1: not by myself. It is so amazingly awesome. Only am
Speaker 1: I not by myself? But I didn't even have to
Speaker 1: pick the topic. My guest did it for me. And
Speaker 1: my guest, of course, is someone you all know and love,
Speaker 1: Joe McCormick. Beloved in our office. We sing his phrases
Speaker 1: when he's not around. Joe. Welcome back to the show.
Speaker 1: Thank you for having me. Jonathan, You're welcome, Joe. It's
Speaker 1: like a little it's like a two thirds forward thinking
Speaker 1: reunion right now. So I wanted to talk today a
Speaker 1: little bit about a subject that is recently near and
Speaker 1: dear to my heart. Not a long time fascination, a
Speaker 1: recent obsession, and that is the idea of radio direction finding. Yeah,
Speaker 1: this was something I knew. I mean really, I knew
Speaker 1: nothing about it when you brought this to my attention.
Speaker 1: And the more I learned about it, the more I realized,
Speaker 1: not only is it a fascinating subject, but it also
Speaker 1: in many ways. It's kind of a spiritual cousin to
Speaker 1: some other topics I've covered, like geo cashing. Just for
Speaker 1: one specific part of radio direction finding that we'll get
Speaker 1: into in this episode. Okay, so, uh to introduce you here,
Speaker 1: I want you to imagine you have a favorite radio station.
Speaker 1: You don't have to imagine, you really do it. What
Speaker 1: do they play on Power nine. Well, they don't play
Speaker 1: anything anymore because now it's but back in the nineties,
Speaker 1: Power ninety nine was the station that slowly introduced Atlanta
Speaker 1: to the wonderful world of alternative music. Okay, so R
Speaker 1: e M got a lot of play. In fact, the
Speaker 1: very first time I ever heard R e M Losing
Speaker 1: my religion was on Power ninety nine. Yeah. Do you
Speaker 1: listen now to point one the River? You know what?
Speaker 1: Not a big not a big fan of the River,
Speaker 1: but I do still listen to ninety nine X, which
Speaker 1: is not one seven anymore. I can't remember which station
Speaker 1: it's on, but I still listen to that. Okay, Well
Speaker 1: take yourself back in time, Jonathan, go back to the
Speaker 1: days of power and imagine. You know, Power ninety nine.
Speaker 1: It just gets you through the morning. You wake up
Speaker 1: every day, you know. Uh, it gets you through the
Speaker 1: t d M of peeling those thirty seven hard boiled
Speaker 1: eggs you're gonna eat for breakfast and accurate so far,
Speaker 1: and it's just it's your favorite part of the day.
Speaker 1: But one morning you switch on your radio to Power
Speaker 1: ninety nine. You think you're gonna hear some great new
Speaker 1: R E M singles, But instead, something is wrong. Instead
Speaker 1: of the regular programming of your of your regular favorite
Speaker 1: radio station, you are treated to an unending loop of
Speaker 1: Mick Jaggers solo love ballad hard Woman. Is this the
Speaker 1: one that has the terrible music video? Yeah, that was
Speaker 1: put together by a Ray supercomputer. Yeah, now I remember this.
Speaker 1: I remember you showing me that music video. And and
Speaker 1: the only thing worse than the music video was, in fact,
Speaker 1: the song itself. It's it's hard to know which is worse,
Speaker 1: but yeah, so it's looping. In fact, they don't even
Speaker 1: let the song finish. Each time it plays, the loop
Speaker 1: begins about ten to fifteen seconds before the song's over. Maddening. Yeah. Uh,
Speaker 1: so you call up the station, You call up Power
Speaker 1: nine and nine, say hey, what's up with hard Woman
Speaker 1: all the time? Where's my R E M? And they say,
Speaker 1: I don't know what you're talking about. We're running our
Speaker 1: regular programming. Somebody is jamming you. So what they're doing
Speaker 1: is they're using a transmitter, presumably one much closer to
Speaker 1: you than the radio station's transmitter, and had a power
Speaker 1: that overpowers the incoming signal for that radio station. Right,
Speaker 1: because they're closer to you than the radio station is.
Speaker 1: They can do this because the only other way they
Speaker 1: could do that is if they were actually putting in
Speaker 1: more power in their transmitter than the radio station is,
Speaker 1: which is not likely. But somebody in your neighborhood, somebody
Speaker 1: near your house with a with a vendetta against R. E.
Speaker 1: M or maybe just an unending, powerful, overflowing love for
Speaker 1: Mick Jagger's hard woman, or some sort of curmudgeon in between,
Speaker 1: is broadcasting this malicious interference on the same frequency as
Speaker 1: your beloved station. Now, obviously this is intolerable, but the
Speaker 1: station themselves, well, they probably can't do anything about it.
Speaker 1: So you contact the FCC. Right, this should be their
Speaker 1: job to deal with here in the US. That's exactly
Speaker 1: who I would have got them on speed dial. Right,
Speaker 1: Signal intrusion. Right, you're supposed to regulate the airwaves. So
Speaker 1: you call up the FCC, but they tell you to
Speaker 1: take a hike. They're busy undoing net neutrality too, So
Speaker 1: what are you gonna do? Are you just going to
Speaker 1: allow this radio freak to jagger up your mornings for
Speaker 1: the rest of your life. That doesn't sound like me, Joe. Uh,
Speaker 1: if you're If that's not your style, One thing you
Speaker 1: could do is try to take matters into your own hands. Now,
Speaker 1: how would you do that? You would have to track
Speaker 1: down the jagger jammer yourself and give this creep a
Speaker 1: piece of your mind. But how could you do that?
Speaker 1: Like the song loop doesn't say, hey, by the way,
Speaker 1: here's the address of my secret jamming transmitter, at least
Speaker 1: not explicitly, So then I'd have to figure out some
Speaker 1: way independent of the content of the signal to track
Speaker 1: the location of the transmitter. Yeah, and that's what today's
Speaker 1: episode is going to be about. If you know a
Speaker 1: few techniques, and if you have some special equipment on hand,
Speaker 1: you actually should be able to locate this jammer through
Speaker 1: the art of radio direction finding or r DF as
Speaker 1: I'm sure we'll refer to it throughout this episode. It's
Speaker 1: the act of hunting a radio broadcast to its physical source.
Speaker 1: UM So today we're gonna talk a little bit about
Speaker 1: r DF in general, a little bit about the history,
Speaker 1: about the science behind it. But we also wanted to
Speaker 1: focus somewhat on the sport of transmitter hunting, also known
Speaker 1: as t hunting or fox hunting, which turns this activity
Speaker 1: of radio direction finding into a recreational activity. And this
Speaker 1: this ties into a lot of those other subjects I
Speaker 1: was talking about, like from the aspect of geocashing, where
Speaker 1: we're using technology for some sort of recreational activity that
Speaker 1: it wasn't necessarily intended to be when we first started
Speaker 1: developing that tech, all the way to the story Chuck
Speaker 1: and I did about the infamous Max Headroom incident right
Speaker 1: where somebody another case of signal intrigues exactly, someone was
Speaker 1: able to do signal intrusion in the Chicago market and
Speaker 1: uh overpower television signals and present a an absurd, slightly
Speaker 1: disturbing and very surreal Max Headroom type of intrusion. Well,
Speaker 1: those those things, I mean, that's that's kind of why
Speaker 1: we're talking about this, is like, how would you detect
Speaker 1: where such an intrusion is coming from if you had
Speaker 1: enough time to do so. In the case of the
Speaker 1: Max Headgroom incident. Yeah, by the time anyone knew what
Speaker 1: was happening, it was too late to really figure out
Speaker 1: where's the signal coming from. They had general ideas just
Speaker 1: based upon the architecture of the city, because things like
Speaker 1: buildings and stuff can get in the way of radio signals,
Speaker 1: so that that limits where a signal can come from.
Speaker 1: But you need something more sophisticated in order to narrow
Speaker 1: down the actual direction and specifically the locality of a transmitter.
Speaker 1: So this has a really long history. It dates back
Speaker 1: pretty much shortly after we started sending radio signals. Uh.
Speaker 1: In fact, the very first person to kind of associate
Speaker 1: directionality with radio signals was Heinrich Hurts. And that name
Speaker 1: Hurts probably rings some bells. We're gonna be talking about
Speaker 1: a lot about Hurts, the unit of measurement, and not Hurts,
Speaker 1: the person in this episode. He discovered with an open
Speaker 1: loop of wire which was acting like an antenna, or
Speaker 1: it really wasn't antenna wasn't acting like one. Yeah, but
Speaker 1: this was a loop of wire that had a gap
Speaker 1: between the two ends of the loop. So it's not
Speaker 1: a closed loop. It's an open loop, it had some
Speaker 1: direction finding properties to it. He found that if he
Speaker 1: used this loop near a transmitter, and if the looper
Speaker 1: position so that it's ends faced the transmitter. In other words,
Speaker 1: if you're looking at the face of a transmitter and
Speaker 1: you're looking at a loop, the loop is at a
Speaker 1: ninety degree angle, it's it's the wire part is facing
Speaker 1: the ends of the wire parts facing the transmitter as
Speaker 1: opposed to the open face. UH, it would create a
Speaker 1: real big spark between those two ends. If he started
Speaker 1: to rotate the loop of wire so that the open
Speaker 1: face the o if you will, of the loop faced
Speaker 1: the transmitter, it didn't create that spark. So rotating it
Speaker 1: would create sparks. And the biggest spark would be if
Speaker 1: it was in this ninety degree alignment with the transmitter.
Speaker 1: And that showed that there was some directionality with radio
Speaker 1: waves and antenna Yeah, and that specifically you could put
Speaker 1: together an antenna receiver in certain ways that it would
Speaker 1: respond differently depending on how it's oriented exactly with respect
Speaker 1: to the source of transmission exactly. So the next one
Speaker 1: you would talk about the actual One of the earliest
Speaker 1: successful UH implementations of this idea would be the Balini
Speaker 1: Tosy apparatus. Uh not the only early direction finding antenna.
Speaker 1: Why am I imagining some kind of dessert making machine
Speaker 1: the Bellini tocy apparatus. Like it's like a large box
Speaker 1: out of which comes big blobs of icing, right, or
Speaker 1: gelato or something. I'm on a diet, Dude, you are
Speaker 1: killing me on diesel. I would eat diesel powered gelato
Speaker 1: right now in a heartbeat, but instead I'm going to
Speaker 1: stick to my Brussels sprouts. Uh So, two Italian officers
Speaker 1: named a Torre Bellini and Alessandro Tosi came up with this.
Speaker 1: Sometimes it's actually called the Marconi Balini Tosi because Marconi's
Speaker 1: name gets attached to everything that might be a little
Speaker 1: bitter tesla left over issues that I have about Marconi's
Speaker 1: name getting associated with stuff that certainly he was instrumental
Speaker 1: in the development of, but perhaps not the primary source
Speaker 1: of that technology the way his name would indicate. Yeah,
Speaker 1: the wireless telegraph. You'd want his name all over everything. Yeah, yeah,
Speaker 1: don't worry about people who worked on that stuff, you know,
Speaker 1: before him, or or had originally secured a patent before
Speaker 1: he had and then had their patents overturned. That's another episode.
Speaker 1: In fact, I've talked about it in previous episodes. So
Speaker 1: the way this worked is that they actually created uh,
Speaker 1: two loops of wire arranged at right angles with respect
Speaker 1: to one another. So you can think of these as
Speaker 1: kind of like a casing, these two big loops of
Speaker 1: wire at right angles in the middle of which they
Speaker 1: put a third coil of wire, but this one could
Speaker 1: rotate freely within those two fixed ninety degree angle loops. Okay,
Speaker 1: so it's like a wire globe and then another loop inside. Yeah,
Speaker 1: and that wire loop inside can freely rotate, and that's
Speaker 1: where they were able to create this directional antenna, this
Speaker 1: direction finding antenna. They the the rotating element is called
Speaker 1: a rotor or sense coil, and then the other two
Speaker 1: are called stators or field coils. And folks, I apologize,
Speaker 1: I'm still over getting over at cold, So you're gonna
Speaker 1: hear me be raspy throughout this episode, just like last time. Yea.
Speaker 1: So these original ones were big, big devices. Yeah. The
Speaker 1: first picture I saw it showed the operator sitting at
Speaker 1: a desk, and the actual TENNA was about twice the
Speaker 1: height of the desk he was sitting at. Now, what
Speaker 1: was this used for At the time, these were used
Speaker 1: as land stations around primarily Europe, and we're used mainly
Speaker 1: to help with navigation. So so how would that work.
Speaker 1: You would have this enormous UH antenna that was detecting
Speaker 1: transmissions coming from other vessels, let's say navy vessels or
Speaker 1: or maritime vessels, and they would be able to detect
Speaker 1: what direction the that transmissions coming from and send information
Speaker 1: back out via radio vessel. So the lost ship says
Speaker 1: where am I sends a transmission saying where am I southwest?
Speaker 1: It knows where it is, and if it knows the
Speaker 1: direction your transmission is coming from, then it can tell
Speaker 1: you where you are in general. Yes, And then eventually
Speaker 1: you actually saw these devices being placed on the craft themselves.
Speaker 1: So then you could have a stationary radio transmission center
Speaker 1: sending out a basic signal sometimes and frequently having the
Speaker 1: the location for that that transmission center encoded in the
Speaker 1: signal itself sent out to sea, and then the the
Speaker 1: vessels would have these type of antenna aboard them. They
Speaker 1: could then use the antenna to figure out what direction
Speaker 1: the transmissions coming from because they know the specific location
Speaker 1: of that center because it's in the signal itself, but
Speaker 1: inverse exactly. So early ones were land based, then later
Speaker 1: on they were actually based on the vehicles themselves, whether
Speaker 1: it was it started off with shops and eventually also
Speaker 1: incorporated aircraft. Now I know that the idea of finding
Speaker 1: the physical location of a radio transmitter, whether it's a
Speaker 1: vehicle or a station of some kind, must have played
Speaker 1: a big role once radio was used in warfare. Absolutely
Speaker 1: there were some instrumental battle in which UH one side
Speaker 1: or the other frequently actually was the Allies had determined
Speaker 1: the that a certain German group of units, typically U boats,
Speaker 1: was really effective naval warfare in World War One, world
Speaker 1: War two. Actually world War One there was some, but
Speaker 1: world War two it really came into play. World War One,
Speaker 1: certainly the U boat communications, which were using very low
Speaker 1: frequency radio waves, it was very important. By the World
Speaker 1: War Two you're talking about more high frequency and radio
Speaker 1: waves being put into use. It's where we get the
Speaker 1: huff duff because it's high frequency direction finder antenna's hf
Speaker 1: DFS or huff duff was the nickname. You get the
Speaker 1: huff duff antennas that would indicate the direction of a
Speaker 1: transmission and that would help be able to track like
Speaker 1: enemy movements, enemy troop movements, particularly in the in the Navy.
Speaker 1: And it can you imagine how disappointed these antennas are
Speaker 1: when they get sorted. Yeah, now right, like you know,
Speaker 1: they all want to be slythering because that's my house.
Speaker 1: I don't know what the house you belong to. I
Speaker 1: that's not for me to say. I've never been sorted.
Speaker 1: I got sorted into slythering. I mean, I'm just saying
Speaker 1: I didn't try to. It just happened. Um, you just
Speaker 1: put on the hat. I do what the hat tells me. Man,
Speaker 1: I live my life that way. So this type of
Speaker 1: antenna was originally meant not for military purposes. It was
Speaker 1: actually meant to help meteorologists learn more about lightning. Was
Speaker 1: developed by Robert Watson Watt back in nineteen six, and
Speaker 1: it was to help locate where a lightning strike occurs,
Speaker 1: because you know, lightning, it gives off electromagnetic rays just
Speaker 1: or waves, I should say, not raised, but waves, just
Speaker 1: as a radio antenna would. And so you would use
Speaker 1: these antenna to detect the location of lightning strikes. That
Speaker 1: also helped you track the pathway of electrical storms. So
Speaker 1: that's what it was intended for, but in World War
Speaker 1: Two it got put to other uses to try and
Speaker 1: track movements of enemy troops. Very important now. Uh. After
Speaker 1: World War Two, we started seeing more development in radio
Speaker 1: direction finding technology, not just in military but also commercial applications. Uh.
Speaker 1: In fact, we also saw a lot of amateur radio
Speaker 1: operators get interested in it, and particularly once ham radio
Speaker 1: in the United States was really starting to take off. Yeah,
Speaker 1: forties and fifties really were really post world War two,
Speaker 1: because during World War Two they were very very picky
Speaker 1: about who got a chance to actually broadcast radio. They
Speaker 1: were like, you know, guys, we need you, guys to
Speaker 1: to unless we're telling you to do it, don't do
Speaker 1: that thing, right. So, but once World War two was over,
Speaker 1: we saw a lot more develop them and go into
Speaker 1: that and there are a lot of a lot of
Speaker 1: purposes for our DF. We talked about navigation, it's not
Speaker 1: really used for navigation that much anymore because we have
Speaker 1: more sophisticated methods for navigation. Yeah, we've got we've got
Speaker 1: stuff beyond like a radio transmitter and a receiver. That
Speaker 1: being said, there's still some places that use radio beacons
Speaker 1: as a means for emergency backup, uh some around the UK,
Speaker 1: not really any in the United States at this point,
Speaker 1: um maritime vehicles held onto it longer than aircraft did.
Speaker 1: But even today you don't really see that as a
Speaker 1: as a even a tertiary method for navigation because we
Speaker 1: have so many other more sophisticated systems at play. But
Speaker 1: there are other reasons that we do still use them.
Speaker 1: I mean, well, one would be like the example hunting
Speaker 1: down illicit broadcasts and jammers. Absolutely, yeah, Now this was
Speaker 1: huge and World War two as well. The UK actually
Speaker 1: ended up getting a big volunteer force of interceptors about
Speaker 1: folks in the UK who were amateur radio operators and
Speaker 1: use them to help suss out any uh enemy transmissions
Speaker 1: that were coming from the UK. Because there a period
Speaker 1: piece movie about this year there should be, although it'd
Speaker 1: be kind of boring because I think they only found
Speaker 1: they found like two and one of them was one
Speaker 1: that they were doing on purpose. Well, that could be
Speaker 1: the angle. Maybe maybe there was a cover up, there's
Speaker 1: some big secret or like like there's the crowd of
Speaker 1: ham operators carrying pitchforks storming the transmitter room of this
Speaker 1: one perceived enemy of the state and it turns out
Speaker 1: that they're just following orders from the UK government to
Speaker 1: send out false UH commands, because that was a thing, right, Like,
Speaker 1: it wasn't just secret information, it was disinformation. There were
Speaker 1: a lot of different campaigns going on in the information
Speaker 1: and intelligence worlds in World War Two. So, but that's
Speaker 1: glorious the image of an army of hams radio hams
Speaker 1: coming at you to to VHF you up, yep, that's right.
Speaker 1: There's there's so much opportunity there for UH edge of
Speaker 1: your seat drama. But the the interesting thing to me
Speaker 1: was that the UK, they were using m I five
Speaker 1: to head this operation because that's their domestic intelligence agency,
Speaker 1: but they determined that really this was a bigger problem
Speaker 1: in Europe. They had a lot more clandestine operators in
Speaker 1: Europe on both sides, really sending out messages via radio transmission,
Speaker 1: and so they switched this operation over to m I six,
Speaker 1: which looked at UH intelligence coming from outside the UK
Speaker 1: rather than from within it. So it's kind of in
Speaker 1: the United States, the difference between our FBI and our
Speaker 1: c I a same sort of thing, and UH in
Speaker 1: Europe was a much different story. Like the r d
Speaker 1: F was incredibly important during World War Two, because there
Speaker 1: were so many different operators using radio transmission as a
Speaker 1: way of getting either spy reports or orders across various borders.
Speaker 1: It eventually got to the point actually where the access
Speaker 1: powers were, um, really shy about transmitting any information because
Speaker 1: they were still worried about it getting intercepted and caught.
Speaker 1: And this is the same era as the Enigma machine, right,
Speaker 1: and once the Allies were able to crack some of
Speaker 1: the Enigma codes, it was a it really became apparent
Speaker 1: that you had to be super careful with your intelligence
Speaker 1: otherwise you were handing the enemy all of your game plans.
Speaker 1: So really interesting story though. Um, then there's other methods,
Speaker 1: are other reasons to use r d F. There's search
Speaker 1: and rescue, Yeah, how about that, so coast guard or
Speaker 1: rescuing it down on plane. Either one. You might have
Speaker 1: a vehicle that is equipped with radio transmission capability, but
Speaker 1: is itself stranded. Yeah, there's a lot of civil aircraft
Speaker 1: that have this. There are a lot of like if
Speaker 1: you are if you're hiking in an area that is
Speaker 1: prone for two avalanches, you may even have a transmitter
Speaker 1: on you as a means for emergency signaling. In the
Speaker 1: case of an avalanche. So this is still a thing, right.
Speaker 1: It's it's something that can send out a steady signal
Speaker 1: with perhaps an encoded message, usually a unique identifier to
Speaker 1: whatever the transmitter is, so that once you tune into it,
Speaker 1: you know that you're actually listening for the right signal.
Speaker 1: You're not going to get distracted by a signal on
Speaker 1: a similar frequency that is not what you're looking for,
Speaker 1: and you can try and narrow down your search to
Speaker 1: find whatever it is that's lost. Now, one thing we
Speaker 1: mentioned earlier is hunting malicious interference, people who are intentionally
Speaker 1: jamming a radio station or broadcasting propaganda or something like that.
Speaker 1: But there's also unintentional interference, and this could be useful
Speaker 1: too for tracking down you know, uh something maybe uh
Speaker 1: radio frequencies are leaking out of some sort of device
Speaker 1: and they're interfering with the broadcast band around there. Yeah,
Speaker 1: I mean, it's uh, it's not necessarily something that's done
Speaker 1: with malicious intent. Really, anything that creates an electrical field
Speaker 1: is creating electromagnetic radiation, and that some form of that
Speaker 1: is in radio waves, and depending upon the power of
Speaker 1: the the device in question, it could be putting out
Speaker 1: radio waves strong enough to interfere with transmission of normal signals.
Speaker 1: You'll hear about this also, Like I remember hearing about
Speaker 1: this with um uh theaters, in fact, theaters that we're
Speaker 1: using wireless radios in order to have back of house
Speaker 1: talk to front of house for stuff like like stage
Speaker 1: managing and lighting changes and stuff, and then you would
Speaker 1: end up getting truckers talking over your system and it
Speaker 1: would just Peter Pan became an entirely different show at
Speaker 1: that point. Like, but but this is the sort of
Speaker 1: thing about the speed trap up there. Yeah, And it
Speaker 1: all has to do with with the frequency you're using
Speaker 1: in the power of the radios in question, right, or
Speaker 1: perhaps more problematically, having that transmission of a high school
Speaker 1: production of Peter Pan being transmitted out to people who
Speaker 1: are using radio for really important reasons. Uh. This is
Speaker 1: one of the reasons why most places around the world
Speaker 1: have very strict rules of what types of equipment can
Speaker 1: use which frequency bands so that it avoids that kind
Speaker 1: of cross contemning. You don't have the problem where officer
Speaker 1: Officer hurts tries to radio in for backup, but instead
Speaker 1: he's being jammed by Peter Pan, right, or suddenly Captain
Speaker 1: hook and a bunch of pirates show up, like, this
Speaker 1: is not the backup I was hoping for. That wasn't
Speaker 1: hoping for a chorus line, I really need physical people
Speaker 1: to help back me up for this dangerous situation. Another
Speaker 1: use that you have here that I didn't even think of,
Speaker 1: but very smart wildlife tracking. Yeah, yeah, and I get
Speaker 1: tagged exactly. These are transmitters that send out a study
Speaker 1: signal so that scientists can continue to monitor the movement
Speaker 1: of various wildlife. Usually you do this to track migration
Speaker 1: patterns and how those might change, particularly in light of
Speaker 1: things like human uh enter like humans moving into what
Speaker 1: used to be territory. For animals, how do their migration
Speaker 1: patterns change, or in the face of changing weather patterns,
Speaker 1: that kind of thing. And you need obviously to have
Speaker 1: a direction finder in order to know where the animals
Speaker 1: are actually going. Plus, if you ever want to go
Speaker 1: into a physical check, let's say that you are doing
Speaker 1: like a drawing blood from a specific animal every few months,
Speaker 1: then you need to be able to track where that
Speaker 1: animal is and and narrow down its range so that
Speaker 1: you can actually get to it and do that. So
Speaker 1: that is another use. And of course we've already kind
Speaker 1: of talked about. But spies, I mean not not just
Speaker 1: not just someone trying to transmit something. Sometimes it's like
Speaker 1: trying to find a bug. Like bugs that have been
Speaker 1: planted in places they're they're sending out little radio transmission. Typically, Uh,
Speaker 1: I mean, you could have one that's just recording natively
Speaker 1: to a device, but that means you have to go
Speaker 1: back into that place and retrieve the device in order
Speaker 1: to hear what's been recorded on it. Most bugs are transmitters,
Speaker 1: so that means that you have to have a radio
Speaker 1: direction finder to figure out where a transmission is coming from.
Speaker 1: Let's say it's a nice big embassy building. You might
Speaker 1: need to narrow down exactly where is this thing? Um
Speaker 1: and that. You know, we see those in spy movies,
Speaker 1: but it really does happen. At the Spy Museum in Washington,
Speaker 1: d C. Fascinating you can actually see some of the
Speaker 1: devices that were used to both plant bugs and to
Speaker 1: detect them. I want to go to that sometime. I've
Speaker 1: read a little bit about I remember seeing online a
Speaker 1: thing about their ex a bit on spy pigeons. Yeah,
Speaker 1: it's fun, it's it's weird in that I don't mean
Speaker 1: this to become like an ad for the Spy Museum
Speaker 1: in d C. It's weird because I feel like the
Speaker 1: presentation is really perfectly geared towards kids, but there's so
Speaker 1: much text involved in in the exhibits that I don't
Speaker 1: know that your average kid has the the tension span
Speaker 1: or desire to read that much while going through a museum.
Speaker 1: So my experience was that I was trying to read
Speaker 1: the same paragraph fifteen times while kids were running all
Speaker 1: over the place trying to play with stuff. So it's
Speaker 1: a little frustrating for me, but fascinating exhibits, really well
Speaker 1: laid out, and lots of fun stuff. They incorporate both
Speaker 1: real world spy gadgets and also movie stuff, so they
Speaker 1: had like an entire James Bond section that was really
Speaker 1: a lot of fun. Yeah, yeah, so that's cool. And
Speaker 1: then one of their modern use for radio direction finding
Speaker 1: is what we're really going to focus on towards the
Speaker 1: end of the show, which is using it recreationally for sport.
Speaker 1: So this idea of fox hunting trying to you know, competitively,
Speaker 1: you mean the sport itself, not like using radio direction
Speaker 1: finding to find a lost ball in golf. I mean,
Speaker 1: there's no reason you couldn't do that other than the
Speaker 1: fact that you would have to have a golf ball
Speaker 1: with a transmitter and have to build it in such
Speaker 1: a way that it could withstand enormous force being placed
Speaker 1: upon the ball and still not, you know, still continue
Speaker 1: to transmit. Probably would have keep going. Yeah, No, I'm
Speaker 1: thinking about all the this is the thing you're gonna
Speaker 1: put out a joking hypothetical, and I'm going to go
Speaker 1: through why it's going to be difficult to implement. Well, impossible,
Speaker 1: but difficult. Maybe we should stop you there and take
Speaker 1: a break. Yeah, let's do that. Let's take a quick
Speaker 1: break to thank our sponsor. All right, we're back now.
Speaker 1: Before we dive into the wonderful world of fox hunting, Uh,
Speaker 1: it would probably behoove us to understand a little bit
Speaker 1: more about radio waves, how they work, transmitters and antenna
Speaker 1: in order to get at what transmitter hunting is all about.
Speaker 1: So we're gonna start at basic like elementary level radio physics.
Speaker 1: We're gonna build from there. So radio waves are a
Speaker 1: subset of electromagnetic waves, so are also called E M
Speaker 1: waves or N waves. You have to put your finger
Speaker 1: up to your chin like you're thinking in waves now,
Speaker 1: e M. Waves come from stuff that generates an electric field.
Speaker 1: Doesn't have to be a particularly sophisticated setup. You can
Speaker 1: actually do this with something as simple as a nine
Speaker 1: volt battery and a coin. Yeah, if you put a
Speaker 1: coin across the the terminals of a nine volt battery,
Speaker 1: you are generating an electric field, because all you're doing
Speaker 1: is closing the circuit from the negative and positive terminals
Speaker 1: and allowing electricity to flow through. That creates an electric field, right,
Speaker 1: But I'm assuming you're saying this because doing that would
Speaker 1: generate some kind of radio signal that can be detected. Yes,
Speaker 1: it's a very weak radio signal. But if you were
Speaker 1: to do this very close to an AM radio first,
Speaker 1: you would you would want to tune the AM radio
Speaker 1: to uh something that's just static. You're not actually getting
Speaker 1: a signal like a strong signal in And if you
Speaker 1: were to place the coin against the terminals and listen
Speaker 1: closely to the radio, you should hear a crackle as
Speaker 1: the coin makes contact with those terminals because you're sending
Speaker 1: out this little radio signal and the radio is detecting it. Now,
Speaker 1: you're not sending out anything meaningful. You're just it's just noise.
Speaker 1: That's why you're just getting a crackle. You could send
Speaker 1: a signal in Morse code, so you could encode a
Speaker 1: signal by the sound and absence of sound of this crackle,
Speaker 1: but there's nothing meaningful in the crackle itself. Right. But
Speaker 1: that does show you that doesn't take very much for
Speaker 1: you to generate radio waves. Uh. The the electromagnetic waves
Speaker 1: that we talk about all have kind of common features,
Speaker 1: even though they may do very different things. There's certain
Speaker 1: things that we can use to describe them that's common
Speaker 1: across all of them. So when we plut those waves
Speaker 1: on a graph, you know it's a little up and
Speaker 1: down the crests and troughs that you would see usually
Speaker 1: across X and y axis. Uh. We would call the
Speaker 1: height of those waves the amplitude. This typically like in
Speaker 1: sound waves, this would be the volume of sound. Right.
Speaker 1: The higher the amplitude, the louder the sound is. The
Speaker 1: length of the wave is the wave length. That's really
Speaker 1: kind of tricky, right, Um, And the number of waves
Speaker 1: that pass through any given point on that graph within
Speaker 1: a second, that's the frequency. But because these waves always
Speaker 1: move at the same speed, which is the speed of light. Yes,
Speaker 1: if you know one, or if you know the wavelength
Speaker 1: or the frequency, you know the other exactly. You know
Speaker 1: how fast it's going, right, right, So when we talk
Speaker 1: about different frequencies, we're not talking about speed of the signal,
Speaker 1: because the signals still try like at the speed of light.
Speaker 1: No matter what. We're talking about the number of times
Speaker 1: a wave passes any given point within a second. Typically
Speaker 1: it's within a second. It's really any unit of time,
Speaker 1: but for the purposes of measurement, we talk about hurts
Speaker 1: and it hurts talks about the number of uh times
Speaker 1: a wave passes a point in a second. So one
Speaker 1: hurts would be once a second. That would need to
Speaker 1: be an extremely long wave because for it to take
Speaker 1: a full second for the wave to pass that point,
Speaker 1: and it's traveling at a speed of light, that's incredibly long. Right,
Speaker 1: So how far does light go in a second. Let's see,
Speaker 1: I don't know, like further than I've ever been. I
Speaker 1: can tell you that, Okay, Well, so how do you
Speaker 1: get to using radio though? Because we so, yes, we
Speaker 1: live in a universe of radio signals. They're they're electromagnetic
Speaker 1: waves all over the place around us, but that's humans
Speaker 1: use radio for specific purposes. They can take these waves
Speaker 1: and incode information with Yeah, and this this comes from
Speaker 1: manipulating either the amplitude or the frequency of those waves,
Speaker 1: modulating them in some way. Typically that's how we can
Speaker 1: encode information into them. So, uh, let's say that you
Speaker 1: build a circuit containing a capacitor and an inductor. These
Speaker 1: are two very basic circuit components. So you build your circuit,
Speaker 1: You've got a capacitor and an inductor involved in this
Speaker 1: that this will allow you to create a sign wave
Speaker 1: that's just a very smooth, continuously varying wave. It's you
Speaker 1: know that kind of smooth up and down like like
Speaker 1: your typical let's show, uh, ocean waves kind of viewpoint
Speaker 1: and just nice little hills and valleys. This saltwater crocodile
Speaker 1: and the saltwater crocodile would be carrying information. So without
Speaker 1: any saltwater crocodiles, you're still not you're still not transmitting
Speaker 1: anything meaningful. Right, It's just a sign wave. There's no
Speaker 1: information there. But if you modulate it, then you can
Speaker 1: encode information in it. One way to do that is
Speaker 1: with pulse modification. This is similar to what I was
Speaker 1: talking about with that nine volt mattery. This just involves
Speaker 1: turning a signal on and off so that when the
Speaker 1: signals on it might indicate a dot or dash in
Speaker 1: morse code, so you're not Again, nothing within the signal
Speaker 1: itself is necessarily meaningful. It's when you detect it versus
Speaker 1: when you don't detect it that gives you information. Then
Speaker 1: you have amplitude modification or our modulation I should say,
Speaker 1: or a M that's changes the peak to peak voltage
Speaker 1: of the sine wave UM And the way you do
Speaker 1: this with a M radio as you start with a
Speaker 1: basic SiGe wave. That's your that's your baseline. You take
Speaker 1: whatever you want to transmit, whether it's you know, the
Speaker 1: cool hits of the seventies or some talk show hosts
Speaker 1: or whatever. You take that that yeah, it could be
Speaker 1: hard woman. You take that signal and you overlay that
Speaker 1: signal on top of the baseline sine wave to modulate it.
Speaker 1: This changes the amplitude of that sign wave. You get
Speaker 1: kind of a uh, you know, a product from the
Speaker 1: modulation of these two. Like by adding the two together,
Speaker 1: you get a new frequency, a new wave. It's not
Speaker 1: really the same frequency, it's different amplitude, but you get
Speaker 1: a new wave with a different amplitude than both of
Speaker 1: your basic ones. This is what you transmit to a
Speaker 1: a radio tower. You actually have to amplify it by
Speaker 1: quite a lot. Obviously, the further you want this signal
Speaker 1: to go, the more you have to amplify it, the
Speaker 1: larger your antenna tends to be. And then the signal
Speaker 1: goes out over the air and then people with receivers
Speaker 1: tuned to that frequency can pick it up, and the
Speaker 1: signal gets converted uh, back into something that a radio
Speaker 1: can play, amplified again so that you can hear hard Woman. Uh.
Speaker 1: Frequency frequency modulation is similar, except instead of changing the
Speaker 1: amplitude like modulting the amplitude, you're moduling the frequency of
Speaker 1: the signal. So you again you start with a base
Speaker 1: sine wave for the radio station. This is what transmitting,
Speaker 1: whether any noise is coming out of it or not,
Speaker 1: it's just this base sine wave. Then you take on
Speaker 1: the the the wave created from whatever you're trying to
Speaker 1: transmit hard Woman, and it changes the frequency. Now, Jonathan,
Speaker 1: I wonder how exactly, if if you're not a radio expert, um,
Speaker 1: how does modulating the frequency not affect the uh you know,
Speaker 1: the station you're listening to, because the station you listen
Speaker 1: to the radio on is the frequency. When there's a
Speaker 1: number in front of a radio station power that's mega
Speaker 1: hurts right nine seven. Yeah. Well, part of it is
Speaker 1: that each radio station really has a range like there's
Speaker 1: it's you get a number that's the base frequency, but
Speaker 1: there's a range within o our surrounding that frequency that
Speaker 1: allows for this modulation. The modulation doesn't change the frequency
Speaker 1: so dramatically that it will bleed into another station. That's
Speaker 1: why we have stations that have very defined um uh frequencies,
Speaker 1: because if you didn't have that, if they were too
Speaker 1: close together, they would bleed over. Occasionally. You might have
Speaker 1: actually experienced this if you're listening, particularly to AM radio,
Speaker 1: because it travels much further. If you start traveling around,
Speaker 1: you might get two stations coming in simultaneously because you
Speaker 1: might you might move from the broadcast area of one
Speaker 1: station into the broadcast range of a station that's got
Speaker 1: a similar though not necessarily identical frequency, and then you're
Speaker 1: hearing both at the same time. That's really uh disconcerting.
Speaker 1: Um if you it could be like if you're if
Speaker 1: you're hearing r E M and hard woman, you might
Speaker 1: discover something interesting about yourself. I don't know, fire and
Speaker 1: brimstone sermon, and uh, I don't know some some good
Speaker 1: something about college sports here in the Southeast to be
Speaker 1: college sports and sermons. Yeah, But from my experience of
Speaker 1: listening to a M radio um SO receiving antenna, what
Speaker 1: they do, Like we just talked about you, you take
Speaker 1: your transmitter, you send a signality. It gets amplified a
Speaker 1: couple of times, usually before it hits the broadcast antenna
Speaker 1: and sends out over the airwaves. A receiver does the
Speaker 1: same sort of thing, but it does this in reverse.
Speaker 1: So antenna's are tuned to specific electromagnetic frequencies. Usually they
Speaker 1: have elements that are a certain size specified yep. And
Speaker 1: so what will happen is, uh, they resonate with a
Speaker 1: certain range of frequencies and if those frequencies are present,
Speaker 1: like if the antenna is present in the in the
Speaker 1: within those frequencies, then it can send it this get
Speaker 1: This creates an electrical current that it can then amplify
Speaker 1: and convert into sound so that we can hear it
Speaker 1: on our radios. Um the you know the purpose of
Speaker 1: the amplifiers just really to boost thatsnal. You're typically using
Speaker 1: like something along the lines of a transformer to do that,
Speaker 1: and I've talked about that in the past. So that
Speaker 1: means you can get your talk radio or your greatest
Speaker 1: Hits of the Ramones, which lasts twelve minutes, not because
Speaker 1: they're so few, but because Ramones songs are so short. Guys,
Speaker 1: we had a lot more to talk about when it
Speaker 1: comes to transmitter hunting. This is always the case Joe
Speaker 1: and I will end up having a conversation and we
Speaker 1: think at the beginning it's gonna take maybe forty minutes,
Speaker 1: and at the end it takes longer than an hour
Speaker 1: and a half. That's what happened this time. So we're
Speaker 1: splitting this episode up. That means next week you get
Speaker 1: to hear part two about transmitter hunting, where we really
Speaker 1: focus on the core aspects of the sport. So join
Speaker 1: us next week for the exciting conclusion. Remember, you can
Speaker 1: listen to Joe on Stuff to Blow your mind, and
Speaker 1: you can see a lot of his work at how
Speaker 1: stuff works dot com. And if you want to get
Speaker 1: in touch with me, maybe you've got a suggestion for
Speaker 1: an episode topic or someone I should have on the show.
Speaker 1: You can always write me The email address is tech
Speaker 1: stuff at how stuff works dot com, or drop me
Speaker 1: a line on Facebook or Twitter. To handle at both
Speaker 1: of those is text stuff hs W and I'll talk
Speaker 1: to you again really soon. For more on this and
Speaker 1: thousands of other topics, is it how stuff works dot com.