Doppler Radar Explained | How Radar Works | Part 3

Ever wonder what Doppler radar does? Then this video is for you. This part three of the introduction to radar series. We'll go over what the Doppler effect is and how it can help radars find out more about a target.
Radar Explained Playlist: • Radar Explained
Obligatory disclaimers:
The presence of DOD Visual Information in this video does not constitute endorsement by the DOD or any of its departments. Any views expressed by the presenter are those of the presenter and do not represent the views of the DOD or any of its components.

[@MattWagner]

Great stuff, Mike. In a future video, you may also want to touch on JEM.

[@juliusEST]

Wut real Wags...

[@TheOpsCenterByMikeSolyom]

That would be a neat topic to cover. When it comes to radars and EWs it's a pretty deep rabbit hole. So there's definitely plenty to go over.

[@_Breakdown]

What’s JEM?

[@radoslawbiernacki]

HI thank you for this but it is worth to mark couple of mistakes made. 5:11 You are mixing aliasing with PRF here. You cannot send "pulses". All what all radio system does is using are waves. A pulse of any kind is very long compared to wave length (several thousand cycles at best). A "Dirac delta" signal which you are trying to explain here has unlimited frequency response. This part is very badly described. The "blind spots" as you call them are from "ground clutter" and "side lobe clutter" Doppler filtering (both separated by ~ 100kts in terms of contact speed). They have nothing with aliasing which is domain of signal sampling (namely the Nyquist theorem), not reflection aliasing as you are referring to this as well. Namely PRF also has nothing to do with signal aliasing. Explaining PRF with some strobes superimposed on sinusoid is making impression that you can send "Dirac delta" kind of signal. This is very confusing. You always sending chirps or continuous wave pings and those are couple of thousands cycles long compared to base frequency. Or you send waveform with multiple frequencies in newer radars (spectrum to be processed). PRF only changes the resolution of the radar plus influence on range as it packs more energy. The DCS'ism for PRF (like in Mig-29 of F-14) is just stupid and unrealistic. Higher PRF just limits your range because you send less energy with shorter pulses plus the echo can overlap with next pulse. This though is totally solved by signal coding in new radars. Those pulses though are ~ hundred of microsecond long composed by set of frequencies (or chirp in compression methods).

[@sloppydog4831]

The best radar tutorials I've ever found on the internet. Great video!

[@A320B737Pilot]

Great video, love the way you explain really complicated matters on a very understandable and easy way. Thank you. 👌

[@Pekins_]

Well, let me tell you, KZbin is doing a terrible job. I've been watching these DCS videos about tactics and all the in-depth stuff for a long time and this is the first time I'm seeing your channel being recommended. Great video. Thanks.

[@colinterry7261]

I want to keep saying that I am really enjoying these videos! I’ve always been super interested in RF and microwave engineering, and subsequently how radars work. This really helps me get closer to that goal.

[@roostercogburn3272]

This playlist cleared up a lot. Are you still planning to continue the series? I looked around your other videos (which are great, btw) but didn't see any more like these. Thanks for the help.

[@Detr0y]

You deserve more views

[@TheOpsCenterByMikeSolyom]

Thanks for the kind words.

[@yappydawg8985]

Great information. At approximately 06:57, the graph showing Unambigious Range and Unambigiuous Velocity has an intersection point. Does this point have a name or is it less useful that I think it is? My assumption is that this would be the best PRF setting to use but there might also be more to it than that.

[@TheOpsCenterByMikeSolyom]

I've never seen a name for it. But I know pilots would probably equate it to the maximum lift-drag ratio since it sounds like a similar sort of sweet spot. Unfortunately, it isn't necessarily the best and could give a radar operator a "worst of both worlds" situation. The best thing to do is to switch the PRF. Then you get the best of every aspect.

[@RestoringReality]

If the ground were actually spinning in a manner described by so-called science and popular opinion, the velocity of that movement would vary, almost infinitely when speaking in terms of milliseconds, depending on the location between the equator, which would be moving at approximately 1,040 mph and either pole which would be moving much, much slower. So, I’m left to ask, how can the radar equipment possibly factor in and then filter out returned echoes that match the velocity of earth’s rotation when that number is not fixed in the first place? Additionally, is there some sort of technology built into the radar unit itself, which in addition to determining the time that it took for an echo to return, also identifies what specific angle or direction that the signal was returned from? In other words, can Doppler radar identify the directional source of a returned signal? My understanding is no. If I am wrong, and you are willing, please walk me thought it and help me understand how because I don’t believe Doppler radar would be possible on a spinning ball and that’s not even considering the fact that we are told it is moving in found different directions simultaneously, all at speeds that are virtually impossible to comprehend. Thanks in advance and cheers!

[@Detr0y]

Do you plan on making any videos about BVR combat?

[@TheOpsCenterByMikeSolyom]

Yes. The next series I'm working on is Air Supremacy. There will be an introduction to BVR in that series. It's a fairly deep topic so more videos will come in the future to explore it.

[@Detr0y]

​@@TheOpsCenterByMikeSolyom Great! Can't wait. BVR combat is the one thing I'm not that great at, hoping to get better

[@r.ksangwan1633]

Sir give more videos in this series please

[@darthrevan1785]

Thank for the physical explanation, waiting for the new videos :)

[@charlesmagrin6260]

So interesting, thank you for putting this together !

[@nikolagaborov2428]

I just discovered you today, and now you're already one of my favorite aircraft-tech youtubers! Keep up doing a great job!

[@ROTNReaper]

As a Patriot missile operator I've been trying to find unclassified material to help my students understand radars, and these videos are perfect.

[@ROTNReaper]

@@SubParPilot I agree. We know how to use ours, but not why or how it works unless you go to master gunner or top gun school

[@kerbalairforce8802]

Avionics instructor here. I agree. I use youtube DCS clips to explain instruments to students.

[@ROTNReaper]

@kerbalairforce8802 that's awesome!

[@Youtube..Enjoyer]

@@ROTNReaper Is there a reason why your students do not have access to the unclassified material? Eventually they would have the same material as you do right now, right? I'm just curious.

[@ROTNReaper]

@KZbin..Enjoyer because It's not in our POI, but during break times I can play this for those who have questions or have it available for personal time research

[@roter_milan]

Awesome Mike, an absolute great explanation of the doppler, thanks. Greetings Milan

[@mikewoitt8111]

The Avro Arrow used Doppler Radar in 1958.

[@thejhonnie]

Great explanation. Still waiting on that stealth video! You earned a sub for sure.

[@erbenton07]

I watched all 3 of these radar videos and learned a lot. Can you keep them coming and get more advanced as we go?

[@rango_gt]

this let me understand why changing prf is important

[@dustin8335]

What should I study if I want to learn more of this?

[@TheOpsCenterByMikeSolyom]

"Introduction to Airborne Radar" by George Stimson is a great book which I used as a source. That's a good place to start.

[@corvanphoenix]

This is great! I've got your entire back catalogue to enjoy! Not until I've watched this again though, it's brilliantly balanced between the science & presentation, so it's competing yet accessible. Thank you very much!

[@TheOpsCenterByMikeSolyom]

Awesome. Glad you liked it.

[@mitch_the_-itch]

This is perfect for those of us coming to grips with jet fighters. TY so much.

[@surendrakverma555]

Good

[@aniksamiurrahman6365]

Tthanks.

[@hmabboud]

I wish everyone online would be as good as you explaining any topic :)

[@r.ksangwan1633]

Please add more videos in this playlist sir

[@OKOK-hm2is]

But how much use does Doppler give us if it only measures speed in the direction of a radar? Which is almost never is the case, as the targets vector is not pointed directly at us

[@TheOpsCenterByMikeSolyom]

Good question. The Doppler shift measurement isn't so much in the direction of the radar but rather the relative movement of the target. So even if the target is moving at an angle (like say 45 degrees off the radar-carrying aircraft's nose) then there is still some radial movement. The Doppler shift can still be measured in this case. The only time it disappears is when its exactly perpendicular to the radar. Or if its motionless relative to the ground. Then it fades into the clutter. Hopefully that makes sense.

[@r.ksangwan1633]

Ever best Radar knowledge sir

[@S3NTRY]

Awesome stuff as always, thanks Mike!

[@nibbler2281]

Really great videos.

[@codyphillips5196]

this helped a lot

[@alexandrebelinge8996]

That was fantastic !!!