Forum: General F-22A Raptor forum

If radar waves have to travel to a target and back to the transmitter, is it safe to assume that the range at which other aircraft can detect an aircraft's emissions is well in excess of 2 times the radar's maximum range?

So if for example, some F-22's are somewhere near a Mig-31 with its big Zaslon-m radar with "supposedly" 400km max range, they could possibly see it coming from maybe 800-1000km+ (and triangulate its approximate position if the F-22's are spread out enough).

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I posted this in the other thread before you removed it, so I'll put it here too.

If by maximum range you mean maximum distance the radar's emissions can be detected by some other receiver, then yes you're correct. That's why potentially the most important sensor on the F-22 isn't the APG-77, it's the ALR-94. It's also why there's a growing emphasis in passive sensors on the newest fighters. The LPI features of the latest AESA radars helps cut down on this as well.

In counter-air sorties where the goal is to eliminate defensive fighter patrols, the attacking aircraft usually leave their radar in standby and use passive or 3rd party sensors (AWACS, Rivet Joint, etc.) to get into the most effective position for their weapons.

Elite 1K Joined: May 26, 2005 - 08:39 PM Posts: 1496

If you have a receiver and antenna that are tuned to the transmitting radar's frequency with a known pulse width then yes, you can detect its transmissions from much farther away than it can detect you (think of a man walking through a wide open field on a moonless and starless night). The trouble is you don't KNOW what frequency the enemy radar is using. SIGINT may be of some help, but LPI is a collection of methods of taking advantage of this inherent uncertainty in frequency, pulse width, etc. Especially with AESA radar you can do all sorts of neat tricks to try and hide from RWRs or fool their electronics so even if they detect the transmission they may not recognize it as a threat.

Of course like any other military technology it's a race between the detectors and the detectees if you will. Also, like Lightndattic said, 3rd party sensors like AWACS and/or directional or one way secure datalinks are also quite useful in avoiding detection.

Without trying to calculate it, the curvature of the earth may be a factor when detecting at ranges of up to 1000Km, as these are high frequencies that do not bend like old fashion long wave radio signals. The obvious exception would be the (experimental) radars that use long waves/low frequencies to see over the horizon.

Yes and not only that, but it wouldn't depend on the Zaskon's power it would depend on how sensitive the F-22's detectors are. If they are very, very sensitive, long as a little tiny bit of the emissions get to the antenna the computer would be able to detect and report it. Also, on guysmileys point that you wouldn't know what freq. they were using I think it wouldn't matter that much. Emissions would fall into 3 categories. Ours, Enemies, and unknown and if it's unknown you'd want to investigate and assume it was hostile for the time being. You can change freqs. scramble comms. but you still have to radiate them out and something on our side will see it and check it out.

Ok, I know almost zero about radar, but have a question for some of you who know a lot.

munny wrote:

If radar waves have to travel to a target and back to the transmitter, is it safe to assume that the range at which other aircraft can detect an aircraft's emissions is well in excess of 2 times the radar's maximum range?

Here's the question. Since the target RWR antenna is much smaller than the transmitter/receiver antenna, wouldn't that tend to reduce the target aircraft's RWR detection range capability compared to the transmitter range?

yes, but they are scattered out over a wider area. also, the amount of energy in the radar signal decreases with range, so at twice the detection range you are receiving the same amount of power at the enemy receiver does at the detection range.

Commentary on RWR detection range versus transmitter range, and I quote "Jack":

"...to say the least, i am one of the most manaical, dangerous, and most skilled drivers on the road, usually averaging out 50 MPH in any part of the city, this piece of junk offers too little, too late, already, in the short time i have had this unit, i have almost been bagged 3 times for driving at obscenely high speeds, don't purchase this, dont even steal it.... go with a Bel, coincidentally enuff, they are also the ppl who make the radars for the cops......"

OL

(I think he's including school zones)

thanks for the replies...pretty much answers it.

Lightndattic wrote:

... where the goal is to eliminate defensive fighter patrols, the attacking aircraft usually leave their radar in standby and use passive or 3rd party sensors (AWACS, Rivet Joint, etc.) to get into the most effective position for their weapons.

Which might of course also raise the hypothetical of the 'other guys' leaving their radars in standby and using passive and/or 3rd party sensing as well? Then perhaps it would come down to who has the most superior, effective weapon position capacity to best exploit one's passive tactics?

Regardless, for pondering purposes only (no details are of public use), I'd be curious how a 'Growler-lite' ALQ-218 type equipped platform configured in air defense/intercept role would compare in passive geo-locating capabilities vs forinstance, the ALR-94?

IMO, I think its unlikely that the situation will arise that opposing platforms will be evenly matched to the point that each negates the other's capabilities. Both may be stealth but one will probably be stealthier. One or both may have LPI radar, but again one will probably be less detectable. Advantages may seem small but the effect could be incremental and enough to provide one side a substantial advantage. Then of course you need to factor in the other assets that each side can bring into play. Again, I think its unlikely that the matchups will be that even.

geogen wrote:

Which might of course also raise the hypothetical of the 'other guys' leaving their radars in standby and using passive and/or 3rd party sensing as well? Then perhaps it would come down to who has the most superior, effective weapon position capacity to best exploit one's passive tactics?

I don't think this is going to happen, at least not in the near future (~10 years). Radars are far superior to passive (IR) detection methods. I think the most possibe is:
1. Third party targeting (AWACS, or for example Eagle/Raptor combo - Raptor closing the target to get a good firing solution while the Eagle with active APG-63(v)3 is passing data while staying behind and drawing attention away from the shooter.
2. IRST will be a supplementary sensor that in good weather conditions will assure you that you won't be helpless against VLO aircrafts.
And some more, but I have to go now.
later.

exec wrote:

or for example Eagle/Raptor combo - Raptor closing the target to get a good firing solution while the Eagle with active APG-63(v)3 is passing data while staying behind and drawing attention away from the shooter.

This is the situation I was thinking of when I mentioned the the Mig-31 in the OP. I read somewhere that the Mig-31 is to be used as the mini awacs in the same way.

I'll look forward to hearing more of Execs thinking when he gets to it.

As for now, I'll remain in the camp that even in the near-term and certainly from 2015 and beyond, that there will absolutely be 'potential' scenarios where the so-called 3rd party and off-board netted (supplemented by passive sensing) meet-ups in the air will sufficiently cancel out each other's advantage and at which point it will in part become a matter of which party has a more superior tactical firing position capability to gain any relative advantage. imho.

geogen wrote:

Which might of course also raise the hypothetical of the 'other guys' leaving their radars in standby and using passive and/or 3rd party sensing as well? Then perhaps it would come down to who has the most superior, effective weapon position capacity to best exploit one's passive tactics?

Regardless, for pondering purposes only (no details are of public use), I'd be curious how a 'Growler-lite' ALQ-218 type equipped platform configured in air defense/intercept role would compare in passive geo-locating capabilities vs forinstance, the ALR-94?

Which gets us into the measure-countermeasure game. Most defensive minded foes will want to detect any incoming raid as early as possible. Depending on the assets available, operating silently may not be an option.

I too would love to know how the -218 compares to the -94, but we'll likely never see that in the public arena.

Forum: General F-22A Raptor forum

Question on RWR detection range