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I would be real curious how this passive radar design helps in an actual war environment. Even if you discount all the possible issues like the F-35s not being

I would be real curious how this passive radar design helps in an actual war environment. Even if you discount all the possible issues like the F-35s not being in "stealth operational mode", having reflectors, etc.. this is not a real world test at all. In the real world test there will be a massive amount of ECM energy hitting this passive radar... it might totally blind a sensor like this. In addition a lot of the civilian radio frequencies/transmitters will be getting knocked offline and it won't have it's energy sources.

mannykannot 7y ago
Would active ECM not be a source of illumination of the target that passive radar could take advantage of?
- inetknght 7y ago
  Sure it would if you also assume that the ECM transmitter is also the target. Decoys might break your assumption though. It seems logical to mount ECM on a decoy target.
  - mannykannot 7y ago
    Passive radar depends on the reflection of ambient RF by the target. A drone radiating for ECM purposes (or any other) might illuminate the airplane it is supposed to be protecting. On the other hand, the algorithms behind passive radar might depend on knowing where the transmitters are. Maybe one could triangulate the drone directly, but not so easily if you have multiple drones transmitting short bursts asynchronously. And if there are enough decoys, it would be like chaff.
    - inetknght 7y ago
      > Passive radar depends on the reflection of ambient RF by the target. A drone radiating for ECM purposes (or any other) might illuminate the airplane it is supposed to be protecting. That's a very good point which I neglected to consider.
- AnimalMuppet 7y ago
  If someone is shining a spotlight in your face, the spotlight may also be illuminating the room. That doesn't help you see any better.
  - mannykannot 7y ago
    You can shield your eyes from the direct glare. If the enemy does not know where you are (unlike conventional radar, you are not radiating), he can only spotlight you by chance.
- angry_octet 7y ago
  Not passive RADAR no, that is looking at distortion of a known signal. Picking up ECM is one aspect of ESM or ELINT, which through wide area triangulation can provide approximate location. But it's tricky, ECM can be a lot lower power than a search RADAR, e.g. repeating echos, distorting the return signal to have a different signature, etc. If it is a powerful jammer it's likely to be quite directional so distant receivers might not pick it up well.
openasocket 7y ago
I was thinking about this also. Practically speaking, I don't think you would be able to get much from civilian sources. It could be used to effectively boost the range of your own radar stations though. If you put a passive receiver (of the same receiving sensitivity as your radar station) at the maximum range of your radar station you would effectively increase the range of your system by 50%. But there are some caveats. The biggest is that both your emissions source and your passive receiver need line of sight to the target, making it easier for a jet to break contact at the outer range.

mannykannot 7y ago

Would active ECM not be a source of illumination of the target that passive radar could take advantage of?

inetknght 7y ago
Sure it would if you also assume that the ECM transmitter is also the target. Decoys might break your assumption though. It seems logical to mount ECM on a decoy target.
- mannykannot 7y ago
  Passive radar depends on the reflection of ambient RF by the target. A drone radiating for ECM purposes (or any other) might illuminate the airplane it is supposed to be protecting. On the other hand, the algorithms behind passive radar might depend on knowing where the transmitters are. Maybe one could triangulate the drone directly, but not so easily if you have multiple drones transmitting short bursts asynchronously. And if there are enough decoys, it would be like chaff.
  - inetknght 7y ago
    > Passive radar depends on the reflection of ambient RF by the target. A drone radiating for ECM purposes (or any other) might illuminate the airplane it is supposed to be protecting. That's a very good point which I neglected to consider.
AnimalMuppet 7y ago
If someone is shining a spotlight in your face, the spotlight may also be illuminating the room. That doesn't help you see any better.
- mannykannot 7y ago
  You can shield your eyes from the direct glare. If the enemy does not know where you are (unlike conventional radar, you are not radiating), he can only spotlight you by chance.
angry_octet 7y ago
Not passive RADAR no, that is looking at distortion of a known signal. Picking up ECM is one aspect of ESM or ELINT, which through wide area triangulation can provide approximate location. But it's tricky, ECM can be a lot lower power than a search RADAR, e.g. repeating echos, distorting the return signal to have a different signature, etc. If it is a powerful jammer it's likely to be quite directional so distant receivers might not pick it up well.

openasocket 7y ago

I was thinking about this also. Practically speaking, I don't think you would be able to get much from civilian sources. It could be used to effectively boost the range of your own radar stations though. If you put a passive receiver (of the same receiving sensitivity as your radar station) at the maximum range of your radar station you would effectively increase the range of your system by 50%. But there are some caveats. The biggest is that both your emissions source and your passive receiver need line of sight to the target, making it easier for a jet to break contact at the outer range.