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JF irradiation in RWR


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The greatest threat is always inside the circle, if its radar is illuminating you then you have a squared box around it, the circle on RWR is not a range indication, it is a threat indication afaik.

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2小时前,Furiz说:

The greatest threat is always inside the circle, if its radar is illuminating you then you have a squared box around it, the circle on RWR is not a range indication, it is a threat indication afaik.

I have tried to use 18,15,14,16 for comparison, all in the outer circle

2小时前,Florence201说:

RWR’s work on received power, checked against a database. They should then display either outside or inside the inner ring on the scope based on that 

This is very strange, only JF17 is always in the inner circle. But other aircraft (SU27, F14, F15) are on the outer circle, and will slowly shrink to the inner circle at a certain distance.

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Some radars are stronger and some are weaker,

RWR threat display also depends on the track they are conducting, for example in the F-16 if you TMS UP once, it will bug the target but it will keep scaning, target wont know that you buged it and the power output towards the target is lower then when you press TMS UP twice, then it goes into a single target track mode and directs all the radar power to to one spot where the target is, hence providing a stronger power output towards that target.

 

We don't know was that Jeff, foxhound or eagle in STT mode or they just illuminated you with their radars.

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1小时前,Furiz说:

Some radars are stronger and some are weaker,

RWR threat display also depends on the track they are conducting, for example in the F-16 if you TMS UP once, it will bug the target but it will keep scaning, target wont know that you buged it and the power output towards the target is lower then when you press TMS UP twice, then it goes into a single target track mode and directs all the radar power to to one spot where the target is, hence providing a stronger power output towards that target.

 

We don't know was that Jeff, foxhound or eagle in STT mode or they just illuminated you with their radars.

All of the above comparisons are based on radar illumination, and no tracking is performed. But the JF17 irradiates me at 120 nautical miles and will be in the threat circle, and other aircraft 60 nautical miles are also outside the threat circle.

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9 hours ago, Furiz said:

Some radars are stronger and some are weaker,

RWR threat display also depends on the track they are conducting, for example in the F-16 if you TMS UP once, it will bug the target but it will keep scaning, target wont know that you buged it and the power output towards the target is lower then when you press TMS UP twice, then it goes into a single target track mode and directs all the radar power to to one spot where the target is, hence providing a stronger power output towards that target.

 

We don't know was that Jeff, foxhound or eagle in STT mode or they just illuminated you with their radars.

Radars don’t generally change power, they switch to higher PRF/PRI for faster update rates. 

[sIGPIC][/sIGPIC]

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7 hours ago, Florence201 said:

Radars don’t generally change power, they switch to higher PRF/PRI for faster update rates. 

Probably depends on how you look at radar power: transmitted power, spatial averaged power throughout the scan volume, or time averaged power at a point.  The transmit power doesn't change in STT, but the received power changes, depending how you measure it.  The individual pulse power will be the same at the receiver, but the time average of received power will be much higher (one or two orders of magnitude) because the target is continuously bathed in pulses rather than momentarily scanned at an interval of several seconds.

"Subsonic is below Mach 1, supersonic is up to Mach 5. Above Mach 5 is hypersonic. And reentry from space, well, that's like Mach a lot."

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2 hours ago, Florence201 said:

The received power level has to do with transmitted power, range, atmospheric conditions etc. not how many pulses hit the tgt. 

Yes, that's the definition of raw instantaneous received power. Also the transmitting antenna aspect (main lobe vs side lobe vs null) and receiver antenna gain pattern/aspect.  The fact that the radar in STT mode will center its main lobe on the target will probably increase the power received by the RWR.

 

Radars and GPS receivers use a technique called coherent integration, which is a form of time averaging, to increase the effective signal to noise ratio so they can read the data. I don't have any direct knowledge how RWRs work, but I'm making an educated guess that they infer a higher threat level in part using some kind of time average, not just raw instantaneous signal power, to detect if transmitters are in STT mode. They may also use PRF and the pulse pattern.  If you know more about them please correct me. 


Edited by Machalot

"Subsonic is below Mach 1, supersonic is up to Mach 5. Above Mach 5 is hypersonic. And reentry from space, well, that's like Mach a lot."

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Modern day RWR and Self Defence systems are far more capable than what DCS is modeling. 
 

What we currently have is based on basic 3rd gen RWRs which used a database of certain parameters. 
 

Let’s not over complicate the original post. Jeff radar received RWR symbology appears incorrect based on the RWR threat table. 

[sIGPIC][/sIGPIC]

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On 8/28/2021 at 3:08 PM, Furiz said:

The greatest threat is always inside the circle, if its radar is illuminating you then you have a squared box around it, the circle on RWR is not a range indication, it is a threat indication afaik.

In the F18, dangerous Bandits are moved to the inner ring, but this does not apply to the F16 only the distance decides

 

in DCS it is partly a "distance indicator" but especially in the F16


Edited by Hobel
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The real questions are: 

 

  1. Do the F-16 RWR rings indicate range, threat, or a combination of threat and estimate range? 
  2. Why is the behavior different between a Mig-31 and the JF-17 in the F-16 RWR?

 

Some myths you guys have said:

 

  • 'PRF/PRI effect update rate.'
    • common misconception. PRF/PRI effects range and doppler ambiguity and average power (duty cycle).
    • The radar scan speed/frame time effects update rate. 
  • 'All RWRs determine threat range.'
    • Not all.
  • 'Lower power output effects displayed range.'
    • Assuming the RWR estimates range; the RWR will compensate for this once the radar is identified. (ie the range is estimated via the received amplitude, by multiplying that radars known radiated power by the inverse square law until it matches the received amplitude) So a Mig-31 and a JF-17 in formation should appear roughly together in range on the RWR, despite the different power outputs. 
  • 'RWRs use coherent integration.'
    • Nope. Doing so would reduce their time resolution (FFT) and thus their ability to determine PD and PRI. 
    • On the plus side, RWRs only have to deal with one way path loss, where as the radar needs to deal with two way path loss. 
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1 hour ago, Beamscanner said:

The real questions are: 

 

  1. Do the F-16 RWR rings indicate range, threat, or a combination of threat and estimate range? 
  2. Why is the behavior different between a Mig-31 and the JF-17 in the F-16 RWR?

 

Some myths you guys have said:

 

  • 'PRF/PRI effect update rate.'
    • common misconception. PRF/PRI effects range and doppler ambiguity and average power (duty cycle).
    • The radar scan speed/frame time effects update rate. 
  • 'All RWRs determine threat range.'
    • Not all.
  • 'Lower power output effects displayed range.'
    • Assuming the RWR estimates range; the RWR will compensate for this once the radar is identified. (ie the range is estimated via the received amplitude, by multiplying that radars known radiated power by the inverse square law until it matches the received amplitude) So a Mig-31 and a JF-17 in formation should appear roughly together in range on the RWR, despite the different power outputs. 
  • 'RWRs use coherent integration.'
    • Nope. Doing so would reduce their time resolution (FFT) and thus their ability to determine PD and PRI. 
    • On the plus side, RWRs only have to deal with one way path loss, where as the radar needs to deal with two way path loss. 

PRI/PRF DOES affect update rate. For a given scan volume, increasing PRF will give you a greater update rate. Basic physics. More pulses more updates 

[sIGPIC][/sIGPIC]

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5 hours ago, Beamscanner said:

'RWRs use coherent integration.'

  • Nope. Doing so would reduce their time resolution (FFT) and thus their ability to determine PD and PRI. 
  • On the plus side, RWRs only have to deal with one way path loss, where as the radar needs to deal with two way path loss. 

 

I appreciate the correction.  In my defense, I only said "some kind of time average".  My intuition was that it would not merely use the instantaneous signal power.  The FFT uses data gathered across a finite time window, so I claim partial credit! 🎓


Edited by Machalot
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"Subsonic is below Mach 1, supersonic is up to Mach 5. Above Mach 5 is hypersonic. And reentry from space, well, that's like Mach a lot."

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19 hours ago, Florence201 said:

PRI/PRF DOES affect update rate. For a given scan volume, increasing PRF will give you a greater update rate. Basic physics. More pulses more updates 

 

Maybe I'm misinterpreting you but, it seems you are thinking that the radar irradiates in all directions at the same time.

 

In reality its a "pencil" beam that scans the sky, therefore for the update rate it matters how frequently that beam passes over a target (only talking about scanning, not STT).

 

WHEN it passes over a target, for the small amount of time that it is painting it, the number of pulses that will be reflected by the target will depend on PRF, and that will, as Beamscanner, be used to resolve range and doppler ambiguities.


Edited by SFJackBauer
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On 8/31/2021 at 6:33 PM, Florence201 said:

PRI/PRF DOES affect update rate. For a given scan volume, increasing PRF will give you a greater update rate. Basic physics. More pulses more updates 

This is incorrect. 

 

In real life, Radars don't detect targets with a single pulse. Pulses are integrated for improved gain and a Fourier transform is applied for separating returns into doppler bins.

 

Even the ancient WW2 radars integrated pulses via the phosphor coating on their CRT displays. 

 

 

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All real life theory aside, this is a good question:

  

On 9/1/2021 at 2:27 AM, Beamscanner said:
  1. Why is the behavior different between a Mig-31 and the JF-17 in the F-16 RWR?

 

And not just between a MiG-31 and the JF-17, but according to the OP the JF-17 is being displayed on the F-16's RWR in a totally different manner than pretty much all the other fighter jets. How come the JF-17 is so very different in that regard?! I don't see any reason for this.

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The JF radar, in game, has a very, and IMO unreasonably, high signal strength. You can see this very obviously on the SPO-15, any JF within like 30nm will completely overwhelm it and show it near max strength. In the DCS framework its ultimately just simple signal strength measuring, and in that aspect its too powerful for sure, the tiny radar just isnt putting out that much power.

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