reported AG Radar Cursor Movement Question

[Terzi]

I had STPT 4 selected in front of me and tried to move the cursor without going to FZ or SP. I move the cursor and then cursor comes back again and again. Everytime the radar sweeps that point, cursor comes back to its original place. What am I doing wrong?

[Frederf]

Awful isn't it? The crosshairs don't actually move back. The terrain display shifts under the cursors in an unexpected way. The way the radar is currently displaying the series of images it feels like the cursor moves back but it's not what's happening. Whenever the image seems to "snap back" to where you started slewing, don't panic and just wait for the next image to scan which will happen on the next sweep toward the nose. You did move the SPI and if you wait for the next image to process you'll see you're just where you thought you were when to released the cursor switch.

The "snapback" on the current image slice is a weird artifact. Just ignore what you see when you release the cursor switch until the radar has a chance to make a new image. The imagery will appear to change but it's false.

Under the current radar model you have to slew and then wait for the image update to see where the cursors are. It takes a lot of patience. If you chase a dot on the radar image without waiting you'll slew onto it and then before the image refreshes you'll slew again thinking you aren't on it. This will cause you to slew off it and then the cycle repeats.

[Terzi]

6 hours ago, Frederf said:

Awful isn't it? The crosshairs don't actually move back. The terrain display shifts under the cursors in an unexpected way. The way the radar is currently displaying the series of images it feels like the cursor moves back but it's not what's happening. Whenever the image seems to "snap back" to where you started slewing, don't panic and just wait for the next image to scan which will happen on the next sweep toward the nose. You did move the SPI and if you wait for the next image to process you'll see you're just where you thought you were when to released the cursor switch.

The "snapback" on the current image slice is a weird artifact. Just ignore what you see when you release the cursor switch until the radar has a chance to make a new image. The imagery will appear to change but it's false.

Under the current radar model you have to slew and then wait for the image update to see where the cursors are. It takes a lot of patience. If you chase a dot on the radar image without waiting you'll slew onto it and then before the image refreshes you'll slew again thinking you aren't on it. This will cause you to slew off it and then the cycle repeats.

Thanks for the info. I will try it next time.

[Northstar98]

On 10/30/2021 at 4:12 AM, Frederf said:

Awful isn't it? The crosshairs don't actually move back. The terrain display shifts under the cursors in an unexpected way. The way the radar is currently displaying the series of images it feels like the cursor moves back but it's not what's happening. Whenever the image seems to "snap back" to where you started slewing, don't panic and just wait for the next image to scan which will happen on the next sweep toward the nose. You did move the SPI and if you wait for the next image to process you'll see you're just where you thought you were when to released the cursor switch.

The "snapback" on the current image slice is a weird artifact. Just ignore what you see when you release the cursor switch until the radar has a chance to make a new image. The imagery will appear to change but it's false.

Under the current radar model you have to slew and then wait for the image update to see where the cursors are. It takes a lot of patience. If you chase a dot on the radar image without waiting you'll slew onto it and then before the image refreshes you'll slew again thinking you aren't on it. This will cause you to slew off it and then the cycle repeats.

It's been a few months, but is this behaviour accurate?

Whereby you slew and the radar cursor moves, but when you stop slewing it snaps back to where it was and you have to wait until for the image to update to see where you slewed it?

In this video (pre-CCIP C model), the crosshairs are always centred in the display and the image moves underneath it, the image just updates for the new center position, and there's no snapping.

Edited June 21, 2022 by Northstar98

[Carbon715]

On 12/13/2021 at 6:07 AM, Northstar98 said:

It's been a few months, but is this behaviour accurate?

Whereby you slew, and the RADAR image moves, but when you stop slewing the whole thing snaps back to where it was and you have to wait until for it to update to see where you slewed it?

In this video (pre-CCIP C model), there's no 'snap back', when the slew is released, it stays where it is and the image just updates at the new center position. When slewing though, your just confined to the boundaries of the last scan (which we already are).

 

Curious to know as well the whole radar image slewing now is nearly as bad as it was before, is this correct?

[Northstar98]

Curious that this is marked 'correct as is' with no explanation and in spite of evidence that the AN/APG-68 (albeit an older version) doesn't do this.

[NineLine]

20 hours ago, Northstar98 said:

Curious that this is marked 'correct as is' with no explanation and in spite of evidence that the AN/APG-68 (albeit an older version) doesn't do this.

As always, if you have evidence for the version we are using, you can submit it to us, if you are worried about it being against rules you can talk to us in PMs. 

If it is marked correct as-is, then that means it is correct to the available documentation and information we have.

[Northstar98]

On 1/10/2022 at 5:57 PM, NineLine said:

As always, if you have evidence for the version we are using, you can submit it to us, if you are worried about it being against rules you can talk to us in PMs. 

If it is marked correct as-is, then that means it is correct to the available documentation and information we have.

This video (though isn't the right block (C block 25(?)) and older version of the radar (though still an AN/APG-68)) is my main reference point.

It shows similar behaviour and symbology to DCS, but when the cursor switch is released and the image under the cursors stops moving, the image doesn't briefly snap-back to where it was before updating, the image just recentres on the cursors as the radar completes another scan.

You'll note that when a new image is produced, the cursors may not be over the position they were released at in the previous frame and as such you need to wait for a new image to be produced before you can refine it.

Getting wary of 1.16 but a non-nuclear weapons delivery manual for Hellenic F-16CJ Block 50 c. 1996 doesn't state anything about the image in EXP/DBS1/DBS2 snapping back to centre when the cursor switch is released and the only considerations it mentions is that refinements in its position only take effect at the start of a frame, specifically in the DBS modes, which as mentioned above, is shown in the video. The other considerations are for scan limits.

If the current behaviour is accurate, fine, it just raises a little bit of scepticism when an earlier version doesn't do this (and as a result is a bit more intuitive and makes for much smoother transitions between images).

Edited June 21, 2022 by Northstar98
grammar

[toilet2000]

On 1/10/2022 at 12:57 PM, NineLine said:

As always, if you have evidence for the version we are using, you can submit it to us, if you are worried about it being against rules you can talk to us in PMs. 

If it is marked correct as-is, then that means it is correct to the available documentation and information we have.

What information? There is not a single document describing that behavior.

Also, there is not to my knowledge a single ground radar acting this way in any aircraft.

And finally, it makes 0 sense to do so because that means for a significant amount of time, the designation cross is pointing at a location that does not fit at all with the actual designation. Anybody with knowledge of sensor systems and HMI knows this is a big no-no and a high risk. By 2005 such a behavior (if it existed to begin with) would have been fixed.

Also, it makes the AG radar unusable in anything but freeze frame because it is impossible to know how much to move the cursor otherwise. There’s a reason why Wags couldn’t do it without freeze and active pause in the video.

As Northstar linked, there is a ton of evidence to the contrary.

Edited June 21, 2022 by toilet2000

[Northstar98]

18 minutes ago, toilet2000 said:

And finally, it makes 0 sense to do so because that means for a significant amount of time, the designation cross is pointing at a location that does not fit at all with the actual designation. Anybody with knowledge of sensor systems and HMI knows this is a big no-no and a high risk. By 2005 such a behavior (if it existed to begin with) would have been fixed.

And, if the video is anything to go by, was fixed (if it needed fixing in the first place) in 1985 on the baseline AN/APG-68.

[Frederf]

Every pixel on the display is of the true position it was measured. DCS's handling violates this concept in two ways.

First when the plane turns the prior image doesn't remain in its recorded position but sticks in screenspace. Second when slewing the image under the expanded cursor and slewing ceases the image snaps back to show the old position imagery under the new position (imagery in wrong position).

F-16 paints its findings on a "world canvas" and then displays from that as appropriate. When the cursor is slewed to a new area it shows imagery for that area either some data if it is in memory or blackness until the radar can get new. But it doesn't show the wrong data in the meantime.

Edited June 21, 2022 by Frederf

[NineLine]

The team has confirmed this is an error with the SME, this is now reported, thanks.