hello and welcome to another fantastic
best ever episode no pressure Phil of
EEs Talk Tech my name is Mike Hoffman i'm
Daniel Bogdanoff and with us again we have
Phil Gresock and today we're going to
talk about radar which I'm pretty pumped
about I do have to say before we get
started because one there's probably
more exciting applications of radar to
spend time on but I rented a car
recently out in Detroit that had the
adaptive cruise control
assuming use this radar and at first I
didn't trust it and so I had it turned
on and cruising and I had my foot just
hovering on the brake but this thing is
life-changing every car should have this
technology super awesome
I could be in stop-and-go traffic and
it's just creeping along for me all the
way down to zero miles an hour
especially in Detroit where I used to
live it it could be bone-crushing on the
stop about ran definitely the road
quality did muscle you can pay extra
attention to this podcast while driving
because you don't have to worry about
the crime front of you
exactly watching your YouTube video on
the dashboard so let's start kind at the
beginning I don't know how much of the
history of radar you know my
understanding is actually the original
display for like World War 2 era what
for radar was on an oscilloscope screen
you know I you have to fact-check beyond
that sounds accurate at least you're
being confident when you say yeah yeah
pretty sure was it was like I think he
was some sort of XY mode I'd love to
hear in the comments if you know more
than I do I did a little bit of research
couldn't find too much on it but there's
a great article about like the blip on
the oscilloscope screen when it was bro
Harbor and all that yeah a Raiders been
around for a really long time and
obviously it was I don't say popularize
but used exceptionally in world war ii
especially for early warning radar so
like Pearl Harbor they had quite a few
radars along the islands there and they
saw planes coming they just didn't have
a good way to communicate that yeah so
you know you've heard that if you eat
carrots it's better for your eyes yeah
another origin of that that's actually
an urban legend that's not actually true
I'm gonna guess I was the big carrot
lobby
that was because the original like early
warning radars were yes so no no we're
like top-secret right the fact that they
existed and could see things before you
could visibly see them was top secret
so the British military government
started the rumor that the reason that
we were detecting enemy craft so early
was because they made sure to feed all
their shoulders extra carrots is that
explanation I like it so you know
checking on that but that's my
understanding of the origin of carrots
make your eyesight better his attribute
is radar this is why Daniel has a very
deep distrust of the government and
glasses and a slight orange tinge
speaking of the British though you know
in radar they had a really interesting
radar system that was all along the
coastline called the chain home radar
system and it comprised of I somewhere
in the the teens to low 20s of radar
sites that was all pointed towards you
know their their Western Front and you
know the real reason that they wanted an
early warning radar sorry kind of jump
to that is they had a limited size of
force so limited number of aircraft
their offensive in ships so they needed
some sort of time to coordinate their
counter-attack or defenses so the sooner
they could identify you know friend or
for phone and coming inbound over the
channel then they can make plans and
organize accordingly interesting yeah so
so radar and its emphasis was really a
defensive and information mechanism um
you know to drive certain types of
strategic and tactical actions so
originally as radar the way I understand
it is you basically send out a known
frequency and if you measure it back
then there's something there in a very
basic sense I mean if we're talking
about say a pulse radar we're gonna send
out a pulse in time and if you listen to
our RF podcast that's modulated on a
carrier frequency and that pulse just
like sonar or echolocation of like bats
and dolphins if that pulse gets
reflected back
we know the time we sent it and the time
it comes back so
we could figure out different know how
to bounce it travels yeah
so it was it originally I'm sure it's
not now was originally just like one
town or one pure for you can see that
they checked her how did well cuz you
said modulate like you know you have to
modulate something with them make sure
but I don't know set originally how is
done or so I'm sure something you know
usually it's done at a particular
frequency so lower frequencies tend to
be more useful for search type radars in
early warning so okay it was probably in
the you know high megahertz the low
gigahertz range and they would send out
a pulse with that single frequency on
that pulse okay and see what kind of
characteristics changed when they got
the return pulse back okay yeah and what
is a modern radar look like so I know
that's a big jump yeah sorties but so
modern radars it really depends on the
application
it could be giant radars that are
installed on basically old oil rigs for
early warning systems so those exist and
they move it or there's these old oil
rigs like anchored out in the middle of
oceans incra down the middle of the
ocean with this giant you know basically
white golf ball sitting on top of it
with a radome and inside that
radome they have kind of a big radar
dish that you know spins around or they
move it in different directions to
detect targets that they expect now one
thing I've always been curious about and
if you can speak to this or not but say
we have one of these radar
you know radome some oil that will rig I
don't know what's what's let me say a
thousand miles is like it may be a
typical range of how far away could see
something is that reasonable yeah so I'm
a thousand miles away and in a couple
thousand feet up you're looking at a
pretty low angle that it's to being a
that it's able to detect something you
know and the planes are pretty sharp how
is anything being reflected back at all
but from just from the geometry of the
shapes that it's referring so so a lot
of it has to do with what frequencies
you're going to use as well as a ton of
different processing techniques but uh
if you're trying to go for super long
range and very small object detection
you're going to choose those things to
make sure you can resolve the target
that you're trying to identify but more
importantly you could take advantage of
different effects of the earth so
bouncing off the sea bouncing off the
earth as well as bouncing off you know
the troposphere and things like that so
that signal ends up going further and
bounces back in equal distance obviously
there's a lot of different technical
issues with that you know I'm sure the
ham radio guys that listen will tell us
all about like bouncing oh yeah their
signals to Japan and stuff so it just
really depends how you know when you ask
what that what does the radar look like
or how can you do this or that it
depends well what are you really trying
to do so one radar that's really good
for you know if you're flying in towards
the airport you know say Breckenridge
they might have a lot of wind shear no
you know the pilot needs the point their plane down to take care of this
updraft and then when he crosses a wind
shear barrier he needs to pull up sharp
because you know otherwise he's gonna
slam it to the ground
to identify this year so identify that
wind it's like you can actually I tell
the difference in pressure and that's
gonna reflect some things I've seen like
ocean and you know scuba diving in some
cases where saltwater and freshwater hit
it almost looks like there's like
saltwater river flowing
yeah refresh water rivers going it's the
same same physics I'd imagine so similar
concept you just have this change of
medium that's gonna affect something and
that's what you want to measure that
makes sense and there of course is you
know radars on you know the tips of
missiles you know do enough find its
target that it's locked in on and doing
really fast corrections for its last
phases before it uh its terminal will
say okay yeah so is it you know obvious
so you know there's a couple techniques
that can you go into a little more
detail on those with that giving away
like you know sure yeah so ultimately
with any radar what you're trying to do
is detect something sure so you're
trying to figure out range you're trying
to figure out angle elevation you know
angle could be azimuth you're also
trying to figure out velocity change and
things like that so different techniques
revolve around
how wide of a pulse do I send out like
how wide it in frequency how I'm okay
you know so what's my pulse with is it a
millisecond is it a microsecond okay
what's that gonna do to what kind of
targets I can resolve what kind of
ranges I can resolve so the targets add
a thousand miles and if I send a really
long pulse and it starts being sent back
is the next pulse I'm gonna send out
start to interfere with that sure
versus do I send out a really short
pulse a like a microsecond or sub
microsecond where I have a lot longer
dead time before my second pulse comes
out so I can listen longer to for any
reflections that may come back so that's
one thing to make sure that you have
good range resolution sensitivity
azimuth you know if you just think of a
spinning radar mm-hmm you know you know
what direction you're pointing so you
can reduce that elevation same kind of
thing you know usually it's a physical
attribute of the radar or the elements
they pointing for velocity you know
you're gonna send out a pulse with a
certain frequency well based on Doppler
shifts that kind of if you think of the
classic highschool physics example
you're standing on a train platform and
the trains coming towards you
hears it sound yeah you're pitched or
lower picture when it's coming closer
it's gonna be a higher pitch so and
based on the pitch track you should be
able to know how fast exactly exactly so
all those things come together to help
you figure out where is this in distance
elevation as AM youth how fast is it
moving and things like that okay yeah
that makes sense so those are some of
the simplistic things and when you get
into some of the more detailed topics if
you think about radar cross-section so
if I send this pulse towards 747 the
reflective pulse back isn't gonna look
exactly the same as what I sent sure the
power is gonna change because there's
different scatters at you know emulate
different directions what comes back at
you because if to say if it's a really
not a cube flying at you right yeah they
actually have spheres in space for
calibration say what
so for radar calibration they have
spheres up in space basically satellites
and they know where they're at so they
send you know radar pulses to the sphere
and since it's a perfect sphere yeah
everything as you get you know they they
have an idealized
really estimation of what that return
posture looked like so they can
calibrate their systems what are these
made out of that I don't know ah okay we
have a recurring theme of space lasers
on this podcast
well that was basically it right just
not visible lasers yeah that's pretty
cool I did not know that we have spheres
in space 2001 a Space Odyssey kind of
stuff they have like reflectors on the
moon so people use like laser telescopes
to send a signal to sorry bounce it back
to measure the distance the Apollo
missions like left the mirrors on the
moon yeah mirrors or certain types of
reflectors what yeah where have we been
Mike not the moon I guess unfortunately
yeah that was like spring break okay so
so oh look this all coming back to is uh
you send this pulsed wait where else are
there weird space objects that we should
know about places you know in places you
don't the secret moon so NASA puts
throws up in space for government
agencies and just anyone can use are
they geosynchronous I guess so I don't
know exactly if they're geosynchronous
around a particular orbit and I'm not
sure if NASA sent them up or if secret
NASA anyway let's not go there so what
this is all coming back to is uh we send
that pulse out it gets returned and
there's different scattering effects I
get less power different change of
frequency on my Paul's and based on what
that profile comes back really advanced
processing what they might do is have a
library of what that return pulse looks
like for a given okay excitation pulse
I could say oh that's a bird
that's a fighter jet that's a blimp so
people start to catalogue what things
are so they can identify them based on
so you run a cow so you can basically
normalize that you're sending pulse and
you basically normalize your return
pulse through and compared against this
library of library has to get bigger and
bigger every day right yeah and there's
different techniques this is a very
simplistic way how many people think oh
you get certain effects off of propeller
planes because the pulse hits
essentially those propellers have edges
and that provides a very unique return
characteristics so make sense things
like that are different characteristics
people look for to try to classify
different targets or different returns
so you mentioned I think near the end of
the last podcast there's some like
subterfuge if you if you detect that
you're getting painted with a radar sure
and you want to send back that you're
like a different location how the
response time like how fast would you
have to process that information to be
able to send back a reasonable pulse
like that's got to be pretty darn fast
so you have to like be anticipating it
essentially well there's different
techniques so so ultimately it starts
with understanding that there's a target
illuminating you
so usually Jets of different types if
we're talking military jets
they'll have several antennas placed
around the jet okay and that will all
come back to a what they call a radar
warning receiver and it will start to
pick up the pulses that is being
incident upon it and generally you know
what kind of radars are in a certain
theater of operation so it says hey
you're being painted with this kind of
radar we should do something about it
sure
so maybe an electronic warfare officer
starts to take a manual action to do
something this is not someone in the
plane I assume this is some other okay
yeah so someone you know in a full G
suit and everything and in a jet copilot
I just like to take a take a personal
moment here and say if you or anyone
else can get me on a fighter jet that's
always been a
like a bucket list item for me so next
to care yeah yeah okay free double ease
talk tech podcasts for the rest of your
life yes my fighter plane I don't know
how committing to that but rings you
might be able to make a buddy at the air
force okay now I actually you have ice
cream is but anyway they picked me up
anyway I just I hat you know you never
know who's watching there you so you
know now how do they know you said
there's usually an idea of what radars
are being used in whatever theater of
operation but isn't the whole idea of
using radar to maybe have them not know
that you're doing that yeah do they are
they checking literally every frequency
possible than some sort of range what's
what's stopping them for maybe using
different frequencies between the every
polls there's gonna be all kinds of
crazy yeah there's a lot of different
techniques frequency hopping so you
change the frequency of radar from pulse
the pulse camp modulation on each pulse
so aside from just having the frequency
of the carrier you could do different
things like phase shifts amplitude
changes frequency chirps so you're
changing the frequency from you know two
gigahertz to 2.1 gigahertz over just the
narrow duration walls so difference to
avoid detection to get better
performance out of radar or to reduce
your susceptibility to jamming so I
guess if you know like if you know your
you know calibration characterization
profile you can do almost whatever you
want with yours transmitted signal as
long as you can normalize it back when
it comes so yeah okay yeah so all these
techniques come into play to you know
enhance your sensitivity and your
capability to resolve something that
you're looking for okay but it kind of
looping back to the question that you
had of you know how do you spoof a radar
to say you're somewhere you're not well
you have to know what is incident on you
you know what what's the pulse with
frequency all those things and then you
have to have an idea of how that's gonna
act over time and then you start to send
out different pulses maybe advance in
time or legging in time to make it think
that you're closer in this thing are the
further away or maybe a Doppler shifts
you're speeding up or slowing down or
things like that okay so this is gonna
put a whole new level of insurance fraud
out there for a motive break it down
fool Buddha now this is assuming that
you're able to fully absorb any radar
that's being fired at you or you somehow
adding to whatever you know is being
reflected back to modify it maybe gonna
be one of both well to say the tip of
your fighter jet is always going to
reflect some of that power back so you
know the original or the the intended
reflection that the radar wants to see
is always going to be there what you got
to do and there's different techniques
to do this you know is maybe drown out
the the pulses that are being returned
with a higher power or something like
that so that your pulses are looked at
instead of the actual real pulses so it
would almost require a pretty intimate
understanding of the new other other
guys yeah there's hardware you have to
have a really understanding of the radar
you're trying to defeat you have to have
a good system to you know take care of
that in a very quick fashion as well as
good knowledge on board that you know
something's happening so you could take
action if there's a manual intervention
needed
that's what's still blowing my mind
you're saying the tip of the airplane is
reflecting something back I'm just
imagining like sound waves or pressure
waves or something coming at a plane and
all of it just basically going around
the plane because it's like a like a
needle point at the tip usually is there
just like one little tiny micro spot on
the tip that somehow mouth has a direct
angle back source or if you think about
it if you have a perfect sphere in space
that you're able to calibrate against if
it's actually perfect then you're gonna
have an infinitely small return you know
yeah point that's but I mean if if
that's you know the level of calibration
that were able to get to surely in
airplanes you're looking at a plane
there's a lot of edges you know don't
think of the plane as a one singular
reflector you know it's not just this
flat plane'll
panel flying at you you know you got all
the wingtips
you got the nose tip you got the
interface between the cockpit glass and
the fuselage you know all these
different things and when you look at
you know stealth aircraft you see a lot
of geometric designs on it to help break
up or scatter the returned energy in a
different direction than directly back
so there's always energy reflected
you're you know there's techniques to
mitigate and minimize that but you gotta
understand what that is and then find
ways that you're jamming signal can
overpower that reflection I mean
obviously it works so what we're not
debating are works or not sorry about
that
so what I really want are some
flashcards to hold up with profiles and
we could play you know fighter jet or
bird yes I think that's actually what
they have to do right essentially yeah I
teaching with flashcards I think if a
bird flew right in front of a radar
transmitter is it no longer a bird like
is it that kind of energy here well yeah
I mean peak energies could be anywhere
from like kilowatts the megawatts
certainly okay it's pretty impressive of
how much power they put out and things
like that
and speaking of energy and you know is
it a plane or a bird I mean is it a ship
or you know a dinghy I mean there's a
there's a really good article I think
there's about a year old or so the US
Navy came out with a new Newhall design
for one of their destroyers I think the
zumwalt-class and they had to turn on
like this crazy beacon this is about
they almost like started just plowing
into oats because everyone was looking
at the radar and fog and they thought it
was like a dinghy where in reality it's
just like like 100 massive yeah long
destroy yeah they have to like out put a
radar pulse so that other ships don't ya
like running to them and the target dark
so yeah it's we'll try and find that
Lincoln it's awesome radars just not
about you know pulses it's you know
physical design and things like that so
it's it's pretty complex
okay we're kind of running out of time
is there anything else you want to talk
about um radars are really cool it's
they're in a lot more places than you
think and expound on
so it's rules well I mean aside from
more so and cars and things like that I
mean people are using you know laser
radars you know to measure distances
really accurately I use one on the golf
course
there you go okay perfect everyday
example Morita rangefinder yep awesome
cool can't think of a better way to end
it okay well I mean every episode we
always run out of time how does it work
well we basically talk and tell we're
out of time so you know if you're not
running out of time then it's probably
not something we should have been
talking about stupid questions for Phil
man best part would you rather radar be
sensing a bird or a fighter jet bird
okay but it could always end up being a
fighter jet what does radar stand for
ooh
radio detection and ranging that was
like a reverse usually the stupid
question is supposed to make me sound
stupid but I think I just got got yeah
sorry bloops what country has the
favorite right now I'm checking so
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individually so that's all for today
thanks Phil for your time we appreciate
having you on here if you have questions
for Phil or you want to hear about a
specific topic let us know in the
comments or just probably in the
comments is the best way to do it thanks
for watching we'll see you next time
Cheers thanks
levena I don't know Richard help sorry
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