right
doesn't cover that
next week in recitation you're gonna be
doing your milestone two presentations
updating us on alphabet Park A win this
week
remember the week after that is going to
be your mile or your lab five
presentation keep in mind that the
schedule is a little bit different for
those of you who have Tuesday classes for EG 103 keep in mind that next
Tuesday is on the Monday schedule so do
pay attention to that today we've got
professor Knox in the electrical
engineering department to give you a
great presentation on the ins and outs of
Electrical Engineering so please give
him a warm welcome
the department im from, we do what we have
electrical engineering and computer
engineering some students gravitate towards the comp-e
some gravitate towards the e my background
registry also I'm a poly grad the school
was called polytechnic before it became tandon a few years ago but I also
graduated from here twelve so I
have a lot of ike cables and buttons and
things to push so I'm hoping that it
doesn't the long-term disability and
tripping on something but maybe a lot of
live demos today if you looking at
screens and test equipment we also have
a small robot system that's gonna be
running around the lab here my research
assistant Ashton is going to that sort of
operating that that row but we'll talk a
little bit about aspects of Electrical
Engineering
so from an outline point of view just to
get you in the mindset of what an
electrical engineer you know the
tools and the moment that they try to work
in we're gonna be talking a little bit
about signals in the time domain and
then relationships of the same signals in
the frequency domain
and as an electrical engineer we kind
of always have our feet in both of those
domains so we had to be comfortable as
one versus another so some of the
demos we'll be looking at im going to
pull up some invitation we're going to
be able to measure cellular signals
Wi-Fi Bluetooth signals the beacon
project is plugged row quick thing here
I'll describe that in you know in a
little while and then also do an RFID
demo later what we go so we try to pack
a lot into the one hour that we're here but
then we move on and we'll answer these
two questions later but I want you to
start thinking about if you were standing in a
jungle yeah if you had the opportunity to do that it would be great if you want a movie or see something
usually the sound effects in movie in the jungle is very noisy but that really
doesn't take what's going on in the
jungle there's a lot of birds and frogs
and their old kind of chirping and
barking  yeah they're
making noises all simultaneously and yet
with all that happening there are
still able to communicate over
very large distances so one of the
questions would be kind of late so all
we do is in an electrical engineer is
well how's that possible
our role of different species of animals
able to communicate simultaneously the
other question would be and we'll answer this
little bit later but the end is can it's
your keys that you carry around in your
pocket to make communicate like is it
possible that your keys somehow could talk to you
so we will  try to answer
both of these when  move on so first one
is a little bit about time and frequency
domain so what we have here is all the
waveforms  we look at are all going to
be amplitude
verticals so this is the amount if you
think of it like in this case its voice
it's the sound level so how big the
sounds are and the amplitude that goes
for both the frequency and time domain
so the top the top waveform is time so
as time progresses I'm talking right now
that microphone and I put that
microphone on its own implementation I
could see my the sound waves of my voice
guys moving along in time
now I also and most people would be
comfortable with that because we live in
time right you have time always
launches forwarding we have
an idea what time is like but we can
also look at this in the frequency
domain the frequency so frequency along the bottom
here we have low frequencies down here
so this is all your base tones and then
the high frequency up here would be
maybe an opera singer with a very high
voice so so I can also look at those
same waveforms in both time and
frequency so for instance if we look at
that frequency domain
evolution has it that as we sought to
speak louder and louder the frequencies
in around a thousand kilohertz tend to
be dominant
so my guess is devolution is correct we
probably our ears of more sensitive to
around a thousand kilohertz so that we
can hear people far away this is you how
a thousand from evolution but when we are talking in a casual voice is
he amplitude is relatively
flat across the frequency
domain so we take this a little further so if youre lets say
you attended an opera anybody go to an
opera? oh wow some classic people in
the audience did you see I guess the
question is that you sleep during the
Opera
so if you've gone to an opera
you know what an opera is there is a
live orchestra playing music and then
it's the opera singer that comes out and
what opera singers try to do is put this
frequency of their voice higher than the
orchestra is playing now
most of the instruments in the orchestra
are about 800 Hertz and lower so when
in the orchestra plays they were
operating down here in the frequency
domain and when the opera singers are
singing they're trying to get much
higher so that you as the observer you can hear both of those signals at
the same time so this is sort of how you
know we separating things in the
frequency domain which you will be able
to detect at the time domain so it's a
review a few things this is from the
engineering point of view there's as a
function of time than something we call
direct current DC you probably play with
it you're all carrying around DC devices
in your pocket these are batteries so as
a function of time there is absolutely
no change to the waveforms amplitude it just sits there static
eventually your battery is
going to die and eventually this will start to fall off
but over a short period
time is relatively flat and in the
frequency domain again we're going to be
comparing time things that happened in
time and things in either the frequency in
the frequency domain
there's no frequency content there's
nothing changing theres nobody singing
there is nobody playing the piano so all the
frequency is all said that it is zero
Hertz right so there's no changing
frequency at all so what so I would as
an engineer if I'm trying to design
system
I always have my thoughts in both of
these at the same time so so what are
our
DC source is obviously the batteries
truly a DC source there is no variation
over time other than
eventually the chemical reactions start to decay but
although these you are quite familiar
with you probably carrying around two of three of these in your pocket you're always
looking for the plug-in also solar
panels these are actually converters
they start off with a time-varying
waveform like light which is sinusoidal
it's a time varying waveform and they
convert it to DC for you because our
electronics generally works in DC so
it's electrical engineers we design some
of these you know generally a chemist
with design paired with the battery so
let's all get no change over time
things get a little more interesting though if
we look at trying to change time
variation wayforms things that change to time so you'll take
some physics classes and
things that they'll be showing you this as
well this is what's called the
sinusoidal wave form and sine omega-t
you are probably familiar with sine omega-T so in
this case it's again it's time and this
is a sine wave amplitude increases and
then it drops it goes negative and back
to zero and then it repeats so
this is one period of the wave for this
particular example I'm saying this is
point zero zero one second or a  milli
second and I might be interested in this
for a variety of reasons so again time domain
now I can also convert this to
frequency taking the inverse of time so
you're gonna learn this if you have this
already you're gonna learn there is a
intimate relationship between these two
they're inversely related so if I take
the time I just taking one over that I
get frequency units that we use it Hertz
this so in this case this
is a one kilohertz so so we can
hear this our ears are tuned that we can
hear as low as 20 hertz and we can
hear as high as 20 kilohertz and then
generally our hearing then starts to
drop off beyond that now this is there
is some theory I don't think it's theory
that they could well known and dogs can
hear higher of the 20 kilohertz
greater these things called silent dog
whistles you can blow into them and the
dog would hear that but we wouldn't hear
anything so evolution has it for some
reason they are able to hear higher frequencies than
we can but again so this would be
something that we'd be here now in this
case if I look at this that's this
sinusoidal a common frequency here's our
sine way here going up and down and heres my frequency domain if this is a single
sine wave either to see a single tone of
one frequency and this would be from the
previous examples to be one kilohertz so
what it shows shortly is a finish show
you instrument displays that measure
waveforms in time and I'm going to show
you some that measure
waveforms in frequency now today a lot
of my talk has to do with wireless
communication and why are those people
tend to think of everything in frequency
domain they think less about time waveforms
but if you were designing a gaming
computer any gamers in the audience if you were the engineer designing that
i guess you build your own pc you dont buy
like everything is custom built but if
you were designing the microprocessor
your Intel or AMD and I guess you can
argue a game or which processes are
better you think everything at time domain you know you're looking at these
digital waveform moving as fast as they
can between memory the microcontroller
and these ones and zeros as fast as
possible so those engineers tend to
think in time domain and I'll show you
shortly why wireless engineers have to take into frequency domain
so
what would be some sources associated
with this obviously the Sun any light
source that's those the sine waves that
are coming out those sine waves
have to be very high frequencies and our
eyes can capture those these other
devices here obviously you know they
either the wall socket that's a 60 Hertz
sine wave that comes out this in history
why that was generated to be 60 Hertz it was to test this Function generator
have some of these up here as well and
then we'll just look at your radar
system a little bit later and then
cellular base station which is how you
get all your Instagram or Facebook it
was my generation of myspace anybody know what myspace is? anybody use myspace?
coming back bringing it back? no
some pictures somewhere out there with
me all right so let's look at a base
station so so I've been generally kind
of a hint you know how do all these
animals communicate at the same time
when you're making a cell phone wall
they want it to be as fluid as
this now right now I'm doing all the
talking
you're really not talking but if you're
having a conversation with someone it's
it's kind of flexible loop lecture
interrupt each other you want that it's
a natural flow communication so they
wanted that with the bland wine tones
which you know you have a landline phone
and also in celluar and how do they do it
in cellular is they essentially split
the frequencies into two separate them
so in this case when you make a cell
phone call or it let's just say cell
phone call it this way because it is
someone talking you can talk you're
assigned two frequencies so one frequency
is somewhere in the band of the other I
call the uplink  and there are some
frequencies in the downlink
so they're actually assigning you two
separate frequency between the first
register to make that phone call
and what they're trying to do is they
said well we we know we can't
communicate on the exact same frequency
because what we've knock   we'll
interfere with each other so we'll put
the call from your phone to
the base station the uplink in one set
of frequencies and we'll put the call
from the base station to you in a
different set so that allows full-duplex
allows us to simultaneously communicate at 
the same time so this is where it's this what a electrical engineer would use
one of our tools is see we have a lot of
one of our tools is that when we have a lot of frequencies let's split up frequencies
in different places so now another
thing is that this is a cellular
application so here I am in this cell
and right now I'm communicating to this
base station
in here and I'm hoping along the street
or I'm driving my car I only have so many
frequencies available as I make this
motion going to the adjacent base station
there's some a process called handoff
pretty seamless to you  one base station
hands your call off to another base
station a lot of times you don't even
know what's happening and now you're
reusing those frequencies again at the
adjacent base station
so but not only can I use
frequency to my benefit I
can also  space physical distance to
allow me to then reuse things that I
used before
so this is how a cellular system works so
we'll do the the first demo let's see
there's a lot going on here with
cables and things so let's see how we
know this will work out so what I'm showing you now is a an instrument called a spectrum
analyzer and what this does is measures
frequency along the bottom axis and
amplitude in the vertical axis
don't break okay there it is so you can
see I'm along the bottom right now it's
just a noise bouncing around at the very
bottom and its gone
okay so again so north so frequency along the bottom and all right you see this
so one more time
I don't I don't want to speak because
I'm afraid by screechy voice all right
so we may have to come back
alright I'm gonna try then we will to
another piece of equipment and hope for
the best maybe that one did want to be
friendly today
okay it's a little bit better so all
right that looks good
hold on for a second one of
the back things set up the the next demo
so skip it over the the cellular level
per second we'll see if we can get back
to it
and go back to the slides I want to set
up the robot control up here which is in
excellent alright so so what we have
here is um my Rover it's when you first
look at a robot a first impression it's
not what's this mechanical engineering
right this is a mechanical engineering
project and part of my pitch today is
to show you that there's a probably a
lot more electrical engineering in the
small Rover than there is in the camera
a lot of students come to Delhi handle
easy these robots show new robots as a
career and I would argue that yeah you
could also be in the robot business
making electrical engineering as well so
the setup here is is up this Rover his
job is to find one of these two beacons
now what I did what's in the beacon is
they're making two different frequency
sounds one of them is the 5 kilohertz
tone and one of them is an 8 kilohertz
tone now we go off here this is the
frequency range in here we're gonna be
able to hear those two tell me and the
robots job is to go to the five pillar
right so so we're gonna in a few seconds as part of the demo we will turn the rover 
on the rover's job is to listen with its
internal microphone and try to identify
which was the 5 kilohertz beacon and
then drive to that one and stop now
we're on it we're unsuccessful I guess
we'll get the net for the class or so
it all relies on how well she does
today on this robot demo and
then what we'll do also gonna show some
some slides so I'm gonna show you a
little bit what's in the robot and then
we'll look will then actually see if we
can get this to work so here's why so this is
this is the circuitries electronics
that's in the rubber to make it work
so one thing we have is the is this the
structure I call it the cone if there
was a 3d printed device the kinda narrowed
the focus of the sound waves being
captured we didn't want just the
microphone capital all the sound because
without directionality we have no idea
where the sounds coming from we actually
as a human we do a great job we have two
ears and we have we can, our brain can
detect slight delays in the same sound
in each ear so we can kind of know
directionality but this robot only has
one ear effectively it has to try to
find something so person who puts this
3d printed cone the sound wave comes
in we have a standard microphone now a
microphone is a converted device it
takes the sound pressure wave to bring
it to an electrical signal then the
attendant robot captures the electrical
signal sending it to a small Arduino type
microcontroller in this case it was a
teensy the teesiest of brains of the
operation
it measures this signal and also at the
same time sends out has an ultrasonic
sensor it's constantly looking not to
bump into things we don't want it to
crash into these beacons
it gets close to it it's supposed to
stop so this works as a mini radar it
sends out an ultrasonic signal and that
we can't hear the sensor associated with
here but there is a 40 kilohertz 
signal that bounces off the object
comes back in that's captured by the
team teensy it's listening it's
measuring its environment with
ultrasound we've got some cool lights
blinking on and off kind of just tells  us how
things working and then it drives the
motors so that as it moves around it's
kind of changing its direction and it's
using that cone kind of probe the
environment and it's looking for the
loudest signal once it pointed it then
drive to the direction towards that so
all of this the motor driver it's a
board that sits on top of the
microcontroller and the motors
themselves all designed by ease so so
the structure of the device I went down
playing the mechanical engineers in here
but the structure device and how much
weight it can support those things those
that would be mechanical engineering
design but also the the the I was almost
using appeared intelligence but then
again I'm down playing with my
mechanical engineers I don't want to
install the SI am i insulting you
there's a lot of intelligence is the
mechanical stuff but be like things in
time toss them - how cool is something
but anyway so this is so all this stuff
again is all designed by by computing
system now the beacons themselves all
these are just oscillators and they just
have a small speaker and then just beeping
it out into 5 kilohertz or 8 kilohertz
and then again then the buzzer come down
and then this is this is what to choose
to identify which is it to be going into
this demo it is one we got our equipment
screen back on the two beacons  are
to the flash one's going to flash 5 kilohertz
ones going to flash 8 we have a microphone here
we're going to put all of this into an
instrument
that measures amplitude as a function of
time and we're going to see you know the
robots gonna do its thing we're going to
talk a little bit about the waveforms
and you know we'll  have you decide if Ashley
actually gets an A or an F at the end of
the demo so not too much pressure on you
so that I'll be able to asjust this
yea we look good
alright so the three way poems you're
looking at this is time time is marching
on the upper waveform and i think it was oh okay there it goes
the yellow waveform is all on one channel so what
we're seeing is amplitude changes when
that beacon is on you're seeing ithis burst of signal other words this is all this
is the first 5 kilohertz beacon its
energy is here and then it shuts off so
you're hearing it on here too often if I
all say quiet per second you give these
two beacons going back and forth
the green one the green one here the
lower one that's the other beacon that's
that's the burst of sound at 8 kilohertz
and what we're seeing down here is the
blue one this is the microphone now the
microphone's also picking up you know
your your background noise me talking so
right now it's kind of messy but so I'm
going to be quiet while the robot does its thing
so I actually going to turn on the robot
and it's going to now scan around
it's job is to look for the yellow
signal at 5 kilohertz and drive over
to it and stop when it finds it so we're
going to, ill pause and we'll see if it
works
we did it! (applause)
much smarter than I t so so right
now I mean if you listen you can kind of
hear like with all the intelligent of the brain you can kind of hear the two
different tones right ones a little
louder than the other one and because they are
separated in time as an
engineer this is a trick I can perform I
can make sure that only one beacon is on
at a time when where's a synchronized our system that only one is on so if
you've been on folks I can have one of
you to come up with you can kind of hear
the one I can have you walk over it and
it would work that you would be able to
do that and that's and right now it's
easy for the robot to do this in time
the question is what happens if I lose
control and the two beacons are not
connected in any way and they just
arbitrarily just start beeping there's
a chance that the two of them can line
up and then we can have possibly have an
experience it's going to definitely be
harder for us so that pulls onto that mode
now you don't have to have the robot go
but I just want you to recognize this
other moment so now both of them are on
at the same time now I'll have to listen
to see if you can tell me is there two
signals now aligned and you know it's
it's because they're pretty close on
frequency yeah I know it anybody back there hear it?
this spool two happening at the same time
or so so much harder to distinguish
right to have that now for us it might
sound a little nicer having the two
tones that's really Channel playing and
guitar you know it's usually
many frequencies together it's a little
more pleasant but for the robot how is
the Roobot gonna figure this out like it
it sees its microphone captures both at
the same time so here's where we an
engineer would move into the frequency
domain let's see what happens in
frequencies and see if that would
actually use it to help the robot so I'm
going to pull up another file here so I
had saved in Sherman states here go go
back to the other boat first
so in the previous moment we're only one
is on at a time and what we're looking
at here at the perfect display is this
is frequency now it's no longer time
it's frequencies and it amplitude
the first moment or only ones on at the
time so you can see frequency hopping up
the frequency here at 8 kilohertz this
is high frequency is an 8 kilohertz and
this is 5 kilohertz so you can see there
pop pop and back and forth now let's go
into the modeof with a simultaneous
both of them a popping up at the same
time but I can decide the electronic
filter and I could filter out the 8
kilohertz I can actually have a device
that removes this energy and I just
focus on this enemy so what we're
looking at here is something that the
mathematical formulation or the fast
Fourier transform
it takes time wave hogs and very easily
mathematically changes them into
frequency and then I can give this to
the brains of the outfit the
microcontroller and say you know what
you now filter out and just don't even
think about game
one only focus on the 5 kilohertz and
use that to drive here for few pointers
so ok so I think we're good with that
one oh yes you can get you publish it a
little down
so let me switch back to presentation oh
you're gonna do this with frequency
table
just quit while you're ahead alright you could shut it down i appreciate that
so a round of applause so going back to that question i asked you earlier
in the jungle how to they all communicate?
so essentially what evolution is done as
they set different bird species and frog
species at different frequencies so they all chirp at different frequencies
like this is our earlier where we had to
beacons sort of simultaneously
transmitting birds are tuned in and
only listen to their own species and they
separated out is evolution has
them all sort of assigned to different
places the frogs are on their own frequency
certain birds have much higher frequency
chirps sso that's how we're all in
community or they are able to
communicate simultaneously the other
thing so they so they're really up you
know so as an electrical engineer we're
kind of leveraging what evolution has
already figured out for us but we use
the same things so what they do leverage
is a time they could I'm sure two birds
are talking to once one bird chirps
here i am here i am im looking for a date this weekend and the other bird says
says yeah not available and I'm attached
to someone else check my Instagram right
so I cuz I can do this in a time  obviously if you frequency
mentioned everybody evolution has them in different onces
but also space you don't necessarily
have the same species of different
places I'm sure there's some species
that migrate it to the very tops of
trees some reason maybe to get away from
all the noise and obviously the frogs
are way way down they also use the same
technique so this is all available to us
so let's go back let me go through these
slides and I may have maybe do a study
about me to try to get back that
equipment again but let's look at them
another way to communicate so right now
you will have active transmits the
question at the time when you're you're
asking for a website when we making the
phone call you're sending a signal out
you're actively sending sine waves out that have
information encoded or modulated onto
those  sine ways and that's how you were
able to communicate by just sending out
an active transmit but radar works
slightly different radar said you wanted
it send out a signal I'm gonna let it
bounce off my target and my own signal
eventually going to return to me and I'm
gonna measure to that to that signal so
it so in this case the in this case I'm
showing a plane it definitely a passive
transmitter it's not trying to
communicate it just happens to be metal
and anything that bounces the energy
that bounces off of it just return back
so that would be a good thing or a bad
thing depending on the application so
again so I can communicate this by
what's called reflected signal
reflective communication so one of my
favorite movies is James Bond
now I'm an old guy so I'm the I'm the
Sean Connery James Bond
Sean Connery's Daniel Craig you know
Daniel Craig yeah we know Sean Connery
okay so so so
the earlier Bond movies I don't think
Daniel Craigs too cool for this
but the earlier Bond movies
Bond would walk into his apartment and
the first thing we do is to pull up a
little device and he carry it around and
he's looking from what's called a bug a
transmitter right so essentially
it's like the equipment I have up here
in handheld form he's looking for energy
being transmitted these are essentially
its microphone somewhere in the room cuz
he knows who that  the enemy's
trying to listen in on it and of course
they gave them the one hotel it has the
bug where is it usually a
up high in the lamp if it's the only like
as it nobody would look there so in that
case that's an active transmitter so
that so the bug the device itself is an
 antenna as a transmitter or a
microphone and a battery and it is
sending out sine waves into space and all
Sean Connery with the double of
seventies is a receiver and he just
measures that energy and says oh yea the bug is there and takes it out
well this one was from From
Russia With Love that's where the image
came from Italy usually dropped it in a
glass of water you have something to get
rid of it i dont think he flushes it down the toilet thats uncool
so obviously so the transmitters so now
with an ounce take it to the real world
so
spy situations happen in the real
world so something look at this device
here this is this this plaque that was
given from the Boy Scout acquittal in
and Russia they had given it to this
embassy in Moscow so that was a building
created in Moscow the United States and
after World War two and we still have them 
they were called ambassadors they send
them to that country and and this
individual stay in that country and then
report back negotiations and things so
so of course at the time we knew about
these active transmitters im moscow they said oh here you go heres
new building move on in I'm sure the
first thing they did was just like like James Bond
they looked for bugs they look
for transmitters because I'm sure
Russian would just love to hear the
communications between the US ambassador
and the president at the time so so
here's this device it's a carved wooden
plaque they checked it out it was not
transmitting energy at the time look
perfectly safe and it hung in the US
Embassy in there dead for seven years so
again not transmitting anything at least
when they check it it was actually
pretty ingenious device inside and not
an active transmitter there was still
microphone and there was an antenna
device so how this works is the it's
sitting in of the u.s. ambassador's
office across the street the the Russian
agents turned on a transmitter the
transmitter was pointed across the
street to the u.s. embassy the energy
bounce off of this thing and vibrations
of the microphone inside reflected
energy back was like a mini radar but
they didn't know what was happening so
anytime you come in and you try to see
if this thing is sending energythey
just turn off the department ones across
the street just sit there have some
coffee soon as they leave or all the
equipment they turn it back on so wasn't after seven years
that they finally bust this thing open
and they found this very unique device
very inside so the device itself sits
down if you're interested in spying
things there's a really cool museum in washington dc called the spy museum
here and this device hang in there that
actually have it turned around so you
can see the back of it and how it was created
the engineer the time that created it
was this individual theremin you have
anybody know what if it Big Bang Theory
the main character played some musical instrument
so so the theremin is named after the
inventor of that musical device but he
also invented this thing as well so
Tariq so again if I can use reflected
energy as a communication you and you
actually everybody here I assure you all
have a reflective communication device
you carry one around with the Russians
in put there so no stop
running out the door but if you did
anybody know what it is yes what NYU ID
exactly right that's what's called
an rfid tag this thing does not transmit
energy we're not tracking you all the
time
the only when you come close to the guard
comes and you hold it close to the guard
door the energy from the guard door
lights this thing up then a little thing starts to
a reflect energy back
and essentially tells the guard that
you know I have the ID  and then the ID is sent to the
databases you know I guess
taking billing out of when you should
come in so okay that's that's an RFID
nuisance so I'm gonna bid there now is
I'm going to try to switch back to to my
demo with the equipment the other
instrument and see if we can kind of resolve
the issues
okay what was afraid of dog at this
point
it's like you like Bill Gates in the
blue screen of death
yeah
im going to try one more thing
okay maybe alright so so what we have
set up here is a an analyze that device
called the spectrum analyzer so what the
spectrum analyzer does is it measures
amplitudes and signals as a function of
frequency so I'm actually I'm backing up
I'm going to go to these to the early
part of the presentation just to start
it off then I'll show you an RFID tag so
we're looking at here is along the the
bottom axis is frequency right now the
center frequency is 915 megahertz and
I'm looking at this slightly around that
right I don't see anything over there
just see some noise bouncing around so
the signal is pretty clean and what
im connected to here is I have a
sine wave generator that's just sending
out a single tone single sine wave at
915 megahertz is 915 times 10 to the 6
hertsz sine wave so it's a very rapid sine
wave then is amplified and sent down
through this device here this is an
antenna that's just sending energy out
in this direction so so I'm going to
turn on to the sine wave so as we showed
earlier a single sine wave just shows a
single pump it's just a spike straight
up and the amplitude , thats how strong
the amplitude is now where it's being
received from this is my transmitter
an active transmitter without the RFID
yet it's being transmitted from here and
it's being received on this device this
is called a horn antenna this is very
directional it's capturing energy kind of
like the cone of video there over here
it's capturing energy only in a cone so
it's a once ou see energy in this
direction now in this case I pointed
over here I'm still seeing energy because
this is kind of bouncing around the room RF
energy bounces all over the place are at
the radio frequency this is what I'm
calling this frequency but if I turn
this directional antenna towards that
one you'll see the amplitude pop up as I
get closer to this one so I could use
this as a form of direction-finding and
see the signal is getting
bigger so as I get closer it gets larger
and larger because I'm capturing more of
this energy again if I point away even
with me standing between the two I still
have some energy because it's bouncing
off the floors the ceilings you're
absorbing a lot of the energy on them so it's much less
much much less amplitude runs again
this is an active transmitter this is
the receiver
so the pointed RFID let me I'll back up
a little bit and we'll look at cellular
signals so they think it's some cases
those those are that are interesting as
well so let me just turn this one off
so so this is this same antenna will
allow me to capture those cellular
signals as well as a lot of cell
signals in here for the most of you
can make a phone call right now if it'll
work and what you're seeing here are the
different uplink and downlink frequency
bands so it's two small markers here as
you can see these is a marker one and a
marker two - these are the cellular bands
for the uplink and every once in a while
you see something somebody's something's
peeping up in here so I'm popping out of
the noise this is all the noise floor
the instrument so anything above this
level is a measured signal so I'm seeing
some stuff popping up this is the uplink
that means someone in the room is
probably texting someone so I get so big
brother's watching so should i walk around and see if i could find it
so 1 to 2 is the uplink oh so now everyones getting involved with this right
now and then the frequencys at the marker
here 3 to 4 you see this is one for most
of the time this is the base station
energy so somewhere in this community
with several basestations we're here
probably the closest one is what when
measuring base stations tend to transmit
all the time because it's talking to many
many users not just the ones in this room
but there are other users outside out
the atrium and buildings around so you
see there's a lot more base station
energy in the downlink and occasionally
someone's doing something in the uplink
somethings happening if we'd actually
make a phone call and stay on the call
this would be more steady you would see
 you see a signal pop out of here
and stay here this is very bursty so it
is something quick it's a request for a
web page it's a iinstagram photo upload or something happening
very quickly work to MySpace and
maybe that's a myspace upload just
the old guy in some room somewhere but
that said that's so this is the cellularband so lets look at some of the ones youre mostly interesting in because I
don't think any of you actually make a phone call have any of you made a phone call
a smartphone oh we had a couple people
all right so you called your parents right
I need no money right then you guys
better than
I think that's probably better than a
penny so let's look at tWi-Fi
and I think most of your activity is
sitting up in the Wi-Fi bands so this is
the Wi-Fi band actually just changed
the frequency and instrument I said why isnt anyone interested in cellular anymore let's move to
the frequency of the bubbling of Wi-Fi
Wi-Fi it's higher it's 2.4 gigahertz 2.4
gigahertz a 2.48 gigahertz so that's
what we're seeing here see the
instrument setup the 2.4 and then over
here is 2.4 8 5 
so that's the frequency fband that's been
assigned by our government the Federal
Communications Commission is assigned
these frequencies to the Wi-Fi there's a
lot of activity here so this actually
might be more of your Wi-Fi
communication and then this some stuff
going on it's all very bursty because
most of this is data and these bands you
only allowed to transmit very quickly
you only have less than half a second
you have to turn off your transmitter
let me try one thing see if we can sort
of detect the maximums assume we can
start to identify you know over a period
of time now in capturing hold of maximum
amplitudes and there's a lot of activity
here you can see then sort of this big
blob up here there's another one here
this is the Wi-Fi when you send out an
energy you're sending out a lot of
frequencies at once but don't do it for
very long so that's this you also see
these small little spikes here these are
Bluetooth signals white white Bluetooth
coexist in the same frequency band and
they it's been designed that they don't
interfere with each other
so this is Bluetooth a lot of you have
smartphones that they have your
Bluetooth on though most if you probably
turn that off to the battery
consummation but that's whats happening
here so this kind of a mix of Wi-fi and bluetooth at the same time so alright let's
believe that so let's go back to the RFID
let's go back to to the RFID case any
questions on this side anybody got any real general
questions you can scream out nothing no
these are the best yeah I know that yes
I heard
I'm sorry oh yes so so where is about
research along with connectedness to do
the research at the NYU wireless
NYU wireless right now we are looking at 5G
Idaho and are carrying around 4G phones
when you look 4G showsup on your
phone so I was trying to decide whats the next thing you know to
me the next generation is always more
bandwidth you know more data I want 4k
YouTube to strieam to my phone
well you can't get that with LTE 4G so
they're trying to say well how could we
do that with 5g so that's the the big
picture specifically its 5g research I'm
doing something called specifically more
full duplex communication
remember the uplink and the downlink
example it with two separate frequencies
everybody make a phone call
you're really using twice the frequency
resource every single bit of frequencies
is spoken so if you're using twice is it
possible that you can communicate both
up and down at the state frequencies
without interfering with yourself and
that set which might right now that
you've been the trust in my research but
you have to talk if anybody's interest
stop up and we can talk with you more
specifics all right so let's look a few more minutes left let me switch back
to the RFID example in this case of
course I got to switch to the other and
you trim it again so give me a second
decision see this one works seem to have
much success with the time domain you
commit to some reason
oh im sorry was there a question
nothing nope
oh that's an excellent question so the
question was when snip screen 5
gigahertz Wi-Fi and 5g so so Wi-Fi
bands the band I showed you before was a
2.4 gigahertz gigahertz is think what
the frequencies the sine wave is
actually transmitted to the so when you
talk about Wi-Fi at 5.6 gigahertz that
just means that the carrier frequency is
higher so effectively what happened is
you make a Wi-Fi signal you're
negotiating with the access port which
is somewhere here maybe or maybe on the
hall and the access port is telling you
it's better for you to work at 5.6
gigahertz it's essentially moving into a
certain frequency to communicate completely
unrelated to 5g the g I mean they are
both  be kind of confusing
the g 5g is generation so right now
we're at the fourth generation of
cellular technology 5g is the fifth
generation so it's really just usually
like a decade to do things about ten
years during the cellular so I'm old
enough I lived through 1g which was
the first cellular system we just
essentially carried the mobile phone
back in the 80s was essentially a suitcase carry around another suitcase with
you and everything was in there it was a
huge antenna that you found on the top
of the car with a magnet and that's how
communicative as time went on
two G second generation cellular
that's when they make the switch to
digital and we've been digital all along
now what do I mean by digital we're
officially voice to taking your voice
we're converting it from analog to a
digital representation that's what's
transmitted is essentially ones and
zeros and then at the back end and I
think those digital bits when zeros I
converted back to analog so unfortunately
live we live in an analog world
let's watch the matrix where they plug
into the back of the headwhich is really
cool right is that that new that's a
digital world I'm not sure but good
questions so I hope that answered yes
question
 
802 11 is a specification
802 ADG the A represents what frequency
I think the a is at 5.6 gigahertz and
the certain tricks the modulation up
there the B I believe that 2.4 gigahertz
that I think the G is also at 2.4
gigahertz so it's just a specific
standard on how we're gonna negotiate
how we're going to communicate I have my
bits I got to send them from point A to
point B how do I get them there and it's
just you know how I take those bits
put it on to the sine wave is it this
really in effect but it is a great
question
all right so I'm switching back to the
keys I have another question right so we
did the birds I have one more question
for you we still have about 8 more minutes
all right so where am I wanna make sure
everything's on all right so back to the
CW case before so this is a only 
at 915 megahertz sine wave there's no
information on it
it's just blasting out of this white
antennae here and sending it into the
environment so right now it's working
effectively like a radar I'm gonna
target the the energys coming up off the
antenna and it's bouncing off my face
seeing some change as it has came around
because I'm changing my distance by
heading to going they see some changes
so here was the question about
the keys so can keys communicate so
obviously they can communicate like have
been transmitted in this case sound
pressure waves so it's sstill
the sinusoidal waveform and you can hear
that that more interested from an
electronics point of view how do I do
this wirelessly so this is we're going
to go into us all the backscatter mode
I'm just gonna dangle the keys in
front of me is the transmitter and it's
going to receive it of the same one and
you can see some pretty fast changes
here where and that doesn't look like
data but if I was to jiggle them at a
certain rate I could represent ones and 
zero that I do this so so this so you
can so the answer to the question again
yea keys can communicate sort of
but the more interesting thing that
was really let's look at
rfid tag
so this is the things you're carrying
i think someone pointed out smartly that we all have RFID tags with
us so if I have another one here the
tags that you carry are designed for
lower frequencies so you're carrying a
tag that has about 125
kilohertz sine waves and some
communication as a result of that you
only hit distances of a few inches which
means that you have to get pretty good
to get your tag pretty close to the
guards black box to get that things that
actually beep successfully going I know some of you
probably like it's close enough
no beep I'm in I think they're fortunate
some of the guards
you know they're checking Instagram
but this is this particular
tag here and a much higher frequency
using the different types of antenna
structure now and I think it tag read
that is about five feet or 10 feet and
that would be great because that means
you can just walk into the building and
if I use this technology I can actually
read your tag in your bag in your pocket
in your wallet you dont even have to take it out
 
so if I if I push this in front of the
system we should start to see digital
data so they so so what you're seeing
there are zeros logic zeros sitting down
at zero volts at low amplitude and
the logic ones are sitting up much
higher I can zoom in on here so you can
see there are you ones ands zero so every
time you see a pulse that  represents
a 1 and a 0 I can scan to this you can
see in the beginning of the second
series of numbers ones and zeros and
then I can scan through and you can see
that there's bigger changes going to the
end so we're seeing here out of this
particular code there's 128 bits I could
change that those 1 to 0 420 ones and
zeros into a number and then I could
associate the number with 
whenever I catch this - so this is you
its called UHF RFID it's really good
application for this
Walmart  most of you shop at
Walmart when Walmart gets a delivery of
product to their warehouse ten years ago
someone had to come with a handheld
barcode scanner and scan every single
box that's let's say on the pallet that
the falklands is bringing in off the
truck every single one was to  scan it
was scary
Walmart is all about low prices as you
know in terms of a interior
the commercials as we have the lowest
prices well how do they have the lowest
prices they come up with technologies
that effectively remove the human
element how do I eliminate the job of
someone having to physically scan every
box and what they did is they switched
to these types of tags and now as the
forklift comes into the building of the
truck I automatically read every single
barcode every single ID wirelessly and I
no longer need someone
to scan them so from an efficiency point
of view from a cost point of view that's
that's the
application for this the problem with
this though to replace your your ID
cards is there's a lot of people walking
in the door I would read 10 tags and
it's kind of hard to are there 10 people there or 11 people there its
called singulation i need to singulate down to the
individual that's why we still use the
technology that's much closer reads
that's why we don't want this this type
of technology at our entrances
someone could sneak in with a big crowd
I would read everybody that I could read
the ten that's supposed to be there is
it possible that one can sneak in so
that makes sense so ill leave you with the one last application
another good application for this is the
let's say the supplier and you're
running out the door you're not scanning in
your bed just you're running out the
door if you have one of these in your
pocket I can actually identify that
you're leaving so that if the firemen
come and we have to make sure that
everyone's here but I make sure jack is
still in the bathroom if I don't have
his tag leaving the building then I can
send the firemen in and say we know
jacks hanging out in the
second-floor bathroom
is that true? no its not true no spread that dont post that everywhere ill get in trouble
so thats the application so I'll leave you
with one thing like i said
125 yeah okay so I just want to switch
back into the different types of careers
that electrical engineer can have and
then we'll get you out of here
so let me talk about a lot of different
technologies today
so I'd
appreciate you coming taking the time
not doing too much hosting I'll hang
around here a few minutes if anybody has
any questions about a career electrical
engineering technology
yes
Thanks
we go look at radar
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