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DDD PD scale


huppel

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Hi,

 

 

After reading the manual and watching some video's on the subject I'm still puzzled about the DDD and scale in PD modes.

 

 

If in PD non STT modes I thought I understood the scale was on the right side and either fixed (0-800) or influenced with the vcx4/norm/vid switch. However the Vcx4 switch does not make any difference when I have a target in PD showing closure, however if I change the Aspect switch to the left of the DDD that makes the target move in the DDD, so that one seems to influence scale. So in a PD non STT mode the scale is on the left and is the scale set with the aspect button? And what is the scale?

 

 

 

If in PD STT if I'm right the right scale shows a line in the scale indicating closure (and indeed the line moves when I change the Vcx4 switch) but what scale is used? (Does not seem to be fixed as the line changes when I change the vcx4 switch position)

On the left I see a target image as well that also shows closure but then depended on the aspect switch (as the target moves in the scale when I change that switch), correct?

 

 

Also sometimes the RDROT is just lighted when I have a target locked, sometimes it is flashing, What is the difference in what it is indicating if it is just on vs flashing?

 

 

Thanks, Marcel

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From what I comprehend in PD modes the DDD shows only closure, the aspect switch changes closure scale. I haven’t found much use of this as most interceptions are within 1000 knots of closure and are within the normal “ aspect “ range, with exception of say trying to intercept a cruise missile going Mach 10 then the aspect switch would be used to adjust closure scale.

This applies to all the Doppler modes PD search RWS TWS and PDSTT.

 

As far as Pulse modes goes I have found it to be unreliable at best, failing to show contacts despite the IFF getting returns and displaying the returns on the DDD.

Also note the aspect switch in pulse mode directs the AWG9 to focus on the leading edge of the target ie. nose. Etc. And the DDD now displays range only which is scaled with the range select buttons above the DDD

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Thanks, but indeed this I already got from the manual.

 

However the manual is confusing on the scale and what influences it.

 

Take the paragraph in the "AN/AWG-9 radar/Pulse Doppler Mode" section that starts with "The scale shown on the DDD (what rate region is shown) can be set by the Vc switch on the DDD panel. X-4 sets..." that seems not in line with how its working at the moment.

 

So I'm still curious what the scale is used on the DDD in the different PD modes and how it is influenced by the aspect and x4 switches.


Edited by huppel
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Ah, was trying to find some info using google and although I used the search function of the forum before posting that gave me two hits here and one on another forum (which I don't know if I'm allowed to link to here so I wont do that) on which also somebody apparently from heatblur replied.

 

 

But what I get from it indeed in PD search the scale on the left indicates closure rate and the aspect switch moves the rate scale up and down it does not zoom (see one of the link for details). The closure rate mark on the right side is only shown in STT hence the vc switch only has an effect there. It is an error in the manual that it is mention to be shown in other modes then PD STT.

 

Reply by 'gyrovague' from heatblur on the vs scaling: "OK, I checked our docs and the implementation again. AFAICT, it's correct, however it does not change the scaling of the DDD itself, only the Vc bug on the right hand side of the DDD in STT modes... It seems like it might be wrongly described in our manual therefore."

 

 

https://forums.eagle.ru/showthread.php?t=237319

https://forums.eagle.ru/showthread.php?t=236649

 

 

Hope this helps!

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Played around with STT modes and found yes closure is on the right while in both STT modes but also range is shown in the centre. Shown as a contact in PSTT and a flat line in PDSTT. Range scale is changed by range buttons above DDD.

As for what the closure scale is I have found if you check the TID it gives closure as a numeric prefixed by + or -

If you reference this while switching the Vc you can deduce what the scale is.

 

Probably unrelated but I’ve tested in both SP and MP and in MP the azimuth and elevation jump around when switching between radar modes.

Elevation being more problematic as azimuth is obvious on the DDD.

Same occurs when entering super search.

Also pulse modes as far as I can tell in MP are broken with some contacts showing at 120+ miles and others undetectable at 10-20 miles only to have said contacts vanish in super search.

 

In SP elevation holds between modes and pulse was showing returns out to 80-90 miles even distinguishing between surface ships and airborne contacts with ease.

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The current wording in the manual is a bit ambiguous, I'll add it to the list for things needing improvement.

 

Like you guys have discussed, the Vc bug only controls the scale of the Vc bug in the STT modes. X-4 being 800 knots opening to 4000 knots closing, NORM 200 knots openening to 1000 knots closing and VID 50 knots opening to 250 knots closing.

 

It's the aspect switch that controls the whole DDD scale in the pulse doppler modes. NOSE has the screen show -600 to +1800 knots, BEAM -1200 to +1200 knots and TAIL -1800 to +600 knots. All this with higher positiv rate being towards the top of the screen.

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  • 7 months later...
The current wording in the manual is a bit ambiguous, I'll add it to the list for things needing improvement.

 

Like you guys have discussed, the Vc bug only controls the scale of the Vc bug in the STT modes. X-4 being 800 knots opening to 4000 knots closing, NORM 200 knots openening to 1000 knots closing and VID 50 knots opening to 250 knots closing.

 

It's the aspect switch that controls the whole DDD scale in the pulse doppler modes. NOSE has the screen show -600 to +1800 knots, BEAM -1200 to +1200 knots and TAIL -1800 to +600 knots. All this with higher positiv rate being towards the top of the screen.

 

 

Sorry I don't get this comment xD.

 

for me there is deep confusion between :

 

NORM 200 knots openening to 1000 knots closing

 

and

 

BEAM -1200 to +1200 knots

 

the last quote leads me to believe that the scale should be :

 

 

 

Where is this

NORM 200 knots openening to 1000 knots closing

you speak of then ?? for me those two info do not match ?

 

In BEAM-NORM the whole span of the screen is from -1200 to +1200 : ok

It would make sense that in BEAM-x4 the center of the screen would stay at 0kts, but the scale are stretched x4 => whole span of the screen from -1200*2 = -2400 to 1200*2 = +2400 span = 4800 OK : (though for me the switch should rather be called x2 then... but anyway)

 

But from your quote above it seems that changing the scale switch from NORM to x4, streches the scale but also moves the '0tks' point downward ? Is this correct ?

 

What happens then if you have BEAM-x4 ? how does the combined change to 0kts point from the aspect & scale switch combine ?

 

 

This Is how I understand it. first image for BEAM-NORM.

Second image for BEAM-x4 and NOSE-x4

 

https://imgur.com/a/KSBLKVK

 

Z7w4CDI.png

 

717iHBR.png

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Ok, there is definitely something wrong :

 

setup :

 

Me : flying north @6000ft 430kts GS

 

target : flying north @5000ft 650kts GS

 

See images bellow, with the scale switch in all three positions :

 

 

No differences at all on the DDD screen ??? how could this be, for me scale switch is non functional !

 

Vc Switch x4 :

HkmFk8B.png

Vc Switch NORM :

pqLQMko.png

Vc Switch VID :

ZvQ2OQl.png

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Vc switch only controls the scale of the so-called Vc "bug" on the right of the DDD, shown only in STT modes.

 

The Aspect switch controls the scale of the main display in PD modes, essentially shifting everything up or down.

____________

Heatblur Simulations

[sIGPIC][/sIGPIC]

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