Of DAS, EOTS etc..

Cockpit, radar, helmet-mounted display, and other avionics
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sprstdlyscottsmn

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Unread post15 Jul 2018, 21:13

Just a thought, if the DAS can provide 20/40 display to the visor then the largest possible degrees per pixel would be 0.03333, which at 95deg FOV corresponds to a 2,850x2,850 array. Corresponds to a 35ft pixel coverage at 10nm which is plenty for frontal aspect detection of a fighter.
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wrightwing

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Unread post15 Jul 2018, 22:34

sprstdlyscottsmn wrote:Just a thought, if the DAS can provide 20/40 display to the visor then the largest possible degrees per pixel would be 0.03333, which at 95deg FOV corresponds to a 2,850x2,850 array. Corresponds to a 35ft pixel coverage at 10nm which is plenty for frontal aspect detection of a fighter.

What's the pixel size for 20/20? Most of the claims I've seen are "near 20/20 acuity."
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sprstdlyscottsmn

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Unread post16 Jul 2018, 00:00

Over 5k x 5k. So a 4k x 4k would be "near"
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marauder2048

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Unread post16 Jul 2018, 06:33

sprstdlyscottsmn wrote:Over 5k x 5k. So a 4k x 4k would be "near"


Consider that at 16 Megapixels, 12-bits per pixel and 30 Hz you could very easily
saturate the available fiber channel bandwidth.
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SpudmanWP

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Unread post16 Jul 2018, 16:27

Given that each EODAS unit is connected via fiber optics to the avionics bay, it's just a matter of upgrading the transceivers to handle the bandwidth as capacities increase. Besides 4k * 30hz * 12 bit = Bandwidth Per Channel of 6.72 Gbps which is perfectly fine for fiber.

Https://k.kramerav.com/support/bwcalculator.asp

However, 8Gbps FC was not available in the early 2000's (2Gbps in 2001, 4Gbps in 2004, etc).

Https://en.wikipedia.org/wiki/Fibre_Channel

The workaround would obviously be only streaming data that is needed (eg hi-res data of area of interest, relevant view for HMDS, etc).
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marauder2048

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Unread post17 Jul 2018, 02:27

SpudmanWP wrote:Given that each EODAS unit is connected via fiber optics to the avionics bay, it's just a matter of upgrading the transceivers to handle the bandwidth as capacities increase. Besides 4k * 30hz * 12 bit = Bandwidth Per Channel of 6.72 Gbps which is perfectly fine for fiber.

Https://k.kramerav.com/support/bwcalculator.asp

However, 8Gbps FC was not available in the early 2000's (2Gbps in 2001, 4Gbps in 2004, etc).


There's ~ 20% encoding overhead so even 8 Gbps couldn't handle it. That changed with 10 GFC though.

SpudmanWP wrote:The workaround would obviously be only streaming data that is needed (eg hi-res data of area of interest, relevant view for HMDS, etc).


There was a suggestion in at least one article that they do some processing (possibly compression) at the sensor front-ends.
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Unread post17 Jul 2018, 10:52

Raytheon’s DAS Sensor: Weighs Less, Uses Less Power, Lockheed Says
16 Jul 2018 Colin Clark

"...Greg Ulmer, the new head of Lockheed’s F-35 program, describes here why the company went with Raytheon’s sensor. He offered new details about it, noting it weighs less than Northrop’s and uses less power than does the current version."

Source: https://breakingdefense.com/2018/07/ray ... heed-says/
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Unread post17 Jul 2018, 16:30

I would sure hope so given the last 15+ years of component miniaturization and power improvements. It makes complete sense that it would be smaller along with cheaper, more durable, and more powerful to boot.
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Unread post17 Jul 2018, 19:54

Ulmer highlighted the recent award to Raytheon of a contract to replace Northrop Grumman as the supplier of the Distributed Aperture System (DAS) on future F-35 production aircraft. Raytheon’s product is twice as capable and five times more reliable, while saving 10 to 15 pounds (4.5 kg to 6.8 kg) of weight, he said.


https://www.ainonline.com/aviation-news ... ustainment
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