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F-14 Update: ALR-67 RWR Development Snapshot


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For the F-14's ALR-67 (-B) and ALR-45 (-A), we're working on a new, in-depth simulation of RWR antennas and how they're affected by various factors. This also includes recreating the way the cockpit systems interpret and process the data received by the system.

 

AN/ALR-67 is the radar warning receiver (RWR) system used in the F-14B. The eyes of the system are four spiral high-band wide-field-of-view antennas looking front right (45°), back right (135°), back left (225°), and front left (315°). The two front antennas are located on the sides of the air intakes, and the two rear antennas are attached to the horizontal stabilisers. When the aircraft is pictured by a radar beam, the RWR antennas receive the emission. The closer the beam direction is to the antenna centre of the view, the stronger the registered signal is. The AN/ALR-67 electronics compares signal amplitudes from the antennas and uses the strongest two to reconstruct the incoming signal direction.

 

In the video, the simulated radar location is to the aircraft rear and below. When the left stabiliser rotates and moves the trailing edge up, the antenna rotates up too, and the incoming radar signal shifts away from its centre of view - thus the registered signal becomes weaker. At the same time, the signal in the front left antenna doesn't change. The electronics don't know about the horizontal stabiliser deflection and interpret the change as the emitter moving away from the rear left antenna field of view.

 

Heatblur AN/ALR-67 will simulate: radar wave attenuation, signal reception for each antenna independently, antenna condition (damage), signal amplification and threat direction reconstruction from the received signal amplitudes. Just as a real unit does, no faking or RWR-magic.

 

Here's a quick video from the Chromecat branch showing how the location of the RWR antennaes influences signal processing and display in the F-14.

 

Nicholas Dackard

 

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Heatblur Simulations

 

https://www.facebook.com/heatblur/

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great detail!

but... still chorme cat?

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Wow. So much detail. I don't think anyone even expected this much detail from a relatively "simple" system. KUDOS!

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Is this realistic? Doesn't ALR67 compensate for the elevator pitch when representing in the RWR screen?

 

The electronics don't know about the horizontal stabiliser deflection and interpret the change as the emitter moving away from the rear left antenna field of view.

 

I think he answered that.

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I think he answered that.

 

With 20/20 hindsight and total ignorance of 70s technology such a design flaw is very surprising. They must have had the deflection information for A/P features so I don't understand why it couldn't be used for this too.

104thblazesig400x100.png.8a2c291bd2343972ec5a1f1455971315.png

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Thanks for sharing...I would never have dreamed of such level of detail, and would probably never have noticed this in game if it wasn't for the video.

 

It smells like a hype train indeed, it's about time the Tomcat gets pushed on to one of the elevators from the hangar deck!

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Who's also tired of the chromecat ?

 

Im not. In fact Im officialy requesting a chromecat skin for the module once it comes out :smilewink:

Current specs: Windows 10 Home 64bit, i5-9600K @ 3.7 Ghz, 32GB DDR4 RAM, 1TB Samsung EVO 860 M.2 SSD, GAINWARD RTX2060 6GB, Oculus Rift S, MS FFB2 Sidewinder + Warthog Throttle Quadrant, Saitek Pro rudder pedals.

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I already said this in regards to the INS update and I will reiterate it here.

 

As someone who really is more into the scientific/engineering backgrounds then the flying part I am really happy to see this being done.

[sIGPIC][/sIGPIC]

 

*unexpected flight behaviour* Oh shiii*** ! What ? Why ? What is happening ?

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With 20/20 hindsight and total ignorance of 70s technology such a design flaw is very surprising. They must have had the deflection information for A/P features so I don't understand why it couldn't be used for this too.

 

 

Probably for the same reason why you can't control your dishwasher with the TV remote. Unless the RWR is part of a highly integrated avionics suite, there is no way for it to know where the control surfaces are pointing.

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So on this particular RWR, we are rolling, pitching, operating surfaces and the RWR reads out as a jumbled mess until we fly level?

 

It won't be a jumbled mess, at the most the offset will be about 30 degrees for the painting radar until you return to level flight. Even modern RWRs aren't "magical" know-it-all detection instruments. Even current DCS level modules have big gaping blind-spots in their RWR detection systems, which is exactly as it should be.

 

With that said I do have a question for whoever at Heablur is coding this: What kind of performance hit will this kind of detail add to the simulation, if any? As a followup: Do you guys balance performance vs modeling detail during the coding of your modules, or do you just go all out on the modeling and let the performance be whatever it ends up being?


Edited by OnlyforDCS

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Cool.

Who's also tired of the chromecat ?

 

great detail!

but... still chorme cat?

 

Because it looks like it's not textured.

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Radar warning receivers of this type are simple devices regarding direction finding. There are four antennas. For each radar pulse received, the amplitude of the signal received by each antenna is measured. Then the results are compared, and the two strongest signals are used to reconstruct the direction. Effectively, out of that, you can only reconstruct the total signal strength and one angle - you can't even tell if the pulse came from above or from below. That is also why applying stabiliser position correction doesn't even make any sense, because instead of improving direction reconstruction accuracy, you can make it worse under certain conditions. Finally, even with fixed antennas, a typical error in direction finding for this type of RWR is 5-10° root mean square. Hence for most of the time, the stabiliser-induced error is much less significant than the other types of errors.

 

We simulate different effects leading to those errors. Nevertheless, the impact of the moving stabiliser was the easiest to show and the most spectacular one smile.gif.

 

 

Regarding the performance - the RWR computations aren't CPU heavy. Of course, we are monitoring the impact of each system on the overall performance. However, optimisation and profiling is a vast topic, so this topic is not a right place to discuss it smile.gif.

Krzysztof Sobczak

 

Heatblur Simulations

https://www.facebook.com/heatblur/

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Thanks for the reply Super Grover :thumbup:

Current specs: Windows 10 Home 64bit, i5-9600K @ 3.7 Ghz, 32GB DDR4 RAM, 1TB Samsung EVO 860 M.2 SSD, GAINWARD RTX2060 6GB, Oculus Rift S, MS FFB2 Sidewinder + Warthog Throttle Quadrant, Saitek Pro rudder pedals.

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Radar warning receivers of this type are simple devices regarding direction finding. There are four antennas. For each radar pulse received, the amplitude of the signal received by each antenna is measured. Then the results are compared, and the two strongest signals are used to reconstruct the direction. Effectively, out of that, you can only reconstruct the total signal strength and one angle - you can't even tell if the pulse came from above or from below. That is also why applying stabiliser position correction doesn't even make any sense, because instead of improving direction reconstruction accuracy, you can make it worse under certain conditions. Finally, even with fixed antennas, a typical error in direction finding for this type of RWR is 5-10° root mean square. Hence for most of the time, the stabiliser-induced error is much less significant than the other types of errors.

 

We simulate different effects leading to those errors. Nevertheless, the impact of the moving stabiliser was the easiest to show and the most spectacular one smile.gif.

 

 

Regarding the performance - the RWR computations aren't CPU heavy. Of course, we are monitoring the impact of each system on the overall performance. However, optimisation and profiling is a vast topic, so this topic is not a right place to discuss it smile.gif.

 

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