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From: engineerguyvideo
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  • Ahh!! I still don't get it! I need to understand the difference between fiber optic and coaxial cables and I am completely lost. :( I need apples and oranges.

  • that's the best under-30-seconds explanation of PCM

  • Thanks :) Very helpful.

  • I love these videos so freaking much.

  • a Home theater fiber cable is made up of nylon and a commercial fiber cable is made up a glass, why they use nylon because is it is way cheaper than glass and your equipment doesn't know the difference.

  • Amazing presentation on fiber optic wave lengths. Basic for all the pions, advance for the mathematicians.

  • Engineer guy, did you die?

  • Just a few thing: TAT-8 was installed in 1988 (Wikipedia).

    And for me it starts from Europe to join USA :)

  • I'm a networking student and this helped my understanding of fiber optic cabling. Thank you

  • amazing what science brought to us..

  • when are you going to release new videos?? we want more!

  • @Hellraiserzzz Yes! Series #4 is in preparation ... we just shot the 7th video in the series Monday, there will be eight total. The others are in post-production. We are also finishing the companion volume for that series that goes into more detail. Details at my web site.

  • what is the power of the laser?

  • Sir you should become my engineering professor.

    My university's engineering professors are all boring and narrow-minded.

  • i cant help making more positive comments ...

    i used to take stuff apart as a kid constantly, anything broken (and sometimes not!) just to see how it works, these videos take me right back to that amazement and excitement!. So well presented and so well articulated. Fantastic, i want more!

    i'll be getting that book!

  • i love how these videos popularize science and engineering, i cant wait for a world where the superstars and rockstars are engineers and scientists!

    dont get me wrong, i love music and movies (absolutely hate politics), but i hate that the most famous people are something almost manufactured and mostly pretty brainless.

    i want my kids to grow up with superstars like the engineerguy :)

  • That bucket demonstration was pretty amazing. Showing the reflection of the light propagating all the way down, seemingly bending with the flow of water, is nothing short or modern day magic.

  • I accidentally pressed the dislike button, and for that I am so sorry.

  • that water demonstration was great.

  • how are they amplified? sigh... i guess I have to google that.

  • @bv90andy Good question. In the first cables they had to convert - every X miles (I think 25 to 50) - the signal to an electronic impulse )Think of a the photoelectric effect that turns light into a current or voltage difference) which can be amplified electronically. Today an amazing device called a EDFA (erbium doper fiber amplifier) boosts the light signal using stimulated emission. We're planning to have a short section on this device in our book that comes out in 4-6 weeks ...

  • @engineerguyvideo this EDFA, i assume it requires power ? so every X kilometers under the sea there are 'powered amplifiers' ? which means the cable would need to carry a power core, with its own losses aswell ...

    i really wish this video gave a brief statement on the method of amplification but its brilliant all the same :)

    love your videos!

  • @quosmo1 Indeed they do requires power ... but so did the electronic amplifiers. I'm pretty sure the EDFA requires less. Regardless the power is transmitted down the copper section of the cable ... In the video I mention that the copper protects from water. It does that and also is conductor for electricity to power everything along the cable.

  • @engineerguyvideo very nice, thankyou! :)

  • this is a racing radiator coolant advertisement

  • man real godd

  • dang it!! wished i applied for UIUC now. Great videos!! I watched them all.

  • Can you share the subtitles as .srt or .txt, I want to make an offline archive of your videos.

  • Excellent videos.

  • Hello Bill, Love your videos! Please do one on Radio Frequency in wireless communication. Wireless technology fascinates me - how we have come from wired technology to an increasing wireless world. Keep uploading videos. :)

  • this is education really

  • Just finished watching all of your vids. So entertaining and educational! Somewhere within the mess of college politicization, terrible teachers, and uninterested students I had forgotten why I was studying engineering. Thanks for the reminder!

  • Credits will be properly given if you allow me, of course.

  • Hi engineerguyvideo, I learnt a lot from your videos.

    I am in events management and currently I am running an educational/informational roadshow for my client, a Fiber Optic Internet service provider in my country. I would like to show this video during my roadshow to help educate the masses, with your permission of course.

    However, I do not have internet access at the roadshow as it is not available at that location. Is there a way that I can get your video in a soft copy?

    Thanks in advance!

  • Thanks a lot for an awesome video. You and your channel are VERY underrated. Check out the "supercontinuum laser" fiber-combined laser they're going to use in helicopters to fool heat-seeking missiles into seeking the beamspot instead of the heli. A fiber-combined laser could easily be used to make a powerful laser rifle with diode lasers / DPSS without having to use chemical lasers.

  • thats amazing. thats the best demonstration of the idea of total internal reflection in fibre optics.

  • can we hear the sound of the laser?

  • Per second or per minute?

    1600 meters per second is over 3500 mph!

  • This is what i do for living!

  • Bill, thanks a lot for this video! It was amazingly simple, yet so informative! It's bound to help me and my colleagues on a rather important personal study of the optic cable!

  • This is the essence of my work!

  • can you make a video about USB Flash drives ?

  • Кипкей настолько отдыхает по сравнению с engeeneerguy , что я отписался от его канала .

  • An excellent video, but I have one question: Does the cladding have a higher or lower index of refraction than the core? This has helped so much.

  • Mind-blowing. Thank you very much for helping me understand and appreciate it.

  • When did they sink the cable in the Atlantic. How long did it take and what year. that's what I also would like to know how they did it.

  • How do they stop the glass on the inside of a fiber optics cable from breaking when bent? absolutely love your channel :D Thank you for posting.

  • Great video, this is probably the only Youtube channel I subscribe to with the full intention of watching every new video it releases.

    The design you described was really interesting. Back in the Middle East we have a big issue of ships destroying these cables. I never quite understood how they manage to do that but it's a real pain because the phones and internet service really takes a huge plunge in quality (and for weeks at a time!)

  • I wish you were teaching my electronics class

  • as always, you managed to explain simply

  • Amazing job, Bill...your videos on electronics and this one on optic fiber stunned me really good. Keep up the good work, hope one day i can be as good as an engineer as you. o/

  • You deserve 10,000 more percent than what you have, you are waaaaayyyyy underrated

  • @tashtan1 10,000 percent more money? More hits? More likes? .... ;-) ... thx for kind words ... more videos in production ....

  • @engineerguyvideo i meant hits, but I wanna go for all now! btw I was considering university of Illinois but because of my financial crisis and my lack of any capabilities what so ever I decided to go to our community college, lol its easy to graduate from hah. good day to you, love your videos, cant get enough!

  • @engineerguyvideo I'm so glad you are working on more videos! I just discovered your amazing channel. Please keep up the good work!

  • @engineerguyvideo more money so u can send me some :D

  • @engineerguyvideo how can i help u make fiber optics better

  • @engineerguyvideo you are my hero

  • @engineerguyvideo Yay more videos! I can NOT WAIT!!!

  • Damn magnets, how do they work?

  • This video was great. I find this stuff fascinating. Thanks.

  • great!

  • @gavranarh So this one is a series #3 ... copier was series #1! That's what I mean (I saw your comment under photocopier!)

  • @engineerguyvideo I was a bit harsh back there, hope you don't take it personally. Keep up the good work, much appreciated.

  • @gavranarh Don't worry ... I tell people if you don't have thick skin don't work in new media! ... no offense taken, glad you found series #2 and #3 to your liking ...

  • This would have been a great video 2 years ago when I first learnt about fibre optic cables in high school. Thumbs up!

  • engineerguy; MIA. Most likely dead.

  • Tnx for a great video...

  • @PCEasyWay Your welcome ... more on the way ...

  • How do they keep the glass from breaking/cracking when the cable is bent?

  • Its been way too long since the last video update -- I hope everything is okay.

  • @Flashtone08 Everything is fine. This next series has a book that goes with it that has taken time. We shot one on the atomic clock last week, and today we'll shoot two more videos ... eight into total in the next series. It takes a while to make these!

  • Great video! This is better than a whole week in school! :P

  • Transcribe audio is surprisingly good on this video.

  • I've sent you Russian captions a while ago, could you tell me why didn't you put them up? If there was something off about them, I'd like to know that so I could improve my skills.

  • @randomusername6 I don't know why they weren't posted soon after they arrived. I have corrected this: They are posted now. Thank you for doing the translation and also for posting this comment ....

  • mr engineer guy you remind me of Dr. octopus with those goggles :0

  • awesome video! thanks!

  • At 3:30 You said 'signal', not code as mentioned in the subtitles. You may fix that.

  • How much creamer do we need? What is its use?

    plz reply asp

  • PLEASE make more videos. Your explanations are fantastic.

  • Why did you use propylene glycerol? Can we use water instead? Will the result be different?

  • @fliplee93 The glycerol has ten times the viscosity as water so that when flow out the hole in the bucket there is less turbulence. This means that beam goes for many more bounces than in water.

  • I need a sentry here!

  • Welcome to my westore ..:fieber optic.

  • Welcome to my westore ..

  • Just sub

  • I just sent Turkish translation.

  • @vkfkts Thank you it is now in the subtitle/captions menu for this video.

  • so cool, thanks for the video

  • Hey can you put a dispenser here?

  • Bill Hammack is a straight G! (genius)

  • You should definitely get Mark Hamill on your show.

  • ur one of the best "explainer".

  • How does the computer tell the difference between calls and who many 0s there are? My guess would be (for the first one) a series of specific flashes between each call. I know for a fact though that the calls are divided into pieces and then the correct piece of the signal is sent through the correct cable. So if you have a cable with 2 separate phones on one end, the signal switches very rapidly from one phone to the other. As for the 2nd question...timers?

  • damn, only 50km. so for each thousand km there will be 20 amplifiers.

  • Can you do a video on solid state storage?

  • wait... wtf was the creamer for????

  • I'm still a little fuzzy on how six cables can handle 40,000 simultaneous phone calls. If all you can send through the wire is "on" or "off," how does the receiving end tell the difference between one phone call and another?

  • @tangerine734 A simple way to think of it as this: 6 bits can go through encoding which call ID it's communicating. 6 bits (1's or 0's) can encode a number between 0 and around 60,000. Then the next 16 bits will be the value of the audio wave at that moment (digitally encoded). So looking at the pulses in the fiber, every 22 1's and 0's is data regarding an individual call. This is not technically correct, but this is basically the idea of it. It's called "Packets", and happens very rapidly.

  • @dag101101 so it basically tells the reciever" here is one millisecond of call #1, now here is one ms of call #2, ..." etc on and cycles through all the calls?

  • @tangerine734 Essentially, yup! Of course, it's much more complicated than that, but you have the basic idea! Remember, it's all digital, which means data doesn't just have to be pure encoded sound waves. Metadata is encoded with every packet of data sent--metadata being additional information.

  • where is the dislike bar?

  • The map is just plain wrong - France, Spain, Portugal, the UK, Ireland, etc. are also in Europe. Having that big green blotch is most misleading. What happened the other countries there? Interesting video apart from this :)

  • @wrt54gs Sorry ... search the comments below where I responded to this ... was not trying to make a political statement but wanted viewer to quickly get bearings .....

  • @wrt54gs Does this look like the engineerguyvideo or geographyguyvideo

  • @yangkx I'm not the only one to point out the error and it's bound to annoy a number of people living on that continent. However, the Engineer Guy gave a good explanation for the hiccup and that's good enough for me.

  • Why did you use propylene glycol? Wouldn't the same principle have applied to water as well?

  • Up next, heat sinks?

  • Light comes in, light goes out, you can't explain that!

  • Can you make a video about graphics cards?

  • So did they really sink a repeater every 50 km under the Atlantic? Did they run a power line alongside?

  • @AlRoderick Yes ... in this cable they did ... the power comes via the copper tube that I mentioned earlier when discussing the construction of the cable.

  • @AlRoderick And perhaps an amplifier for the power line too

  • magnets: how do they work?

  • Monster cable? Really? Surely the Engineer Guy knows that Monster Cables don't make your bits more shiny. Hopefully he didn't PAY for it. Cheap cables FTW! (otherwise AWESOME video!)

  • excellent video yet again. i could listen to you all day

  • 7 people didn't get it

  • How does the cable get amplified?

  • @xXBluefox4Xx Something along the lines of adding some other atoms into a segment of the cable. Then shine a light into the cable to excite those atoms. Then light pulses causes those excited atoms to release the energy as a photon following along the original pulse. This is similar to how laser light is produced in the first place.

  • Also, at 2:33 you say that the they wind the drum at speeds up to 1600 meters per second, but your subtitles read "per minute". Which one is correct?

  • @randomusername6 Per minute ... sorry for error.

  • Great video. Other processes affect propagation besides reflection and refraction include scattering from impurities or flaws in the material, scratches on the fiber surface. These fibers were developed at Bell Telephone Laboratories and were often referred to as optical waveguides. What about acoustic waves? and "acoustic fiber guides?" Not dixie cups and string, but acoustic waves in a solid medium flexible enough to be like cable? Sounds like a homework problem.

  • These videos may be my favorite result of the invention of the internet

  • Im going golfing this weekend. How about a video on the mechanics of achieving the perfect swing?

  • Muito massa.

  • I LOVE THESE VIDEOS!!! sooooo cool!!!!

  • Can you make a video on how electronic gyroscopes work (like on the iPhone)? I don't know much about it. :P

  • @aydarsh Its an accelerometer and it will likely be in series #4; earlier this month I did quite a bit of work to understand it: Fascinating thing, and fascinating technology to make them.

  • @engineerguyvideo

    Do you have any plans to make a video about touchscreens?

  • are you luke skywalker?

  • Comment removed

  • Absolutely amazing, well explaind and easy to follow for non-engineering audiences (but I'm a Mechatronics engineer). Congrats MR. Engineer man... you made my day.

  • just wondering, what purpose does the creamer serve? Is it just for contrast in the liquid that pours from the bucket, or does it affect the refractive index of the liqud? Thanks

  • @euanmcdonaldsmith14 It scatters the laser beam a bit so you can see it more clearly on video.

  • I'm in school for this certification right now. I thunk I will really love This field of work.

  • I'm wishing you do a video on how touch screens work (:

  • I'm wishing you do a video on how touch screens (:

  • Another great video. If only my Cisco teacher had illustrated this so clearly in high school!

  • I love your videos!

  • How can thousands of calls/messages be transmitted at once and told apart?

  • @tiger55331 That is a superb question, one that the video JUST about gets to buy doesn't. Two way: 1) Pulse Code Modulation: Imagine those pulses going down the fiber for a digitized conversation. We could do this: at 0 second send the pulse for conversation 1, at 1/3 sec send a pulse for conversation 2, a 2/3 sec send a pulse for conversation 3, then at 1 sec a send the next pulse for conversation 1, at 1 1/3 second the 2nd pulse of conversation 2, etc. Of course, it isn't really 1/3 ....

  • @tiger55331 ... of a second its much faster; in fact so fast that the human ear doesn't hear a delay. BTW The computer at the other end would know by time which pulse belong to which conversation. (This a reason that atomic time is useful in communications!) b) Fiber optics offer another method called "wavelength division multiplexing." In its essence image this: Conversation #1 is carried by a green laser, Conversation #2 by a blue one, and Conversation #3 by a red one ...

  • @tiger55311 .... at the end we could sort out these colors and know what belong to what conversation. (In practice it is tricker than this: One uses laser very close in wavelength, and a very sensitive device to separate them, but the idea's the same. Note that this method is unique to fiber optics; the other will work on a copper wire.

  • @engineerguyvideo

    Thank you for this detailed answer- you really know your stuff! i knew how optic fibers worked basically, but no-one explained well what you jsut did, about many-messages being sent at once. So are atomic clocks used in such systems?

  • @tiger55331 I don't yet know the answer to that. I THINK they need microsecond resolution and ASSUME they use a time signal tied to an atomic clock ... but I hope to do a video on atomic clocks in series #4 and answer these concretely.

  • @engineerguyvideo

    Ah, looking forward to that! So then the largest number of 'simultaneous messages' depends on the smallest time frame that can be accurately measured using the clock? Hope that question made sense, not sure how to explain it properly...

  • Isnt it total internal Refraction?

  • Incredible but rather simple. Sound really interests me if you could do more on sound engineering that would be cool

  • @gurrenlagann153 you could if you went to the great institution of the University of Illinois Urbana-Champaign. I was lucky enough to take Professor Hammack's introductory engineering class a year or so ago. Every day was like this, he is just as charismatic and a pleasure to be taught from as he is in the videos. He truly enjoys what he does.

  • Engineerguy, how does a light pulse represent a sting of 0's? If it was 1000000001011000000, the light would just remain off. Is there a time-analysis that lets it "count" how many 0's have gone by?

  • @mphmm Good question. Each end of the cable has a clock that is synchronize - and takes into account the time it would take light to travel. So at say time_1 the first number is sent ("1" in your example) and the other end looks at its lock and says "Its time_1 I should get the first bit ... ok there it is a flash for a 1"; then at second bit is sent at time_2, the receiving end says "ok, its time_2 so what info was transferred. No flash, it must be a zero" ... and so. Does this make sense?

  • @engineerguyvideo

    Ah :D Thanks

  • @engineerguyvideo

    i although dont speak english that well..

    info send from 1 end at time_1 was actually received by the receiver end at time_2,, this would happen to each and every bit and delay time (that is time_2-time_1) would be same for all bits.. if the information send was bit 1 at time_1 then the recieved info at receiver would be 1 at time_2..... where as the received info would vary at time_1 at receiver end(according to earlier bit)

    info is transferred correctly with a small delay..

  • @mphmm There are special codes used to decrease the chance of long stretches of the same symbol. But beyond that, fiber optic cables have a much more complex system than just on and off, in reality. The cable is never dark.

  • @mphmm The explanation is slightly simplified. In fact you have to add extra bits because once you have too many identical bits in a row you cannot count them anymore. The simplest encoding would add a final step that actually doubles the number of bits on the physical medium. Every 0 could be turned into 01 and every 1 into 10. That way you have no more than two identical bits in a row. More complicated schemes can improve the overhead such that it doesn't grow by a factor of 2 but only 1.x.

  • Maybe someone else pointed out, but if the Internal Reflection was "Total" then we would not be able to see it!!

  • Why can't school make science this interesting

  • @Gurrenlagann153 ya if they did i might not fail that class lol

  • Woah, woah, hold on there Engineer Guy.

    Light goes in, light comes out.

    Can't explain that.

  • I just love your videos

  • does he wear the same shirt for every video?

  • How do they attenuate the signal to cover for the losses every 50 km across the Atlantic?

  • @TotoMarten They have devices that strengthen the signal mounted on the cable.

  • How do they attenuate the signal to cover for the losses every 50 km across the Atlantic?

  • Many years ago I did some work for Alcatel in Portland (before they relocated) and got a tour of their plant. Very interesting process of manufacturing. Even with all that technology in the product and plant, they would use old tire rims as guides to move the cable around their plant and onto vessels for transport.

    Entertaining videos, keep up the good work.

  • I really like your videos so much and I am subscribed to your great channel . Although , it would be really appreciated if you explain things in slower and more explained way .

    Thanks a lot :)

  • I'm just curious, have there been any talks about you becoming the next Mr. Wizard? Your explanations are great, and I gain a better understanding and appreciation of the technology I use on a day to day basis.

  • Anyone whom dislikes Engineerguy dislikes knowledge and is therefore useless to society.

    I love your videos, please keep teaching us in this fashion.

  • networks are future of IT !

  • @engineerguyvideo: You didn't actually explain how they worked - just that they worked. What, precisely, is the 'interface' between air and liquid ? When light travels from air INTO glass (or liquid) there is a surface (or 'interface') of that denser medium, but when light travels from glass - or, here, liquid - then there is no such surface. So HOW is the light reflected ? What is it reflected from ? And, as its all liquid, how is the light not reflected earlier ?

  • @1thermon - He did explain how they worked - via TIR and PCM encoding. It sounds like you want to know how TIR works, as in how reflection/refraction occurs, are there limitations in medium interfaces, etc. Basics: An "interface