Do note that the this claim comes from the same people who don’t hand out any actual specs and always fly with an additional reflector. The latter makes it easy for radars to see them again. This is helpful in allied airspace, but it also makes it impossible to verify the claim.
Also note that modern radars are sensitive to how fast an object approaches (or leaves) the radar. Bumblebees don’t break the soundbarrier usually, so it is possible to see these planes, but you do have to tweak your radar for it. (Hence why the US doesn’t give specs.)
Also note that modern radars are sensitive to how fast an object approaches (or leaves) the radar. Bumblebees don’t break the soundbarrier usually, so it is possible to see these planes, but you do have to tweak your radar for it. (Hence why the US doesn’t give specs.)
You are talking about Doppler processing. Basically you can filter out all the things that are not moving fast based on how much the frequency is compressed and lower your noise floor. You will still have other noise sources but minimizing clutter will help, if the return is below other noise sources you still will not be able to detect it.
Correct. But integrating over multiple pulses, and using the latest Tx and Rx modules, sensitivity is not the problem anymore. Radars can easily see every damn bumblebee in a 100km radius. The problem is filtering data, so that processing and/or the user is not overloaded. For example, if you track every single bird with a radar that has a 100km radius, you will not be able to see anything on the operator screen other than birds.
Doppler is easy to filter on early in the processing stage. Meaning that if you can detect the aircraft, you can still separate it from all other bumblee like objects. Clutter tends not to move that fast.
Doppler processing eliminates clutter it doesn’t eliminate EMI, thermal noise, or atmospheric issues.
China’s 366 radar can detect 0.1 sq meter targets at 20km. It’s China’s most modern radar and it’s not close to 100km detection range for LO aircraft.
Play around with the radar range equation.
For a 100km detection range.
1 MW of output power, 30 dB antenna gain, 1Ghz Tx frequency, radar cross sectional area 0.1 m sq, minimum detection signal 0.005 nano watts.
On low power systems where you can have much lower internal emi, -100 dB (0.1 nano watts) is as low as you can get outdoors.
You’d be surprised the velocity you get from the return on a bird’s flapping wing. Also the Doppler ambiguity smears with SNR, so you’ll see a bird as something moving between 30 and 300mph at the edge of sensitivity.
That is called passive sonar. I suspect that it is kinda hard to hear from the missile. Anything behind you is certainly not hearable, since the missile goes faster than sound. I have no idea if you could measure the sound coming from the front. You also have to take into account that you are chasing an after image, since the plane is also faster than sound. But torpedoes use this, so the idea is valid.
That is truly amazing.
Do note that the this claim comes from the same people who don’t hand out any actual specs and always fly with an additional reflector. The latter makes it easy for radars to see them again. This is helpful in allied airspace, but it also makes it impossible to verify the claim.
Also note that modern radars are sensitive to how fast an object approaches (or leaves) the radar. Bumblebees don’t break the soundbarrier usually, so it is possible to see these planes, but you do have to tweak your radar for it. (Hence why the US doesn’t give specs.)
You are talking about Doppler processing. Basically you can filter out all the things that are not moving fast based on how much the frequency is compressed and lower your noise floor. You will still have other noise sources but minimizing clutter will help, if the return is below other noise sources you still will not be able to detect it.
Correct. But integrating over multiple pulses, and using the latest Tx and Rx modules, sensitivity is not the problem anymore. Radars can easily see every damn bumblebee in a 100km radius. The problem is filtering data, so that processing and/or the user is not overloaded. For example, if you track every single bird with a radar that has a 100km radius, you will not be able to see anything on the operator screen other than birds.
Doppler is easy to filter on early in the processing stage. Meaning that if you can detect the aircraft, you can still separate it from all other bumblee like objects. Clutter tends not to move that fast.
Doppler processing eliminates clutter it doesn’t eliminate EMI, thermal noise, or atmospheric issues.
China’s 366 radar can detect 0.1 sq meter targets at 20km. It’s China’s most modern radar and it’s not close to 100km detection range for LO aircraft.
Play around with the radar range equation.
For a 100km detection range. 1 MW of output power, 30 dB antenna gain, 1Ghz Tx frequency, radar cross sectional area 0.1 m sq, minimum detection signal 0.005 nano watts.
On low power systems where you can have much lower internal emi, -100 dB (0.1 nano watts) is as low as you can get outdoors.
So they just need to build an aircraft that moves at the same speed and height as a bumblebee. Bam ! Undetectable killing machine.
You’d be surprised the velocity you get from the return on a bird’s flapping wing. Also the Doppler ambiguity smears with SNR, so you’ll see a bird as something moving between 30 and 300mph at the edge of sensitivity.
This how we get echolocating missiles.
Radar is echolocation with EM waves (low frequency light) instead of sound waves. And there are already plenty of radar guided missiles.
I meant to put ears on the missile. I’m sure the plane is still plenty loud.
That is called passive sonar. I suspect that it is kinda hard to hear from the missile. Anything behind you is certainly not hearable, since the missile goes faster than sound. I have no idea if you could measure the sound coming from the front. You also have to take into account that you are chasing an after image, since the plane is also faster than sound. But torpedoes use this, so the idea is valid.
Those are likely quite valid points. This being noncredible defense they have no place here.
Put a bat in the missile and let’s give Project Orcon another go