DDD Nuances

[bonesvf103]

Some questions regarding the DDD behavior I've been seeing lately...

I have a tanker, co-altitude with me, nose cold, about 8 miles away.  He is doing 300 knots, I am doing 130.

Radar is in PD search, azimuth is set to 20, bars set to 4, Vc is set to normal, antenna elevation is centered.

When I have the aspect switch set to tail, his blip appears at the bottom of the DDD.  I take this to mean that he up to and around 1800 kts opening.  When I set it to aspect he is halfway between the DDD cross and the bottom of the screen,  I take that to mean he is 600 knots opening.  But when I set it to nose, his blip is slightly above the cross in the DDD, which I take to mean that he is around 200 knots closing.  How can that be if he is flying away from me?

Also, the Vc switch appears to have no effect on the blip, in any aspect switch setting.  Is that correct?

Note that these are round numbers as I'm going off of my head right now, but the scenario is basically correct.

Thanks.

v6,

boNes

 

[Naquaii]

2 hours ago, bonesvf103 said:

Some questions regarding the DDD behavior I've been seeing lately...

I have a tanker, co-altitude with me, nose cold, about 8 miles away.  He is doing 300 knots, I am doing 130.

Radar is in PD search, azimuth is set to 20, bars set to 4, Vc is set to normal, antenna elevation is centered.

When I have the aspect switch set to tail, his blip appears at the bottom of the DDD.  I take this to mean that he up to and around 1800 kts opening.  When I set it to aspect he is halfway between the DDD cross and the bottom of the screen,  I take that to mean he is 600 knots opening.  But when I set it to nose, his blip is slightly above the cross in the DDD, which I take to mean that he is around 200 knots closing.  How can that be if he is flying away from me?

Also, the Vc switch appears to have no effect on the blip, in any aspect switch setting.  Is that correct?

Note that these are round numbers as I'm going off of my head right now, but the scenario is basically correct.

Thanks.

v6,

boNes

I'm not really sure what to tell you, what you're saying doesn't make sense. What you're describing for Tail and Beam seems about right but slightly above the cross in Nose would be more than 600 knots closing. But neither of this makes sense if it's the same target, his velocity would of course not change because of the Aspect switch, that's something I've never seen. That's not something I can explain from the information you've given me.

As for the Vc switch, that's correct, the Vc switch only sets the scale on the DDD for the Vc indicator in the STT modes. It doesn't do anything in search.

[bonesvf103]

Thanks for your response.  Yes, the first thing I thought when doing this was it didn't make sense, primarily because the tanker was clearly moving away from me, so the closure should be opening--this is what was shown in beam and tail, but in nose it was showing closing--whether it was 200 kts or 600 kts, it still showed closing,and that doesn't make sense.

I'm assuming that when in PD search, opening is below the DDD center cross and closing is above the cross.

Is the aspect closing scale shown on the leftmost vertical axis in the DDD while the Vc closing scale is shown on the rightmost vertical axis on the DDD?  I ask because in the HB online manual under AWG-9 and the section entitled Pulse Doppler mode there is a shot of the DDD and the leftmost axis is graduated from -1200 on the bottom and +1200 on the top and on the rightmost axis it is graduated from 0 at the bottom to 800 at the top.  On that rightmost scale there is a tick mark, I assume shows the closure?  It's not labeled in that shotor in the text I can find.

I am off site now but when I can, I will post video of it as it is something I reproduced many times.

So the Vc switch works in ONLY STT modes?  I am also confused by this because in the HB manual it says "The Vc switch (18) controls the rate scale on the DDD in the pulse doppler search modes" but doesn't mention its roll in STT.

Thanks.

v6,

boNes

Edited January 30, 2024 by bonesvf103

[Naquaii]

3 hours ago, bonesvf103 said:

Thanks for your response.  Yes, the first thing I thought when doing this was it didn't make sense, primarily because the tanker was clearly moving away from me, so the closure should be opening--this is what was shown in beam and tail, but in nose it was showing closing--whether it was 200 kts or 600 kts, it still showed closing,and that doesn't make sense.

I'm assuming that when in PD search, opening is below the DDD center cross and closing is above the cross.

Is the aspect closing scale shown on the leftmost vertical axis in the DDD while the Vc closing scale is shown on the rightmost vertical axis on the DDD?  I ask because in the HB online manual under AWG-9 and the section entitled Pulse Doppler mode there is a shot of the DDD and the leftmost axis is graduated from -1200 on the bottom and +1200 on the top and on the rightmost axis it is graduated from 0 at the bottom to 800 at the top.  On that rightmost scale there is a tick mark, I assume shows the closure?  It's not labeled in that shotor in the text I can find.

I am off site now but when I can, I will post video of it as it is something I reproduced many times.

So the Vc switch works in ONLY STT modes?  I am also confused by this because in the HB manual it says "The Vc switch (18) controls the rate scale on the DDD in the pulse doppler search modes" but doesn't mention its roll in STT.

Thanks.

v6,

boNes

 

Yeah, that part about the Vc switch is a lingering error.

What the aspect switch does is that it selects which parts of the doppler filters that are used in the pulse doppler search modes, so not just PD Search but RWS and TWS as well.

In beam the screen covers from -1200 to +1200. In tail it's +600 to -1800 and in nose it's +1800 to -600. So the middle cross is 0 in beam, -600 in tail and +600 in nose. And yes, opening is towards the bottom and closing towards the top. The actual scale marking numbers shown on some DDDs became defunct quite early on and should be disregarded.

 

 

[bonesvf103]

Ah, OK, that makes more sense especially to disregard the side scale numbers.

Another question:  If you use the HCU in radar mode to lock a target, is range displayed in the DDD?  If so, what is the scale of the DDD?  Is it 0 on the bottom and whatever the range scale is set in the buttons above the DDD ?

Thanks.  I'll post that video and/or trackfile later.

v6,

boNes

[Naquaii]

14 minutes ago, bonesvf103 said:

Ah, OK, that makes more sense especially to disregard the side scale numbers.

Another question:  If you use the HCU in radar mode to lock a target, is range displayed in the DDD?  If so, what is the scale of the DDD?  Is it 0 on the bottom and whatever the range scale is set in the buttons above the DDD ?

Thanks.  I'll post that video and/or trackfile later.

v6,

boNes

When coming from pulse search it's range and and when starting in a PD mode it's rate. The only time you get range on the DDD in a PD mode is in PD-STT.

But both STT modes show range and the current range scale should be indicated on the readout above the screen.

[bonesvf103]

OK, I had a look again, and like I said in my original post, I was going off the top of my head and had it backward.  When aspect is set to nose, the blip is on the bottom and when it is in tail it is slightly above the cross, not the other way around (I tried it 3 times to be sure)--so no need for video examples.  I think what really threw me was that the 0 point on the DDD shifts.  In the manual it mentions the scale limits but not the 0 point shifting accordingly so I thought 0 was always the cross.  So I thought above the cross was one scale and below was another scale, not the same scale but shifted.  Now it makes perfect sense.

Thanks!

v6,

boNes

[Naquaii]

47 minutes ago, bonesvf103 said:

OK, I had a look again, and like I said in my original post, I was going off the top of my head and had it backward.  When aspect is set to nose, the blip is on the bottom and when it is in tail it is slightly above the cross, not the other way around (I tried it 3 times to be sure)--so no need for video examples.  I think what really threw me was that the 0 point on the DDD shifts.  In the manual it mentions the scale limits but not the 0 point shifting accordingly so I thought 0 was always the cross.  So I thought above the cross was one scale and below was another scale, not the same scale but shifted.  Now it makes perfect sense.

Thanks!

v6,

boNes

No worries, it's very likely something that could be expanded upon in the manual. Truth to be told there was a time when it had us confused about it as well.

[bonesvf103]

On 1/30/2024 at 3:37 PM, Naquaii said:

When coming from pulse search it's range and and when starting in a PD mode it's rate. The only time you get range on the DDD in a PD mode is in PD-STT.

But both STT modes show range and the current range scale should be indicated on the readout above the screen.

Oh, I thought when you said when coming from PD search it's range that you meant that if I was in PD search then locked with the HCU in the DDD then it's rate only--but then I saw that it gave both.  So I think what you meant is that when you are in PD search BEFORE you lock on with the HCU it's rate, and in the case of Pulse then it's range (ie, the usual behavior).  I was misunderstanding until I played around with it myself.

So when you are in PD search and you lock with the DDD and the lock strobe shifts to the left, is the blip on the left at the vertical axis rate then?  What does the synthetic blip tell you, just azimuth?

When I lock in Pulse with the HCU in the DDD it shows range but not rate, which I understand.  But I also saw that in the TID it shows a rate.  Is that rate valid?  Is that the workaround to getting rate when you are using a pulse mode?

I'm also having an issue with the radar in Pulse search.  I am using the stock radar training mission, but elimated all the C-17s except for one heading right at me (I'm on the ground).  He is at 10.500 ft about 30 miles away.  I set the radar to pulse search and put the elevation above 3 deg to turn off the MLC.  I set azimuth to 60 and another time to 20.  I set the bars to either 6 or 8 depending but the idea was to keep the scan limits shown in the TID for the appropriate range in such a way that his 10500 altitude is within it.  Even though the lower and upper limits of the scan limit place him inside that range, I still don't get a blip.  I don't seem to get him in the DDD until he is really close.  I guess I don't get why id the lower limits it say 9 and the upper is 60 why he wouldn't show up at his 10500 ft altitude.

I'm guessing it has to do with bar setting?

v6,

boNes

[Naquaii]

13 hours ago, bonesvf103 said:

Oh, I thought when you said when coming from PD search it's range that you meant that if I was in PD search then locked with the HCU in the DDD then it's rate only--but then I saw that it gave both.  So I think what you meant is that when you are in PD search BEFORE you lock on with the HCU it's rate, and in the case of Pulse then it's range (ie, the usual behavior).  I was misunderstanding until I played around with it myself.

So when you are in PD search and you lock with the DDD and the lock strobe shifts to the left, is the blip on the left at the vertical axis rate then?  What does the synthetic blip tell you, just azimuth?

When I lock in Pulse with the HCU in the DDD it shows range but not rate, which I understand.  But I also saw that in the TID it shows a rate.  Is that rate valid?  Is that the workaround to getting rate when you are using a pulse mode?

I'm also having an issue with the radar in Pulse search.  I am using the stock radar training mission, but elimated all the C-17s except for one heading right at me (I'm on the ground).  He is at 10.500 ft about 30 miles away.  I set the radar to pulse search and put the elevation above 3 deg to turn off the MLC.  I set azimuth to 60 and another time to 20.  I set the bars to either 6 or 8 depending but the idea was to keep the scan limits shown in the TID for the appropriate range in such a way that his 10500 altitude is within it.  Even though the lower and upper limits of the scan limit place him inside that range, I still don't get a blip.  I don't seem to get him in the DDD until he is really close.  I guess I don't get why id the lower limits it say 9 and the upper is 60 why he wouldn't show up at his 10500 ft altitude.

I'm guessing it has to do with bar setting?

v6,

boNes

Both STT modes build a trackfile that drives the target tracking, the difference is just how it calculates the different values. In P-STT it tracks using angles and range but that is then used to calculate rate as well so the rate shown is valid. In PD-STT the target is tracked using angles and rate and the range is then measured using FM-ranging, kinda how it is in RWS and TWS. To be able to show range vs azumith in PD-STT the AWG-9 shifts the real target return to the left and generates a synthethic target return at correct azimuth and range instead.

It's a bit hard though to say too much about the scenario you describe other than that it can be hard to get the radar pointing exactly where you want it too. An IRL RIO would likely use a 1bar or 2bar scan and try to point it straight at the target instead but that can take much training. Also the range of the pulse modes is much less than the PD modes. Also remember that the altitude coverage indication is for coverage at the selected TID range and only shows coverage at TID cursor when you're in half-action.

[bonesvf103]

Thanks, I tried to apply what you said and I was able to find the target easier and lock him.

Another question though, in the DDD, I have a target locked in PD STT, and on the right side vertical scale I read about 755 kts closing which is what it says in the TID also.  But on the left side vertical scale where the target is shifted over, since I'm set to nose aspect, I'm reading it to be about 300 kts opening.  Why is that?  Also, when I switch the aspect from nose to beam to tail, the marker shifts as I expect it to, but it shows 2 markers in beam and 3 in tail.  What does that tell me?

[Naquaii]

2 hours ago, bonesvf103 said:

Thanks, I tried to apply what you said and I was able to find the target easier and lock him.

Another question though, in the DDD, I have a target locked in PD STT, and on the right side vertical scale I read about 755 kts closing which is what it says in the TID also.  But on the left side vertical scale where the target is shifted over, since I'm set to nose aspect, I'm reading it to be about 300 kts opening.  Why is that?  Also, when I switch the aspect from nose to beam to tail, the marker shifts as I expect it to, but it shows 2 markers in beam and 3 in tail.  What does that tell me?

Seems like you've actually stumbled upon two unknown bugs here (at least to me). The extra markers seem to be the target returns from the two other aspects which shouldn't be there and the positioning of the target rate vertically seems to take azimuth into consideration when it shouldn't. (Normally you have to consider the location for the MLC for targets offset in side for azimuth). So both of these seems to be bugs and I'll save your screenshots and report them.

At least it shouldn't hinder anyone as you're better off using the closure rate on the right anyway. So please disregard the location of the target return on the left side in PD-STT for now.

Edited February 3, 2024 by Naquaii

[Naquaii]

12 hours ago, Naquaii said:

Seems like you've actually stumbled upon two unknown bugs here (at least to me). The extra markers seem to be the target returns from the two other aspects which shouldn't be there and the positioning of the target rate vertically seems to take azimuth into consideration when it shouldn't. (Normally you have to consider the location for the MLC for targets offset in side for azimuth). So both of these seems to be bugs and I'll save your screenshots and report them.

At least it shouldn't hinder anyone as you're better off using the closure rate on the right anyway. So please disregard the location of the target return on the left side in PD-STT for now.

 

I've been able to reproduce but the first issue is likely not a bug, if you switch between the different aspect settings the previous location remains for a moment before being erased, that's just how a screen like this works, like an after image. So unless those extra markers remain over time that's not a bug, that's just how the screen works.

The other one is a bug though but a minor one as far as I can see.

[bonesvf103]

Hi,

Yes, I can confirm that when I wait a little longer those blips do fade away and only the current one remains.  I guess I was a bit too hasty when I observed the change and took the screen shots.  So what does the reading on the left vertical scale mean then?  If it is also closure, but considers azimuth, I'm not sure what the point of it is if we have closure on the right vertical scale.  Can you explain more?

I also tried to find the target in the DDD in pulse mode and although I do find it after a while, I'm a little baffled that I don't find it sooner because I have the setting set pretty much where the target would be in the envelope.  He is heading at me at 10300 about 30 miles away initially.  I set pulse search so that there is no MLC or zero doppler to worry about.  I Set the DDD range to 50, I turn the TID range to 50 as well--that way I can better visualize the radar cone.  If I half action in the TID in the middle, that should be at 25 miles and since he is at 30 I'd expect him to be a little further up the TID, so when I half action in that region, the upper and lower scan limit shows 0 lower and above 10000 upper (don't recall exactly but it is above 10000)--so the target should be visible in the DDD, but it's not.  I play around with the bars and intuitively the target should be there but it's not.  As he gets closer and I mess arou nd with elevation, bars, and acimuth, as well as center, I eventually do get him, but only after he is 20 nm or less. 

I attached a trackfile and mission.  Can you see what I may be doing wrong?

Thanks.

v6,

boNes

LastMissionTrack.trk F-14B-AWG-9-3.miz

[Naquaii]

56 minutes ago, bonesvf103 said:

Hi,

Yes, I can confirm that when I wait a little longer those blips do fade away and only the current one remains.  I guess I was a bit too hasty when I observed the change and took the screen shots.  So what does the reading on the left vertical scale mean then?  If it is also closure, but considers azimuth, I'm not sure what the point of it is if we have closure on the right vertical scale.  Can you explain more?

I also tried to find the target in the DDD in pulse mode and although I do find it after a while, I'm a little baffled that I don't find it sooner because I have the setting set pretty much where the target would be in the envelope.  He is heading at me at 10300 about 30 miles away initially.  I set pulse search so that there is no MLC or zero doppler to worry about.  I Set the DDD range to 50, I turn the TID range to 50 as well--that way I can better visualize the radar cone.  If I half action in the TID in the middle, that should be at 25 miles and since he is at 30 I'd expect him to be a little further up the TID, so when I half action in that region, the upper and lower scan limit shows 0 lower and above 10000 upper (don't recall exactly but it is above 10000)--so the target should be visible in the DDD, but it's not.  I play around with the bars and intuitively the target should be there but it's not.  As he gets closer and I mess arou nd with elevation, bars, and acimuth, as well as center, I eventually do get him, but only after he is 20 nm or less. 

I attached a trackfile and mission.  Can you see what I may be doing wrong?

Thanks.

v6,

boNes

LastMissionTrack.trk 5.7 MB · 0 downloads F-14B-AWG-9-3.miz 4.36 MB · 0 downloads

It should be positioned in the right spot according to seen closure but you also have the closure rate on the other side so there's really no reason to use that. The point of it existing is that it's the actual radar return and that you want to see that visually, the other readouts are better for basically everything else in STT.

The part about the azimuth is that the radar doesn't adjust for seen groundspeed (ownspeed) at each azimuth, it just applies own speed across it all. That's why the MLC is a curve, not a line. So with greater azimuth you have to compensate for that curvature yourself as you should really measure distance to the MLC curve, not to a straight line across the scope. In this case my guess is that the deflected real return in code is using that position to display the return, not what it would be at the actual azimuth.

Unfortunately I don't really have the time and ability to load those files in atm and have a look so if there's anyone else here that feels like helping that'd probably be quicker.

[bonesvf103]

Thanks!  I really appreciate the time you have taken for this.

v6,

boNes