What causes ABRIS (GLONAS) display deviation?

[Usagi]

I am not sure how this should be and how could this kind behaviour be possible in real life (with out electrical warfare).

The thing is that sometimes KA-50's ABRIS display will display location and heading incorrectly (way more than GLONAS display shows as accuracy).

 

My heading is directly towards the target village and still according to map, my heading is off the village:

The satellite positioning is accurate. 2D plane is within 20 meters and altitude within 23 meters:

 

Shkval and heading towards point marked on map as 'Start'. The map display shows around 15° offset:

 

This happens sometimes and I really aren't sure why. Is this known problem of real ABRIS system or just thing in the DCS (using Open Beta MT 2.9.0.47168). No rearming and repairing done during mission.

 

 

[MAXsenna]

@Usagi which alignment did you use? Or did you hot start?

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[Usagi]

16 hours ago, MAXsenna said:

@Usagi which alignment did you use? Or did you hot start?

Sent from my SM-A536B using Tapatalk
 

This was quick alignment. Does it affect ABRIS too?

[MAXsenna]

This was quick alignment. Does it affect ABRIS too?

Reading post from other users, it seems the quick alignment is not very accurate. I might have misunderstood your post, but are you sure the ABRIS is wrong and the Shkval is correct? Could it actually be the opposite? And have you corrected the magnetic declination?

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[Usagi]

On 11/11/2023 at 4:11 PM, MAXsenna said:

Reading post from other users, it seems the quick alignment is not very accurate. I might have misunderstood your post, but are you sure the ABRIS is wrong and the Shkval is correct? Could it actually be the opposite? And have you corrected the magnetic declination?

Sent from my SM-A536B using Tapatalk
 

 

I can try reproduce this. As I approached the village, it was on my 12 and shkval looked directly towards it (boresight). According to ABRIS I wasn't flying toward the village.

The last screenshot was when I was flying towards to FARP, but according to map I wasn't.

I did not corrected the magnetic declination - If ABRIS heading is not taken directly from GNSS.

[Usagi]

The mission actually requires no alignment and fix points:

 

[BigBorner]

Is it maybe more precise if you range it with the laser?

shooting in the dark here. 

[PawlaczGMD]

You need to laser range to produce an accurate Shkval target position on the ABRIS. You don't have a range on the screen, so you didn't do this. In this case the system will try to guesstimate the target position just based on angles, but sometimes this is wrong by a lot.

Another issue is for the heading angle- the GNSS doesn't know your heading, only position, so this is taken from your instruments. Check on the F10 map that your HSI shows the true heading correctly. If not, you can manually adjust it. One way is to switch the Man/Gyro/MH toggle to MH for a few seconds while keeping constant heading, then back to Gyro.

I'm not sure if this is affected by the INU alignment precision, but quick alignment might cause your heading to degrade quicker.

 

On 11/10/2023 at 9:28 AM, Usagi said:

I am not sure how this should be and how could this kind behaviour be possible in real life (with out electrical warfare).

The thing is that sometimes KA-50's ABRIS display will display location and heading incorrectly (way more than GLONAS display shows as accuracy).

 

My heading is directly towards the target village and still according to map, my heading is off the village:

The satellite positioning is accurate. 2D plane is within 20 meters and altitude within 23 meters:

 

Shkval and heading towards point marked on map as 'Start'. The map display shows around 15° offset:

 

This happens sometimes and I really aren't sure why. Is this known problem of real ABRIS system or just thing in the DCS (using Open Beta MT 2.9.0.47168). No rearming and repairing done during mission.