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Old 02-14-2020, 01:04 PM   #11
GGTharos
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Quote:
Originally Posted by mattag08 View Post
I didn't think about sidelobes, but that makes sense.

For 2, I get launch warnings from aircraft that are 100+ NM away. Pick whatever number you want, eventually there should be a cut off where the RWR can't distinguish it from background noise.
100nm isn't that cut-off.

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For 3, I wasn't clear, but I'm talking about missiles, launches, and spikes. All things you would know have dropped off quickly. I do agree with your point about nails. One of the big offenders is the missile radar indication will continue for 15+ seconds after the missile has passed you by and is no longer pointed at you at all (180° behind the missile).
That's a good point, these types of signals should be dropped quickly. But this isn't necessarily the RWRs fault either - all it does is receive a 'signal type' flag from the offending object, and there's a radar memory for that object that may continue to trigger the RWR.
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Old 02-14-2020, 01:20 PM   #12
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This is a little inside of how it's done in F-14 module:
https://forums.eagle.ru/showpost.php...0&postcount=11
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Old 02-14-2020, 09:57 PM   #13
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Quote:
Originally Posted by GGTharos View Post
The RWR in game resolves the type of radar from its type library which simply relates the symbol to an in-game object (ie. if it's an F-18, it will show '18') and if course, if there's no entry, it shows unknown.

There is zero RF-type processing. There is a basic signal strength calculation based on the distance between the two objects.
Actually HB do some "ish" processing based on signal strength and antennas. They had a big post in the F14 forum on how they are doing it.

Not like thats classified, I have fricking USB dongle that does it...

ETA, and beat by one post!
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Old 02-14-2020, 10:33 PM   #14
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Discussing about inverse square law doesn't work when you have a beam shaping/focusing done.
If you have a simple radiating point, like a light bulb. Then inverse square law explains the light behavior correctly.

But if you place a parabolic mirror behind that light bulb, beaming that light like a spotlight. Inverse square law doesn't anymore apply, you will have much stronger emission on distance and far less drop in power per distance.

Radars are not pointy radio emitters. But shaped by various means, and inverse square law doesn't apply as is. As well inverse square law doesn't apply to energy that is reflected.

Yet, the RWR systems are designed to be far more sensitive than the threat radars would be at their maximum power to detect the aircraft with the RWR. Example the SPO-15 is designed to be 125% sensitive to that radar maximum power, requiring the radar to receive and echo to detect the aircraft. So RWR in hypotheses has 25% more range to detect an radar before radar can detect it.

And as we don't have radar emissions in most aircrafts. The RWR and radars (including missiles radars) are in most modules "instantaneous" by knowing what is where. This is as well problem with missiles radars that are instantly knowing where targets are and what they do without any search patterns or logic to observe targets first.
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Old 02-14-2020, 11:57 PM   #15
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The inverse square law applies for radars as well as for any(?) other antenna.

It is just that you always have to be at the same azimuth/elevation in the antenna diagramm when you make the simple power calculation.
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Old 02-16-2020, 07:14 AM   #16
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inverse square law applies to all radiation. radars included, its a universal rule, and no fancy antenna lets you get away from it, AESA or otherwise. For those specific focusing antennas, all they do is up the gain and focus the power in the beam, IE make less of its energy spill out, it still loses power at the same rate due to the inverse square law.

Best way to think of it is if I put 1 unit of power through an omnidirectional (non focused) antenna, then if I measure the power 1 unit of distance away in each cardinal direction I would get 1/360th of the power output over each degree (since its spreading all that power over 360 degrees)

If I put 1 unit of power through a 1 degree focused antenna I then should get 1 unit of power 1 unit of distance away (all the power is in 1 degree now) the inverse square law still applies (2 units of distance away I will get 1/4th power, 3 units of distance 1/8th, etc...)

This is beamwidth in a nutshell (which also isnt perfect, beamwidth is just an arbitrary definition, there will always be spill over, sidelobes, and backlobes, no perfect antennas)

Radars also dont lose power to the inverse square of the range, they actually lose it to the inverse 4th power of the range, this is because the radar energy doesn't just have to get to the target, it also has to get back.

Just google radar range equation

here https://copradar.com/rdrrange/ Look down at the bottom of the page, lays it all out, and this 100% applies to every radar in existence, no fancy antenna lets you get away from this.

if you want to derive it https://www.radartutorial.eu/01.basi...uation.en.html

Last edited by KlarSnow; 02-16-2020 at 07:23 AM.
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