1 00:00:00,320 --> 00:00:02,880 Speaker 1: Brought to you by the reinvented two thousand twelve camera. 2 00:00:03,200 --> 00:00:09,000 Speaker 1: It's ready. Are you get in touch with technology with 3 00:00:09,080 --> 00:00:17,920 Speaker 1: tech Stuff from how stuff works dot com. Hello again, everyone, 4 00:00:17,960 --> 00:00:20,880 Speaker 1: Welcome to tech stuff. My name is Chris Pollett, and 5 00:00:20,920 --> 00:00:23,360 Speaker 1: I'm an editor here at how stuff works dot Com. 6 00:00:23,480 --> 00:00:26,079 Speaker 1: Broadcasting from the seat across from me, as usual, is 7 00:00:26,160 --> 00:00:29,319 Speaker 1: senior writer Jonathan Striffland. You gave them all those old 8 00:00:29,320 --> 00:00:33,000 Speaker 1: time stars through wars of worlds invaded by Mars. You 9 00:00:33,000 --> 00:00:35,680 Speaker 1: made him laugh, you made him cry, you made us 10 00:00:35,680 --> 00:00:42,159 Speaker 1: feel like we could fly. Just remember video killed the 11 00:00:42,240 --> 00:00:46,200 Speaker 1: radio stars. But for now, we're still going to talk 12 00:00:46,200 --> 00:00:49,720 Speaker 1: about radio. Yeah, and you guys might remember not that 13 00:00:49,760 --> 00:00:52,280 Speaker 1: long ago, we did a podcast about who invented the 14 00:00:52,360 --> 00:00:55,640 Speaker 1: radio and we came up with a conclusion of I 15 00:00:55,680 --> 00:00:59,640 Speaker 1: don't know, although actually Chris and I both agreed that 16 00:00:59,680 --> 00:01:02,600 Speaker 1: if if gun were held to our heads, we would 17 00:01:02,920 --> 00:01:06,800 Speaker 1: we would claim that Tesla was the the inventor of 18 00:01:06,840 --> 00:01:09,080 Speaker 1: the radio. It's just that he did not He was 19 00:01:09,120 --> 00:01:12,119 Speaker 1: not able to implement it in the same sort of 20 00:01:12,360 --> 00:01:17,520 Speaker 1: scale as Marconi, whose implementation depended somewhat on Tesla's work. 21 00:01:17,840 --> 00:01:20,600 Speaker 1: But yeah, but it had gone on for some time 22 00:01:20,680 --> 00:01:22,640 Speaker 1: there were a number of people as and and this 23 00:01:22,680 --> 00:01:26,120 Speaker 1: happens a lot in science that uh, you know, their 24 00:01:26,120 --> 00:01:29,240 Speaker 1: contributions made radio possible. They were it was sort of 25 00:01:29,360 --> 00:01:33,920 Speaker 1: invented in increments really. Um. And of course Tesla was 26 00:01:33,959 --> 00:01:38,199 Speaker 1: a very prolific inventor. He had his fingers and lots 27 00:01:38,240 --> 00:01:42,760 Speaker 1: of different pies. I'm sorry, I had to watch Jonathan's 28 00:01:42,800 --> 00:01:46,319 Speaker 1: high clay everyone, and um, I'm having a little moment here. 29 00:01:46,400 --> 00:01:50,400 Speaker 1: And Marconi was was really a radio guy. He really 30 00:01:50,440 --> 00:01:53,200 Speaker 1: was interested in radio. So it's it's really kind of 31 00:01:53,200 --> 00:01:57,480 Speaker 1: no surprise that he really pushed radio very hard, harder 32 00:01:57,480 --> 00:02:00,360 Speaker 1: than Tesla did, and so he got a lot of 33 00:02:00,360 --> 00:02:03,600 Speaker 1: the credit for it. But um, we were going to 34 00:02:03,640 --> 00:02:08,240 Speaker 1: talk today about the invention itself, how radio itself actually works, 35 00:02:08,280 --> 00:02:10,320 Speaker 1: and to really talk about this first we have to 36 00:02:10,919 --> 00:02:16,400 Speaker 1: understand a little bit about radio frequencies, radio waves, and 37 00:02:16,520 --> 00:02:22,799 Speaker 1: uh so let's talk about radio waves first. Now, waves 38 00:02:22,840 --> 00:02:26,000 Speaker 1: are this is a complicated issue because there are different 39 00:02:26,040 --> 00:02:29,320 Speaker 1: types of waves, right. There's there are mechanical waves, which 40 00:02:29,360 --> 00:02:31,680 Speaker 1: are the waves that we can observe with our own 41 00:02:31,680 --> 00:02:33,800 Speaker 1: eyes through various means. Like there's you know, if you 42 00:02:34,080 --> 00:02:36,560 Speaker 1: look at a notion and you see the waves coming across. 43 00:02:36,800 --> 00:02:40,680 Speaker 1: Those are mechanical waves. Due, yes, they are, in fact 44 00:02:40,800 --> 00:02:45,120 Speaker 1: gnarly During an earthquake, the earth moves in mechanical waves, yes, 45 00:02:45,720 --> 00:02:50,880 Speaker 1: and sound travels through mechanical waves. But yeah, now you 46 00:02:50,919 --> 00:02:52,920 Speaker 1: may not think of sound as a mechanical wave because 47 00:02:52,960 --> 00:02:55,240 Speaker 1: it's not something that you can typically see. Although if 48 00:02:55,240 --> 00:02:57,400 Speaker 1: there is a sound loud enough, it can create a 49 00:02:57,400 --> 00:03:01,000 Speaker 1: mechanical wave powerful enough to vibrate uh an objects. So 50 00:03:01,040 --> 00:03:03,680 Speaker 1: you can see that, right, Well, you could see um 51 00:03:03,760 --> 00:03:10,120 Speaker 1: if you've ever watched videos of explosions, especially when a 52 00:03:10,200 --> 00:03:14,440 Speaker 1: video shot from overhead, you can see the shock wave, yeah, 53 00:03:14,560 --> 00:03:17,520 Speaker 1: traveling outward from that, which is you watch any Michael 54 00:03:17,520 --> 00:03:20,880 Speaker 1: bay movie, the moment where the two heroes running away 55 00:03:20,880 --> 00:03:23,519 Speaker 1: from the explosion leap into air and are propelled fifty 56 00:03:23,600 --> 00:03:26,240 Speaker 1: feet that is kind of what Chris is talking about. Okay, 57 00:03:26,240 --> 00:03:28,480 Speaker 1: that was an even better description than the one I 58 00:03:28,520 --> 00:03:35,400 Speaker 1: had Michael Bays solves. Anyway, So yeah, so these waves 59 00:03:35,400 --> 00:03:38,640 Speaker 1: they move, they move, and uh there's a crest and 60 00:03:38,680 --> 00:03:41,680 Speaker 1: then there's a trough, right, the crest being the highest point, 61 00:03:41,680 --> 00:03:44,480 Speaker 1: the trough being the lowest point. And you consider the 62 00:03:44,640 --> 00:03:47,120 Speaker 1: point from the top of one crest to the top 63 00:03:47,200 --> 00:03:51,240 Speaker 1: of the next crest, the wave length of that wave, right, 64 00:03:51,320 --> 00:03:54,320 Speaker 1: all right, So these these mechanical waves, they have to have, uh, 65 00:03:54,720 --> 00:03:58,720 Speaker 1: some sort of of medium to move through. They require that. 66 00:03:58,840 --> 00:04:01,400 Speaker 1: Even sound, which is why if you were to be 67 00:04:01,440 --> 00:04:03,680 Speaker 1: in outer space and you were to take off your 68 00:04:03,760 --> 00:04:07,240 Speaker 1: space helmet and shout to your buddy across the way, Uh, 69 00:04:07,400 --> 00:04:10,080 Speaker 1: your buddy would not hear you, because there is no 70 00:04:10,720 --> 00:04:14,160 Speaker 1: medium there spaces of vacuum. More or less. There are 71 00:04:14,240 --> 00:04:18,159 Speaker 1: particles in space, but they're so far there's there's so little, 72 00:04:19,400 --> 00:04:22,200 Speaker 1: there's no contact. Right. The particles in space are are 73 00:04:22,360 --> 00:04:25,000 Speaker 1: so far apart from one another that there's no way 74 00:04:25,040 --> 00:04:28,600 Speaker 1: to to propagate a mechanical wave through space. I think 75 00:04:28,640 --> 00:04:31,040 Speaker 1: we understand the lack of gravity in this situation, thank you. 76 00:04:31,360 --> 00:04:34,080 Speaker 1: So yeah, nature of hors a vacuum, so do I. 77 00:04:34,480 --> 00:04:38,800 Speaker 1: That's why I only sweep vacuum. So anyway, Yeah, you 78 00:04:38,839 --> 00:04:41,800 Speaker 1: need a medium for a mechanical wave to to move through. 79 00:04:41,920 --> 00:04:46,000 Speaker 1: But electromagnetic waves are different. They do not require that. 80 00:04:46,160 --> 00:04:48,600 Speaker 1: They can they can propagate through a vacuum. They can 81 00:04:48,640 --> 00:04:51,800 Speaker 1: move through the vacuum space and in fact, they will 82 00:04:51,880 --> 00:04:58,000 Speaker 1: continue to move once generated forever. Really Um, so the 83 00:04:58,080 --> 00:05:00,440 Speaker 1: radio waves that we generated way back when we were 84 00:05:00,440 --> 00:05:04,600 Speaker 1: first figuring this out, they are now, oh well, let's see, 85 00:05:04,880 --> 00:05:08,039 Speaker 1: more than around a hundred light years away, because radio 86 00:05:08,040 --> 00:05:10,080 Speaker 1: waves travel at the speed of light. And then you know, 87 00:05:10,200 --> 00:05:12,920 Speaker 1: the invention of the radio really dates back a century. 88 00:05:13,720 --> 00:05:17,880 Speaker 1: So anything around there, anything generated at that time, would 89 00:05:18,320 --> 00:05:21,720 Speaker 1: now be traveling a hundred light years away. It's kind 90 00:05:21,720 --> 00:05:25,600 Speaker 1: of cool. Yeah, yeah, because it travels the speed of light. Okay, 91 00:05:25,920 --> 00:05:28,640 Speaker 1: so all those all those broadcasts in the forties and 92 00:05:28,680 --> 00:05:31,640 Speaker 1: fifties of the radio cereals, those are now forty fifty 93 00:05:31,720 --> 00:05:36,440 Speaker 1: light years away. Cereal. Um yeah, it's Chris's weakness was 94 00:05:36,480 --> 00:05:39,320 Speaker 1: cereal is like my weakness with pie. So don't don't 95 00:05:39,360 --> 00:05:41,160 Speaker 1: get me wrong. I like the pie. So yeah, I 96 00:05:41,160 --> 00:05:44,000 Speaker 1: mean light and and radio waves are both forms of 97 00:05:44,080 --> 00:05:48,920 Speaker 1: electromagnetic radiation. Um, and it's I had something I was 98 00:05:48,960 --> 00:05:52,560 Speaker 1: gonna say there, I've got something here. So when we 99 00:05:52,600 --> 00:05:56,080 Speaker 1: say electromagnetic that's really important. Now, when you're talking about 100 00:05:56,080 --> 00:05:59,520 Speaker 1: a mechanical wave, you're talking about a wave and a 101 00:05:59,560 --> 00:06:02,960 Speaker 1: particular our alignment. Let's let's say vertical, you know, like 102 00:06:03,120 --> 00:06:06,680 Speaker 1: waves you would see on a notion. Electromagnetic waves are 103 00:06:06,680 --> 00:06:11,520 Speaker 1: actually a pair of waves. There's an electric field wave 104 00:06:11,640 --> 00:06:13,920 Speaker 1: and a magnetic field wave. Now you've heard us talk 105 00:06:13,960 --> 00:06:17,479 Speaker 1: a lot about the relationship between electricity and magnetism and 106 00:06:17,520 --> 00:06:21,080 Speaker 1: how there is this interesting connection between the two. As 107 00:06:21,080 --> 00:06:24,560 Speaker 1: it turns out, if you were to generate an electromagnetic wave, 108 00:06:25,200 --> 00:06:28,760 Speaker 1: you would then have a an electric field wave and 109 00:06:28,800 --> 00:06:32,000 Speaker 1: a magnetic field wave moving at the same time, and 110 00:06:32,279 --> 00:06:36,640 Speaker 1: each one replenishes the other. The electric field, because it's 111 00:06:36,760 --> 00:06:40,600 Speaker 1: changing over time, generates a magnetic field. The magnetic field, 112 00:06:40,600 --> 00:06:43,719 Speaker 1: as it changes over time, regenerates the electric field, and 113 00:06:43,760 --> 00:06:47,120 Speaker 1: that's why it can continue at infinitum out into the 114 00:06:47,160 --> 00:06:49,240 Speaker 1: forest reaches of space until it hits the end of 115 00:06:49,279 --> 00:06:52,800 Speaker 1: the universe. Or we started getting reruns of I Love 116 00:06:52,880 --> 00:06:58,000 Speaker 1: Lucy from you know, a billion light years away. Yeah. 117 00:06:58,000 --> 00:07:01,480 Speaker 1: I remember hearing as a kid that the shows that 118 00:07:01,560 --> 00:07:05,280 Speaker 1: we watched we're going to be available out in space, 119 00:07:05,320 --> 00:07:08,320 Speaker 1: like people in Mars with the right equipment. Of course, 120 00:07:09,000 --> 00:07:11,320 Speaker 1: theoretically there aren't any people on Mars. I don't think 121 00:07:11,360 --> 00:07:16,840 Speaker 1: there are. Um, I wouldn't call them people, yeah, exactly. Um, 122 00:07:16,920 --> 00:07:18,600 Speaker 1: but yeah, if you had a TV and you were 123 00:07:18,880 --> 00:07:21,000 Speaker 1: you know, at that point they said, if you're watching 124 00:07:21,120 --> 00:07:23,440 Speaker 1: from Mars right now you would be catching reruns of 125 00:07:23,440 --> 00:07:25,800 Speaker 1: I Love Lucy. This was years ago, but I was going, 126 00:07:25,880 --> 00:07:29,080 Speaker 1: really seriously, that's that's very cool. So, uh, you know, 127 00:07:29,120 --> 00:07:31,080 Speaker 1: I hadn't realized that they would they would do that. 128 00:07:31,280 --> 00:07:33,960 Speaker 1: But on the same by the same token, if you 129 00:07:33,960 --> 00:07:37,760 Speaker 1: think about the giant radio telescopes that they use UM 130 00:07:37,960 --> 00:07:41,800 Speaker 1: to search for extraterrestrial life, some sign that other people 131 00:07:41,840 --> 00:07:46,080 Speaker 1: are using radio frequencies. Basically they're just listening to space 132 00:07:46,120 --> 00:07:48,720 Speaker 1: to see if there is something. I mean, there's there's lots, 133 00:07:48,760 --> 00:07:52,040 Speaker 1: there's noise. Besides, there's something that is generated in a 134 00:07:52,640 --> 00:07:56,360 Speaker 1: in a meaningful way as opposed to UM, because lots 135 00:07:56,360 --> 00:08:00,240 Speaker 1: of stuff produces radio waves, lots and lots of stuff. Uh. 136 00:08:00,280 --> 00:08:02,280 Speaker 1: And really, like I was saying, so, the the was 137 00:08:02,280 --> 00:08:04,800 Speaker 1: talking about electric field and the magnetic fields that that 138 00:08:05,240 --> 00:08:10,360 Speaker 1: are traveling in this electromagnetic wave. UM. The electric fields 139 00:08:10,400 --> 00:08:14,920 Speaker 1: they exert forces on electric charges, magnetic fields exert forces 140 00:08:14,960 --> 00:08:19,160 Speaker 1: on magnetic polls. So these waves can do work because 141 00:08:19,200 --> 00:08:24,240 Speaker 1: they can exert force upon particular things. In the case 142 00:08:24,280 --> 00:08:27,560 Speaker 1: of the electric field, of course, is the electrically charged particles. 143 00:08:27,560 --> 00:08:31,640 Speaker 1: That's the important part for radios. Without that, without the 144 00:08:31,640 --> 00:08:34,760 Speaker 1: the ability to do work. Radios wouldn't work at all. 145 00:08:34,480 --> 00:08:37,320 Speaker 1: We wouldn't be able to pick these things up. And 146 00:08:37,520 --> 00:08:41,920 Speaker 1: uh so that's really a fundamental element that you have 147 00:08:41,960 --> 00:08:44,280 Speaker 1: to understand before we can get into the mechanical and 148 00:08:44,440 --> 00:08:49,960 Speaker 1: technological elements of radio. Uh and uh so let's talk 149 00:08:50,000 --> 00:08:52,760 Speaker 1: a little bit about how how we get a radio 150 00:08:52,840 --> 00:08:57,880 Speaker 1: signal from a transmitter to a receiver. Alright, so you've 151 00:08:57,920 --> 00:09:03,319 Speaker 1: got a radio station and the radio station you are recording, 152 00:09:03,480 --> 00:09:06,080 Speaker 1: or you're you're trying to broadcast some sort of sound signal. 153 00:09:07,080 --> 00:09:10,120 Speaker 1: You are using a microphone, let's say. So let's say 154 00:09:10,120 --> 00:09:12,920 Speaker 1: this is a talk radio. So there's a guy talking 155 00:09:12,920 --> 00:09:17,280 Speaker 1: into a microphone. Uh. The I can't picture that, right, Yeah, 156 00:09:17,280 --> 00:09:20,839 Speaker 1: it's so hard to understand when you're facing someone doing it. Uh. 157 00:09:21,160 --> 00:09:24,400 Speaker 1: The mechanical waves from the sound of the voice go 158 00:09:24,559 --> 00:09:27,600 Speaker 1: into the microphone. They hit a little diaphragm which then 159 00:09:28,120 --> 00:09:33,200 Speaker 1: uh manipulates an electric charge, creating a frequency within that 160 00:09:33,240 --> 00:09:37,680 Speaker 1: electric charge, which then goes to a I'm simplifying here, 161 00:09:37,920 --> 00:09:41,520 Speaker 1: but but it goes to a transmitter, which then changes 162 00:09:41,800 --> 00:09:45,880 Speaker 1: this electric charge into one of two different um uh 163 00:09:46,600 --> 00:09:49,199 Speaker 1: kinds of radio signals. You've probably heard of a M 164 00:09:49,240 --> 00:09:53,120 Speaker 1: and FM. Yes, well it's not just two, but those 165 00:09:53,120 --> 00:09:55,520 Speaker 1: are the two weeks, those are the two years for broadcast. Yeah, 166 00:09:55,640 --> 00:09:59,680 Speaker 1: for for broadcast radio. Yes, yes, I'm I'm specifically talking 167 00:09:59,679 --> 00:10:01,560 Speaker 1: about the kind of radios where you tune in to 168 00:10:01,640 --> 00:10:04,360 Speaker 1: listen to music or or or talk or whatever. It's 169 00:10:04,400 --> 00:10:07,120 Speaker 1: not I'm not talking citizens band, I'm not talking any 170 00:10:07,160 --> 00:10:13,040 Speaker 1: of the other other kind of UM. Yeah, So, uh, 171 00:10:13,240 --> 00:10:17,320 Speaker 1: the way you you transmit information across those radio waves 172 00:10:17,440 --> 00:10:20,679 Speaker 1: depends on whether you're using a M or FM radio. Right, 173 00:10:21,040 --> 00:10:24,040 Speaker 1: you have to have a carrier wave, which is a 174 00:10:24,080 --> 00:10:28,120 Speaker 1: frequent a radio frequency wave that is able to hold 175 00:10:28,160 --> 00:10:32,960 Speaker 1: information and take it from the transmitter to the receiver. UM. 176 00:10:33,000 --> 00:10:37,559 Speaker 1: And basically it sort of depends on the frequency and amplitude. 177 00:10:37,760 --> 00:10:40,439 Speaker 1: That's that's exactly what a M and FM are. Its 178 00:10:40,480 --> 00:10:45,400 Speaker 1: amplitude modulation and frequency modulation. So with amplitude modulation, you 179 00:10:45,440 --> 00:10:47,360 Speaker 1: remember we were talking about a wave. You know, you 180 00:10:47,400 --> 00:10:49,959 Speaker 1: have the crests the trough, and the from crest to 181 00:10:50,000 --> 00:10:53,880 Speaker 1: crest is wavelength. Well, the the height I guess you 182 00:10:53,920 --> 00:10:57,080 Speaker 1: could say the height of the crests or the depth 183 00:10:57,160 --> 00:11:00,400 Speaker 1: of the trough, which are equivalent in the case of 184 00:11:00,400 --> 00:11:04,120 Speaker 1: these waves. UM. That is the amplitude, right. The bigger 185 00:11:04,120 --> 00:11:07,760 Speaker 1: the amplitude, the the taller those those waves are going 186 00:11:07,800 --> 00:11:11,240 Speaker 1: to look when you look at them as a wavelength. UM. 187 00:11:11,360 --> 00:11:14,840 Speaker 1: So with amplitude modulation, it's exactly what sounds like. You 188 00:11:14,840 --> 00:11:19,240 Speaker 1: you modify the amplitude to contain the uh, the information 189 00:11:19,280 --> 00:11:23,240 Speaker 1: that you're transmitting. When that information is received by a radio, 190 00:11:23,240 --> 00:11:25,040 Speaker 1: I'm gonna skip a little bit here. We're gonna go 191 00:11:25,120 --> 00:11:27,719 Speaker 1: back to the middle section in a minute. But when 192 00:11:27,760 --> 00:11:31,200 Speaker 1: your radio receives an A M signal, it's going to 193 00:11:31,240 --> 00:11:35,920 Speaker 1: detect it's going to detect the the height of those waves. 194 00:11:36,400 --> 00:11:39,400 Speaker 1: And as the height changes over time, that's going to 195 00:11:39,480 --> 00:11:42,240 Speaker 1: give the speaker in your radio the signal to move 196 00:11:42,320 --> 00:11:45,760 Speaker 1: in or out, and your speaker cone technically your speaker 197 00:11:45,800 --> 00:11:48,000 Speaker 1: cone in the speaker. As the speaker cone in your 198 00:11:48,000 --> 00:11:50,240 Speaker 1: speaker moves in and out, that's what generates the sound 199 00:11:50,280 --> 00:11:54,240 Speaker 1: you hear. So as those waves go up and uh 200 00:11:54,280 --> 00:11:57,480 Speaker 1: down in in amplitude uh, and they're gonna be doing 201 00:11:57,520 --> 00:12:02,920 Speaker 1: this uh thousands of of times per second because along 202 00:12:02,960 --> 00:12:06,280 Speaker 1: with the the crest trough and wavelength, you have the frequency. 203 00:12:06,320 --> 00:12:10,199 Speaker 1: The frequency is how many uh, how many cycles, how 204 00:12:10,200 --> 00:12:13,520 Speaker 1: many wavelengths you go through within a second. We call 205 00:12:13,600 --> 00:12:15,480 Speaker 1: that like, if you were to do one cycle a 206 00:12:15,480 --> 00:12:19,000 Speaker 1: second would be one hurts, right, so it kill hurts 207 00:12:19,080 --> 00:12:22,200 Speaker 1: is one thousand cycles in a second. A mega hurts 208 00:12:22,200 --> 00:12:24,200 Speaker 1: would be a million cycles in a second, a giga 209 00:12:24,240 --> 00:12:27,160 Speaker 1: hurts would be a billion cycles in a second. So 210 00:12:27,559 --> 00:12:31,760 Speaker 1: that's a lot. So you're at home. The radio has 211 00:12:31,840 --> 00:12:35,319 Speaker 1: detected the signal and it's detecting the difference in that amplitude, 212 00:12:35,480 --> 00:12:38,360 Speaker 1: and as that amplitude changes over time, that's what tells 213 00:12:38,400 --> 00:12:41,160 Speaker 1: the speaker how to uh to move in and out 214 00:12:41,160 --> 00:12:44,600 Speaker 1: and generate the sound that you hear. Frequency modulation is different. 215 00:12:45,160 --> 00:12:48,800 Speaker 1: The amplitude remains the same, it remains steady h So 216 00:12:48,880 --> 00:12:51,400 Speaker 1: you don't change the amplitude. That's not what tells the 217 00:12:51,440 --> 00:12:55,240 Speaker 1: speaker what the how to interpret that's that's signal to 218 00:12:55,240 --> 00:12:58,479 Speaker 1: turn it into sound. Instead, you you change the frequency 219 00:12:58,520 --> 00:13:03,920 Speaker 1: itself of the transmission, which is a little tricky because 220 00:13:04,520 --> 00:13:06,520 Speaker 1: to tune a radio you have to tune it into 221 00:13:06,559 --> 00:13:10,520 Speaker 1: a specific frequency to to really pick up a good signal. UH. 222 00:13:10,559 --> 00:13:14,160 Speaker 1: So it really generates it keeps it within a fairly 223 00:13:14,240 --> 00:13:17,080 Speaker 1: tight set of parameters. It can't go far beyond that, 224 00:13:17,200 --> 00:13:18,600 Speaker 1: or else you would no longer be able to pick 225 00:13:18,679 --> 00:13:23,360 Speaker 1: up the radio station. But by changing the frequency, that 226 00:13:23,480 --> 00:13:28,880 Speaker 1: is the the number of cycles that UM wavelength goes 227 00:13:28,920 --> 00:13:32,360 Speaker 1: through in a second, that's what tells the speaker how 228 00:13:32,440 --> 00:13:34,520 Speaker 1: to move in and out and generate the sound you hear. 229 00:13:36,160 --> 00:13:39,760 Speaker 1: Now we have to tackle the magical bit in the middle. Okay, 230 00:13:40,160 --> 00:13:41,880 Speaker 1: you know, so we've got you know, you've generated the 231 00:13:41,880 --> 00:13:44,480 Speaker 1: sound and you've heard the sound. But what's happening between 232 00:13:44,559 --> 00:13:48,280 Speaker 1: those two moments and there's some fascinating stuff here, and 233 00:13:48,320 --> 00:13:51,840 Speaker 1: we're gonna get into some science. Uh So, some apologies 234 00:13:51,920 --> 00:13:55,480 Speaker 1: to uh to Robert and Julie who would normally tackle 235 00:13:55,520 --> 00:13:58,319 Speaker 1: this kind of thing, but we're gonna do it. Um. So, 236 00:13:59,559 --> 00:14:02,800 Speaker 1: when you generate that signal at the transmitter, you actually 237 00:14:02,880 --> 00:14:06,439 Speaker 1: create an electric charge that moves up and down your 238 00:14:06,480 --> 00:14:10,359 Speaker 1: transmitter antenna. All right. So antenna are used for two 239 00:14:10,640 --> 00:14:14,520 Speaker 1: main purposes, to transmit signals and to receive signals. Yep. 240 00:14:14,679 --> 00:14:18,960 Speaker 1: And it's true too that, uh the type of frequency 241 00:14:19,040 --> 00:14:21,960 Speaker 1: you're using requires a different type of antenna. For example, 242 00:14:22,000 --> 00:14:26,040 Speaker 1: if you're broadcasting AM versus FM, it requires a different 243 00:14:26,080 --> 00:14:28,840 Speaker 1: antenna length because that has a lot to do with it. 244 00:14:28,880 --> 00:14:32,240 Speaker 1: And and if you've always wondered why, uh, you know, 245 00:14:32,240 --> 00:14:35,920 Speaker 1: I have a clock radio and it's got it basically 246 00:14:35,920 --> 00:14:38,800 Speaker 1: has an internal AM antenna, but it's got an external 247 00:14:38,840 --> 00:14:40,960 Speaker 1: FM antenna. And I didn't understand why until I you know, 248 00:14:41,000 --> 00:14:42,600 Speaker 1: I just really didn't care to look until we were 249 00:14:42,600 --> 00:14:44,560 Speaker 1: deciding to do this. And yeah, it has a lot 250 00:14:44,640 --> 00:14:48,600 Speaker 1: to do with the exactly what we were just talking 251 00:14:48,640 --> 00:14:51,320 Speaker 1: about or what you were just talking about, which is, uh, 252 00:14:51,560 --> 00:14:54,360 Speaker 1: the ways in which they and the carrier wave is 253 00:14:54,360 --> 00:14:59,320 Speaker 1: transmitted in these different technologies, so you know, you need 254 00:14:59,400 --> 00:15:01,800 Speaker 1: a different kind of antenna to transmit and to receive 255 00:15:02,360 --> 00:15:04,280 Speaker 1: those signals depending on what you're trying to do. And 256 00:15:04,280 --> 00:15:06,920 Speaker 1: in general, a general rule of thumb is the best 257 00:15:06,960 --> 00:15:10,520 Speaker 1: antenna to receive a signal is one quarter of the 258 00:15:10,600 --> 00:15:15,960 Speaker 1: length of the radio waves wavelength. But here's the thing. 259 00:15:16,120 --> 00:15:21,040 Speaker 1: AM radio that gets big. I mean AM radio can 260 00:15:21,080 --> 00:15:25,440 Speaker 1: be uh so big. That's larger than a football field. 261 00:15:25,760 --> 00:15:29,440 Speaker 1: And so having an AM radio antenna receiver antenna that's 262 00:15:29,480 --> 00:15:32,120 Speaker 1: a quarter the size of a football field is not 263 00:15:32,240 --> 00:15:38,520 Speaker 1: really on most people's list of home improvement UM projects. 264 00:15:38,640 --> 00:15:41,720 Speaker 1: So there are ways around that, but that's the ideal 265 00:15:41,840 --> 00:15:48,560 Speaker 1: length for a reception antenna. Now, when you when you 266 00:15:48,600 --> 00:15:52,119 Speaker 1: create this electric charge that's going up and down the 267 00:15:52,120 --> 00:15:55,840 Speaker 1: the antenna, you're actually you're using an oscillator to change 268 00:15:56,000 --> 00:15:59,560 Speaker 1: the charge. So you're you're essentially switching the charge. You're 269 00:15:59,560 --> 00:16:02,920 Speaker 1: you're switching voltage on and off up and down this 270 00:16:02,920 --> 00:16:06,280 Speaker 1: this antenna, and that electric charge has it changes over 271 00:16:06,320 --> 00:16:08,120 Speaker 1: time up and down the antenna. That's what creates the 272 00:16:08,160 --> 00:16:13,400 Speaker 1: electromagnetic wave that propagates out from the the transmitter antenna. 273 00:16:13,760 --> 00:16:17,080 Speaker 1: You know, I've watched a lot of movies where um uh, 274 00:16:17,120 --> 00:16:19,200 Speaker 1: you know you've got your giant radio antenna and these 275 00:16:19,240 --> 00:16:21,640 Speaker 1: little electrical things come out the top. You mean that's 276 00:16:21,640 --> 00:16:25,720 Speaker 1: not exactly right. No, you're thinking of our ko Ka 277 00:16:25,920 --> 00:16:29,160 Speaker 1: the old arcade. Yeah, no, you can't see them, although 278 00:16:29,200 --> 00:16:31,960 Speaker 1: it was. Although here's Here's the interesting thing though, is 279 00:16:31,960 --> 00:16:36,600 Speaker 1: that you can pick up you can receive electricity this way, 280 00:16:36,640 --> 00:16:39,720 Speaker 1: although it's a minuscule amount. In fact, that's that's the 281 00:16:39,760 --> 00:16:42,880 Speaker 1: basis of why this ends up working. So you you 282 00:16:43,160 --> 00:16:45,920 Speaker 1: pump lots and lots of electricity into this antenna. We're 283 00:16:45,920 --> 00:16:49,080 Speaker 1: talking about thousands of watts for for an a m station, 284 00:16:49,840 --> 00:16:54,280 Speaker 1: and you are using an oscillator to to move that 285 00:16:54,840 --> 00:16:57,440 Speaker 1: that electric charge up and down the antenna at a 286 00:16:57,480 --> 00:17:01,040 Speaker 1: certain rate. And UH, at that rate depends upon what 287 00:17:01,160 --> 00:17:03,800 Speaker 1: the FCC in the United States has designated as your 288 00:17:03,840 --> 00:17:07,720 Speaker 1: broadcast range. You broadcast your signal that way. Now, let's 289 00:17:07,760 --> 00:17:13,080 Speaker 1: say you want to pick that signal up. The electromagnetic waves, UH, 290 00:17:13,400 --> 00:17:16,119 Speaker 1: move out from that antenna, their directional, they move out 291 00:17:16,200 --> 00:17:19,760 Speaker 1: in every direction really from the antenna. Uh. And then 292 00:17:20,320 --> 00:17:23,359 Speaker 1: you are a certain distance away. You have your radio, 293 00:17:23,400 --> 00:17:28,000 Speaker 1: You've got your antenna extended up. As the electromagnetic waves 294 00:17:28,600 --> 00:17:32,320 Speaker 1: move towards your antenna, your antenna actually can we'll pick 295 00:17:32,400 --> 00:17:35,760 Speaker 1: up a little electrical charge because you've got you know, 296 00:17:35,800 --> 00:17:40,160 Speaker 1: the antenna. That's the whole reason why the radio works 297 00:17:40,240 --> 00:17:43,680 Speaker 1: is that electric field is able to enact the work 298 00:17:44,160 --> 00:17:46,320 Speaker 1: on an electric charge. You've got a little electric charge 299 00:17:46,320 --> 00:17:50,000 Speaker 1: inside that antenna. It alters. But due to this radio wave, 300 00:17:50,520 --> 00:17:53,840 Speaker 1: and assuming that you have your radio tune to the 301 00:17:53,920 --> 00:17:58,119 Speaker 1: right station, UH, what's gonna happen is the electric charge 302 00:17:58,119 --> 00:18:03,000 Speaker 1: in your antenna, your receptor antenna is going to move 303 00:18:03,080 --> 00:18:05,320 Speaker 1: up and down a certain frequency. If you have tuned 304 00:18:05,359 --> 00:18:08,280 Speaker 1: your radio properly, it's going to be at the circuit 305 00:18:08,320 --> 00:18:11,080 Speaker 1: in your radio is gonna be at a resonant frequency 306 00:18:11,240 --> 00:18:14,920 Speaker 1: with that charge that's moving up and down in your antenna. Now, 307 00:18:14,920 --> 00:18:19,240 Speaker 1: if you've heard about resonant frequencies, that's when you can 308 00:18:19,760 --> 00:18:25,040 Speaker 1: uh make something essentially vibrate at uh an ideal frequency 309 00:18:25,320 --> 00:18:29,800 Speaker 1: for stuff to go crazy like we we've seen. You know, 310 00:18:29,920 --> 00:18:32,000 Speaker 1: you might have seen a MythBusters episode where they started 311 00:18:32,000 --> 00:18:34,640 Speaker 1: talking about resonant frequencies. Yes, the idea being that us 312 00:18:34,880 --> 00:18:39,440 Speaker 1: should wind blow across a bridge at a particular frequency 313 00:18:39,760 --> 00:18:43,560 Speaker 1: of a particular speed. It would create this uh, this 314 00:18:44,359 --> 00:18:47,720 Speaker 1: sort of uh vicious cycle that feeds into itself where 315 00:18:47,720 --> 00:18:51,400 Speaker 1: the bridge itself starts to shake apart. Well, resonant frequencies 316 00:18:51,480 --> 00:18:54,520 Speaker 1: are a real thing, and if you do generate uh 317 00:18:54,680 --> 00:18:58,280 Speaker 1: the right resonant frequency, you can create a larger and 318 00:18:58,400 --> 00:19:03,199 Speaker 1: larger um uh vibrations in a medium. So think of 319 00:19:03,240 --> 00:19:05,119 Speaker 1: it kind of like you've got a kid on a 320 00:19:05,240 --> 00:19:08,560 Speaker 1: swing and you're pushing the kid on the swing. If 321 00:19:08,560 --> 00:19:10,240 Speaker 1: you push the kid at just the right time, the 322 00:19:10,320 --> 00:19:14,120 Speaker 1: kid's gonna go up higher each on each swing, Right, 323 00:19:14,480 --> 00:19:17,120 Speaker 1: You're you're adding more energy into it, and it's and 324 00:19:17,320 --> 00:19:20,520 Speaker 1: uh you see the output as the kid goes up higher. 325 00:19:20,680 --> 00:19:23,320 Speaker 1: If you push it the wrong time, the kid just 326 00:19:23,400 --> 00:19:25,680 Speaker 1: ends up drinking around and falling off the swing set 327 00:19:25,720 --> 00:19:31,280 Speaker 1: and crying like like I did. Thanks Dad. Anyway, uh So, 328 00:19:32,200 --> 00:19:35,239 Speaker 1: the the circuit in your radio, when you tune it, 329 00:19:35,320 --> 00:19:37,800 Speaker 1: you actually alter the circuit a little bit so that 330 00:19:38,040 --> 00:19:40,640 Speaker 1: it will resonate at a different frequency once it hits 331 00:19:40,640 --> 00:19:43,240 Speaker 1: the right frequency for the radio wave that's hitting your antenna. 332 00:19:43,720 --> 00:19:46,960 Speaker 1: Those little uh the electric charge is going up and 333 00:19:46,960 --> 00:19:51,600 Speaker 1: down your your antenna will cause a larger reaction within 334 00:19:51,720 --> 00:19:54,720 Speaker 1: the circuit in your radio, which is what you're is 335 00:19:55,119 --> 00:19:58,400 Speaker 1: picked up by the amplifier and then converted into um 336 00:19:58,480 --> 00:20:04,640 Speaker 1: sound through your speaker. Yeah. Yeah, So should we get 337 00:20:04,640 --> 00:20:07,560 Speaker 1: into some of the other cool stuff? Yeah, like hit 338 00:20:07,600 --> 00:20:10,960 Speaker 1: me with stereo. Oh man, I didn't even go into stereo. 339 00:20:11,040 --> 00:20:13,600 Speaker 1: I was. I was so concentrated on I want to 340 00:20:13,640 --> 00:20:16,119 Speaker 1: make sure I can explain the science of how this 341 00:20:16,240 --> 00:20:19,520 Speaker 1: radio wave moves across. Um. It's actually really fascinating stuff. 342 00:20:19,560 --> 00:20:21,200 Speaker 1: And all, you know what we should do before we 343 00:20:21,240 --> 00:20:25,720 Speaker 1: talk about stereo. Crystal radio. Okay, that's the simplest kind 344 00:20:25,720 --> 00:20:28,440 Speaker 1: of radio I can think of. As a matter of fact. Um, 345 00:20:28,520 --> 00:20:30,480 Speaker 1: when I was a kid, I had I probably still 346 00:20:30,520 --> 00:20:34,080 Speaker 1: do in the box somewhere a crystal radio kit. UM. 347 00:20:34,119 --> 00:20:35,800 Speaker 1: And yeah, when I was when I was doing a 348 00:20:35,800 --> 00:20:40,080 Speaker 1: little research. UM, one of the things that really lead 349 00:20:40,160 --> 00:20:45,840 Speaker 1: to radio being functional was UM the ability to when 350 00:20:45,840 --> 00:20:48,760 Speaker 1: they discovered the ability to tune a radio. It's like 351 00:20:48,800 --> 00:20:51,480 Speaker 1: I I don't want to just search for whatever. I 352 00:20:51,480 --> 00:20:53,800 Speaker 1: want to be able to lock it in to to 353 00:20:53,960 --> 00:20:58,440 Speaker 1: detect a specific UH signal. And and when they developed 354 00:20:58,440 --> 00:21:01,879 Speaker 1: the ability to tune a radio, that basically made UM 355 00:21:02,000 --> 00:21:05,200 Speaker 1: what is what is now the radio industry possible because 356 00:21:05,240 --> 00:21:08,320 Speaker 1: you can tune into a specific UH station and leave 357 00:21:08,400 --> 00:21:11,320 Speaker 1: it there and it's not going anywhere. UM. Of course, 358 00:21:11,520 --> 00:21:14,560 Speaker 1: you have to be very careful, especially if you're the 359 00:21:14,560 --> 00:21:18,240 Speaker 1: the licensing group. UM. Here in Atlanta there are tons 360 00:21:18,240 --> 00:21:20,320 Speaker 1: and tons of radio stations. And I had this problem 361 00:21:20,320 --> 00:21:26,240 Speaker 1: with UM. UM. I had an iPod with a broadcaster 362 00:21:26,359 --> 00:21:28,560 Speaker 1: that I used to use trying to play through my 363 00:21:28,720 --> 00:21:31,119 Speaker 1: radio rather than you know, hooking it up in some 364 00:21:31,160 --> 00:21:34,159 Speaker 1: way physically with a tape adapter or a plug or 365 00:21:34,160 --> 00:21:36,879 Speaker 1: something like that. And UH, you know, you have to 366 00:21:36,920 --> 00:21:41,679 Speaker 1: have a certain distance between stations for the signal not 367 00:21:41,760 --> 00:21:43,800 Speaker 1: to for the carrier waves not to bleed over and 368 00:21:43,800 --> 00:21:47,160 Speaker 1: and basically muddle the information in between. And I had 369 00:21:47,640 --> 00:21:49,840 Speaker 1: as I would drive around Atlanta, I would have to 370 00:21:49,920 --> 00:21:54,479 Speaker 1: change the station that my iPod broadcaster was broadcasting on 371 00:21:54,560 --> 00:21:57,959 Speaker 1: because um, you know, I would start to enter another 372 00:21:58,000 --> 00:22:00,600 Speaker 1: station more powerful signal would start to interfere with it, 373 00:22:00,600 --> 00:22:03,840 Speaker 1: and I would have to to do that. UM. So yeah, 374 00:22:03,920 --> 00:22:09,680 Speaker 1: this the crystal set that's really really basic. UM. In fact, 375 00:22:09,720 --> 00:22:12,399 Speaker 1: the one I got from radio Shack was basically, uh, 376 00:22:12,440 --> 00:22:14,679 Speaker 1: it was already hooked up, so to speak. It had 377 00:22:14,720 --> 00:22:17,359 Speaker 1: It was one of those that has the springs and 378 00:22:17,400 --> 00:22:20,600 Speaker 1: you you connect the wires using the springs. And if 379 00:22:20,600 --> 00:22:23,639 Speaker 1: you haven't seen these kits, um, you know, basic electronics 380 00:22:23,640 --> 00:22:26,560 Speaker 1: type kits. There's a h the board is wired underneath 381 00:22:26,840 --> 00:22:31,159 Speaker 1: and there are very tight, tightly coiled springs installed in 382 00:22:31,240 --> 00:22:33,920 Speaker 1: the top. And to make a connection from one point 383 00:22:33,960 --> 00:22:36,320 Speaker 1: to the other to finish your kit build the radio. 384 00:22:36,359 --> 00:22:39,600 Speaker 1: In this case, UM, you have wires that are um 385 00:22:40,160 --> 00:22:42,800 Speaker 1: uh not insulated on the very ends and you bend 386 00:22:42,880 --> 00:22:45,240 Speaker 1: the spring stick the end of the metal end of 387 00:22:45,240 --> 00:22:47,359 Speaker 1: the wire and let go and the spring holds it 388 00:22:47,400 --> 00:22:50,399 Speaker 1: into place. UM. And with that, you know, and I 389 00:22:50,440 --> 00:22:51,959 Speaker 1: had a long wire that I would use to pick 390 00:22:52,040 --> 00:22:54,840 Speaker 1: up a M signals. That would be your antenna. The antenna. 391 00:22:55,640 --> 00:22:58,000 Speaker 1: But yeah, if you're you know, if you don't know 392 00:22:58,040 --> 00:23:00,199 Speaker 1: what's going on, it looks sort of a lot the 393 00:23:00,280 --> 00:23:02,159 Speaker 1: other wires in the kit, but you know, you'd have 394 00:23:02,200 --> 00:23:04,439 Speaker 1: to extend it away, and and a small knob that 395 00:23:04,480 --> 00:23:06,600 Speaker 1: you would use to tune that. But it also had 396 00:23:06,920 --> 00:23:10,920 Speaker 1: a coil of metal. It looked like electromagnet. Yeah, I 397 00:23:10,960 --> 00:23:13,400 Speaker 1: can actually talk a little bit about that. There are 398 00:23:13,440 --> 00:23:17,080 Speaker 1: four basic components of a crystal radio. These are These 399 00:23:17,119 --> 00:23:19,480 Speaker 1: are literally the only four things you need to make 400 00:23:19,600 --> 00:23:25,720 Speaker 1: the most basic a M radio. You need an antenna, 401 00:23:25,760 --> 00:23:27,800 Speaker 1: so some sort of wire to act as an antenna. 402 00:23:28,200 --> 00:23:31,520 Speaker 1: That you need a tank circuit, which is what looked 403 00:23:31,560 --> 00:23:34,400 Speaker 1: like the electro magnet to you, I'm guessing, yes, you 404 00:23:34,440 --> 00:23:38,840 Speaker 1: need a diode, and and then you need an earphone 405 00:23:38,960 --> 00:23:42,320 Speaker 1: of some sort. In this case it was hardwired in 406 00:23:42,480 --> 00:23:46,320 Speaker 1: was one of those petty color uh you know, yeah, 407 00:23:46,560 --> 00:23:49,360 Speaker 1: and the and the and you don't need a battery. 408 00:23:49,440 --> 00:23:51,320 Speaker 1: And the reason you don't need a batteries because, like 409 00:23:51,359 --> 00:23:55,000 Speaker 1: I said, when you have the antenna, the electromagnetic field 410 00:23:55,200 --> 00:23:57,520 Speaker 1: will cause an electric charge to move up and down 411 00:23:57,520 --> 00:23:59,520 Speaker 1: that antenna on its own, it don't. You don't need 412 00:23:59,560 --> 00:24:03,160 Speaker 1: a battery to create that electricity from the start. Now, 413 00:24:03,200 --> 00:24:05,280 Speaker 1: the signal you're going to receive will be very weak, 414 00:24:05,600 --> 00:24:07,960 Speaker 1: even unless well the closer you get to the to 415 00:24:08,080 --> 00:24:10,080 Speaker 1: the radio station, the more powerful the signal will be, 416 00:24:10,119 --> 00:24:12,240 Speaker 1: but still be pretty weak. And but you're the human 417 00:24:12,280 --> 00:24:15,520 Speaker 1: ear is remarkably sensitive, so you'll be able to hear 418 00:24:15,640 --> 00:24:19,800 Speaker 1: the transmission even if the signal itself is weak. By 419 00:24:19,800 --> 00:24:22,080 Speaker 1: the way, Uh, this the fact that you are able 420 00:24:22,119 --> 00:24:24,760 Speaker 1: to to collect in a way, or that you're able 421 00:24:24,800 --> 00:24:27,159 Speaker 1: to receive electricity over the air this way, that was 422 00:24:27,200 --> 00:24:29,840 Speaker 1: one that was one thing that Tesla was obsessed about 423 00:24:30,280 --> 00:24:34,720 Speaker 1: the idea of broadcasting electricity and too, you're gonna find 424 00:24:34,760 --> 00:24:40,760 Speaker 1: if you do a search online, you'll find some um wow, 425 00:24:41,680 --> 00:24:44,040 Speaker 1: to call them Charlottean's might be too strong a word, 426 00:24:44,080 --> 00:24:46,760 Speaker 1: but you'll find some people who claim that they have 427 00:24:46,880 --> 00:24:51,080 Speaker 1: created a way to generate electricity through or transmit electricity 428 00:24:51,080 --> 00:24:54,679 Speaker 1: through through broadcast using this method. Well, it's true that 429 00:24:54,760 --> 00:24:57,600 Speaker 1: you can get electricity this way, but it's on such 430 00:24:57,640 --> 00:25:01,720 Speaker 1: a tiny amount that you would need a receptor antenna 431 00:25:01,800 --> 00:25:05,760 Speaker 1: that would be enormous in order to generate to receive 432 00:25:06,119 --> 00:25:10,560 Speaker 1: enough electricity for it to be enough to power a 433 00:25:10,680 --> 00:25:13,800 Speaker 1: light bulb even yeah, be basically a trickle. Yeah. So 434 00:25:13,800 --> 00:25:16,919 Speaker 1: so it's it's it's more likely than not if you 435 00:25:16,960 --> 00:25:19,480 Speaker 1: see someone who says that they have this new free 436 00:25:19,560 --> 00:25:21,520 Speaker 1: energy type thing where you're just gonna be pulling in 437 00:25:21,720 --> 00:25:24,720 Speaker 1: radio waves and changing that into electricity. And since since 438 00:25:24,760 --> 00:25:27,000 Speaker 1: so many things out in the universe create radio waves, 439 00:25:27,000 --> 00:25:30,520 Speaker 1: therefore it's almost free energy, be on alert because that's 440 00:25:30,520 --> 00:25:33,680 Speaker 1: not exactly true. I mean, you will get electricity that way, 441 00:25:33,680 --> 00:25:36,480 Speaker 1: but it won't be enough to do any real significant 442 00:25:36,480 --> 00:25:41,720 Speaker 1: work anyway. So you've got those four basic UH components. 443 00:25:41,720 --> 00:25:45,199 Speaker 1: So so the antenna UH projects up. It collects the 444 00:25:45,200 --> 00:25:49,119 Speaker 1: electromagnetic or into the electromagnetic fields that's passing by UM, 445 00:25:49,240 --> 00:25:51,560 Speaker 1: and then that creates the difference in charge up and 446 00:25:51,600 --> 00:25:54,879 Speaker 1: down the antenna. And then you've got the tank circuit, 447 00:25:54,880 --> 00:25:57,320 Speaker 1: which is it's a coil of wire and it's connected 448 00:25:57,320 --> 00:25:59,959 Speaker 1: at each end to the two ends of a capacitor. 449 00:26:00,520 --> 00:26:02,720 Speaker 1: So you've got a capacitor and UH and a coil 450 00:26:02,720 --> 00:26:05,560 Speaker 1: of wire. That's what a tank circuit is. And generally 451 00:26:05,600 --> 00:26:07,679 Speaker 1: the way you tune a radio is that you either 452 00:26:08,160 --> 00:26:11,760 Speaker 1: alter the coil, or you alter the capacitor, one of 453 00:26:11,800 --> 00:26:14,280 Speaker 1: the two most radios they work on. You know you 454 00:26:14,280 --> 00:26:16,879 Speaker 1: you are are changing one of those two elements in 455 00:26:16,960 --> 00:26:21,800 Speaker 1: order to tune the radio. Um. The diode is an 456 00:26:21,840 --> 00:26:25,639 Speaker 1: interesting electrical component. I'm not sure that we may have 457 00:26:25,680 --> 00:26:29,040 Speaker 1: talked about it in our Basics of Electronics podcast, but 458 00:26:29,080 --> 00:26:31,480 Speaker 1: I can't remember exactly I want to say we did. 459 00:26:31,840 --> 00:26:34,960 Speaker 1: But a diode it kind of a it's it's something 460 00:26:35,000 --> 00:26:37,479 Speaker 1: that allows electricity to flow one direction but not the 461 00:26:37,480 --> 00:26:39,840 Speaker 1: other way. It's like a it's like a one way 462 00:26:39,920 --> 00:26:44,479 Speaker 1: street in a way, and using that connected to the 463 00:26:44,520 --> 00:26:47,879 Speaker 1: tank circuit, and then you have the earphone connected through there. 464 00:26:48,520 --> 00:26:51,960 Speaker 1: That's what allows you to have have the right electric 465 00:26:52,000 --> 00:26:56,359 Speaker 1: signals sent to the earphone that then oscillates at the 466 00:26:56,480 --> 00:26:58,600 Speaker 1: right frequency to create the sound, and then you can 467 00:26:58,640 --> 00:27:00,840 Speaker 1: hear it. Although again it's gonna be very very faint. 468 00:27:01,280 --> 00:27:03,560 Speaker 1: It's not gonna be like, you know, hey, is that 469 00:27:03,600 --> 00:27:07,800 Speaker 1: freedom rockman? Will turn it up? Man? Do you remember 470 00:27:07,800 --> 00:27:13,840 Speaker 1: those commercials our listeners don't anyway for them? Yeah, you're 471 00:27:13,880 --> 00:27:18,439 Speaker 1: better off for it, but uh so, yes, so that 472 00:27:18,560 --> 00:27:20,239 Speaker 1: that I just wanted to talk about that since it's 473 00:27:20,280 --> 00:27:22,919 Speaker 1: the most basic and our listeners. If you're interested, you 474 00:27:22,920 --> 00:27:25,679 Speaker 1: can actually go out and find components and build one 475 00:27:25,720 --> 00:27:28,359 Speaker 1: of these yourselves. Uh. There's some places that sell the 476 00:27:28,480 --> 00:27:32,040 Speaker 1: kits um. Depending upon the electronics stores that maybe in 477 00:27:32,040 --> 00:27:34,480 Speaker 1: your area, you might even be able to buy the 478 00:27:34,480 --> 00:27:38,320 Speaker 1: the individual components and and build your own AM radio 479 00:27:38,400 --> 00:27:40,880 Speaker 1: from scratch that way. Now, keep in mind again this 480 00:27:41,000 --> 00:27:46,560 Speaker 1: is a very uh primitive and therefore um limited piece 481 00:27:46,560 --> 00:27:51,760 Speaker 1: of technology, and your your experience with it will depend 482 00:27:51,800 --> 00:27:54,000 Speaker 1: heavily on how close you are to the nearest a 483 00:27:54,080 --> 00:27:58,160 Speaker 1: UM transmitters, because the further way you are, the weaker 484 00:27:58,160 --> 00:27:59,600 Speaker 1: that signal is going to be, and it may get 485 00:27:59,640 --> 00:28:01,520 Speaker 1: to the point where you just can't get enough of 486 00:28:01,520 --> 00:28:06,480 Speaker 1: a signal to be able to hear the transmission. UM. 487 00:28:06,480 --> 00:28:09,200 Speaker 1: So yeah, I had a number of other related things 488 00:28:09,240 --> 00:28:13,000 Speaker 1: that I had been curious about. UM. One of them 489 00:28:13,200 --> 00:28:15,480 Speaker 1: was stereo, although not as much together. And stereo is 490 00:28:15,480 --> 00:28:20,040 Speaker 1: actually fairly simple um because basically you have the two 491 00:28:20,119 --> 00:28:23,240 Speaker 1: you have two microphones you absolutely uh well this will 492 00:28:23,240 --> 00:28:25,320 Speaker 1: be obvious really when you think about it. The stereo 493 00:28:25,359 --> 00:28:27,800 Speaker 1: signal has two separate channels, you know, one for the 494 00:28:27,880 --> 00:28:30,760 Speaker 1: left one for the right. UM. So that means you 495 00:28:30,760 --> 00:28:34,920 Speaker 1: would need more than one microphone, and uh, the trick 496 00:28:35,040 --> 00:28:37,440 Speaker 1: is that you have to you know, it essentially works 497 00:28:37,440 --> 00:28:39,560 Speaker 1: the same way that you have two feeds going into 498 00:28:39,600 --> 00:28:42,760 Speaker 1: the box and you know they go from the box 499 00:28:42,800 --> 00:28:44,840 Speaker 1: to the tower and through the air and back to 500 00:28:44,880 --> 00:28:46,720 Speaker 1: the thing. The thing is you have to make sure 501 00:28:46,760 --> 00:28:49,160 Speaker 1: that the wave is able to carrier wave is able 502 00:28:49,200 --> 00:28:52,040 Speaker 1: to handle that. And for a long time that was 503 00:28:52,120 --> 00:28:57,080 Speaker 1: only possible through frequency modulation UM just because it has 504 00:28:57,720 --> 00:29:01,800 Speaker 1: more capacity UM than AM UM. And you know, we 505 00:29:01,800 --> 00:29:05,320 Speaker 1: really didn't talk about the frequencies used. That's true. We 506 00:29:05,400 --> 00:29:07,920 Speaker 1: talked about in our CB radio I think I remember 507 00:29:07,960 --> 00:29:10,160 Speaker 1: we did talk about the electromagnetic spectrum and we talked 508 00:29:10,200 --> 00:29:12,480 Speaker 1: about which parts of the spectrum were allowed for H 509 00:29:13,080 --> 00:29:17,400 Speaker 1: for radio use. Yeah yeah, and that was years ago. 510 00:29:17,680 --> 00:29:20,400 Speaker 1: Yeah yeah, but yeah, you need that. That's one of 511 00:29:20,400 --> 00:29:23,040 Speaker 1: the reasons why. And I know that they were able 512 00:29:23,120 --> 00:29:28,480 Speaker 1: they promoted AM stereo some years ago. UM. But basically 513 00:29:28,520 --> 00:29:32,480 Speaker 1: the difference being that the frequency modulation signal is able 514 00:29:32,520 --> 00:29:35,840 Speaker 1: to carry more information. Therefore you can UH, you can 515 00:29:35,920 --> 00:29:37,800 Speaker 1: do that, but you have to UH to make it 516 00:29:37,840 --> 00:29:42,160 Speaker 1: possible and then carrier wave to carry a stereo signal 517 00:29:42,160 --> 00:29:47,160 Speaker 1: with more than one UH channel of information. Um, you 518 00:29:47,160 --> 00:29:49,760 Speaker 1: want to talk about the ionosphere any I was gonna 519 00:29:49,840 --> 00:29:53,240 Speaker 1: just mention that the ion a sphere. Uh. You might 520 00:29:53,280 --> 00:29:58,040 Speaker 1: wonder why at night you can hear radio stations much 521 00:29:58,080 --> 00:30:00,600 Speaker 1: further away, or at least in the evening, late evening 522 00:30:00,600 --> 00:30:03,959 Speaker 1: at dusk you can hear radio stations much further away 523 00:30:04,400 --> 00:30:07,320 Speaker 1: than normal, and that that does have to do with 524 00:30:07,320 --> 00:30:12,320 Speaker 1: the ionosphere. And uh, the ionosphere has its own sort 525 00:30:12,360 --> 00:30:16,600 Speaker 1: of Uh. Well, it's it's like an electric mirror in 526 00:30:16,640 --> 00:30:20,200 Speaker 1: a way. If if radio waves of a particular uh 527 00:30:20,320 --> 00:30:24,640 Speaker 1: frequency and and wavelength hit the ionosphere, they could be 528 00:30:24,680 --> 00:30:27,200 Speaker 1: reflected back down toward the Earth. And you can actually 529 00:30:27,240 --> 00:30:31,080 Speaker 1: bounce a radio signal off the ionosphere and back towards 530 00:30:31,120 --> 00:30:33,800 Speaker 1: the surface of the planet, and therefore it will travel 531 00:30:33,920 --> 00:30:36,840 Speaker 1: much further than it would just through line of sight. Yeah, 532 00:30:36,880 --> 00:30:40,480 Speaker 1: they discovered that in two Um. There were there were 533 00:30:40,520 --> 00:30:42,440 Speaker 1: a couple of people who were involved with that. Arthur 534 00:30:42,560 --> 00:30:46,080 Speaker 1: Edwin Kennelly who was an electrical electrical engineer in the 535 00:30:46,160 --> 00:30:50,520 Speaker 1: United States, and Oliver Heaviside from UH from England, was 536 00:30:50,560 --> 00:30:54,760 Speaker 1: a mathematician. Um. Again one of those situations. Uh, there 537 00:30:54,800 --> 00:30:56,280 Speaker 1: seems to be a lot of that in radio where 538 00:30:56,280 --> 00:30:59,960 Speaker 1: people sort of simultaneously discovered this UM and I got 539 00:31:00,040 --> 00:31:03,000 Speaker 1: lot of information from the article about radio and Britannica. 540 00:31:03,080 --> 00:31:06,160 Speaker 1: This is where I picked this particular bit up. But yeah, 541 00:31:06,160 --> 00:31:09,240 Speaker 1: they were the ones who u Ino had figured out 542 00:31:09,320 --> 00:31:14,200 Speaker 1: that UM you could basically transmit towards the sky and 543 00:31:14,240 --> 00:31:18,120 Speaker 1: the iono sphere would refract them back towards Earth and 544 00:31:18,120 --> 00:31:20,720 Speaker 1: that would help you extend the range of your transmitting. Yeah, 545 00:31:20,800 --> 00:31:25,120 Speaker 1: it's it's interesting because and during the daytime, the ionosphere, 546 00:31:25,240 --> 00:31:29,000 Speaker 1: the the electrically charged particles in the ionosphere, they don't 547 00:31:29,040 --> 00:31:32,120 Speaker 1: act as a very good electrical conductor. Uh. It's only 548 00:31:32,760 --> 00:31:35,880 Speaker 1: really once you hit UH in the early evening that's 549 00:31:35,880 --> 00:31:41,880 Speaker 1: when the conductivity actually improves. And we don't the ionosphere, 550 00:31:41,920 --> 00:31:47,600 Speaker 1: the magnetosphere, these elements of the the Earth's uh hesitate 551 00:31:47,600 --> 00:31:50,600 Speaker 1: to use the word ecosystem, but the these elements connected 552 00:31:50,640 --> 00:31:53,959 Speaker 1: to Earth are still things that we are learning about today. 553 00:31:54,480 --> 00:31:56,440 Speaker 1: So we don't have all the information on it because 554 00:31:56,680 --> 00:32:00,040 Speaker 1: scientists are still really building on the knowledge that we 555 00:32:00,080 --> 00:32:03,200 Speaker 1: already have. You gotta keep in mind that until until 556 00:32:03,600 --> 00:32:06,200 Speaker 1: a little over a hundred years ago, we didn't even 557 00:32:06,240 --> 00:32:08,800 Speaker 1: know these things existed, at least not in the way 558 00:32:08,800 --> 00:32:11,800 Speaker 1: we do now, and not in the level of detail, right. 559 00:32:11,880 --> 00:32:15,360 Speaker 1: I mean, we knew that compass has worked, but there 560 00:32:15,440 --> 00:32:17,920 Speaker 1: was you know, our our level of knowledge about the 561 00:32:17,920 --> 00:32:21,680 Speaker 1: magnetosphere was limited. We didn't know anything of the geomagnetic 562 00:32:21,800 --> 00:32:25,000 Speaker 1: storms and uh and how the Sun can affect our 563 00:32:25,040 --> 00:32:28,080 Speaker 1: own magnetosphere. So this is information that we're still building 564 00:32:28,080 --> 00:32:30,640 Speaker 1: on today. But yeah, so and in the evening, the 565 00:32:30,960 --> 00:32:35,000 Speaker 1: conductivity improves. That's what allows the the A M waves 566 00:32:35,040 --> 00:32:38,280 Speaker 1: to to bounce off the ionosphere and back on the Earth. 567 00:32:38,760 --> 00:32:42,200 Speaker 1: FM waves. By the way, the uh, the wavelength is 568 00:32:42,240 --> 00:32:44,600 Speaker 1: too small and the frequencies too high, they actually just 569 00:32:44,640 --> 00:32:47,680 Speaker 1: passed right through the atmosphere. They don't they don't bounce 570 00:32:47,680 --> 00:32:50,760 Speaker 1: back down. So that's why FM stations you aren't. You 571 00:32:50,800 --> 00:32:52,600 Speaker 1: aren't going to get that same effect. It's not like 572 00:32:52,640 --> 00:32:55,400 Speaker 1: at night you're gonna start picking up the FM station 573 00:32:56,000 --> 00:32:58,560 Speaker 1: from the city, you know, a hundred miles away, when 574 00:32:58,600 --> 00:33:00,960 Speaker 1: normally you'd have to be on top of the city 575 00:33:01,040 --> 00:33:03,440 Speaker 1: to pick it up. It's just not gonna happen. Yeah, 576 00:33:03,680 --> 00:33:05,320 Speaker 1: and um, I mean there are there are a lot 577 00:33:05,360 --> 00:33:08,440 Speaker 1: of differences too. I mean, you don't notice that the 578 00:33:08,560 --> 00:33:14,120 Speaker 1: changes um at nighttime with FM, so in such a 579 00:33:14,120 --> 00:33:16,120 Speaker 1: pronounced fashion. Le's not in my experience as you do 580 00:33:16,200 --> 00:33:19,080 Speaker 1: with AM. UM. There are a lot of things that 581 00:33:19,120 --> 00:33:21,840 Speaker 1: you can detect. AM is a lot more finicky. Also, 582 00:33:22,040 --> 00:33:25,720 Speaker 1: some radio gets dirtier at night. I noticed that, not 583 00:33:25,840 --> 00:33:28,600 Speaker 1: the programming. Oh sorry, I was thinking about all the 584 00:33:28,680 --> 00:33:31,440 Speaker 1: songs that I hear once, you know, once the primetime. Okay, 585 00:33:31,560 --> 00:33:35,040 Speaker 1: I'm clearly I'm off off base here, so but uh 586 00:33:35,080 --> 00:33:37,240 Speaker 1: but yeah. And also that the direction. You know, there 587 00:33:37,280 --> 00:33:40,320 Speaker 1: were in the United States clear channel stations that were 588 00:33:40,360 --> 00:33:43,520 Speaker 1: given more range, you know, to to go ahead and 589 00:33:43,600 --> 00:33:48,200 Speaker 1: keep broadcasting full strength at night, UM, whereas other stations 590 00:33:48,200 --> 00:33:52,240 Speaker 1: were asked to back off at certain times of the day. UM. 591 00:33:52,280 --> 00:33:54,000 Speaker 1: And something else I wanted to I know, we're getting 592 00:33:54,000 --> 00:33:56,440 Speaker 1: towards the end of our time, but something else I 593 00:33:56,480 --> 00:33:59,160 Speaker 1: wanted to, uh to point out was if you've ever 594 00:33:59,280 --> 00:34:02,280 Speaker 1: been in a car are like mine, for example, where 595 00:34:02,320 --> 00:34:04,920 Speaker 1: you want to tune into an AM station and it's 596 00:34:04,960 --> 00:34:07,680 Speaker 1: just a pain in the neck because you get a 597 00:34:07,680 --> 00:34:10,279 Speaker 1: lot of static. Well with that FIM stations you don't 598 00:34:10,400 --> 00:34:15,320 Speaker 1: have the interference from all kinds of things like for example, 599 00:34:15,800 --> 00:34:19,919 Speaker 1: UM power lines or lightning or lightning or in some 600 00:34:20,000 --> 00:34:24,239 Speaker 1: cases UM I would assume it's the rebar and overpasses 601 00:34:24,280 --> 00:34:27,720 Speaker 1: and stuff like that. Um, you know that are interfering 602 00:34:27,719 --> 00:34:29,600 Speaker 1: with your signal. You'll go under something and you get it, 603 00:34:31,160 --> 00:34:33,040 Speaker 1: you know sort of thing. Maybe they're electrical wires in 604 00:34:33,080 --> 00:34:37,440 Speaker 1: there that I didn't notice. But also spark plugs. My 605 00:34:37,520 --> 00:34:40,600 Speaker 1: spark plugs interfere with the AM signal. You know, if 606 00:34:40,640 --> 00:34:42,760 Speaker 1: you are in an area that has a lot of antenna, 607 00:34:42,920 --> 00:34:45,480 Speaker 1: you can actually get interference because the antenna, as the 608 00:34:45,560 --> 00:34:47,960 Speaker 1: electrical charge moves up and down the antenna while you're 609 00:34:48,000 --> 00:34:51,440 Speaker 1: receiving it, it's being it's being created by the electromagnetic field. 610 00:34:51,760 --> 00:34:55,040 Speaker 1: That means your antenna is also creating an electromagnetic field. 611 00:34:55,080 --> 00:34:58,440 Speaker 1: It's much it's a much lower powered electromagnetic field, but 612 00:34:58,520 --> 00:35:02,320 Speaker 1: there are enough antenna packed into a small enough space 613 00:35:02,600 --> 00:35:08,000 Speaker 1: that can create interference, uh for him, especially for AM transmissions. Yeah, 614 00:35:08,080 --> 00:35:10,160 Speaker 1: but but I have a station that I try to 615 00:35:10,160 --> 00:35:11,800 Speaker 1: listen to on a m every once in a while 616 00:35:11,840 --> 00:35:15,600 Speaker 1: and um, you know, catch the game from the local 617 00:35:15,640 --> 00:35:21,560 Speaker 1: sports team. And uh apparently yeah, um, apparently the the 618 00:35:21,600 --> 00:35:24,480 Speaker 1: spark plug in your car will when it fires, it 619 00:35:24,560 --> 00:35:28,319 Speaker 1: creates interference in a very high frequency range, which is 620 00:35:28,360 --> 00:35:33,520 Speaker 1: the thirty mega hurts range, and that's just at the 621 00:35:33,600 --> 00:35:39,279 Speaker 1: right frequency to seriously irritate the the AM signal and 622 00:35:39,360 --> 00:35:45,560 Speaker 1: cause problems. You know what's that that one right there? 623 00:35:45,760 --> 00:35:48,719 Speaker 1: Sorry everybody, I just blew up our listeners ears that 624 00:35:48,800 --> 00:35:51,560 Speaker 1: in the sixty cycle. Hum, Hey, Casey, can you lower 625 00:35:51,600 --> 00:35:53,279 Speaker 1: that a little bit so that they don't they don't 626 00:35:53,280 --> 00:35:56,080 Speaker 1: all write to me and complain thanks, You can just 627 00:35:56,239 --> 00:35:58,920 Speaker 1: uh if if the answer is yes, lower it a 628 00:35:58,920 --> 00:36:04,080 Speaker 1: little the answer is no, I'll direct all emails to Casey. Alright. 629 00:36:04,120 --> 00:36:07,279 Speaker 1: So there's a lot more to radio. There's tons more 630 00:36:07,400 --> 00:36:10,040 Speaker 1: and then and it gets into quite a bit of detail. Yeah, 631 00:36:10,080 --> 00:36:12,520 Speaker 1: but like I said, we we kind of gave the 632 00:36:12,520 --> 00:36:14,879 Speaker 1: the bird's eye view of the science on this. So 633 00:36:15,000 --> 00:36:17,320 Speaker 1: but it's really fascinating stuff. We do have an article 634 00:36:17,400 --> 00:36:19,879 Speaker 1: on the site about how radio works. Um, there are 635 00:36:19,880 --> 00:36:24,440 Speaker 1: plenty of other sites out there that that discuss radio 636 00:36:24,760 --> 00:36:28,200 Speaker 1: and the technology behind it, the science behind it. Uh. 637 00:36:28,239 --> 00:36:33,360 Speaker 1: There's a Center for Cosmological Physics has a a great 638 00:36:33,840 --> 00:36:37,319 Speaker 1: summary on it. It was it was for a summer program, uh, 639 00:36:37,360 --> 00:36:41,640 Speaker 1: the Yerkey's Summer Institute two thousand two program. But they 640 00:36:41,640 --> 00:36:44,640 Speaker 1: have a a PDF document that's available online. So if 641 00:36:44,640 --> 00:36:49,320 Speaker 1: you do a search for uh cosmological physics radio wave basics, 642 00:36:49,400 --> 00:36:52,279 Speaker 1: it'll tell you not just the radio wave basics the 643 00:36:52,560 --> 00:36:56,719 Speaker 1: science behind it, but also the actual basics behind radios themselves. 644 00:36:57,080 --> 00:37:00,040 Speaker 1: So that's a that's a helpful guide, and it was 645 00:37:00,239 --> 00:37:03,000 Speaker 1: it was made for science classes who were going out 646 00:37:03,040 --> 00:37:06,120 Speaker 1: and actually doing creating their own radios and kind of 647 00:37:06,160 --> 00:37:09,520 Speaker 1: explaining the science behind it. So I recommend a read 648 00:37:09,560 --> 00:37:10,959 Speaker 1: of that if if you want to get a little 649 00:37:10,960 --> 00:37:12,880 Speaker 1: more information. And of course, like I said, there's tons 650 00:37:12,960 --> 00:37:16,000 Speaker 1: of of of references out there on the web that 651 00:37:16,080 --> 00:37:18,839 Speaker 1: you can use. So we're gonna wrap this discussion up. 652 00:37:18,880 --> 00:37:21,440 Speaker 1: If you guys have any suggestions for topics that we 653 00:37:21,480 --> 00:37:25,400 Speaker 1: should tackle, let us know on Twitter and Facebook are handled. 654 00:37:25,400 --> 00:37:28,759 Speaker 1: There is tech Stuff hs W, or you can send 655 00:37:28,800 --> 00:37:32,359 Speaker 1: us an email and that address is text stuff at 656 00:37:32,600 --> 00:37:34,719 Speaker 1: how stuff works dot com. Chris and I will talk 657 00:37:34,719 --> 00:37:40,359 Speaker 1: to you again really soon. Be sure to check out 658 00:37:40,360 --> 00:37:43,560 Speaker 1: our new video podcast, Stuff from the Future. Join how 659 00:37:43,600 --> 00:37:46,120 Speaker 1: Stuff Work staff as we explore the most promising and 660 00:37:46,200 --> 00:37:50,839 Speaker 1: perplexing possibilities of tomorrow. The How Stuff Works iPhone app 661 00:37:50,880 --> 00:37:58,600 Speaker 1: has arrived. Download it today on iTunes. Brought to you 662 00:37:58,640 --> 00:38:01,600 Speaker 1: by the reinvented two thousand and twelve camera. It's ready, 663 00:38:01,800 --> 00:38:02,160 Speaker 1: Are you