How Cell Service Actually Works

[@mountbikejeff]

I've done communication engineering courses, the amount of background requireded to understand how this stuff works is crazy. The fact that you managed to provide a Layman's explanation for such an advanced topic is very impressive. No Fourier transforms or complicated math, well done.

[@adarshmohapatra5058]

Man seeing this video made me realize how much thought is put into communication. Last video I learnt about how much engineering goes into transmitting electricity. Respect for those who make all this possible.

[@KRYMauL]

Insane? It's just Elementary Linear Algebra to make the most basic encryption, the more complicated encryption require more complicated matrix math.

[@thunderb00m]

Wish this video was there when I was starting to study communications engineering. The CDMA part triggered my PTSD of struggling to calculate transfer functions, bit error rates, transmission loss, etc. Of course I have moved into another field since I graduated.

[@TV-8-301]

I'm surprised how much I've taken this tech for granted

[@thunderb00m]

@@KRYMauL you are missing the loads of Fourier transforms, constellation diagrams, bit error, etc needed to understand cellular transmission. That is hardly basic encryption. Understanding RSA or ECDH is much simpler than communication Engineering.

[@kittybaps]

my dad told me that when he dropped out of school in the 70s, his dad asked him what he wanted to do with his life-- and he told him "i wanna know how they take a signal out of the sky and turn it into something you can see or hear" .. he ended up becoming a tech that specialized in repairing antique radios and he was heavily into tinkering with new electronics as they came out, his room was covered in antennas and oscilloscopes, and he was always very excited to share any stories he had about broadcasting and loved finding out stuff like this he passed about a year ago but i'm very sure he would have loved this video, great stuff

[@caralhoguy]

Interesting

[@JustinSmith-ik3tu]

Your dad sounded an awesome guy man 👏

[@GeoffJop]

Big respect to your father, he was very passionate

[@panospapadopoulos]

Sounds like a great person, respect. Thank you for sharing your story and good luck!

[@lsactive8006]

Beautiful story! He sounds like a genius

[@redhidinghood9337]

This video single-handedly filled a huge gap in my knowledge about everyday things. Thank you

[@Escritorez]

@@yukierose9225 seems legit

[@veezerrscharnhorst]

Even Mr beast watch this channel regularly

[@Escritorez]

@@veezerrscharnhorst who?

[@Digitalhunny]

Red Hiding Hood, you're not alone in this educative process. I'm right with ya. Well, sorta? You _are_ alone however, in your "hiding hood" though... cause it's how the game is played. Not cause we don't love you. 😂😂😂

[@cakeisyummy5755]

@@yukierose9225 Begone, Th- Bot.

[@meteoro300]

I have been in the wireless communication field for over 20 years. I have seen the growth and change. Brought many memories when i started working on analog networks, IS-136, GSM, CDMA. Very well done!! You managed to explain very complex processes in a manner an average person can understand. Mobility, how the phone switches from one cell to the other, is the next hurdle. But overall great video. Congratulations.

[@decidiousrex]

My dad worked in telecom for over 20 years with Motorola and Bell Labs. He passed away in 07, when I was in middle school, and ever since I've wished I knew more about what he did. He had a master's degree in computer science, and I always wondered how that was applicable to telecom. I did not realize at all how complex and fascinating this field truly was and is, and I have a new found respect for my old man and people such as yourself who continue to provide the rest of us with services we often take for granted.

[@unemployedgringo]

I wouldn't say any average joe could fully understand this. I think you need at least a little background knowledge on physics and whatnot to understand this completely.

[@jkjkjk100]

Reminded me of a lot of statistics we had to do in school around the topic… Some of the topics he discussed in case you’re interested: AM - Amplitude Modulation FM - Frequency Modulation Symbols PSK - Phase Shift Keying BPSK - Binary Phase Shift Keying QPSK - Quadrature Phase Shift Keying QAM - Quadratic Amplitude Modulation 8PSK, 16PSK, constellation diagram TDD - Time domain duplex OFDM - orthogonal frequency division multiplexing CDMA - Code Division Multiple Access SNR - Signal Noise Ratio BER - Bit error rate

[@richardbloemenkamp8532]

So many of us had to learn it but only very few still use it. Me too I learned this stuff but fortunately I recognized soon enough that it is the same a learning screw heads. Note that knowing screw heads is more useful in day to day life. On telecommunication protocols, the essential stuff was done by Claude Shannon with his work on channel capacity as a function of SNR of the channel. The rest are just different choices based on SNR over the usable bandwidth and historic development. None of this stuff actually manages to increase beyonds Shannons limits but, of course, our SNR has become better with smaller cells and with the increase of computing and processing power we can more optimally use the full bandwidth optimally even if the SNR is strongly varying over the bandwidth or fluctuating in time.

[@sadekomar]

but, I don't think he talked about BER or SNR.

[@TheTaxGeek]

This video just blew me away. To break down such a complicated technological subject, starting with the nature of light itself, to transmitting thousands of messages simultaneously, step by step, so that each step builds on the other, is a very rare talent. I have a new respect for our telecommunications system and the people who make it work.

[@Dmullins81]

And Sam for being able to explain it the way he did in this video!

[@asphere8]

It's even more complicated than this; this video tops out at 2G technology! 3G, 4G, and 5G continue to get yet more complex. Additionally, in high-density areas like cities, cells don't have one omnidirectional antenna in the middle, but rather three or more directional antennas at the corners.

[@MrT------5743]

@@asphere8 CDMA is 3G technology. That is where this video topped out.

[@asphere8]

@@MrT------5743 The original CDMA is a 2G technology; CDMA2000, WCDMA, and HSPA are sometimes referred to as simply "CDMA" but are 3G technologies.

[@ben6573-l1p]

This is one of those video’s where the transition between “duh, this is basic stuff” and “wow this stuff’s incredible” happens without me noticing. Keep up the great work!

[@vigilantcosmicpenguin8721]

It's a good way to communicate things. Make sure people know A, then gradually move on to B.

[@cuesunny]

More like this stuff is boring for most people. This stuff is very interesting for me though

[@bertholtappels1081]

Yeah. This is a masterpiece. I’ve been designing cell networks since 1997, so this is second nature to me, but I’ve never seen such an non-intimidating explanation of things like QAM and CDMA. Like 100% of all books whack you over the head with matrix transformations or polynomials on page 1, and they lose all but the most determined learners right there.

[@draskocis]

I wish he mentioned them by name and showed the constellations to better explain visually why you can switch to a higher MCS if the channel is clean enough. Basically, he could have very easily compared 16QAM to 64QAM

[@danpeterson708]

This -comment- is a masterpiece 🥰

[@Paulkjoss]

I think this video may be his crowning achievement

[@ShpanMan]

It is so difficult and rare to break down a topic like this to its simple fundamentals and transfer that knowledge so efficiently to dumb(er) receivers. In effect, WP have created their own fantastic compression algorithm in this video.

[@kyerussell_au]

Absolute PTSD from my university networking textbook struggling so hard to even provide the introductory explanation of CDMA that this video provided so easily.

[@dammtri]

I watched several sections of this video repeatedly so I could understand what was being explained. It was like attending a Telecommunications Engineering Lecture but with a super interesting professor who had amazing visual aids to explain concepts and and you could ask him to repeat what he said multiple times until you got it. This is the way learning should be. I knew parts of this earlier but never has anyone explained so clearly everything starting from scratch. Thank you so much. More people need to watch this.

[@MoPoppins]

I _so_ agree with you, having gone to school in the Dark Ages of the pre-Internet era, where instructors would ask you to hold your questions till the end, which isn’t helpful if you can then no longer understand anything that follows what you already needed an explanation for. 🙄 KZbin is my favorite learning platform! 💕 🎁 Podcasts are second, since they don’t have the visual aspect, which is sometimes necessary or helpful.

[@monhi64]

Hey at least you didn’t trash teachers lmao, so many just go into the comments saying why can’t you be my professor in x class and just teach this because my current professor sucks and is boring. There’s no comparison this is a guy (presumably with a team) who puts out less than some single class sessions worth of material a month on whatever the hell he chooses and most importantly for entertainment not just education. And it’s also a video you specifically chose to watch because you have some interest in it. It’s not weird at all this is way more fun than class it has a million advantages

[@DarkNexarius]

Just image how good the "education" will be in 100 years when we can just get this type of video for literally EVERY topic.

[@pyropulseIXXI]

If you think this is at a engineering level, you are seriously beyond hopeless. This video taught virtually nothing. All it did was give you an illusion of understanding. In an actual engineering course, you'd be able to do the mathematics yourself and set up your own system. I seriously doubt you can do that from watching this video. This is why I hate KZbin; it makes people think they are actually learning stuff, when it is just entertainment. It only teaches at a surface level, a shallow level. And creators usually tell people this, and the viewers still say they learn from watching. No; you have to practice and solve problems to learn anything

[@siamimam2109]

Dude I wish!! If every teacher taught like this, then we would all be engineers 😂 Unfortunately teachers don’t get paid enough to put this much effort into teaching material

[@mattpopovich]

I just bought CuriosityStream specifically to watch your "The Colorado Problem". As someone who has lived in Colorado for the last 3 years, I had no idea how interesting the task of "getting everyone water" in the state (and southwestern part of the country) could be. Happy to support you and the others that spend their time educating us. Thank you!

[@jpaugh64]

Believe it or not, it also has huge implications on real estate law. For states with plentiful water supply, land owners own half of any river that flanks the edge of their land. However, in arid states where water is scarce, the state owns all bodies of water which aren't enclosed by a private property. I think some states even claim water bodies which are wholy contained within your property.

[@coloradostrong]

What?

[@olmkiujnb]

You packaged a hugely complex object into an understandable format without using formulas. That's very impressive.

[@SyNcLife]

I literally forgot my tea watching this video.

[@brandonsmith8166]

As someone who works in the telecommunications industry I want to thank you for this video. Making such a complex topic relatively easy to understand. The average consumer gets mad when their data slows down or call gets choppy, but they don't understand that there are quite literally physical limitations to cell service. Now throw in multiple telecommunication competitors all fighting for spectrum and the logistics of providing cell service gets even more complex.

[@stevencooke6451]

After watching this I think we should be excited when the network actually delivers. So much goes into making it happen. I once worked customer service for a telecom back in the 90s and people expected wireline quality everywhere.

[@h4tch3tt74]

Don't forget the natural noise of modern society as wireless tech become more prominent. On top of that noise from emergency services, airlines, military radar, etc.

[@ninthcloud6331]

As a cell tower field tech, I can't agree with you more, Brandon. It's very difficult to explain to my friends/family how telecommunications work. This video sums it up in understandable terms. Now I have a simple video to share with everyone complaining that they "want answers, and they want them now!" Lol

[@Vysair]

Yet people hating 5G for bullshit reason

[@svampebob007]

as a tech savvy person I had an understanding of how it all worked... boy was there much that I didn't actually know!

[@danieldelpozosanchez4398]

As a Telecommunications engineer graduate, I wish I had seen this video a few years ago. Really helpful and well explained information

[@rigira]

What exactly did you learn in ur degree? I'm currently a CS major, but telecommunications have always interested me. didn't know there was a degree associated with it

[@MrBrayden24]

What would happen to our networks if a massive solar flare happened

[@mastershooter64]

what books would you recommend if i wanna learn about telecommunications engineering?

[@2life4ever777]

yup, I am also a Telco graduate and this video wraps up information pretty good

[@nataliegrn17]

As a Taco graduate, this video wrapped up the topic nicely.

[@novachromatic]

Just as cell service tries to cram as much data as possible, you've managed to pack so much genuinely interesting information in this video while still making it understandable to the average person. I've learned so much. Thank you.

[@tlo1216]

I hate you for being better at explaining these things than every engineering professor I've had, and yet I just have to listen to you for free even if it's mostly just surface level. I love you for all of it, and nebula is super worth it, thanks for your content

[@evanbelcher]

I keep expecting the Half As Interesting guy to make a terrible joke but he's actually just really helpful over here

[@Veilure]

what do you mean? those are two separate channels

[@Agate717]

@@Veilure it's the same guy doing it

[@angadsingh9314]

Haha so true. I can't stand his other channel.

[@nityodaytekchandani701]

Ikr lol

[@jonathanbean5520]

He did sneak a "meow" in around 14:47

[@ryanb9873]

As an EE who specializes in RF for the last 20 years, thank you for this video! Well put, and not too complex. To me, even now, CDMA is black magic. I get how it works, and have even written baseband code for it, but it just still seems like it shouldn't work. Now we're multiplexing signals over codes, freqs, amplitudes, phases, etc, over multiple spatial streams all at once. I really think the average person doesn't get how unbelievable the physics is when they use LTE or WiFi 6 to do something basic. 1024 QAM should just not be a thing.... and yet it is.

[@yzrippin]

Hey you're just the kind of guy i need to talk to i'm working at Hearst Castle flagging traffic control. I have radio communication between three flag men that is constantly disrupted, broken up, or not even coming through we have a repeater box at the highest point we could get it too but Channel 2 seems to work more reliably than repeat. We have rugged V3 radios with 16 inch whip antennas please help

[@ryanb9873]

@@yzrippin hey happy to help, but it doesn't sound like you're using cellular or wifi technologies based on what you said. Are you using CB (citizens band) 2 with walkie talkies on the flagmen? Or licensed freqs and HAM channels? You might be best served with a FM solution like old school Motorola private licensed 2 way radios and a repeater (sounds like you may be already trying that) if your area supports private LTE that's the way to go. Just pay the carrier for the service and enjoy regular phones on their service with full duplex communication.

[@BrandonGaza09]

Haha so you’re the guy that writes my codes!!

[@foxphire0093]

as an undergrad EE junior taking Intro to Electromagnetics, hearing black magic is all to familiar.

[@dolamyte]

Same, 20 years EE in wireless/RF, covering aviation, LMR, MIL/critical comms, some cellular and a most of it in the secured realm. FSK, PSK, QAM, CDMA, OFDMA and other modulation schemes, especially the last two still seem like voodoo even though I'm deeply rooted in them and many others. Watching subscriber, spectrum and channel efficientcy grow by orders of magnitude, it's what's next that has me most fascinated, even going back to school, yet again...

[@benstravinskas4146]

I’m an Electrical Engineering student and I’ve studied communication systems, I did not understand most of what I studied until this video. Thank you.

[@ruripapi]

just take a ccna

[@theairaccumulator7144]

@peace we especially need these verses in these times

[@linkisraw]

Im an Electrical Engineering graduate and did not learn a single thing in my communications class or my digital signal processing class. In this video, I learned more about those 2 subjects than an entire semester worth in those classes. Classes in university just teach you the math B.S, like using fourier transforms

[@chosen_x_create7708]

jeez, i have been studying computer science for the past 6 years of my life, but I have never seen any explanation as perfect as this, good job! I do not even understand how people survive without watching wendover contents. this is currently the best channel yet.

[@Paiper14]

Brilliant. The communication engineering courses we went through broke our spirits on complex polynomials and transforms. To see TDMA QAM and CDMA explained so clearly was mind blowing!

[@bracco23]

Really nice explanation of CDMA. Just a note, that didn't seem clear to me from the video but I think is important: when he says that we add the codified messages to obtain that sum, out of which the receiver has to get the messages back, we don't do the sum on purpose. It's the media, the way the messages are represented is such that if two users send their message at the same time to one receiver, the receiver gets the sum of the two messages. The ability to craft the messages in such a way as to always be able to retrieve the original components in a consistent way is where the mathemagic happens.

[@Celastrous]

Basic wave superposition does the addition itself, yeah?

[@vigilantcosmicpenguin8721]

Dang. I can't imagine having to be the person who had to figure out how to work on that receiver.

[@basketballprodigy12]

Ya but how would they ensure the waves are in phase to allow for additive behavior between them. It seems like unless all 3 signals came from the same position they would likely be out of phase

[@ElectraFlarefire]

This.. There was a missing part of the explanation.. It sounded like it was all done in the devices. That one of the mixing stages is done in the media is the last part that explains how they don't mess up each other.

[@hge437]

The part I don't get is how the receiver separates these and knows which data come from which user

[@zpiritual]

Impressive video! Having worked on 5G in the telecom industry recently (backend, not radio) the amount of data the teams working on radio figured out how to send seemed like magic. After this video it doesn't, bravo!

[@Dac_DT_MKD]

Were there some lunatic Karens trying to destroy the 5G towers, and then wonder why The Facebook didn't work?

[@scienteer3562]

The reality is that things are much much more complex than this video makes out.

[@serraramayfield9230]

@@scienteer3562 Which he blatantly states multiple times

[@uncletrashero]

its basically data compression using the equivalent of an encryption algorithm

[@pawala7]

@@scienteer3562 Sure. Once you reach orthogonal time frequency space (OTFS) modulation and MIMO antenna systems, it definitely can be. Heck, I'm still trying to wrap my head around some of the underlying mechanisms of non-orthogonal multiple access, and most of the math still seems like magic. But, I still thoroughly enjoyed his take and his explanations for everything. Hopefully, it will help demystify how radio signals work for the people who think tech like 4G and 5G are basically black magic.

[@KonaSuba]

The Wendover team doing great work again!

[@olafcreed4726]

You are absolutely an amazing teacher, illustrator, storyteller, and information gatherer. Thank you person or persons behind Wendover Productions.

[@ayy1892]

this is such an advanced topic to understand,we had an entire subject dedicated to cell networking. But you really put things altogether for us to understand, i was even able to recall some formulaes just by watching this video. Great work man👏

[@lavidawithjoey]

I have not actively watched TV in years and I cannot thank creators like Wendover enough for helping me make this transition. I went from absorbing unhelpful and mainly useless information to constantly having access to high quality intriguing content. Hats off for another wonderful video!

[@androidaleccc]

Whoever does the writing for these episodes consistently impresses me with how thorougly they actually research/comprehend the video topics. The videos on air traffic/planes seem like they could only come from a professional in the industry, even this one has that same feeling.

[@toomanyopinions8353]

The description says that the episode was written by Sam himself (the narrator). I saw someone say the other day that at some point Sam said he was an engineer.

[@isawrooka4]

Yeah the video he made about cyber warfare (which, while I’m not military / not a threat intel person I was a pentester and now a SOC architect) was pretty amazingly accurate for a video made by non-experts. Really made me appreciate their work even more, these videos are incredible quality.

[@onr-o1h]

The brilliance of this channel is that it's created by Sam. The narrator.

[@VTGGT]

You just packed a half semester class of "Wireless Communications" into a 17min video. It was actually one of my fav classed back in my Uni days and one of the Few passing with A

[@michaeltaylors2456]

This old tower dawg here is so impressed. The real world footage and your explanations are perfect. I’ll be sending everyone here

[@eliannafreely5725]

I have a father who was a computer engineer, a brother who is a computer scientist, and a brother who is a theoretical physicist. This video, and a couple on electricity by ElectroBoom and Veritasum, are the closest I have ever come to understanding so many conversations I've heard over the years. Extremely clear explanation, thanks!

[@JustcallmeJayrot]

I LOVE the depth on this video. I feel like I've seen a billion videos with the first layer of knowledge (frequencies). But I'm so glad Sam is willing to go deeper.

[@jimmymifsud1]

I’m a radio frequency technician, with a specialisation in LTE; the was this was explained was amazingly simple and very accurate. I’m totally going to share this with people who I’m trying to explain cellular standards

[@philsfreshfudge1688]

As someone who deals with this for a living, you really did a great job at explaining it.

[@michaelkawwa88]

Just out of curiosity, what’s your job?

[@TacomanDezzy]

@@michaelkawwa88 he’s a salesman at T-Mobile lol

[@walidfakhfakh3660]

@@michaelkawwa88 hdech layks

[@FerociousPancake888]

You explained quadrature amplitude modulation quite well. Our current cell tech is pushing 1024QAM. That’s very new though it’s mostly 256QAM.

[@emilne83]

This is an amazingly well done video. I've been working in the cellular industry for well over a decade and I've never seen these fundamentals explained so eloquently with amazing visualizations such that it can be informative to somebody at any level of experience. I expect that I will be sharing this video with future coworkers for many years.

[@Sonad47]

as someone who recently went to school for this, and now works with communications & two-way radios - this was really well done. it helped fill in some holes in my knowledge for sure. next up, i challenge you to make a video so easily understandable about Antenna theory

[@Damindeater]

Yes, and maybe explain yagi-udas

[@Sonad47]

@@Damindeater I'd love to be able to see it broken down so well. im sure there's probably already videos out there, but i rarely go searching for them. i just watch what pops into my sub box

[@herlescraft]

I challenged him to make the same thing but for MRI... So yeah basically the same thing :P

[@dennispremoli7950]

Thats sounds more like a Veritasium video

[@JOSEPHELBOSS]

this guy went to schoool for this but he still learn new things from this video. mindblowing 🤯

[@TheCoBBus]

I spent my time in the military as a radio officer, this video summed up about 3-4x 1-2h lessons on how telecommunication works with out mathemstics like fourier etc… Fantastic job!

[@LandofBobiness]

I'm impressed at how good this explanation is. Respect for the amount effort that must've gone into writing and visualising this!

[@mushrifsaidin]

I did a degree in communications engineering back then and this video summed up my whole degree in under 20 minutes lmao good stuff

[@ZiPolishHammer]

One of your best videos ever. I had a basic understanding of how a phone communicated with towers and a network, but had no idea how much ingenuity was required to overcome the limitations of carriers having such a narrow band of the electromagnetic spectrum.

[@_adinfinitum_]

I’ ve been doing wireless R&D work for almost 15 years. I watched this video with a skeptical eye but man this is really well done. Next time someone asks me what I do at my job, I’ll send them this video. Incredibly complex knowledge summarised so brilliantly. Do a follow up on 5G too.

[@kedarpatil7095]

Yeah... 5G would be a bit much to explain, this one topped out at 2G and everyone knows how much it has advanced since.

[@bv2010]

“This is where it gets complicated.” Safe to say for me it got complicated well before that point. Great video.

[@connerrocha5124]

It’s amazing how humans have been able to create these things all within the span of just a few decades, and most of these upgrades within just the past few years. Truly amazing how far we have come in technology in the past century.

[@britishempires]

Humans didn't create none of this.. it was given by the creator of this simulation.

[@juliussokolowski4293]

I'm an RF service engineer. This was probably the best concise explanation of the evolution of radio access networks i've ever seen. Brillian job!

[@2Pish]

This is why I love KZbin, you find content creators that just PUMP out quality like WP

[@rainroos5628]

The fact that u can make such a hard subject understandable is amazing. Keep up the work, love it!

[@uncletrashero]

this guy should explain the evolution of Data Compression so people can understand more fully what the cell network does

[@MightyRob1]

As someone who has been involved in communication for the past twenty years this video best sums up what is taken for granted by every 15 to 25 year old using TikTok and Instagram. This is why AT@T was slammed when the iPhone dropped. They literally had no idea what to expect and no system in place to handle that much traffic all at once. What we have today is just shy of magic and is why when it does fail to meet expectations people freak the F out. Also this is your best video ever. Bravo. 👍🏻

[@atk05003]

This complexity is why I've told people that it's a miracle that WIFI and cell phones work at all, much less as well as they do. Several people have said, "That just means you don't understand it". I understand the protocols and math, it just feels magical to see it in action. It's like a well executed magic trick. I may know how they did it, but I can still be impressed by how well they did it.

[@tuan.hoang_]

@@atk05003 "Any sufficiently advanced technology is indistinguishable from magic." - Clarke's law. Magic is present in our everyday lives

[@jakubkandera95]

Could not agree more!

[@archiox0628]

As a former Telecoms Engineer, I had been slow clapping throughout this video. This was so well written

[@wickypickyvicky]

This has to be one of the most complicated videos by Wendover for me to understand. Being from a non-science background, I think I got about 10% of it.

[@RanDom-if2ee]

I feel you

[@Numba003]

This was very fascinating. As a teacher, I may use this video in a lesson plan sometime lol. Thank you. Stay well out there everybody, and God bless you friends! :)

[@utubeaddict29]

8:54 all I'm hearing is that Hexagons are the Bestagons

[@carsonballou6850]

CGP grey would be proud 😂

[@Manabender]

"This is electromagnetic radiation. *You can't see it,* but it's there." 380-740nm range: *Am I a joke to you?*

[@Skyler827]

There was infrared and radio radiation. I couldn't see it, but it was there.

[@kundeleczek1]

Thank you! Why I have to scroll so long for this?

[@Zaptosis]

This is one of your best videos ever created, I've always been fascinated by cell phones & how they operate. This was the best produced video that went into a section of understanding I didn't even consider thinking about, the protocol. 10/10 content!

[@domidomi917]

From AM to FM, to ASK, FSK, PSK and finally QAM. Thereafter, cell towers and TDMA, CDMA all in 18 mins so well summarized for a layman. Awesome!

[@nigelwest5776]

I'm so glad there are people smart enough to come up with this

[@iangray3137]

This is something I've always wondered about phones/data transmission but never had the time to research on my own. Such a wonderfully condensed video on an amazingly complex topic!

[@Celastrous]

Loved this! As an Electrical Engineer that specialized in wireless communications, this was a wonderful refresher - the information presented is accurate and is essentially a slice of what you'd learn in a Communications (the engineering kind) class.

[@zenithparsec]

Yeah, it's like the slice you take off an apple that got dropped. Mostly still edible, but some parts.... yech.

[@tissuepaper9962]

@@zenithparsec like the first part where he pretended that an LCD was a laser... Still great for a layperson though.

[@llydrsn]

The way the video evolved from the very basics, easing things up until it reached the very complex concept of CMDA is just genius and very engaging! Kudos to the team for a job well done. Probably one of the best explainers I've seen.

[@_Breakdown]

GREAT OVERVIEW ON THE EVOLUTION OF TRANSMITTING CELL DATA 9:10 - - tree 16:30 - - packing as much data as possible into a single transmission 16:35 - - then packing as much transmissions as possible into a single radio wave 16:43 - - newest method (orthogonal frequency division multiple access) - - packs even more transmissions into a single wavelength

[@ariellemartinez8412]

There’s all these genius tech people appreciating the video but this college dropout enjoyed the simple learning to it got crazy and made me feel the joy of learning again thank you so much

[@valmarsiglia]

I remember those car phones. In terms of call quality, it was one step up from tin cans connected with fishing wire. The sound quality sucked, and there was a significant delay, so after you spoke, you had to remain silent for a few seconds to give your signal time to get to the listener and for the listener to respond. And if either of you happened to speak a second too soon, it would often lead to a spiral of "Sorry, go ahead..."

[@StephenTack]

Interesting note: The noise/interference (mostly) older cell phones caused in audio equipment was due to TDMA. Switching the radio on and off hundreds of times per second induced AC voltage in nearby wires, that could them be amplified by stereos, TVs, Etc. and heard as a buzz from their speakers. CDMA creates much less audio interference, as the radio is always on, and there is no modulation of signal in the audio-frequency range.

[@Celastrous]

That is very interesting! So the frequency of the full cycle must have been within human hearing ranges. If that's the case, that means data was packed so efficiently as to allow a ~1/1,000,000* compression rate compared to analog! *Used toy numbers of a 1GHz carrier wave and a 1kHz transmission rate (the one that causes the audio interference)

[@icannotfly]

so THAT'S what that sound was when you would get an sms

[@jaimelopez2503]

@@icannotfly Yup

[@StephenTack]

@@icannotfly or just before a call came in.

[@scottdotjazzman]

I get that noise with LTE too (my phone does not have CDMA and only functions on the LTE network for Verizon).

[@danieljensen2626]

I've done a bit of analog RF stuff but I never actually knew how digital signals were transmitted over radio, I guess that makes sense as far as being able to pack in more information without changing the frequency you're transmitting at. Really informative video.

[@mobslayer1553]

Wendover is on a different level. Keep it up, guys 👍

[@bradbrening3957]

Excellently presented! Usually Wendover videos are too jokey for me, this was perfect.

[@spenceredford4403]

No flashy introduction. Just straight to the content. Best channel on YT!

[@MarkHatlestad]

Coming over from Nebula. This is one of the best explainer videos I’ve ever seen; breaks down the concepts well and builds up so you can understand the complexity. Great work!

[@rajagopalanvg2142]

A great video, thanks to wendover productions, I am pursuing Electronics and Communication Engineering, a subject wholly related to this video, I know how to encode, decode, transmit and design these techniques such as QAM, QPSK, BPSK, CDMA, MIMO but never knew the evolution and why they are designed and how they are designed. At the end of this video I completely understand the whole thing behind digital Communication. I think I would be lucky if I had a professor like you.

[@SAYYAM55]

One of the best Wendover videos honestly! A little sad that you didn't cover the spat between airlines and cell companies in US

[@cheesebusiness]

16:03 The channel capacity is not tripled. The channel transmits the same amount of data, it’s just shared between 3 users.

[@leo_brooks]

I’ve watched and loved you for many years. Been here since the beginning. This may just be the best video you’ve ever made. Spot on info, hyper simplified, and perfectly explained. This is amazing. You and team are amazing. Wow

[@DavidMcGuizz]

I am not even finished it yet and this is already one of the most mind blowing videos you have ever done. Incredible stuff.

[@AnirudhGiri]

All this ingenuity just so some Dream stans can have the ability to yell at me on Twitter. Truly beautiful

[@angadsingh9314]

LMFAO

[@angadsingh9314]

LMFAO

[@TexasVernon]

This stuff is so far above anything I could ever imagine I feel like I am a caveman living with super intelligent aliens.

[@ThomasHuitric]

Brilliant. I work in telecommunications and I have never seen a better, simpler explanation of CDMA/OFDMA, love your videos, they should be shown to engineering students!

[@nawassamwan4085]

Where do you work?

[@daviabraga]

That’s an incredible education video and the amount of work required to make must have been insane! Well done, Sam from Wendover!

[@gregbixby1353]

Enjoyed the video - just one small correction. At 1:50 you say a 2M wave (the size of humans) is called a "Ultra High Frequency Radio Wave". 2M waves are Very High Frequency (VHF). Ultra High Frequency (UHF) is in the 70cm range (about 1/3 as long).

[@X02AC3]

I came here to say this as well. I wonder what other critical errors were made in this.

[@David2718281828]

A trivial error and does not materially detract from the outstanding presentation. VHF is 30 to 300 MHz. UHF is 300 MHz to 3 GHz. But in some application areas a different definition is used. E.g., the 225 MHz to 400 MHz military aeronautical band is often called "UHF".

[@ronanfriel6997]

This is one of the most well made, well explained videos I’ve ever seen. Keep ‘em coming Mr. Dover

[@Abitibidoug]

This video is a very good summary of how cell phones work. I studied electrical engineering in the 1980s and covered a lot of this material up to time division multiplexing. Then I got hired on by an electrical utility in 1986 which uses a lot of telecom equipment, and in those days almost all equipment was analog. I think this video would be informative and helpful for anyone studying telecom equipment in college or university, or for anyone hired on as a tech or engineer in a telecom company. Good work!

[@BrendanGeormer]

As many times as I've heard explanations for AM, FM, and then the more advanced technologies for the different Gs; this is definitely the best explanation I've heard. Really impressed.

[@theunheardprophet4315]

As someone who studied communication systems, the thing that surprised me most is just the sheer amount of data that is transmitted just to establish one single connection from a user to the core network - especially for 5G. It happens all the time around us and we are astonishingly oblivious to it during our day-to-day lives.

[@jeffreybernath6627]

This was genuinely fascinating. It's nice to know what 4G, 5G, etc. mean, and that it's not just a scam.

[@zenithparsec]

"It's not just a scam." Yeah, like text messages that cost anything. Or contracts on overpriced devices. Or enormous roaming fees on what is essentially free radio signals. Yes, the terms actually have meanings. The same people who convince you to pay so much every month came up with them, and it's the pricing which is the scam.

[@rcnhsuailsnyfiue2]

@@zenithparsec radio waves are free… but building and operating the infrastructure to transmit them is not 🤦🏻‍♂️

[@nataliegrn17]

Birds are real

[@spartan117zm]

@@rcnhsuailsnyfiue2 still, roaming fees are crap. The fact that Verizon charges $10 per day to use data in Europe is ridiculous, when the only thing that’s changed is that I’m now pinging someone else’s tower. I get they have to negotiate usage contracts, but maybe the way to solve that is making cell towers open access, meaning any phone company should be able to use any tower, and then either the government foots the bill for new towers or the companies divide the cost between them. That would actually work out better for most companies as they’d have less operational expenses. I don’t want to dive into the depths of this idea here, but that basis is what I think should be the future for cell towers, if we need cell towers in the future. The way it’s looking, we’ll be sending the majority of our data via satellite soon, and the cell towers won’t matter so much anymore. If I remember correctly, that’s part of why Google Fi has no roaming fees; they operate some of their transmissions via satellites, meaning you can connect to their network from almost anywhere.

[@d00kieC]

I teach post-secondary IT and the industry certifications don't even go into this much detail. Great detail in an entertaining package!

[@dluv_98]

I’ve been asking myself all day “how does cell service work?” thanks to you i now know. thank you for an incredibly well produced video!!

[@sarahjrandomnumbers]

As someone who does Amateur radio (ham radio for Americans), I was expecting the explanation at the start to be terribly butchered, but nope, you went through all the way from CW to QAM (and other phase modulated signals) in 7 minutes, and was perfectly explained. I thought you were going to have a wobble when not being able to get data through an AM signal thinking "AH HA! ACKTULLEY THERE'S QAM WHICH IS USED ALL OVER THE PLACE!". Then you brought that up. Kudos on a well researched video :).

[@jiminfested]

8:45 Hexagons are after all the bestagons

[@Roxor128]

The CDMA technique is also used by GPS. Each satellite has its own code and your receiver knows all of them, so it can pull apart the composite signal to get the data streams from whatever satellites are visible, and from there use the sent timing data to figure out where you are.

[@jaketaylor3901]

If only college professors could explain things this easily and in depth

[@allysonfcs]

College professors do their work alone, have little to no budget to produce a video with this quality, barely have any knowledge on graphics/UX design, and, most importantly, have dozens of other roles in their department (administrative, research, mentoring, etc.) beyond teaching. Tbh I hope colleges evolve after this pandemic is over to allow that online learning and professionally-made content like this can be used more frequently when teaching instead of forcing professors to keep reinventing the wheel.

[@Skyler827]

this kind of information will never prepare you to solve practical problems in the domain though, it's just a layman's explanation. Training someone to actually synthesize this kind of information is much harder.

[@georgebrantley776]

It's important to note that everything covered in this video is just the surface of how telecoms work. An undergraduate class would easily cover 100× the amount of information, because working out all the little details, how they work, why they work, and then proving correctness & optimality take a lot of time to teach and even more to digest. Now repeat for every single step in the process. Just explaining the spreading codes itself could easily span several hours of lecture at depth. "How does the formula work, how does it scale, and what edits could be made to enhance certain attributes? How do we deal with errors? What limitations exist, what can be done about it, and why? Now mathematically prove all of the above from scratch." It's unfair to ask professors to teach all that, yet compare their lectures' digestibility with what is essentially the summary on the back of the book.

[@Vile_Entity_3545]

I thought you were taught race theory or gender studies 99% of the time in college or university nowadays.

[@zane990]

@@Vile_Entity_3545 not at all

[@nathanshirley9671]

The fact that someone figured this stuff out is mind blowing to me. How did we get to this point haha

[@iamrazor9831]

Well that explains why when service is bad in some areas the solution sometimes isn't just add more towers to the area

[@shinevisionsv]

02:00 UHF (Ultra High Frequency) is from 300 to 3000Mhz isn't it? Don't you mean ULF (Ultra Low Freq..)?

[@namex26]

Broke my mind for a moment there with that mistake

[@Croz89]

There's also one obvious solution to the capacity problem: make the cells smaller. We've been building more and more low power base stations in heavily populated areas for this reason. Mobile phones also adjust their transmission power once they know the distance to the nearest base station, to make it less likely another nearby station on the same frequency will detect the signal. Spatial Multiplexing using arrays of small antennas is also pretty fascinating. I'm not sure exactly how it works, you can use beamforming to transmit two data streams on the same frequency in different directions at the same time, but I'm not sure if it can receive two data streams at the same time if they aren't beamformed themselves.

[@yvrelna]

Making the cells smaller is fine, but it's also very expensive, since that requires installing a lot more cell towers. In addition to just the hardware and operational cost, there are a limited number of sites suitable for cell tower installation. Such location must be elevated, accessible by maintenance operators, suitably priced, don't have objections from locals (don't become an eyesore, etc). If you just make the cells smaller, the remaining suitable installation sites can become really expensive really quickly, so it's still worthwhile to find out ways to transmit more data within the same channel.

[@Croz89]

@@yvrelna It's not as expensive as you might think, in urban areas there's already plenty of readily available places to stick a base station. It can be as simple as bolting a small grey box with a couple of antennae to a wall on a tall building, or a lamp post, and running an ethernet or fiber optic cable to a network switch. Smaller cells don't tend to need to connect to a lot of devices over a great distance, so they can be low power, and transmission attenuation from the device can minimise overlap. Of course data compression and multiplexing is always good, because it's still cheaper than building more base stations, but especially in urban areas with the latest technology, it's not a massive expense to add extra base stations.

[@yvrelna]

@@Croz89 Installing the station itself might not be expensive, but more hardware means more complicated maintenance operations. Getting entry permissions, deploying maintenance workers, scheduling/deploying equipment for working at heights, etc, they all can add up. If you only need to deploy small number of cell towers, these are much less of a problem since you will have many other alternatives if a certain site proves unsuitable for any reason. But as you increase the density of cell towers you're installing, these expenses becomes a lot more important as you'll have to settle with less than ideal locations. You can no longer afford to be too picky with your site selection.

[@Croz89]

@@yvrelna Less than ideal isn't so much of a problem when you're dealing with relatively cheap equipment. If it breaks, you send someone to swap the whole unit out and it gets repaired in a workshop rather than on site. In terms of heights, anyone who can use a scissor lift would be able to service most of them. Others just need access to a roof.

[@xponen]

In 5G only the beamformed incoming data is fast at hundred of MB/s while the uploads from the user's cellphone is only at standard speed at few MB/s. Just try watch reviews of 5G for 5G phone and you can sort of figure out the answer for what you are asking.

[@dk3062]

The fact that you opened with how color and lightwaves works is amazing and enabled me to learn about more than just cell signals.

[@JamesBundySound]

I am very, very impressed with this video. I coordinate RF for live shows, and every once and a while I get to nerd out with others about the concepts of AM, FM, PSK, etc… I have NEVER seen it explained so well. Excellent work!

[@Alteviler]

This video: Very informative and detailed about the functions that affect our daily lives Sam at (14:47): “Meow”

[@TheLocalGeek]

Combing the comments to see if anyone else noticed. Well done.

[@QiyuanZhou21]

1:48 - This should be ultra low frequency waves. Ultra high frequency waves are things like x-rays/gamma rays

[@rickascii]

No he's right- they're ultra high frequency *radio* waves. Radio waves are inherently very low frequency, and that's on the higher end of that spectrum. Much lower frequency than visible light, but higher frequency than most radio waves.

[@archie4oz]

@@rickascii Technically he's still off a bit. 2m would be VHF not UHF. UHF is 10cm to 1m.

[@michaelhowlett4554]

At 11:30, you mention that as each adjacent cell needs different frequencies, you need to divide by 7. However surely you only need to divide by 4 due to the 4 color theorem. In the coloring example shown you can have multiple of the towers shown using the same frequency, in this case green, purple and red could be the same and so could blue, cyan and yellow as they aren't adjacent.

[@DaniErik]

I had the same thought. Always makes me excited to find applications of this beautiful theorem in the wild.

[@draskocis]

Aka the frequency reuse factor

[@darthtace]

It's actually just three for hexagons. Blue in the center, alternate red and yellow on the exterior, then blue between them, and repeat out to infinity. But I'm glad somebody commented on the four color theorem before I did.

[@IanMcCloghrie]

I think this is because 7 gives you two full cells between each reuse of the frequency range, and the extra distance is needed to make sure that a strong-enough signal at the perimeter of one cell has dropped down to non-interfering when it's reused.

[@zenithparsec]

@@darthtace You can't use the 3 color solution because the cellular phone users can move around. Otherwise they'll have to change frequencies more often. Also, you often have overlapping signal by multiple times the signal radiuses from base stations . The hexagonal grid is idealized. A densely populated peninsula, for example might have weirdly shaped cells. (not even gonna try describe it.)

[@Hexspa]

I’m an audio person and that section on phase was excellent! Deriving control signals from a wave is nothing new, but it’s a flexible idea.

[@3ffrige]

An amazing way to teach a complex process! As a professional services engineer of a large test equipment vendor, I work with products that test the various transport networks, various virtual functions of the 5G core, as well as the virtual functions of the radio access network. Getting up to speed on the technology has been a wild and wonderful journey. When we test this stuff in the lab, it’s so incredibly difficult getting past the interop, Routing, and functional issues to just get one single UE to make a call from the radio to the DN. I’m surprised that all of this stuff works in the first place in a production environment. I mean, you can be driving down the freeway at 90 miles an hour, for an hour and a half, and still be on the same phone call or meeting…the whole way! The stuff that happens behind the scenes…handovers from tower to tower, gNB’s using beam forming antenna arrays following you as you drive past the radio. The various components in the cell tower and your phone making real time decisions based on the signal to noise ratio to prepare to hand you off from the serving cell to the secondary cell…and a ton of their stuff that goes on behind the scenes…without the user behind that UE noticing one single thing happening…amazing! Getting up to speed on this stuff definitely gave me a better appreciation of my smartphone and the service it connects to.

[@coolbrotherf127]

This is so well explained and exemplified. There are so many people who think radio waves are evil space magic and educating people what they are and what they do lessens the amount of misinformation they'll accept as true.

[@adarshmohapatra5058]

Indeed. Radio waves are just light with a much smaller frequency and hence much lesser energy. I think many common people don't get that. Because regular visible light (the stuff that we can see) has much higher frequency than that, and hence much more energy. Yet you don't see people freaking out that the light from their lightbulbs is gonna give them cancer. It's really the higher frequency waves like UV rays, X-rays & gamma rays that people gotta worry about cause they carry more energy than visible light. As well as the very specific microwaves which have the same frequency as the natural frequency of vibration of organic matter. Due to resonance they pass their energy to these molecules more easily than other low frequency waves. It's what allows the microwave oven to cook food using only low-frequency microwaves.