this is a 5G phone tower and I'm going to explain why 5G data is so incredibly fast and I'm going
to explain what 5G actually [Music] means I mean that bit's easy uh the five means fifth generation
that's what the capital g means generation so all these things 4G 3G Etc it's just the generation
we're up to the capital G is meaningless it's about as important as the capital G in the
video ID on this video what I care about is the fact that this Tower behind me is putting out
well photons it's putting out radio waves and that's just a standard kind of sine wave but
somehow we're able to encode data at incredible rates into just waves well how is that done okay
spoiler it's Mass it's always Mass it's actually trigonometry in this case and bonus spoiler I'm
currently writing my next book and I think this is technically the official announcement of that
it's why I've got writing a book face uh I'll have a link to pre-orders in the description
more details about that at the end of the video Welcome Back everyone who went to check the video
ID to make sure it did have a capital G of course it does so we're now going to have a closer look
at these waves because if you've got a sine wave there's three things you can vary you can mess
around with the frequency you can mess around with the amplitude that's kind of how big it is and you
can mess around with the phase that's where it starts and we're going to ignore frequency and
amplitude and we're going to focus in on messing with the phase because we can use that to encode
binary data all right give me a wave there it is right so this is our signal wave that's what's
being sent by the phone tower and we're going to split it up into individual wavelengths and
we're going to send one bit of information per wavelength and by bit I mean a one or a zero
they're currently all set to one but what we can do is decide if we're going to send a zero so we
switch that one to a zero it flips the wave the other way up and so what you do now is you take
your message of ones and zeros you have the ones and zeros across the top and you flip the wave
each way depending if it's a one or it's a zero I say flip it's a sine wave what you're actually
doing is moving it across half a wavelength so we've actually got some bits of the wave are
unchanged those are the ones and some are offset by a phase of half a wavelength and those are the
zeros we call this key of information by Shifting the phase phas shift keying in this case binary
phase shift keying because we're only sending ones or zeros but what if we had different amounts of
shift what if we wanted to send up to four options quadrature phase shift key we're going to switch
each of these now to be either z01 1 011 but now we need four different phase shifts so what we're
going to do is have them each a quarter of a wavelength apart and this works this is how
phones way back in the day when there were so few G's used to send data but now we've got more G's
we want to send more data so we need to be able to have more different phase offsets and you're
right we could just split each wavelength up into more and more different offsets but what if we did
bring back our friendly amplitude but what if we bring in some more options so yeah I'm just
I'm inside a giant Georgia profile by the way and now for each of our code words that's what we call
just each string of ones and zeros we want to send for each code word we can assign different amounts
of phase change and amplitude change and if we mess around with these you can see the things
we're sending change and yeah well hang on surely there's a really clever way to adjust the phase
and amplitude for each code word to make them more efficient to send and maybe if we pick just the
right values we can have more than four we can go up to 16 wouldn't that be amazing but there would
have to be some very clever values and probably that form of encoding would have a whole different
name quam of course someone's worked out how to do more it's quam quadrature amplitude modulation and
you can do this with different numbers of code words here's the case for 16 code words this is
called 16 quam so we got four bit code words now and these are the various amplitudes and phases
you need to send those and people very carefully worked out exact what combinations of amplitude
and phase work the most efficiently but if you look at it it looks like a mess and this is where
we need a better way to kind of think about and visualize these phases and amplitudes here I am
with the geile I've got a single wavelength that's what we were using to encode each code word and we
were shifting at different amounts for each code word and as you can see it's a sine wave so it
goes from 0 to 360° that's when it's it starts repeating so in fact we can measure the amount
of shift the change in Phase as an angle and you know what else you can measure with angles angles
so on the side over here I've got a that I can move around as I change the angle a is making
to the positive x axis it changes the phase so whatever angle goes up to a is how far we've moved
the sine wave and so before we were encoding uh one we were doing one bit there and then at 180°
over here we were doing the other bit in fact I can turn uh that on so we can see it so there's
we encode a one there we encode a zero there but you can also see that now amplitude is built in
if I move this closer to the origin the wave gets smaller further away it gets bigger we can encode
more data points which is why when we were doing for code words we had them like weirdly spaced out
with 45° well actually 90° between each pair cuz what we had here is uh code with 0 Z's up there
and then 0 1's down there and then 1 Zer and 1 one now these are technically all on a circle they've
all got exactly the same magnitude and what we started to discuss was could we have other
points where we're changing the both the phases an angle and the magnitude is the distance from
the origin to encode different words and you can the 16 I showed you before here is 16 quam and
look at them they form a grid how incredibly cool is that so if you want to send 11 one0
that's the phase and amplitude you send there's 0111 and so on so you can pick all of these out
because they're spaced out if there's any you know wavering in the signal when it's received
by a device like if it receives one over here it just goes to the closest one it's like that the
code word and so by plotting these on a phase amplitude diagram it makes the arrangement so
obvious suddenly we can see all the logic behind why we have those phases and amplitudes and we
call this a constellation plot check it out 64 quam isn't that amazing it actually goes all the
way up to 256 quam which I'm not going to draw here you know what it looks like it's a lot of
dots on a grid and this is why 5G is so fast it's using quam it can still use the old face
shift keying it's backwards compatible in that regard although it doesn't in quite a clever way
different video but quam is the secret to being able to send so much data so fast just using sine
waves although I may have mildly distracted us with the constellation diagrams I mean I
love them because it's one of those fantastic examples in mathematics where just having the
right way to visualize or to kind of think about something suddenly makes it make sense and the
constellation diagrams are so incredibly useful but we started by looking at adjusting phasee
and I had said we're going to ignore amplitude and we gradually brought amplitude back in again
however it turns out phase almost a distraction it's actually all about the amplitude it's all
about orthogonal amplitudes here I have two sine waves which are 90° out of phase and that's why
we call them orthogonal waves if you just look at the waves you're like how is that orthogonal well
what do we call things that are 90° apart they're perpendicular so which is why this level of phase
difference is called orthogonal waves and you can see on the phase diagram over here why that's the
case cuz a the phase is zero and then B is up here and of course we can move them around as
always but if we plant them on zero and 90 and we only change the amplitude we can actually
get every conceivable other combination of phase and amplitude by adding those two together so if
I turn on the sum of those those two waves in green and now all I do is adjust the amplitude
of a and b so if I bring amplitude of a down and up if I just mess with these I can actually get
that Green Wave to become any wave I want and we have to use negative amplitude is like phase the
other way around totally counts so by using positive and combinations of these two waves
which are orthogonal to each other 90° apart we can generate any wave and this is how quam is
actually encoded you're actually just using the X and Y coordinates of each of the points you put
one of those into each of these waves which is a sine wave and a COS wave you add them together
and that's what gets transmitted from the tower and now for the final bit of plot it's this plot
so this is our 16 quam arrangement of the code words when I first saw this I was like why are
they arranged like that so I looked into it and and they're using something called a gray code
and a gray code is a way you can go from any code word to any other code word and you only
ever change one bit at a time and they're arrange such that all of those gray code Transformations
never go through the origin because if you're sending one signal you got to move continuously
to another one and if it goes through the origin that's zero amplitude that's no signal you don't
want no you don't want a sudden loss of signal just cuz you're switching code words and so by
using this Arrangement or other equivalent ones and only using gray code Transformations one
bit at a time you can change the code word you're sending without going through the origin another
very clever bit of geometry which reminds me I think I'm writing I am I'm writing a book all
about geometry trigonometry data Foria it's incredible you should absolutely check it out
and thank you so much for watching this video uh you can also watch that video uh that that's what
Google thinks you should watch that's not on me whatever that is that's up to you uh up there you
can subscribe I don't know uh we'll put a link in the description down there somewhere you can
pre-order the book uh they're hugely appreciated yeah there you go uh I guess we got a bit more