Radar and Electronic Warfare

Learn about radar basics and get a peek into the world of aerospace electronic warfare. Hosted by Daniel Bogdanoff and Mike Hoffman, EEs Talk Tech is a twice-monthly engineering podcast discussing tech trends and industry news from an electrical engineer’s perspective.

Phil Gresock, Keysight’s Radar Lead, sits down with us to discuss the basics of radar and give us a peek into the world of aerospace electronic warfare.

Agenda:

00:20 Adaptive cruise control for cars works really well.

1:00 the history of radar – the original radar display was an oscilloscope in WWII. (radar test equipment)

http://www.pearl-harbor.com/georgeelliott/scope.html

1:45 Early warning radar

2:00 The rumor that carrots are good for your eyesight was a British misinformation campaign.

2:58 The British had the “chain home radar system” all along the coast that pointed to their western front. They wanted early warning radar because they had limited defensive forces. By knowing what was coming, they could allocate defenses appropriately.

3:45 Radar originally was a defensive mechanism.

3:50 How does radar work? You send out a pulse that is modulated on a carrier frequency. If that pulse gets reflected back, we can do some math and work out how far away something is.

4:30 Typically, there’s a specific frequency used. For long range radar, like search and early warning radar, a lower frequency is used.

5:15 What does a modern radar system look like?

It depends on the application. Early warning systems are often anchored on old oil rigs. The rigs have a radome installed on them.

6:25 How does radar detect something so small and so far away? A lot of it depends on the frequencies and processing techniques you use.

6:40 There are some radar techniques you can use, for example bouncing off of the sea, the earth, the troposphere.

7:15 Radar also has some navigational benefits. For example, wind shear flying into Breckenridge airport. A change in medium is measurable.

8:10 Radars also get installed on missiles to do some last-minute corrections.

8:35 Ultimately, the goal of radar is to detect something. You’re trying to figure out range, elevation (azimuth), velocity, etc.

Different target sizes and ranges require different pulse widths, different frequencies, etc.

Azimuth is easy to determine because you know what direction your radar is pointing.

To detect velocity with radar you can use doppler shift.

10:30 Radar cross section analysis gives even more information.

11:00 There are spheres in space for radar calibration. You can send pulses to the sphere and measure what you get back.

Radar calibration sphere in low earth orbit:
http://www.dtic.mil/docs/citations/ADA532032 (for full paper, click the “full text” link)

11:40 There are also reflectors on the moon so you can use laser telescopes to measure the reflection.

Mirrors on the moon:
https://en.wikipedia.org/wiki/Lunar_Laser_Ranging_experiment

12:30 NASA put reflectors in space.

12:58 So, you send a pulse out and get a return signal, but there was a scattering effect. There are libraries for what a return pulse for different objects looks like so you can identify what you are looking at.

14:00 Radar counter intelligence techniques.

First, you have to know you are being painted by radar. Military jets have a number of antennas all around it. And, you generally know what radars are being used in a theater of operation. So, there will be a warning that will let you know you are being painted by a certain type of radar.

15:30 Get Daniel on a fighter jet

16:05 How do you stop your radar from being detected or interfered with? There are a few techniques.

Radar frequency hopping is changing the frequency used from pulse to pulse.

Radar frequency modulation changes the modulation pulse to pulse – phase shifts, amplitude changes, frequency chirps, etc.

This helps avoid detection, get better performance, or reduce susceptibility to jamming.

If you know how your radar responds to different signals, you have a lot of flexibility in what signal you use.

How do you spoof a radar? You have to know what is incident upon you and know how that will act over time. You can send out pulses advanced or lagging in time or with different Doppler shifts to give misinformation to the receiver.

You can also drown out the pulses so that your pulses get read instead of your reflections.

You have to have an intimate understanding of the radar you’re trying to defeat, a good system to handle that quickly, and good knowledge that something is actually happening.

We need radar profile flash cards.

Radar peak energies are anywhere from kilowatts to Megawatts.

21:10 A recent US Navy ship had a new hull design, and it has to turn on a beacon because it had so little reflections.

https://www.forbes.com/sites/niallmccarthy/2016/10/14/some-of-the-numbers-behind-the-u-s-navys-new-zumwalt-class-destroyer-infographic/#da435a170597

22:00 Phil thinks radars are pretty cool, and it shows up in a lot more places than you’d expect.

Radar stands for “radio detection and ranging.”

 

Intro to RF – EEs Talk Tech Electrical Engineering Podcast #21

Learn about RF designs, radio frequencies, RADAR, GPS, and RF terms you need to know in today’s electrical engineering podcast!

We sit down with Phil Gresock to talk about the basics of RF for “DC plebians.” Learn about RF designs, radio frequencies, RADAR, GPS, and RF terms you need to know in today’s electrical engineering podcast!

 

Agenda:

RF stands for radio frequency

00:40 Phil Gresock was an RF application engineer

1:15 Everything is time domain, but a lot of RF testing tools end up being frequency domain oriented

2:15 Think about radio, for example. A tall radio tower isn’t actually one big antenna!

3:50 Check out the FCC spectrum allocation chart

4:10 RF communication is useful when we want to communicate and it doesn’t make sense to run a cable to what we’re communicating to.

4:50 When you tune your radio to a frequency, you are tuning to a center frequency. The center frequency is then down converted into a range

6:30 Check out Mike’s blog on how signal modulation works:

7:00 Communication is just one use case. RADAR also is an RF application.

8:10 The principles between RF and DC or digital use models are very similar, but the words we use tend to be different.

Bandwidth for oscilloscopes means DC to a frequency, but for RF it means the analysis bandwidth around a center frequency

9:22 Cellular and FCC allocation chart will talk about different “channels.”

Channel in the RF world refers to frequency ranges, but in the DC domain it typically refers to a specific input.

10:25 Basic RF block diagram:

First, there’s an input from an FPGA or data creating device. Then, the signal gets mixed with a local oscillator (LO). That then connects to a transmission medium, like a fiber optic cable or through the air.

Cable TV is an RF signal that is cabled, not wireless.

Then, the transmitted signal connects to an RF downcoverter, which is basically another mixer, and that gets fed into a processing block.

13:50 Tesla created a remote control boat and pretended it was voice controlled.

15:30 Does the military arena influence consumer electronics, or does the consumer electronics industry influence military technology?

16:00 GPS is a great example of military tech moving to consumer electronics

17:00 IoT (internet of things) is also driving a lot of the technology

18:00 The ISM band is unregulated!

19:15 A router uses a regulated frequency and hops off the frequency when it’s being used for emergency communications

20:50 RADAR, how does it work?

22:22 To learn more about RF, check out App Note 150 here:

http://www.keysight.com/main/editorial.jspx?cc=US&lc=eng&ckey=459160&id=459160&cmpid=zzfindappnote150