WEBVTT - How Sonar Works 0:00:00.320 --> 0:00:02.880 Brought to you by the reinvented two thousand twelve camera. 0:00:03.240 --> 0:00:08.959 It's ready. Are you get in touch with technology? With 0:00:09.039 --> 0:00:17.800 tech Style from how stuff works dot com. Hello again, everyone, 0:00:17.840 --> 0:00:20.239 Welcome to tech stuff. My name is Chris Poulette and 0:00:20.239 --> 0:00:22.599 I am an editor at how stuff works dot com. 0:00:22.600 --> 0:00:25.640 Sitting across from me as usual as senior writer Jonathan Strickland. 0:00:25.720 --> 0:00:28.520 Have I got this straight? Jonesy? A forty million dollar 0:00:28.600 --> 0:00:31.480 computer tells you you're chasing an earthquake, but you don't believe, 0:00:31.720 --> 0:00:36.000 and you come up with this on your own. That 0:00:36.280 --> 0:00:39.639 had a direct burying to our topic today, and that 0:00:39.680 --> 0:00:45.960 topic would be sonar sound navigation and ranging. Well, that 0:00:46.240 --> 0:00:49.360 pretty much covers it, so, well, that's exactly what it is. 0:00:49.400 --> 0:00:52.239 It's one of those nice, nice words that sort of 0:00:52.240 --> 0:00:54.760 covers it. So yeah, no, it's it's it's very it's 0:00:54.840 --> 0:00:57.640 very much exactly what sounds like. It's using sound to 0:00:58.080 --> 0:01:02.720 navigate and to to find the distance from other objects. 0:01:03.040 --> 0:01:04.440 As it turns out, there a lot of ways to 0:01:04.560 --> 0:01:07.920 use sonar um and we'll get into that, uh in 0:01:07.959 --> 0:01:09.639 a minute, but there are also a lot of different 0:01:09.680 --> 0:01:13.880 types of applications, uh, different ways to use it as 0:01:14.000 --> 0:01:18.039 in like um, different kinds of equipment that that can 0:01:18.080 --> 0:01:21.480 be used to find depth and identify things in the 0:01:21.520 --> 0:01:24.440 water and even map the sea floor if you want 0:01:24.440 --> 0:01:27.120 to do that. Yep. And uh, actually, the you know, 0:01:27.160 --> 0:01:29.840 we're not the only ones to to use sonar, not 0:01:29.840 --> 0:01:32.560 by a long shot. True. Dolphins and whales use it 0:01:32.959 --> 0:01:37.200 to man to other animals. Yes, that would be an echolocation, Yes, yeah, exactly. 0:01:37.200 --> 0:01:39.240 That's what the sonar is based off of. It's the 0:01:39.280 --> 0:01:42.200 idea of the way sound travels. And so if you 0:01:42.400 --> 0:01:45.040 sound travels and waves, it's a it's actually a physical 0:01:45.680 --> 0:01:48.120 uh thing. It's you know, we don't see it, but 0:01:48.200 --> 0:01:51.880 it is a physical effect. When you make a sound, 0:01:52.560 --> 0:01:57.640 you are causing stuff to bang against each other. Sounds 0:01:57.720 --> 0:02:02.040 so so scientific, it's true. So when sound travels, it's 0:02:02.080 --> 0:02:05.760 really lots of air molecules bouncing against each other until 0:02:06.280 --> 0:02:09.320 well really just until it disperses, so it keeps on going. 0:02:09.360 --> 0:02:12.680 I mean. And we detect sound, of course through hearing, 0:02:13.240 --> 0:02:15.480 but there are other ways to detect it. There there 0:02:15.520 --> 0:02:18.520 are sounds that are outside of our range of hearing 0:02:18.919 --> 0:02:21.440 that we can sense, Like there's some that are so 0:02:21.520 --> 0:02:23.080 low that you know, you can't hear it. But you 0:02:23.080 --> 0:02:29.840 can feel it. That's thrumbing feeling. And when sound hits 0:02:29.880 --> 0:02:34.120 a really solid object, uh, it bounces it, it refracts 0:02:34.120 --> 0:02:37.240 off as some of it reflects back and uh and 0:02:37.440 --> 0:02:41.040 that's where we get the whole echo effect. So when 0:02:41.040 --> 0:02:43.560 you're in the right kind of environment and you speak 0:02:43.600 --> 0:02:46.440 and you hear that echo, that's those sound waves bouncing 0:02:46.480 --> 0:02:48.919 back and coming back to you. Well, you can use 0:02:48.960 --> 0:02:53.840 this to find your way around an environment. Well, um, 0:02:53.880 --> 0:02:56.680 so where does sonar come from? Then we have to 0:02:56.720 --> 0:03:00.880 figure out exactly. Uh really when that all started taking place, 0:03:00.960 --> 0:03:04.160 And I think it was really probably, I mean, people 0:03:04.200 --> 0:03:06.880 have been doing it for a long time. Yeah, you could, 0:03:06.880 --> 0:03:09.800 you could identify things and under the surface of the water. 0:03:09.960 --> 0:03:12.600 But why are you creating him? Because my favorite man 0:03:12.639 --> 0:03:15.800 of all time did some experiments with listening to sound 0:03:15.800 --> 0:03:21.880 through water. Okay, Leonardo da Vinci. We just finished talking 0:03:21.880 --> 0:03:24.400 about him a second ago, which I'll try and make 0:03:24.440 --> 0:03:27.120 sure that the podcast published in the right order. But no, 0:03:27.320 --> 0:03:32.600 Leonardo da Vinci back in experimented with with listening to 0:03:33.000 --> 0:03:35.800 sounds through water. He would in sort a tube into 0:03:36.040 --> 0:03:38.600 into water and put his ear to the two like 0:03:38.640 --> 0:03:41.960 a straw. Yeah, pretty much like a straw larger than 0:03:41.960 --> 0:03:44.160 a straw. Mr da Vinci, why are you listening to 0:03:44.200 --> 0:03:49.160 your drink if you had a drinking problem. So, but yeah, 0:03:49.160 --> 0:03:51.200 he would use this to to kind of listen to 0:03:51.440 --> 0:03:54.960 UH to the two noises, with the idea that if 0:03:55.000 --> 0:03:57.560 you could create the right system, you would be able 0:03:57.560 --> 0:04:01.200 to detect when things were approaching through the water. Now, 0:04:01.360 --> 0:04:04.280 during da Vinci's time, this wasn't really that big a problem. 0:04:04.320 --> 0:04:06.880 Things usually approached on the water, and if they were 0:04:06.960 --> 0:04:09.240 in the water, they weren't really something you needed to 0:04:09.280 --> 0:04:14.320 worry about. The UH frogmen of his day not not 0:04:14.520 --> 0:04:17.919 so effective. But getting all the way up to the 0:04:18.040 --> 0:04:22.200 eighteen or the nineteenth century, rather the eighteen hundreds, UH, 0:04:22.600 --> 0:04:26.479 you started to some some lighthouses would have underwater bells 0:04:27.320 --> 0:04:32.239 that would be UH placed around the area to warn 0:04:32.320 --> 0:04:35.640 ships of of hazards. So ships could actually listen as 0:04:35.680 --> 0:04:37.880 they approached land and they heard bells, they knew they 0:04:37.920 --> 0:04:39.960 were coming up on shoals, and they could they could 0:04:40.360 --> 0:04:45.479 alter their course before running aground. And then UH in 0:04:45.839 --> 0:04:50.480 around nineteen six, UH was an early passive sonar system. 0:04:50.480 --> 0:04:53.200 Will explain what that means UH in a minute. But 0:04:53.440 --> 0:04:56.840 they were using strings of microphones towed by ships, which 0:04:56.880 --> 0:04:59.840 is again something that dates up to the present and 0:05:00.040 --> 0:05:04.400 different form, but by en um and of course thinking 0:05:04.400 --> 0:05:07.359 back on it, that's you know, world War One, the 0:05:07.400 --> 0:05:12.320 British and American scientists had developed an active sonar system. Um. 0:05:12.360 --> 0:05:13.839 You know that that was a big concern at the 0:05:13.839 --> 0:05:17.960 time because of course the German uh U boats were 0:05:18.000 --> 0:05:21.719 patrolling and it was some scary stuff. Yeah, actually it was. 0:05:21.880 --> 0:05:24.640 It was a very intimidating weapon, definitely. I mean there 0:05:24.640 --> 0:05:26.800 had been some sorry I keep kinding, so there had 0:05:26.800 --> 0:05:29.800 been submarines before that, but sure, but the German U 0:05:29.800 --> 0:05:32.320 boats in World War One were a very effective way 0:05:32.320 --> 0:05:37.760 of taking control of the Atlantic Ocean and the shipping 0:05:37.839 --> 0:05:40.640 back and forth between the continents. So sonar was something 0:05:40.680 --> 0:05:43.880 that they were very rapidly trying to work out exactly. 0:05:43.920 --> 0:05:47.120 And it's funny because well not funny, but it's it's 0:05:47.160 --> 0:05:49.960 interesting to me that really the the event that kind 0:05:50.000 --> 0:05:52.960 of started all this off wasn't World War One, because 0:05:52.960 --> 0:05:56.279 by then they they were pretty far into it. But 0:05:56.320 --> 0:05:59.239 they did have an interest, yes, yes, to talk about 0:05:59.360 --> 0:06:01.719 to talk about how this really started off. You really 0:06:01.720 --> 0:06:03.640 got to look back to a certain event that happened 0:06:03.680 --> 0:06:06.840 in nineteen twelve. What was that event, Well, there was 0:06:06.880 --> 0:06:11.600 a little boat that happened to sink. Yeah, that little boat. Yeah, yeah, 0:06:11.960 --> 0:06:15.640 don't let go, um my heart will go on. Yeah, 0:06:15.640 --> 0:06:20.839 the Titanic disaster. Titanic disaster. Following that, that's when we 0:06:20.839 --> 0:06:25.320 saw the first patent for underwater echo ranging demands. So 0:06:25.360 --> 0:06:28.400 that was that was where the first patent was filed 0:06:28.839 --> 0:06:31.120 UM and it was filed at the British Patent Office 0:06:31.200 --> 0:06:34.960 by Lewis Richardson, who was a meteorologist UM and he 0:06:35.440 --> 0:06:38.239 had come up with this idea of creating a way 0:06:38.600 --> 0:06:42.360 to locate objects underwater using sound. You would you would 0:06:42.400 --> 0:06:46.279 fire sound out, you would measure the sound that comes back, 0:06:46.480 --> 0:06:50.280 and through that you would figure out what was there, 0:06:50.440 --> 0:06:53.240 how far away it was, whether it was moving or not. 0:06:53.600 --> 0:06:55.760 I mean, these were all the concepts now back in 0:06:55.839 --> 0:06:59.240 nineteen twelve, they didn't really have a way of achieving this. 0:06:59.320 --> 0:07:02.400 He panted to the idea, but it wasn't until like 0:07:02.520 --> 0:07:05.360 Chris said, around nineteen eighteen that we started to really 0:07:05.400 --> 0:07:09.600 see accelerated development because then you had a wartime use 0:07:09.680 --> 0:07:11.920 for it, and it was really important to find a 0:07:11.920 --> 0:07:15.040 way to to detect those submarines those U boats. Yeah, 0:07:15.120 --> 0:07:19.120 icebergs were were obviously concerned, especially in the North Sea 0:07:19.240 --> 0:07:23.880 and areous like that. UM because you know, as as 0:07:24.160 --> 0:07:26.360 is in the case of many cliches, there is an 0:07:26.400 --> 0:07:28.200 element of truth in it. The tip of the iceberg 0:07:28.320 --> 0:07:31.640 really is, you know, the smallest part, and so much 0:07:31.640 --> 0:07:33.960 of it is underwater, and you can't tell without some 0:07:34.040 --> 0:07:36.960 kind of device, and I think that's uh. The earliest, 0:07:37.040 --> 0:07:43.120 earliest sonar or the earliest echolocation devices were not very precise. 0:07:43.200 --> 0:07:45.200 In fact, they were so imprecise that they could tell 0:07:45.200 --> 0:07:46.880 you that there was an iceberg, but could not tell 0:07:46.920 --> 0:07:50.520 you where the iceberg was, So you you might know 0:07:50.600 --> 0:07:53.280 that there's an iceberg somewhere within a two mile radius 0:07:53.280 --> 0:07:56.040 of your ship, which is not entirely helpful, although I 0:07:56.040 --> 0:07:58.400 guess it tells you to keep an eye out so 0:07:58.440 --> 0:08:00.920 that you you don't see it before you hit it. 0:08:01.000 --> 0:08:03.240 You know, you you know, to keep an eye out 0:08:03.280 --> 0:08:08.400 for for icebergs. UM. By the by the time World 0:08:08.400 --> 0:08:13.160 War two came around, that's when the because early sonar 0:08:13.360 --> 0:08:16.520 was really led by the British, they made the biggest 0:08:16.600 --> 0:08:19.640 advances in sonar technology. They didn't call it sonar, they 0:08:19.640 --> 0:08:23.840 called it as DICK A S D I c UH 0:08:23.880 --> 0:08:26.600 and UH. The A S D was actually a code. 0:08:27.000 --> 0:08:30.200 It was it was so that the people outside of 0:08:30.240 --> 0:08:34.040 the top secret development wouldn't know what the scientists were 0:08:34.080 --> 0:08:36.640 working on. So people say, well, what does as DICK 0:08:36.720 --> 0:08:39.319 stand for? Well, it kind of stands for keep your 0:08:39.320 --> 0:08:42.440 nose out of it MR. So it wasn't really until 0:08:42.440 --> 0:08:45.920 World War Two that the United States actually outpaced the 0:08:45.960 --> 0:08:49.680 British in this technology. And uh, and that's when you know, 0:08:50.360 --> 0:08:53.559 the term sonar started to pop up, and that eventually 0:08:53.600 --> 0:08:57.839 became the de facto term for the technology. Right right now, 0:08:57.880 --> 0:09:00.680 we should probably uh at this point go into the 0:09:00.800 --> 0:09:04.840 two basic, very very very basic types of sonar, so 0:09:04.880 --> 0:09:08.120 active and passive. Active and passive, And I think passive 0:09:08.160 --> 0:09:11.120 is the easiest one to explain. Yes, basically, you're receiving 0:09:11.760 --> 0:09:15.240 the sounds of the water around you. You're listening, yes, 0:09:15.480 --> 0:09:19.840 so simply listening. So passive passive sonar is where you 0:09:19.920 --> 0:09:23.880 have some sort of sound collection device, usually a hydrophone, 0:09:23.920 --> 0:09:25.959 which is just a microphone that you can use in 0:09:26.000 --> 0:09:29.719 the water. You would have hydrophones placed and you may 0:09:29.760 --> 0:09:33.880 have a couple of different passive sonar stations so that 0:09:33.920 --> 0:09:38.280 you have hydrophones directed in specific areas, so that way 0:09:38.320 --> 0:09:40.520 you can tell where the sound is coming from, not 0:09:40.640 --> 0:09:45.000 just that there is sound, and you listen carefully for 0:09:45.559 --> 0:09:49.520 any kind of indication of other activity in the water. 0:09:49.720 --> 0:09:53.880 And it's interesting because as I was doing my research, 0:09:53.960 --> 0:09:58.960 I discovered that that if you were a trained sonar operator, yes, 0:09:59.400 --> 0:10:02.400 and you heard a submarine. Let's say you're in a 0:10:02.400 --> 0:10:06.000 submarine and you heard another submarine, right, you could actually 0:10:06.040 --> 0:10:10.160 identify where that submarine what was from, based upon the 0:10:10.160 --> 0:10:13.920 sound you heard. Yes, that is correct, it is. That 0:10:14.000 --> 0:10:17.000 is to me as phenomenal. Well, every uh, as I 0:10:17.080 --> 0:10:21.560 understand it, every ship of any kind, submarine or ship 0:10:21.679 --> 0:10:24.120 or you know, I guess boat, depending on what's on 0:10:24.160 --> 0:10:28.280 the boat has its own audio signature. Could be the engines, 0:10:29.000 --> 0:10:32.160 um or basically anything that's going on, if they are 0:10:32.160 --> 0:10:35.440 electronics on board that make a noise, if you know, fans, 0:10:35.520 --> 0:10:40.000 things like that. Some those things can help identify um 0:10:40.480 --> 0:10:44.600 another vessel in the water to the listening vessel. Yeah. 0:10:44.640 --> 0:10:47.280 For example, in the United States, most of the submarines 0:10:47.320 --> 0:10:51.439 were operating on a sixty hurts alternating current power system, 0:10:51.440 --> 0:10:55.640 but in Europe they were operating on fifty hurts power systems, 0:10:55.840 --> 0:10:58.520 So just the the frequency of the sound would be 0:10:58.640 --> 0:11:00.760 enough to indicate to you whether you were listening to 0:11:00.840 --> 0:11:05.240 a US ship or a European ship. And uh, you 0:11:05.240 --> 0:11:07.840 couldn't necessarily if everything was running the way it should, 0:11:08.040 --> 0:11:10.079 you might not hear anything at all, or you might 0:11:10.120 --> 0:11:13.480 hear very little. Um. It was if you didn't sound 0:11:13.559 --> 0:11:16.760 proof all of your equipment, like if if the various 0:11:16.800 --> 0:11:22.040 elements weren't uh weren't insulated properly, then stuff would rattle 0:11:22.080 --> 0:11:24.280 and you could you could actually hear the rattling. In fact, 0:11:24.800 --> 0:11:28.040 one source I read said that, uh, you know, the 0:11:28.120 --> 0:11:30.480 location of a submarine might be given away by someone 0:11:30.520 --> 0:11:35.760 accidentally dropping a wrench onto the floor the deck. I guess, um, 0:11:35.840 --> 0:11:37.840 I assume they're decks and submarines. I've never been a 0:11:37.840 --> 0:11:41.520 board one. Yes, so yes, if you were to drop 0:11:41.559 --> 0:11:43.959 a wrench to the deck, it could create a sound 0:11:43.960 --> 0:11:46.360 that someone another sonar operator might be able to pick 0:11:46.400 --> 0:11:50.679 up and say, all right there there support. Um, so 0:11:50.880 --> 0:11:54.360 it's it's a pretty interesting thing. And passive sonar, by 0:11:54.360 --> 0:11:58.760 the way, was more important for submarines because if they 0:11:58.880 --> 0:12:02.520 use the active method, they would actively be giving away 0:12:02.520 --> 0:12:07.559 their location. Yes, that's because active active sonar systems are 0:12:07.720 --> 0:12:13.000 giving off a pulse of sound yea often called a ping. Yes, 0:12:13.200 --> 0:12:16.199 So you ping the sound out and uh, and then 0:12:16.240 --> 0:12:20.720 they wait for the sound waves to come back. And 0:12:20.880 --> 0:12:23.800 based upon how long it takes uh and how much 0:12:23.880 --> 0:12:26.000 how strong the signal is, that's how you kind of 0:12:26.040 --> 0:12:29.000 determine what it is your your hearing or you know, 0:12:29.040 --> 0:12:32.840 how far away the the object is and you know 0:12:32.920 --> 0:12:35.920 what it might be. You know, how many how many 0:12:35.960 --> 0:12:38.640 submarine movies have you seen where they do that tense 0:12:38.679 --> 0:12:41.679 moment where nobody's moving a muscle they got wait wait, 0:12:43.040 --> 0:12:44.840 you know, and there's just like you know, you watch 0:12:44.880 --> 0:12:48.240 the beads of sweat rolled down the submariners faces. Yes, 0:12:48.320 --> 0:12:50.679 there's the there's the one that I quoted at the 0:12:50.720 --> 0:12:54.160 beginning of this podcast. Um, yeah, no, no that, but 0:12:54.240 --> 0:12:56.360 there are many you know that that. And that's the 0:12:56.400 --> 0:12:58.319 thing is you have to be very very quiet and 0:12:58.400 --> 0:13:01.360 that kind of a situation because any little thing can 0:13:01.440 --> 0:13:03.760 be up by the ping. And here's what's really interesting 0:13:04.320 --> 0:13:07.880 to me is that the ping is well really anything 0:13:07.880 --> 0:13:09.880 could be picked up by passive sonar. I know, I 0:13:09.880 --> 0:13:11.920 just want to make it okay, I got you. I 0:13:11.960 --> 0:13:20.000 was about so active, but with you stopped at one 0:13:20.040 --> 0:13:25.000 of three the active sonar. The basis of that really 0:13:26.400 --> 0:13:28.480 rests in the fact that we know how fast sound 0:13:28.480 --> 0:13:34.160 travels through water. But we we do, but it's really complicated. 0:13:34.200 --> 0:13:36.760 You would think, oh, it's got to be some constant right, 0:13:37.280 --> 0:13:41.600 not exactly actually constantly constant. Yeah, The speed of sound 0:13:41.640 --> 0:13:44.640 traveling through water depends on several things. Depends on the 0:13:44.679 --> 0:13:48.000 temperature of the water, the salinity of the water, and 0:13:48.080 --> 0:13:51.160 the depth of the water, and all of these things 0:13:51.240 --> 0:13:54.800 affect the density of the water. Which makes sense, right. 0:13:54.840 --> 0:13:58.160 If you've got more molecules packed together, sounds going to 0:13:58.200 --> 0:14:02.280 travel faster through that because the molecules hit each other 0:14:02.400 --> 0:14:05.360 more quickly, Like it doesn't take much for a molecule 0:14:05.400 --> 0:14:08.400 they'll run into another molecule. The sound travels much much 0:14:08.440 --> 0:14:12.000 further and much faster. Um if you've got them spread out, 0:14:12.320 --> 0:14:15.160 then they lose some of their energy as they are moving, 0:14:15.200 --> 0:14:18.839 and so it doesn't travels far and it doesn't travels quickly. 0:14:20.000 --> 0:14:22.040 So the rule of thumb is that it's four thousand, 0:14:22.120 --> 0:14:26.240 three eight feet per second. And then you have to 0:14:26.320 --> 0:14:29.360 add all these modifiers in right right now, there are 0:14:29.440 --> 0:14:32.760 some some things that you can do. Uh. There is 0:14:32.800 --> 0:14:35.520 a system that I read about, the a n B 0:14:35.680 --> 0:14:39.520 q H DASH one speed of sound measuring system, which is, 0:14:40.440 --> 0:14:44.000 you know, a modern sonar system. Um. But it evaluates 0:14:44.040 --> 0:14:46.360 the depth and temperature and salinity of the water to 0:14:47.120 --> 0:14:50.440 get an idea of how the speed of sound is 0:14:50.440 --> 0:14:54.040 going to travel through that particular water at the time. Obviously, 0:14:54.120 --> 0:14:56.520 that's probably a very expensive piece of equipment because it's 0:14:56.560 --> 0:14:59.560 doing those calculations for you. But that's what modern computing 0:14:59.600 --> 0:15:03.240 technolo gets you. Um. But yeah, it gives you uh, 0:15:03.360 --> 0:15:06.360 you know, sonar technicians can use that equipment to get 0:15:06.400 --> 0:15:09.800 an idea of what's going on with a lot better accuracy, 0:15:09.920 --> 0:15:13.360 and also helps them avoid being detected by other sonar 0:15:13.400 --> 0:15:16.680 equipment because they have an idea of you know, what's 0:15:16.760 --> 0:15:19.840 the current conditions are underwater where they are right. So 0:15:20.000 --> 0:15:22.120 if you're using active sonar, you might be using it 0:15:22.160 --> 0:15:25.920 for uh. Well if in wartime you would have ships 0:15:26.040 --> 0:15:29.400 and and even aircraft using active sonar to try and 0:15:29.400 --> 0:15:32.920 detect submarines and then drop depth charges down to to 0:15:33.160 --> 0:15:37.800 disrupt the submarines. Ah, yes, uh, so active sonar in 0:15:37.880 --> 0:15:41.360 wartime is often used by by vessels that can move 0:15:41.440 --> 0:15:44.200 fast enough so that it's not it's not a big 0:15:44.240 --> 0:15:47.080 deal about giving away your location like destroyers for example, 0:15:47.120 --> 0:15:50.040 exactly exactly, if you're a submarine, you don't tend to 0:15:50.160 --> 0:15:53.840 use active sonar as often. Um Yeah, especially when you're 0:15:53.840 --> 0:15:56.920 submerged in trying to avoid detection, because that's you can't 0:15:56.920 --> 0:16:00.200 move nearly as quickly as a the enemy destroyer you're 0:16:00.240 --> 0:16:04.080 coming after you. Right, So so if you're also you 0:16:04.080 --> 0:16:07.000 could be using active sonar, not just in wartime, but 0:16:07.080 --> 0:16:10.960 also if you're mapping the ocean floor, then you want 0:16:11.040 --> 0:16:13.240 you want to be as accurate as possible, which means 0:16:13.280 --> 0:16:16.040 you have to have you know, you have to factor 0:16:16.080 --> 0:16:17.960 in all those elements we were talking about before, the 0:16:17.960 --> 0:16:20.800 salinity and temperature and depth and all that. Um. If 0:16:20.800 --> 0:16:23.200 you if you're just using sonar as a fish finder, 0:16:23.360 --> 0:16:26.400 because there are plenty of products on the market that 0:16:26.560 --> 0:16:29.520 do that, you don't have to worry quite that level 0:16:29.520 --> 0:16:32.720 of accuracy because you're not you're usually not talking about 0:16:33.080 --> 0:16:35.880 the same kind of distances involved that we're talking about, 0:16:36.440 --> 0:16:39.280 and usually the you know, the depth is not as 0:16:39.320 --> 0:16:43.080 big a factor. So really in that case, uh, you know, 0:16:43.320 --> 0:16:46.520 you could use a constant speed for the sound through 0:16:46.560 --> 0:16:49.960 water and not be so inaccurate. You're looking for schools 0:16:49.960 --> 0:16:52.240 of fish. You're going to be moving around anyway, so 0:16:52.280 --> 0:16:55.520 it's not like it's um, it's not like the kind 0:16:55.560 --> 0:16:58.560 of precision work you need to do with these other elements, right. 0:16:58.560 --> 0:17:00.800 Actually that that's one of the things that I found 0:17:00.840 --> 0:17:05.600 fascinating during part of the the sent our Technicians training. 0:17:06.160 --> 0:17:10.840 They actually uh are known to record things that are 0:17:11.400 --> 0:17:16.760 just natural sounds, like the sounds of fish, um, tectonic plates. 0:17:18.440 --> 0:17:20.600 I'm not sure. I'm not sure what kinds of sounds 0:17:20.600 --> 0:17:25.200 does give off really low, low groaning ones. Yes, my back, 0:17:25.520 --> 0:17:29.480 but that's but that's the the trick is you once 0:17:29.520 --> 0:17:32.719 they understand what those things are, they can eliminate them. 0:17:32.760 --> 0:17:35.520 They go, oh, well, that's just a large school of fish, 0:17:35.560 --> 0:17:38.200 you know. Oh that's you know, an alien spaceship that's 0:17:38.240 --> 0:17:43.040 crashed underwater, that kind of stuff. Um, I make a joke, 0:17:43.240 --> 0:17:46.040 but no, that that that Uh. I was wondering about 0:17:46.040 --> 0:17:48.720 that when I was reading about civilian uses for so 0:17:48.840 --> 0:17:50.480 in our technology and I was thinking, Wow, how do 0:17:50.560 --> 0:17:53.120 they know, you know, what is a school of fish? 0:17:53.160 --> 0:17:56.240 And obviously if you're on a lake and it's it's 0:17:56.240 --> 0:17:58.640 probably going to be the stuff that's moving around underwater. 0:17:58.840 --> 0:18:01.439 It's not likely to be in any submarine. But you know, 0:18:01.960 --> 0:18:05.119 detecting a fish versus you know, a snake or some 0:18:05.280 --> 0:18:10.439 other type of nest monster. We've gotten very silly, very quickly. 0:18:10.720 --> 0:18:13.480 Well no, I mean people have been using that kind 0:18:13.480 --> 0:18:16.720 of equipment to try and determine whether or not there Yeah, 0:18:16.800 --> 0:18:19.880 so in our equipment. Yes, there are plenty of monster 0:18:19.960 --> 0:18:24.520 hunters who have tried to use like a fish finder, yeah, essentially. 0:18:25.080 --> 0:18:27.600 But that's the thing is that there there are schools 0:18:27.640 --> 0:18:30.160 of fish in Lockness and schools of eels as well. 0:18:31.240 --> 0:18:33.400 So you get a school of fish or a school 0:18:33.440 --> 0:18:34.920 of eels that's going to give you a reading. And 0:18:34.920 --> 0:18:37.000 then people say, hey, look there's a monster down there. 0:18:37.040 --> 0:18:40.200 Not necessarily, And I have to say, you know, I've 0:18:40.240 --> 0:18:43.280 mentioned before in the podcast that I'm a skeptic. Out 0:18:43.280 --> 0:18:46.080 of all the things to be skeptical about, the lucknest 0:18:46.119 --> 0:18:48.840 monster was the one I held onto the longest because 0:18:48.880 --> 0:18:51.720 I want to believe it's real. I don't believe it's real, 0:18:51.880 --> 0:18:57.840 but I want to so badly. Um, in a cottage 0:18:57.840 --> 0:19:00.840 on the shore, there's a shadow on the door. No 0:19:01.359 --> 0:19:05.880 different kinds of sonar like side scan sower. UM. This 0:19:06.040 --> 0:19:09.080 is a device used to find objects on the sea 0:19:09.119 --> 0:19:11.280 floor and figure out what they are. UH. They usually 0:19:11.280 --> 0:19:14.320 have a toe fish or a toebody, which is a 0:19:15.040 --> 0:19:18.520 UM basically a sophisticated device that goes in the water 0:19:18.560 --> 0:19:21.199 and is towed behind the ship, and UH a device 0:19:21.280 --> 0:19:24.439 that processes the signals on the top. UM. What happens 0:19:24.480 --> 0:19:28.879 is they used the the sound energy which is transmitted 0:19:28.880 --> 0:19:31.920 in a fan shaped pattern and UH goes about a 0:19:32.000 --> 0:19:37.000 hundred meters down or so. Basically they used the information 0:19:37.040 --> 0:19:40.240 that comes back to create a an image of what's 0:19:40.320 --> 0:19:42.400 on the sea floor. So if they get a really 0:19:42.400 --> 0:19:47.680 strong signal UM back, that appears as a light image 0:19:47.680 --> 0:19:52.760 on the screen, whereas weaker signal would show darker images. 0:19:52.760 --> 0:19:55.720 So UH sort of a black and white image. I 0:19:55.760 --> 0:19:58.399 don't know if it's actually black and white because I 0:19:58.440 --> 0:20:00.480 was reading copy and they didn't bet but i'd be 0:20:00.560 --> 0:20:02.960 bright green and dull, right right. But you can get 0:20:02.960 --> 0:20:06.560 an idea of what the bottom of the area you're 0:20:06.600 --> 0:20:08.040 looking at. I guess it could be a lake or 0:20:08.080 --> 0:20:11.200 the ocean. UM. They don't they don't offer the same 0:20:11.280 --> 0:20:15.280 kind of depth information as the military would use to say, oh, well, 0:20:15.359 --> 0:20:17.719 we you know, we're about to run aground. It's not 0:20:17.840 --> 0:20:21.639 the same kind of application of sonar. Also, we should 0:20:21.680 --> 0:20:24.760 add that at certain depths, once you get really really deep, 0:20:24.800 --> 0:20:28.320 the water gets so dense that it can refract sound waves. 0:20:28.480 --> 0:20:31.400 So you you start to lose the ability to really 0:20:31.440 --> 0:20:36.639 map the ocean floor with sound because the water itself 0:20:36.680 --> 0:20:41.040 is so dense that it's it's it's mucking things up. Also, 0:20:41.119 --> 0:20:42.800 I guess I should go ahead and mention as well. 0:20:42.880 --> 0:20:44.960 We've talked a lot about the sonar. The sonar really 0:20:44.960 --> 0:20:47.439 has three main elements to it. Oh, yes, there's a 0:20:47.480 --> 0:20:50.120 transmitter which transmits the sun right right right. I can't 0:20:50.119 --> 0:20:51.960 believe we didn't. We didn't really talk about it. But 0:20:52.000 --> 0:20:55.640 there's a transmitter that's that's what passes on the signal. Uh, 0:20:55.960 --> 0:20:58.600 it's an electric signal that goes to a transducer. Now, 0:20:58.640 --> 0:21:01.560 transducers what they do is they convert one kind of 0:21:01.680 --> 0:21:04.479 energy into another kind of energy. In the case of sonar, 0:21:04.800 --> 0:21:09.040 it's converting sound electricity rather into sound right. Active for 0:21:09.080 --> 0:21:12.120 this is for active sonar, clearly. And then you've got 0:21:12.119 --> 0:21:14.520 a receiver that receives the signals when they come back 0:21:14.760 --> 0:21:18.440 um and and then you usually have a display, so 0:21:18.560 --> 0:21:21.760 there's a transmitter, transducer and receiver. This is for again 0:21:21.840 --> 0:21:26.440 active sonar. With the passive sonar, you just need receivers 0:21:26.440 --> 0:21:30.199 really microphones, hydrophones, UM and and there are plenty of 0:21:30.320 --> 0:21:35.880 stationary UH sonar UH stations and I guess stationary stations, 0:21:36.480 --> 0:21:39.320 thank you, Jonathan, you're both repetitive and redundant. But at 0:21:39.320 --> 0:21:41.600 any rate, there are plenty of these in the ocean. 0:21:41.680 --> 0:21:45.440 The lots of different militaries have them station stationed at 0:21:45.440 --> 0:21:51.680 different spots along the coast to detect things like possible 0:21:51.760 --> 0:21:55.360 incoming submarines, that kind of thing. UH. And I wanted 0:21:55.359 --> 0:21:59.879 to mention very quickly about an interesting sound that was detected. 0:22:00.040 --> 0:22:03.359 Oh do you want to? Yes, I do, I definitely 0:22:03.359 --> 0:22:07.399 want to. There was a sound detective in It was 0:22:07.400 --> 0:22:12.239 actually detected several times over the summer of U in 0:22:12.280 --> 0:22:17.639 the Pacific Ocean by by a hydrophone array. And the 0:22:17.800 --> 0:22:23.119 sound was a very low frequency sound generated over a 0:22:23.200 --> 0:22:27.720 pretty extended UH time frame several I think it's several 0:22:27.800 --> 0:22:33.320 minutes long. And it's called the bloop. The bloop is 0:22:33.480 --> 0:22:36.560 UM this odd sound that that we're not really sure 0:22:36.600 --> 0:22:40.639 what made this noise. If it was organic, then it 0:22:40.640 --> 0:22:43.199 would have to be a creature larger than any that 0:22:43.240 --> 0:22:46.720 we've previously identified. So if it were a whale, it 0:22:46.760 --> 0:22:49.440 would have to be such an enormous whale that we've 0:22:49.480 --> 0:22:55.679 never seen it. Uh ever, yeah, so be be ginormous, 0:22:55.800 --> 0:22:59.520 right to use the technical term. It's more likely that 0:22:59.600 --> 0:23:04.720 the blue is a h was some sort of geological byproduct, right, 0:23:05.000 --> 0:23:07.639 But at any rate, this sound was located or the 0:23:08.080 --> 0:23:11.440 location of the sound is probably somewhere around fifty degrees 0:23:11.480 --> 0:23:17.000