Re: [Flightgear-devel] Radar Coverage and Text Display

[Geoff]

On Wed, 2008-10-08 at 01:46 +0200, Alexis Bory - xiii wrote:

> Good news, I'm quite lost in the radar technical world.

Hi Alexis - and everyone else who responded.

It does not look to me like you are lost in the radar world.

The input sent to me seems well thought out.  I am glad to see that the
Microsoft "radars are irrelevant" philosophy is not in FG. Having the
radars and then having the radars in platforms is what I am most
concerned with.  Having it built in means less work for what I want to
do with my sim which is controlling the interaction between platforms -
something that FG per se- should not be doing - as it is more of a
server function than an individual flight simulator function.

>  Actually we work on a very basic
> level, but the aim is having a radar behavior being as near from
> reality as possible, I mean from a pilot's point of view.

Yes, I would agree.


> This table exists, it is yet based by aircraft type but already includes
> radar name, range, and other data (originaly by Glazmax/Jettoo and
> updated by me). Radar types are not yet in the table but could be
> added easily. The idea of indexing the table upon radar name is also
> feasible and seems to be a very good idea :-)

Yes, I see the table and I will go through it in more detail to see what
is there.

> One of the next application would be the RWR tone which on some
> systems change with the frequency of the scan or goes continuous
> when having a steady lock.

Yes, the RWR tone is very important - as in the case of attack aircraft
they don't have the sophisticated receivers and displays that ships or -
for example the AWACS aircraft have.  The RWR tells the pilot vital
information about fire control radars locking on.

In recent writings it has been proposed within the simulation world to
give any radar 100% detection ability out to it's maximum range.  The
only conflict comes into play when the radar is looking down on ground
and sea clutter, where reflective returns used to show up on radar
scopes.  Today's processors are pretty efficient at reducing such
clutter.  In my own sim, I have not yet removed the probability of
detection, though I probably (pun intended) will soon.  


> Vivian Meazza wrote:
> Hidden
> away in it all is a simplified version of the radar equation. The most
> significant simplification is that radar waves travel in a straight 
> line.

In my world they do too.  The amount of bending is very minimal given
the relatively short ranges of these radars.  Weather (ie cloud and
atmospherics) can cause RF energy to bounce and "skip" sometimes great
distances.  But for simulation purposes I ignore these as well.

> In addition there isn't enough ground loaded into fg to make the
longer ranges meaningful. Further, random objects, such as ships, and
bridges etc. are not detectable (which is what I was trying to do in the
first place).

That would supposition that every object had a radar cross
section/reflectivity assigned to it.  Actually, that might not be hard
to implement - but it would add another data field to objects.

Thanks folks!

-- 
Geoff McLean
McLean Research Associates

"To be good is not enough when you dream of being great."


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Re: [Flightgear-devel] Radar Coverage and Text Display

[Vivian Meazza]

Geoff

> 
> On Tue, 2008-10-07 at 21:28 +0200,
> 
> 
> As a very concerned military simulationist (is there such a word?) I am
> deeply worried about military radars, indeed the whole radar "thing".
> 
> Every radar has it's own unique qualities - PRR, PRF, discrimination,
> anti-clutter, etc.  From a simulation point of view radar range and
> target size are extremely important.  An AWG-9 is not like an APS-124
> nor like a SPS-10 or SPS-40, much less a Headnet C.  So what I am
> getting at is a radar system is not inherent to a platform - but only to
> itself.  And it's ability to find a target is unique.  So, please do not
> lump radars into a all-in-one category.  Actually - there are at least
> three categories:
> 
> Fire control:  SPG-53/AWG-9, etc.  Usually they are very narrow beam,
> high power and provide continuous tracking
> 
> Track While Scan (TWS):  Medium power.  Provide targeting and search.
> Targeting is availble by their high rotation rate (usually one second or
> less).  (SPS-55)
> 
> Search Radars:  Medium Power, slow rotation rate, very long range.  In
> aircraft typically 60 degree coverage - ships usually 360 degree.  Range
> is usually quite long but depends on PRR and PRF.
> 
> And a fourth might be the new generation of phased array - though granted
> they are not yet on aircraft (that I know of).
> 
> Note PRR = Pulse Repetition Rate   PRF= Pulse Repetition Frequency
> 
> Quite frankly, I would like to see radars put into a table so they can be
> easily modified in/when their data become available.  Janes usually offers
> quite accurate and unclassified data for radar systems.
> 
> Best wishes for continuing development!

I've done some work on this already. I've added a Terrain Warning mode and
an Air to Ground mode to the weather radar. These are modelled on the Blue
Parrot radar fitted to the Buccaneer, but all the major parameters are
configurable in xml. I also extended it to provide a Radar Altimeter. Hidden
away in it all is a simplified version of the radar equation. The most
significant simplification is that radar waves travel in a straight line.

The work has stopped for now. It uses some OSG code which is very heavy in
terms of frame rate, and tends to make fg stagger a bit. In addition there
isn't enough ground loaded into fg to make the longer ranges meaningful.
Further, random objects, such as ships, and bridges etc. are not detectable
(which is what I was trying to do in the first place).

That said, Terrain Warning is up and running, and can be seen in the
Buccaneer in CVS right now.

Vivian   



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Re: [Flightgear-devel] Radar Coverage and Text Display

[Alexis Bory - xiii]

Geoff wrote:

 On Tue, 2008-10-07 at 21:28 +0200,
 As a very concerned military simulationist (is there such a word?) I
 am deeply worried about military radars, indeed the whole radar
 "thing".


Hi Geoff
Good news, I'm quite lost in the radar technical world.


 Every radar has it's own unique qualities - PRR, PRF, discrimination,
 anti-clutter, etc. From a simulation point of view radar range and
 target size are extremely important. An AWG-9 is not like an APS-124
 nor like a SPS-10 or SPS-40, much less a Headnet C. So what I am
 getting at is a radar system is not inherent to a platform - but only
 to itself. And it's ability to find a target is unique. So, please
 do not lump radars into a all-in-one category.


This is not what we want to do. Actually we work on a very basic
level, but the aim is having a radar behavior being as near from
reality as possible, I mean from a pilot's point of view.


 Quite frankly, I would like to see radars put into a table so they
 can be easily modified in/when their data become available.


This table exists, it is yet based by aircraft type but already includes
radar name, range, and other data (originaly by Glazmax/Jettoo and
updated by me). Radar types are not yet in the table but could be
added easily. The idea of indexing the table upon radar name is also
feasible and seems to be a very good idea :-)
One of the next application would be the RWR tone which on some
systems change with the frequency of the scan or goes continuous
when having a steady lock.
Anyway you can have a look at the table (attached file). Be indulgent
as we are not specialists. The table is already in CVS:
$DATA/Aircraft/Instruments-3d/radardist/radardist.xml

In our implementation algorithms are quite mostly guess... Your help
would be appreciated.


 Best wishes for continuing development!


Thanks.
Alexis












	
		
			

	generic
	5
	1.49
	none
	0
	0
	0
	00


	707
	80
	2.34
	none
	0
	0
	0
	00


	737-300
	50
	2.11
	none
	0
	0
	0
	00


	747
	100
	2.34
	none
	0
	0
	0
	00


	787
	777
	35
	1.86
	WXR-2100
	160
	100
	3.16
	00


	A24-Viking
	2
	1.19
	none
	0
	0
	0
	00


	A-10
	25
	2.23
	none
	0
	0
	0
	00


	A300
	80
	2.23
	none
	0
	0
	0
	00


	A320
	50
	1.96
	none
	0
	0
	0
	00


	A380
	100
	2.11
	none
	0
	0
	0
	00


	a4
	10	
	1.77
	APG-53
	15
	5
	1.49
	00


	A-6E
	14
	1.93
	APQ-112
	150
	100
	3.16
	06


	A6M2
	15
	1.96
	none
	0
	0
	0
	00


	Albatross
	40
	2.51
	none
	0
	0
	0
	00


	Aerostar-700
	10
	1.86
	none
	0
	0
	0
	00


	Alouette-II
	15
	2.51
	none
	0
	0
	0
	00


	Alouette-III
	20
	2.11
	none
	0
	0
	0
	00


	Alphajet
	5
	1.49
	none
	0
	0
	0
	00


	an-2
	2
	1.19
	none
	0
	0
	0
	00


	AN-225
	100
	2.59
	unknown
	0
	0
	0
	00


	apache
	30
	2.34
	APG-78
	8
	1
	1
	00


	ASK21
	asw20
	bocian
		1
	1
	none
	0
	0
	0
	00


	b1900d
	20
	2.11
	wx500
	60
	100
	3.16
	00


	B-1B
	4
	1.41
	APQ-164
	296
	100
	3.16
	01


	B-2
	0.0015
	0.19
	APQ-181
	333
	100
	3.16
	02


	b29
	100
	3.16
	APQ-19
	45
	100
	3.16
	00


	B-52F
	100
	3.16
	APQ-166
	296
	100
	3.16
	00


	BAC-TSR2
	15
	1.86
	Blue Parrot
	46
	100
	3.16
	00


	beaufighter
	9
	1.73
	none
	0
	0
	0
	00


	bf109
	15
	1.96
	none
	0
	0
	0
	00


	Buccaneer
	10
	1.77
	Blue Parrot
	46
	100
	3.16
	00


	c310
	c310u3a
	4
	1.41
	none
	0
	0
	0
	00


	c172
	c172p
	c172r
	c182
	c182rg
	2
	1.19
	none
	0
	0
	0
	00


	dhc6
	5
	1.49
	none
	0
	0
	0
	00


	E3B
	100
	2.23
	APY-1/2
	650
	100
	3.16
	03


	F-86
	F-86f
	9
	1.73
	APG-37
	50
	100
	3.16
	00


	f104
	9
	1.73
	ASG-14
	60
	100
	3

Re: [Flightgear-devel] Radar Coverage and Text Display

[Geoff]

On Tue, 2008-10-07 at 21:28 +0200, 


As a very concerned military simulationist (is there such a word?) I am
deeply worried about military radars, indeed the whole radar "thing".

Every radar has it's own unique qualities - PRR, PRF, discrimination,
anti-clutter, etc.  From a simulation point of view radar range and
target size are extremely important.  An AWG-9 is not like an APS-124
nor like a SPS-10 or SPS-40, much less a Headnet C.  So what I am
getting at is a radar system is not inherent to a platform - but only to
itself.  And it's ability to find a target is unique.  So, please do not
lump radars into a all-in-one category.  Actually - there are at least
three categories:  

Fire control:  SPG-53/AWG-9, etc.  Usually they are very narrow beam,
high power and provide continuous tracking

Track While Scan (TWS):  Medium power.  Provide targeting and search.
Targeting is availble by their high rotation rate (usually one second or
less).  (SPS-55)

Search Radars:  Medium Power, slow rotation rate, very long range.  In aircraft 
typically 60 degree coverage - ships usually 360 degree.  Range is usually 
quite long but depends on PRR and PRF.

And a fourth might be the new generation of phased array - though granted they 
are not yet on aircraft (that I know of).

Note PRR = Pulse Repetition Rate   PRF= Pulse Repetition Frequency

Quite frankly, I would like to see radars put into a table so they can be 
easily modified in/when their data become available.  Janes usually offers 
quite accurate and unclassified data for radar systems.

Best wishes for continuing development!
-- 
Geoff McLean
McLean Research Associates

"To be good is not enough when you dream of being great."



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Re: [Flightgear-devel] Radar Coverage and Text Display

[Alexis Bory - xiii]

Manfred Janßen wrote:
>  Hi Alexis,
>
>  it's not bounded to the A-10. The only think I wanna show is the
>  coverage of the radar of the aircraft, let me show you a simple
>  drawing:

Ok with the image that you sent me off list I understand.

You can add a visible shape in place of what could be the radar
vision cone like any other model.

You first need a scaled cone (you may use a smaller one and scale it
at run time*) this cone could be semi transparent. This has to be
done in blender or any modeling sofware and exported as .ac
I use AC3D (which is not free).

Then include your model inside the main aircraft model like we do
usually for 3d instruments.

Have a look at $DATA/Aircraft/A-10/Models/A-10-model.xml you will
find lot of instruments, your cone will be done the same way.

You can have more help on IRC irc.flightgear.org #flightgear

Greetings
Alexis

* this is another story but I'm sure you can :-)



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Re: [Flightgear-devel] Radar Coverage and Text Display

[James Turner]

On 7 Oct 2008, at 07:49, Manfred Janßen wrote:

> I try to add some radar coverage cone to the A-10.
> But at the moment I have no idea, how to start that. Any hints?

It's not relevant now, but once I get my NAV display operating  
correctly, it'll be fairly simple to make it work as a radar display -  
I already need that to support a TCAS overlay.  I will probably review  
the wx-radar code at that point as well, since all these things are  
effectively layers of data that make up the complete display in a  
modern  system, but can be displayed stand-alone in an older cockpit.

However, this is definitely a medium-term thing, so if you want  
something soon, the solutions proposed by other people are better.

James


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Re: [Flightgear-devel] Radar Coverage and Text Display

[Manfred Janßen]

Hi Alexis,

it's not bounded to the A-10.
The only think I wanna show is the coverage of the radar of the
aircraft, let me show you a simple drawing:



Thats what I wanna do, just simply show some cone like a radar-lobe.
Sorry for my explanation, but english is not my native language.
The text you see at the pic is that what my second question meant, it
works not in my DLL ( I use FG as a DLL in an other program to display
real flight data).

Kind Regards
Manfred

Alexis Bory - xiii schrieb:
> Manfred Janßen wrote:
>   
>>  1. I try to add some radar coverage cone to the A-10. But at the
>>  moment I have no idea, how to start that. Any hints?
>> 
>
> Hi Manfred,
> What do you mean by radar coverage ? The A-10 do not have a radar, or 
> may be you are talking about Radar Warning Receiver ?
>
> There is no point on adding a radar to the A-10, it would be like adding 
> turbofan to the c172p... The A-10 as a cannon in place of the radar :-)
>
> If you want to  have a better view on how works the radar in Flightgear, 
> you can have a look at AIBase.cxx, which is the starting point of every 
> computation, then there are two systems: wxradar.cxx and radar2.nas. 
> There is also a per aircraft database, radardist.xml and radardist.nas   
> giving radar performances when the aircraft has a radar and also 
> reflection performances for most of the GA aircrafts, this database is 
> called by radar2.nas but could used by any other system.
> There is also a current developement for a generic RWR instrument 
> (suitable for A-10, F-16, OV-10, A-6E...) giving a display of azimut, 
> strength and type of radar threats. This use radar2.nas and the 
> database. the RWR should be commited in a few days.
>
> Greetings,
>
> Alexis
>
>
>
>
>
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-- 
-
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Fax: +49 49 41 99 19 221
My status 
Get Skype  and call me for free.
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Re: [Flightgear-devel] Radar Coverage and Text Display

[gerard robin]

On mardi 07 octobre 2008, Alexis Bory - xiii wrote:
> Manfred Janßen wrote:
> >  1. I try to add some radar coverage cone to the A-10. But at the
> >  moment I have no idea, how to start that. Any hints?
>
> Hi Manfred,
> What do you mean by radar coverage ? The A-10 do not have a radar, or
> may be you are talking about Radar Warning Receiver ?
>
> There is no point on adding a radar to the A-10, it would be like adding
> turbofan to the c172p... The A-10 as a cannon in place of the radar :-)
>
> If you want to  have a better view on how works the radar in Flightgear,
> you can have a look at AIBase.cxx, which is the starting point of every
> computation, then there are two systems: wxradar.cxx and radar2.nas.
> There is also a per aircraft database, radardist.xml and radardist.nas
> giving radar performances when the aircraft has a radar and also
> reflection performances for most of the GA aircrafts, this database is
> called by radar2.nas but could used by any other system.
> There is also a current developement for a generic RWR instrument
> (suitable for A-10, F-16, OV-10, A-6E...) giving a display of azimut,
> strength and type of radar threats. This use radar2.nas and the
> database. the RWR should be commited in a few days.
>
> Greetings,
>
> Alexis

Which could be, (more or less)  usefull to F-8E  in order to replace the 3D 
specific one which was developed   with the Aircraft in the old time, it was  
limited to 6 'bandit' id  (2 AI and 4 MP)


-- 
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http://pagesperso-orange.fr/GRTux/

J'ai décidé d'être heureux parce que c'est bon pour la santé. 
Voltaire

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Re: [Flightgear-devel] Radar Coverage and Text Display

[Alexis Bory - xiii]

Manfred Janßen wrote:
>  1. I try to add some radar coverage cone to the A-10. But at the
>  moment I have no idea, how to start that. Any hints?

Hi Manfred,
What do you mean by radar coverage ? The A-10 do not have a radar, or 
may be you are talking about Radar Warning Receiver ?

There is no point on adding a radar to the A-10, it would be like adding 
turbofan to the c172p... The A-10 as a cannon in place of the radar :-)

If you want to  have a better view on how works the radar in Flightgear, 
you can have a look at AIBase.cxx, which is the starting point of every 
computation, then there are two systems: wxradar.cxx and radar2.nas. 
There is also a per aircraft database, radardist.xml and radardist.nas   
giving radar performances when the aircraft has a radar and also 
reflection performances for most of the GA aircrafts, this database is 
called by radar2.nas but could used by any other system.
There is also a current developement for a generic RWR instrument 
(suitable for A-10, F-16, OV-10, A-6E...) giving a display of azimut, 
strength and type of radar threats. This use radar2.nas and the 
database. the RWR should be commited in a few days.

Greetings,

Alexis





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