Identify This Odd Blue Angel DDI Mode

[WytchCrypt]

I was just watching a video of the recent joint Blue Angel and Thunderbird flyover of NYC and noticed something very odd in the Hornet. Take a look at the 10:27 mark of the video. Both the left and right DDI's are in some strange mode where they seem to be cycling through various screens repeatedly. Does anyone know what they're doing? Is this some flight software that is customized or specific to the Blue Angels and why in the world would you want your DDI's to be constantly cycling like that?

 

 

Seems the youtube hook may not be working so here's a link to the vid..

 

 

Also an unrelated question, what variant of the Hornet are the Blue Angels flying in this vid? How different are they to the F/A-18C Lot 20's we fly in DCS?

 

Thanks :pilotfly:

[randomTOTEN]

RDDI is on FUEL, LDDI is on HUD.

It's an interaction between the frame rate of the camera, and the refresh rate of the DDI's that gives the flickering effect.

[Odey]

They used to fly A’s. They actually fly older aircraft so the “fleet guys” get newer jets. Probably using C’s by now.

[High_Flyer]

The DDI’s are not cycling. If watch the right DDI you’ll notice it stays in the fuel page every time it “cycles”. The DDI’s are also not blinking. The pilots see what you’d normally see when you’re flying the Hornet in the sim.

 

What’s happening is that the DDI’s are probably powered by some sort of alternating current causing it to refresh every time the current changes direction. This will momentarily shut off the display each time the current alternates. If this momentary off/on/off/on happens fast enough, the human eye can’t detect it. A camera, on the other hand, can. If the camera’s shutter rate is out of sync with the DDI refresh, it may be taking an image just at the moment the DDI shuts off. Remember, videos are just a bunch of images taken in very quick succession.

 

Fun fact: If you live in America then the lights in your House are actually flickering 120 times per second. The power in your house is a 60 Hertz (cycles per second) alternating current. That means the current changes direction every 60 seconds, which means the power will shut off 120 times. Humans eye can only detect flickering up to 50 times per second, so that’s why you don’t see the flickering. A typically camera doesn’t detect the flicker in lights because they’re shutter speed is too slow as well. Get a camera with a high enough shutter speed and it will in fact pick it up.

 

Safe to say that the DDI’s refresh at a rate higher than 50 (cause humans can’t notice it), but slower than 120 (since a typically camera can).

 

Here’s a video taken of various lights by a camera with a really high shutter speed, in case you are interested:

[randomTOTEN]

What’s happening is that the DDI’s are probably powered by some sort of alternating current causing it to refresh every time the current changes direction

LOL that's a nice attempt at an explanation but I highly doubt that's the case. DDI's are just computer monitors, exactly the same as the monitor you're looking at right now.

All monitors have a refresh rate, no matter their power source. It's how they animate their images.

[Odey]

Same principle that makes wheels appear to go backwards when spinning sometimes. Most smartphones have slow-motion camera settings. Take a video with your home lighting as the light source. You’ll see the flickering. Kind of cool.

[Eldur]

Clearly Fuel on the right and HUD on the left as has been said by others already.

 

I'm baffled by the fact you can hear the engines spool... if we just had that with hear in helmet off in DCS...

 

BTW to post videos with that YT button, you just take the alphanumeric stuff that comes after &v=, which is 1JESy0CnYPw in this case. Like this:

 

Edit: Forget about it, this utterly dated board software does drive me nuts. Executes code that's inside of code tags...

 

Well, vBulletin has always been rubbish

 

At least have the result here, you can see how it's done by quoting my post:

 

 

 

Edited May 1, 2020 by Eldur

[Svend_Dellepude]

Bonusinfo:

For most ppl 75Hz is said to be flicker free, but a small percentage need higher refresh rates to have a steady picture. I'm ok with 75Hz, but prefer 85Hz. :)

[WytchCrypt]

RDDI is on FUEL, LDDI is on HUD.

It's an interaction between the frame rate of the camera, and the refresh rate of the DDI's that gives the flickering effect.

 

 

Got it, I see it now..thanks everyone! I thought it might be a display refresh rate issue but what threw me was the way the DDI's seemed to display in steps or waves rather than just flickering on and off. For example, here's 3 screenshots I snapped of the video which show 3 different displays on the RDDI. I was thinking they were 3 different modes or something.

 

 

 

Interesting is the 2nd screenshot where you can see the "BINGO" from the previous screenshot fading out while the data that fills the boxes from that previous screenshot is now fully displayed :smilewink:

 

 

 

[Luzifer]

What’s happening is that the DDI’s are probably powered by some sort of alternating current causing it to refresh every time the current changes direction. This will momentarily shut off the display each time the current alternates. If this momentary off/on/off/on happens fast enough, the human eye can’t detect it.

 

Safe to say that the DDI’s refresh at a rate higher than 50 (cause humans can’t notice it), but slower than 120 (since a typically camera can).

 

Aircraft AC power buses are generally 400 Hz, so that would disprove that already. And of course TVs (since you're referring to broadcast systems designed to match the power line frequency) don't use power line frequency to generate video refresh, they have to synchronize to the received signal after all. Just like monitors.

 

What's really happening, and it's easy to see if you know what to look for, is that these aren't raster displays like TVs or typical computer monitors, they are vector displays. In raster displays the electron beam scans every line from left to right and then the next line below from top to bottom until starting over, in a fixed pattern. There is no electron beam in LCDs and the like and most standards are digital nowadays, but the exact same pattern is still used.

 

Vector displays on the other hand allow the beam to be moved under computer control to directly draw shapes on the screen. Say you want to show a white rectangle on the screen. On a raster display you have to divide it up into pixels and then wait until the beam reaches a pixel, tell the screen to make it bright, and when the beam leaves an area with rectangle pixel tell it to make it dark. On a vector display you tell it to move the beam e.g. to the coordinates of the upper left corner, then move it slowly (speed determines brightness) to the upper right, then to lower right, and so on to draw the shape on the screen.

 

This makes for very sharp pictures that could be equaled only with a high resolution raster display and its associated costs of large framebuffer memory and high frequency electronics. When you think in 1970's electronics, raster displays could not compete for these kinds of data displays.

 

Unlike raster displays, vector displays do not have a fixed refresh. Every line or arc that is drawn takes time, and the more there are, the longer it takes to complete the display. That is why they can become flickery when there are too many symbols to draw, one complete cycle takes long to complete and the refresh rate goes down. It also makes sense to have a maximum refresh and just to wait when a display is done early, otherwise the screen would get brighter the fewer symbols it has to display.

 

Coming back to the video, it has all the signs of it being vector displays. Since raster displays always display from top to bottom, on video and film you might see black bars moving through the picture. Vector displays aren't ordered in location, they are ordered in however the computer draws the symbols at whatever location. Here you can see that on the fuel page, it draws all the numbers, texts and boxes separately, so you get the fading by kind of symbol instead of by location (the bar) as on a raster display.

 

 

LOL that's a nice attempt at an explanation but I highly doubt that's the case. DDI's are just computer monitors, exactly the same as the monitor you're looking at right now.

All monitors have a refresh rate, no matter their power source. It's how they animate their images.

 

And I hope I have made it clear enough how these are very much not like the monitors we are looking at.

[Bunny Clark]

DDI's are just computer monitors, exactly the same as the monitor you're looking at right now.

 

The DDIs in the video, just like our Hornet, use CRT vector displays and not LCD screens. This is totally normal behavior when such a display is recorded on video. It's an interaction between the shutter speed of the camera and the way the screens refresh. Because CRT vector displays draw data across the display with electron beams, it does not appear the same way on camera as an LCD monitor does. You'll notice this same effect on every YouTube video of a legacy Hornet.

 

For example:

 

EDIT: Luzifer beat me to it with a better answer while I was typing

Edited May 1, 2020 by Bunny Clark

[WytchCrypt]

You'll notice this same effect on every YouTube video of a legacy Hornet.

 

For example:

 

 

That's it...same thing I was seeing in the new video. I was looking at that DDI thinking, "that can't be right...who could possibly use that?" :smilewink:

Edited May 1, 2020 by WytchCrypt

[randomTOTEN]

My point was that the refresh rate had nothing to do with current changing direction, and had to do with how the monitor animates the images. I was less precise on the exact method of projection. I should have said "similar" and not "exactly" in my reply.

 

Thanks for the clarification though. Yeah you can see individual image elements rendered in different frames of the recording camera.

Edited May 1, 2020 by randomTOTEN

[High_Flyer]

Aircraft AC power buses are generally 400 Hz, so that would disprove that already. And of course TVs (since you're referring to broadcast systems designed to match the power line frequency) don't use power line frequency to generate video refresh, they have to synchronize to the received signal after all. Just like monitors.

 

What's really happening, and it's easy to see if you know what to look for, is that these aren't raster displays like TVs or typical computer monitors, they are vector displays. In raster displays the electron beam scans every line from left to right and then the next line below from top to bottom until starting over, in a fixed pattern. There is no electron beam in LCDs and the like and most standards are digital nowadays, but the exact same pattern is still used.

 

Vector displays on the other hand allow the beam to be moved under computer control to directly draw shapes on the screen. Say you want to show a white rectangle on the screen. On a raster display you have to divide it up into pixels and then wait until the beam reaches a pixel, tell the screen to make it bright, and when the beam leaves an area with rectangle pixel tell it to make it dark. On a vector display you tell it to move the beam e.g. to the coordinates of the upper left corner, then move it slowly (speed determines brightness) to the upper right, then to lower right, and so on to draw the shape on the screen.

 

This makes for very sharp pictures that could be equaled only with a high resolution raster display and its associated costs of large framebuffer memory and high frequency electronics. When you think in 1970's electronics, raster displays could not compete for these kinds of data displays.

 

Unlike raster displays, vector displays do not have a fixed refresh. Every line or arc that is drawn takes time, and the more there are, the longer it takes to complete the display. That is why they can become flickery when there are too many symbols to draw, one complete cycle takes long to complete and the refresh rate goes down. It also makes sense to have a maximum refresh and just to wait when a display is done early, otherwise the screen would get brighter the fewer symbols it has to display.

 

Coming back to the video, it has all the signs of it being vector displays. Since raster displays always display from top to bottom, on video and film you might see black bars moving through the picture. Vector displays aren't ordered in location, they are ordered in however the computer draws the symbols at whatever location. Here you can see that on the fuel page, it draws all the numbers, texts and boxes separately, so you get the fading by kind of symbol instead of by location (the bar) as on a raster display.

 

 

 

 

And I hope I have made it clear enough how these are very much not like the monitors we are looking at.

 

Nice write up. I truly do love learning about this stuff. You can learn something new every day. I have no shame in being wrong, you can only come out more informed.

[Bluecat]

Is it just me or does the sequence from 12:05 to 12:07 look a bit dangerous?

 

 

If he's a split second slow in reacting, that's a collision.

[lobo]

Is it just me or does the sequence from 12:05 to 12:07 look a bit dangerous?

 

 

If he's a split second slow in reacting, that's a collision.

 

At 12:28 you can see them actually make contact... :pilotfly:

 

But, 12:05-07 does looks interesting.

[Harker]

At 12:28 you can see them actually make contact... :pilotfly:

Made me watch.

[WytchCrypt]

Is it just me or does the sequence from 12:05 to 12:07 look a bit dangerous?

 

 

If he's a split second slow in reacting, that's a collision.

 

 

No doubt...but it's just another day at the office for these amazing pilots :pilotfly:

[danidr]

Aircraft AC power buses are generally 400 Hz, so that would disprove that already. And of course TVs (since you're referring to broadcast systems designed to match the power line frequency) don't use power line frequency to generate video refresh, they have to synchronize to the received signal after all. Just like monitors.

 

What's really happening, and it's easy to see if you know what to look for, is that these aren't raster displays like TVs or typical computer monitors, they are vector displays. In raster displays the electron beam scans every line from left to right and then the next line below from top to bottom until starting over, in a fixed pattern. There is no electron beam in LCDs and the like and most standards are digital nowadays, but the exact same pattern is still used.

 

Vector displays on the other hand allow the beam to be moved under computer control to directly draw shapes on the screen. Say you want to show a white rectangle on the screen. On a raster display you have to divide it up into pixels and then wait until the beam reaches a pixel, tell the screen to make it bright, and when the beam leaves an area with rectangle pixel tell it to make it dark. On a vector display you tell it to move the beam e.g. to the coordinates of the upper left corner, then move it slowly (speed determines brightness) to the upper right, then to lower right, and so on to draw the shape on the screen.

 

This makes for very sharp pictures that could be equaled only with a high resolution raster display and its associated costs of large framebuffer memory and high frequency electronics. When you think in 1970's electronics, raster displays could not compete for these kinds of data displays.

 

Unlike raster displays, vector displays do not have a fixed refresh. Every line or arc that is drawn takes time, and the more there are, the longer it takes to complete the display. That is why they can become flickery when there are too many symbols to draw, one complete cycle takes long to complete and the refresh rate goes down. It also makes sense to have a maximum refresh and just to wait when a display is done early, otherwise the screen would get brighter the fewer symbols it has to display.

 

Coming back to the video, it has all the signs of it being vector displays. Since raster displays always display from top to bottom, on video and film you might see black bars moving through the picture. Vector displays aren't ordered in location, they are ordered in however the computer draws the symbols at whatever location. Here you can see that on the fuel page, it draws all the numbers, texts and boxes separately, so you get the fading by kind of symbol instead of by location (the bar) as on a raster display.

 

 

 

 

And I hope I have made it clear enough how these are very much not like the monitors we are looking at.

 

 

Very interesting explanation. Thank you!

 

 

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[eaglecash867]

I was just watching a video of the recent joint Blue Angel and Thunderbird flyover of NYC and noticed something very odd in the Hornet. Take a look at the 10:27 mark of the video. Both the left and right DDI's are in some strange mode where they seem to be cycling through various screens repeatedly. Does anyone know what they're doing? Is this some flight software that is customized or specific to the Blue Angels and why in the world would you want your DDI's to be constantly cycling like that?

 

Thanks :pilotfly:

 

Its a synchronization issue between the video camera refresh rate and the refresh rate of the displays. You can also see this kind of effect in video of aircraft with propellers or rotors. Sometimes they appear to rotate one direction, then the other, and sometimes appear to stop altogether. Its all an electronically-induced optical illusion.

[WytchCrypt]

They are about ready to stand down and switch to Rhinos.

 

Blue Angels begin the shift to Super Hornets

 

 

Just read the article. Cool that they'll have better low altitude power for possible new maneuvers, but bummed as I don't care for the look of the square jet intakes of the Super Hornet (makes them look like this strange F18/F15 hybrid). I might change my mind when I see the 1st Super Hornet in Blue Angel livery.

 

 

 

I'm sure they'll continue to be amazing whatever they fly :smilewink: