[NO BUG] PDSTT have some problem for lowspeed target

[FWind]

In TWS mode

It can select a target on DDD for a STT lock, but can't get STT lock from TID.test PDSTT.trk

Edited November 12, 2019 by IronMike

[Tiramisu]

I am not able to open your trackfile, but I think it is because usually a Doppler search on the DDD has a higher range than the TWS search on the TID. So this may be no bug.

[FWind]

I am not able to open your trackfile, but I think it is because usually a Doppler search on the DDD has a higher range than the TWS search on the TID. So this may be no bug.

 

Both of them in TWS mode.

[FWind]

I am not able to open your trackfile, but I think it is because usually a Doppler search on the DDD has a higher range than the TWS search on the TID. So this may be no bug.

It will happened target speed on IAS 100-240 knot and altitude around 30000-40000 feets.

[QuiGon]

Can't look at the track atm, but it very much sounds like you're encountering the doppler filters there. I recommend to read up on them in the manual, because this is not a bug, but actual behaviour of the radar in PD modes: http://www.heatblur.se/F-14Manual/general.html#pulse-doppler-mode

 

Because of the way the radar operates the doppler filters it will have two blind ranges. The main lobe clutter (MLC) region which contains most of the ground returns, those returning with zero groundspeed is one of them and is 266 knots wide, centered around own aircraft groundspeed (133 knots slower and 133 knots faster). This is the reason that the radar can be notched as a target with the same relative groundspeed as the ground will also be filtered out. This is however only true for look-down conditions as when the radar antenna looks up into the sky this filter isn’t necessary and can be turned off. If the MLC switch on the DDD panel is in AUTO the radar will automatically turn off the MLC filter if looking more than 3 degrees above the horizon. It can also be turned off manually by the RIO but if the antenna looks down this can make the displays unusable in RWS and TWS as all of the ground returns will be sent to the computer for tracking. In whichever case, with the MLC filter off, the target cannot notch the AN/AWG-9 if it is above the radar. The second filter, and second blind spot, of the radar is the zero doppler filter. This blind area is centered around a closure rate of negative own groundspeed, meaning a target moving away from own aircraft at the same speed as own aircraft. This blind area is a hardware limitation as it is a doppler radar mode it cannot detect targets without a doppler shift. The resulting blind area is 200 knots wide, meaning that a chased target moving at a speed of within 100 knots (+/-) of own groundspeed will be invisible to the radar. This means that when chasing a fleeing target it may very well be necessary to use the pulse modes instead.

 

The second filter, and second blind spot, of the radar is the zero doppler filter. This blind area is centered around a closure rate of negative own groundspeed, meaning a target moving away from own aircraft at the same speed as own aircraft. This blind area is a hardware limitation as it is a doppler radar mode it cannot detect targets without a doppler shift. The resulting blind area is 200 knots wide, meaning that a chased target moving at a speed of within 100 knots (+/-) of own groundspeed will be invisible to the radar. This means that when chasing a fleeing target it may very well be necessary to use the pulse modes instead.

Edited November 11, 2019 by QuiGon

[FWind]

Can't look at the track atm, but it very much sounds like you're encountering the doppler filters there. I recommend to read up on them in the manual, because this is not a bug, but actual behaviour of the radar in PD modes: http://www.heatblur.se/F-14Manual/general.html#pulse-doppler-mode

 

I can found the target on TID and DDD in TWS mode. got PDSTT and PSTT in DDD, but can't got PDSTT when pusse the PDSTT button.

[QuiGon]

got PDSTT [...] but can't got PDSTT when pusse the PDSTT button

Sorry, I don't understand. You got PDSTT, but you can't get PDSTT when you push the PDSTT button? How do you got PDSTT then?

[FWind]

Sorry, I don't understand. You got PDSTT, but you can't get PDSTT when you push the PDSTT button? How do you got PDSTT then?

 

Control the cursor on DDD when got PDSTT.

[Naquaii]

Not sure about your exact specifics but do keep in mind that hooking the target on the TID and then pressing PD-STT or P-STT is a much more unreliable method of locking a target than locking it manually on the DDD. This is intentional as it is described that way in the documentation and by SMEs.

 

Also doing this while maneuvering makes it very hard as TWS is not as reliable when not flying straight and level.

 

Flying stable straight ahead it should work though, while in a turn it's very difficult.

[FWind]

Not sure about your exact specifics but do keep in mind that hooking the target on the TID and then pressing PD-STT or P-STT is a much more unreliable method of locking a target than locking it manually on the DDD. This is intentional as it is described that way in the documentation and by SMEs.

 

Also doing this while maneuvering makes it very hard as TWS is not as reliable when not flying straight and level.

 

Flying stable straight ahead it should work though, while in a turn it's very difficult.

Yeah, I will test it few times.

[IronMike]

Marked as no bug, as for reasons described by Naquaii above.