Radar and Electronic Warfare – EEs Talk Tech Electrical Engineering Podcast #22


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
that’s all we have time for today make sure you subscribe to the keysight
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sense yes it’s automatic but I do hit the post button so therefore write
effectively email all of you 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
cover chit chit check out the melody check out the melody check out the
melody

18 thoughts on “Radar and Electronic Warfare – EEs Talk Tech Electrical Engineering Podcast #22

  1. We changed our channel name!

    To clarify my statement about the first radar display, it appears that it was an oscilloscope and they would measure the distance between the transmitted signal pulse and the reflected pulse on the screen.

  2. I am interested in the "translucent" properties at certain frequencies. As well as frequencies that are used in certain scenarios. For example, the Radome you where talking about has to have a certain Epsilon at given frequency… And the attenuation Weather or other atmospheric conditions have on the signal as discussed early in the podcast.

  3. The first practical demonstration of radar by Watson Watt in 1935 used BBC broadcast transmissions, I read somewhere that they were playing Handel's water music at the time. https://www.express.co.uk/showbiz/tv-radio/504913/The-inventor-who-helped-win-the-Battle-of-Britain

  4. I was told by my parents that WWII Radar was developed and manufactured in the Chicago area—-by various companies.  Primary company was ZENITH. Located on the west side of the city.   See this article:   http://www.encyclopedia.chicagohistory.org/pages/419.html

  5. Radar testing structure in Chicago — https://chicagohistorytoday.wordpress.com/2015/09/16/chicago-grand-avenue-radar-track

  6. I remember one of my teachers gone done by the police for blowing up their radar gun. Old gun used an amplifier with the guns frequency.

  7. Wo, disinformation is a skilled trade of the British. The US Jurisdiction has had more than one war with them or caused by them where we were involved with. I'd say all the wars we've been involved with are due to them. Maybe with Royal Dutch Shell in modern times. Back to the topic of discussion, my genetics descend from the British Commonfilth(/debt/wealth) to a certain extent. Let's get the facts straight as I like carrots and am not a spokes person for the national carrot association or the big carrot lobby. 🙂

    Here is some clarification where carrots are not bad for your eyes and are good for eyesight and in particular night vision: https://www.scientificamerican.com/article/fact-or-fiction-carrots-improve-your-vision/

    Having a biochemistry background, I recall the biochemistry related. Prior to the biochemistry course work there was original USAF reference with hunting grooming growing up; where carrots aid in night vision so, prior to hunting season, start increasing your carrot intake. Why you ask? Beta-carotene breaks down into Vitamin A.

    Here is a reference as to why in more detail from the Brit's even: https://www.britannica.com/science/rhodopsin

    Here is a reference for further vision biochemistry that is really general: https://quizlet.com/16227466/biochemistry-of-vision-11-8-flash-cards/

    Here is an interesting reference to another night vision hack: https://io9.gizmodo.com/this-biohacker-used-eyedrops-to-give-himself-temporary-1694016390

  8. A British guy – Robert Watson Watt drove the early development of radar – he claimed to be the ‘father’ of radar. I was lucky enough to find his autobiography – signed by him – in a thrift store!

  9. Professor Reginald Victor "R. V.' Jones was behind the British Home Chain. After the war Jones was Professor of Natural Philosophy at Aberdeen University and worked on improving accuracy of instruments.. Since you mention space lasers, SAR is widely used in earth observation.

  10. This is not EE level discussion. Sounds like they didn't bother doing much research on the subject. Sad.

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