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  • This episode of Real Engineering is brought to you by Brilliant, a problem solving website

  • that helps you think like an engineer.

  • Okay, I didn't think I would need to make this video, but people are burning valuable

  • infrastructure down out of fear for their health. I'm sure you have heard all the

  • insane theories. 5G towers are weakening the immune system and causing the global pandemic.

  • 5G is causing cancer. 5G is mind control by the lizard people.

  • I don't think I will succeed in convincing many of the lunatics that believe these things,

  • so I'm not going to try, but let's explore what 5G actually is, how it works, and some

  • of it's real problems. Today we are going to learn some interesting things about data

  • transmission science and how our ability to transfer data through the air has evolved

  • over the past 4 decades. Hopefully we can pull a few of the people on the fence over

  • to the side where the rational people live in the process.

  • We have been using different wavelengths of electromagnetic radiation to transmit information

  • for hundreds of years. In ancient Greece they used signal fires to convey messages with

  • visible light. Today we send messages with light through fibre optic cables. These cables

  • are capable of carrying insane quantities of information and are the bedrock of the

  • internet, but we can't connect all devices to it, because many devices need to be wireless.

  • To make wireless data transmission possible, cellular networks needed to be developed and

  • it all started here in Japan in 1979, with the first generation cellular network, which

  • we now call 1G.

  • It began in Tokyo where high power radio towers would communicate directly with phones installed

  • in cars. These towers used radio waves with frequencies sitting around here on the electromagnetic

  • spectrum, and simply transferred the data in analog.

  • Let's see how analog data can be transmitted using a carrier frequency. Say we want to

  • send this sound wave, a simple sine wave of 100 Hertz. We want to apply it to a 850 MHz

  • wave, a wave with significantly higher frequency.

  • We can do this with amplitude modulation, or frequency modulation. AM and FM. You have

  • definitely heard of these terms before with radio stations.

  • AM applies the data to the amplitude of the carried frequency, so it will vary the amplitude

  • of the carrier frequency, like so, basically tracing the original wave with its peaks and

  • troughs. [Reference Image 1]

  • FM applies the data to the frequency of the carrier wave, like so. Varying the distance

  • between peaks to trace the original wave.

  • To transfer a call using this method, you need a dedicated frequency band ,defined by

  • the lowest and highest frequencies used.

  • If another user is using that frequency band on the same tower, then you need to use a

  • different frequency band. The more frequencies you have, the more calls the tower can handle.

  • This is bandwidth.

  • As the number of users grew, the system's capabilities were continually stretched. Adding

  • more frequencies to grow bandwidth is an option, but adding frequencies comes with it's difficulties.

  • Frequencies need to be licensed and there is a lot of competition. Weather radar, military

  • communication and security systems, GPS, television broadcasts, radio stations, radio astronomy,

  • aviation systems and air traffic control. They all need their own frequency bands. In

  • order to gain new frequency bands companies often had to go to auction and purchase the

  • license with huge capital investment.

  • This was done with every new generation of cell network. But a lot was done to cram more

  • data onto a single frequency band through the years.

  • Increasing the number of users that can use the same frequency band can be as simple as

  • increasing the number of towers. Instead of using a single high power tower to cover an

  • entire city, multiple lower power towers could be used. Frequency bands could then be assigned

  • to individual customers within each tower's range without interfering with the same band

  • in neighbouring cells.

  • This increased the number of users networks could support, but it did not increase data

  • transfer rates. At it's best 1G was capable of about 2.4kilobits per second, but describing

  • it in bits per second is a bit counter intuitive, because as we said, it worked in analog. Bits

  • were the units of digital data.

  • 2G ushered in a new era of mobile phones with the introduction of a fully digital system.

  • Instead of encoding an analog signal into a frequency band, we encoded binary data.

  • If you are like me, this was your first experience with cellular networks. My first phone was

  • this beast. The legendary Nokia 3310. Sure it could make calls, but digital data allowed

  • for a new form of communication.

  • This was the era a new language was born. Text speak. a language of gibberish invented

  • to keep within the 160 character limit and prevent your mobile network provider from

  • charging you for two texts.

  • In english, each character in that 160 character text was encoded with 7 bits. [4] Therefore

  • a 160 character text contained 1120 bits.

  • When 2G was first introduced it could achieve about 9.6 kbit/second. It could handle that

  • 1120 bit text message with ease. But the 2G era lasted right up to the launch of the first

  • Iphone, and speeds had increased to 200 kilobits/second thanks to improved internet protocols like

  • General Packet Radio Switching or GPRS, sometimes referred to as 2.5G.

  • By the time the iPhone 2 launched, 3G was the new hot topic.

  • 3G introduced additional frequency bands, it's estimated that in Europe alone companies

  • paid over 100 billion dollars in auctions to gain new frequencies.

  • But 3G also made the change to a system that fully utilized the method of data packet switching,

  • which GPRS utilized. Packet switching allowed thousands of customers to share many different

  • frequency bands far more efficiently.

  • Here data was split into small data packets. Each data packet contains a header, which

  • contains the address of the destination and information on how to reassemble the data

  • packets.Splitting the data up into smaller bite sized chunks allowed us to make better

  • use of the frequency bands available. Instead of trying to find a large gap of availability

  • on a single frequency band, we could split the data into small chunks and send it across

  • many different frequency bands the moment a small availability appeared.

  • Like changing from sending a huge truck of data on a single road, to sending thousands

  • of motorcycle messengers over the roads with the least traffic.

  • This made our use of the frequency bands capacity more efficient and allowed us to carry more

  • data. As time went on these protocols improved allowing even more efficient use of the bandwidth.

  • In 2005 High Speed Packet Access of HSPA, which you have likely seen represented on

  • your phone as a H+, was introduced which increased speeds up to 42 MBPS. This was labelled 3.5G.

  • 4G introduced a new technology called Long Term Evolution or LTE, it introduced even

  • more frequency bands like the 700 MHz band that was previously used for analog TV broadcasts.

  • It also introduced a new way squeezing more data through the existing frequency bands

  • with Orthogonal Frequency Division Multiplexing or OFDM. [6]

  • OFDM allowed us to send far more data. You are probably familiar with the idea of constructive

  • and destructive interference. Where two waves meeting can combine and either enhance or

  • cancel out the amplitude of each other.

  • To prevent this signals traditionally had to be separated out over time to prevent interference,

  • but OFDM allowed the signals to be squeezed together and overlapped, allowing the same

  • amount of data to be sent over a shorter period of time. When the signals arrived they were

  • separated out and converted to binary data once again.

  • How? I don't know. Magic or math or something.

  • Honestly, the fact we can stream HD movies on our phone without a wired connection should

  • seem like magic to the average person.

  • It has gotten so advanced that we are now struggling to increase speeds without adding

  • new frequency bands, but there aren't a whole lot available, so network providers

  • are now reaching into the bargain bin and taking out frequencies no-body wants to use.

  • Higher frequency millimetre waves.

  • Higher frequency waves have normally been shunned for these types of applications. High

  • frequency waves just aren't as good at travelling. They get blocked by practically everything

  • including rain, think of them like visible light. Unless you have a direct line of sight

  • with a torch, you can't see it.

  • To deal with this network providers need to install huge numbers of transmitters. Studies

  • have estimated that to bring 100 Mbps download speeds to 72% population coverage and 1 Gbps

  • speeds to 55% of the US population, about 13 million utility pole mounted 28 GHz base

  • stations would be needed at a cost of 400 billion dollars. [6]

  • Having this many base stations will help relieve congestion over a single frequency band, but

  • 5G will also be using something called massive mimo. Or massive multiple input multiple output.

  • These are basically just groups of antennas that are listening and broadcasting the same

  • frequency bands. This would cause interference, but 5G is also looking to use beamforming

  • which will allow the antenna to aim at your phone instead of broadcasting the signal in

  • all directions.

  • This coupled with the fact that higher frequency waves can carry more data means 5G is reaching

  • speeds of up 1800 Mbps in the US.

  • Higher frequencies can carry more information because we are encoding our information into

  • the wave cycles. Our measure of frequency is hertz, but all 1 hz really means is that

  • 1 wave cycle is reaching us per second, 10 hertz means 10 wave cycles are reaching us

  • per second. 190 Megahertz means 190 million wave cycles are arriving per second. Because

  • we are encoding our information into the wave cycles, that means we can encode more information

  • into higher frequency waves.

  • Up until now we have been using frequencies between 700 MHz and about 2500 MHz. So 700

  • million wave cycles per second to 2500 million wave cycles per second.

  • 5G however is looking to use frequencies as high as 90 GIGAhertz. That's 90 billion

  • wave cycles per second. A major step up.

  • 5G will allow higher download speeds and lower latency. This will be huge for time critical

  • technologies like self driving cars that require rapid communication between vehicles in the

  • network and allow even more devices to join the network. To create the internet of things.

  • 5G has a lot of potential, and no it's not dangerous.

  • The electromagnetic spectrum starts on the far left with gamma radiation, which has very

  • high frequency and short wavelengths. Higher frequencies and shorter wavelengths equates

  • to higher energy, and indeed gamma radiation does cause cancer. Anything over here you

  • need to be worried about, that's ionising radiation. Meaning it removes electrons and

  • damages things like your DNA, but 5G is operating all the way over here towards the lower energy

  • frequencies. Yes, past visible light, which last time I checked no-one is afraid of.

  • Yes, like visible light and microwaves it's possible to cause heating with high enough

  • powered beams of these wavelengths. This is the only non crackpot theory I can find on

  • 5G that actually sits in the realm of plausibility. The military even used high powered 95 GHz

  • beams in their active denial system, which just made the people on the receiving end

  • feel like someone just opened an oven door in front of their face and it could burn people

  • if exposed for long enough. It's uncomfortable and was intended to disperse crowds.

  • This was essentially a focused beam of 95 GHz light, akin to a massive magnifying glass

  • to focusing light to burn a piece of paper. Because yes, just as visible light can be

  • used to cause heating, so can these wavelengths when used in high enough power and intensity.

  • As we said earlier these frequencies are blocked by rain and so they certainly can't penetrate

  • your skin and these transmitters simply don't have the power to cause heating that would

  • be damaging. They are just simply too low power and there are plenty of studies that

  • show that they are not harmful. If you are afraid of 5G in this way, you might as well

  • be afraid of the streetlights because they emit higher energy frequencies.

  • Every day technologies like this can seem like magic until you peel back the layers

  • to their earliest iteration and see that they are just the product of many years of problem

  • solving with each successive generation adding more complexity. If you would like to learn

  • more about the whole electromagnetic spectrum, including which parts are dangerous and which

  • aren't, you should check out Brilliant's course that unravels the physics of Waves and Light.

  • Inside you'll learn things like how light can exhibit particle-like and wave-like behaviours,

  • how much energy electromagnetic radiation can carry, and even how to measure the speed

  • of light.

  • You can set a goal to improve yourself, and then work at that goal a little bit every

  • day. Brilliant makes that easy with interactive explorations and a mobile app that you can

  • take with you wherever you are.

  • If you are naturally curious, want to build your problem-solving skills, or need to develop

  • confidence in your analytical abilities, then get Brilliant Premium to learn something new

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This episode of Real Engineering is brought to you by Brilliant, a problem solving website

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