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What's RFI?


FalcoGer
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What does the radio frequency interferometer actually do?

From what I read before it seemed like it would analyze radar reflections and tell you the type of object you are looking at with the radar like the non cooperating target recognition in an aircraft radar. Like it would be able to tell you SA15 or T55 on the radar screen.

From what I read in ED's manual it was made out to be a passive system. But we already have RWR receivers.

What does it actually do then and how does it work?

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  • 2 weeks later...

Could someone clarify please?

Like what is the difference? It seems like you can select RFI as acquisition sources, for which you would need range. Then why is it displayed on the outside of the ASE box and not, which would make more sense to me, at the range that was found? The cued search button tries to lock an RFI detected emitter, but it can't do the same thing with an RWR detected emitter? Why?

What is it? what does it do? how does it work? and what's the difference between it and the RWR? And why don't all aircraft have that instead of RWR if it can give you a range also? I can understand how you can get the bearing of an emitter with multiple antennas by observing the interference pattern that was created by the different arrival times of the signal, and you could get the range if you fly along a bearing and keep track of there the signal is coming from over time. But that doesn't seem to be the case here.

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RFI emitters are placed outside of the ASE box to separate them from RLWR emitters. The cued search button doesn’t lock the RFI emitter with the FCR, it slaves the FCR to the RFI emitter. The RFI has 5 little antennas which make it better than the normal RSDS. I’m not sure the whole ranging thing, but I believe it triangulates the emitter similar to a HTS (kinda) but a bit better in some ways. 

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No it doesn’t triangulate or provide a passive range at all. 

It’s a more sensitive RWR. RFI can detect a higher frequency range than a RWR and is more likely to make the correct classification. It also provides a more accurate azimuth bearing than the RLWR. 

When RFI is the ACQ source it slaves the sight to the detected bearing in azimuth and the local horizontal in elevation. You need take over and search visually, with TADS from there. 

The cued search function slaves the FCR to the detected bearing and automatically starts a scan. I imagine that if an air defence vehicle target (FCR can classify these) is found along that azimuth it tries to correlate the two detections into one target symbol. 

Bear in mind the FCR only has like a 8km max range, so this doesn’t turn the Apache into a SEAD machine or anything. 

Just now, AvroLanc said:

No it doesn’t triangulate or provide a passive range at all. 

It’s a more sensitive RWR. RFI can detect a higher frequency range than a RWR and is more likely to make the correct classification. It also provides a more accurate azimuth bearing than the RLWR. 

When RFI is the ACQ source it slaves the sight to the detected bearing in azimuth and the local horizontal in elevation. You need take over and search visually, with TADS from there. 

The cued search function slaves the FCR to the detected bearing and automatically starts a scan. I imagine that if an air defence vehicle target (FCR can classify these) is found along that azimuth it tries to correlate the two detections into one target symbol/contact, with range.

Bear in mind the FCR only has like a 8km max range, so this doesn’t turn the Apache into a SEAD machine or anything. 

 

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15 minutes ago, FalcoGer said:

Like what is the difference? It seems like you can select RFI as acquisition sources, for which you would need range. Then why is it displayed on the outside of the ASE box and not, which would make more sense to me, at the range that was found?

An acquisition source does not need to provide range (other acquisition sources like e.g. helmet sight and TADS does not provide range, just direction). And as far as I know the RFI does not provide range either.

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2 minutes ago, arneh said:

An acquisition source does not need to provide range (other acquisition sources like e.g. helmet sight and TADS does not provide range, just direction). And as far as I know the RFI does not provide range either.

It needs at least a bearing and elevation though, which, when combined with the terrain database would be the same as a bearing and range.

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18 minutes ago, FalcoGer said:

It needs at least a bearing and elevation though, which, when combined with the terrain database would be the same as a bearing and range.

Not all ACQ sources need MSL elevation. Many can just be Line of Sight. Azimuth and Elevation (by elevation in this case, I mean just angles not a height/altitude). 

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1 hour ago, FalcoGer said:

It needs at least a bearing and elevation though, which, when combined with the terrain database would be the same as a bearing and range.

No, not necessarily, the source could well be airborne, in which case you have no idea about range. And also I doubt the resolution is good enough to give any sort of accurate range based on elevation.


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