4 ms·

Locating the target isn't the problem, you don't need a Doppler shift to calculate range by time of flight. The problem is detecting the target at all. Radar in

Locating the target isn't the problem, you don't need a Doppler shift to calculate range by time of flight. The problem is detecting the target at all. Radar in these sorts of defense environments will pick up an enormous number of returns off of the carrying vessel and sea surf, which is actually a rather difficult problem for radar because it reflects in myriad directions, it moves, etc. By far the easiest way to select an "interesting" radar return is to use Doppler shift to find something that is moving very quickly. That can't be just a wave, it has to be a missile. The problem is that rotary wing drones are very slow (compared to missiles) and so they don't present an obviously different shift from the background. A lot of R&D is going on right now into better ways to select slow-moving, low-cross-section objects like drones from the background. This sort of thing is much more difficult for missile defense than the more conventional radar application of airspace surveillance, because for several reasons (including the fact that this makes radar detection hard) missiles tend to come at you from close to or below the horizon. This means you're getting a huge amount of clutter (radar returns from the environment) around them.

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icegreentea2 3y ago
Not to minimize the challenges, but I think it's worth pointing out that a lot of the drones of topical interest are -not- quadcopters. The Houthis (for example) have been using UAVs (Samad and Qasef) are prop driven fixed wing drones with total mass in the 50kg+ class (and warheads in the ~20kg class). They have max speeds of 200+ kph, wingspans in the 2-5m range. The Samad has ranges in the 1000km+ range. Obviously, they could slow down in terminal stages of attack, and I have no idea what their stall speed would be like. These are more akin to the Shahed class drones that Russia has been deploying in Ukraine (though still much smaller), than the FPV drones we see attacking tanks/trenches.
- WalterBright 3y ago
  The British used radar guided artillery to knock down wave after wave of V1s, which flew at around 400mph. Surely we could do better today.
  - icegreentea2 3y ago
    Totally. I just guess the US didn't procure/deploy/use/turn-on the appropriate systems. Plenty of other posts in the comments identifying potential modern (and modern-ish) solutions that match your parameters.
  - robbiep 3y ago
    Really? I had heard that sometimes pilots would nudge them off course or shoot them down but nothing about artillery, I thought radar came along a bit too late to use it for targeting with regard to the V1
    - actionfromafar 3y ago
      I thought so too, but lately I have heard and read accounts akin to a lot of what happened in late WW2 with regards to radar technology was highly classified and much didn't enter the history books. Pilots shooting and nudging definitely happened but likely other, more advanced stuff happened too. The germans had fully automatic radar controlled flak guns.
    - lupusreal 3y ago
      > Automatic gunlaying (using, among others, the SCR-584 radar) and the proximity fuze played an important part in Operation Diver, (the British operation to counter the V1 flying bombs). Both of these had been requested by AA Command and arrived in numbers, starting in June 1944, just as the guns reached their free-firing positions on the south eastern coast of England. Seventeen per cent of all flying bombs entering the coastal 'gun belt' were destroyed by guns in the first week on the coast. This rose to 60 per cent by 23 August and 74 per cent in the last week of the month, when on one extraordinary day 82 per cent were shot down. The rate increased from one V-1 for every 2,500 shells fired to one for every hundred. https://en.wikipedia.org/wiki/SCR-584_radar#Operational_use https://en.wikipedia.org/wiki/SCR-584_radar#Operational_use > 90mm anti-aircraft guns were normally operated in groups of four, utilizing the SCR-584 microwave computer and being controlled by the M9 Director. The SCR-584 was accurate to about 0.06 degrees (1 mil) and also provided automatic tracking. Direction and range information was sent directly to the M3 Gun Data Computer, and M9 Director, which directed and laid the guns automatically. All the crews had to do was load the guns. https://en.wikipedia.org/wiki/M9_Gun_Director https://en.wikipedia.org/wiki/M9_Gun_Director
WalterBright 3y ago
I'm talking about a land based system to defend military bases from drone attack, not sea borne vessels.

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icegreentea2 3y ago

Not to minimize the challenges, but I think it's worth pointing out that a lot of the drones of topical interest are -not- quadcopters. The Houthis (for example) have been using UAVs (Samad and Qasef) are prop driven fixed wing drones with total mass in the 50kg+ class (and warheads in the ~20kg class). They have max speeds of 200+ kph, wingspans in the 2-5m range. The Samad has ranges in the 1000km+ range. Obviously, they could slow down in terminal stages of attack, and I have no idea what their stall speed would be like. These are more akin to the Shahed class drones that Russia has been deploying in Ukraine (though still much smaller), than the FPV drones we see attacking tanks/trenches.

WalterBright 3y ago
The British used radar guided artillery to knock down wave after wave of V1s, which flew at around 400mph. Surely we could do better today.
- icegreentea2 3y ago
  Totally. I just guess the US didn't procure/deploy/use/turn-on the appropriate systems. Plenty of other posts in the comments identifying potential modern (and modern-ish) solutions that match your parameters.
- robbiep 3y ago
  Really? I had heard that sometimes pilots would nudge them off course or shoot them down but nothing about artillery, I thought radar came along a bit too late to use it for targeting with regard to the V1
  - actionfromafar 3y ago
    I thought so too, but lately I have heard and read accounts akin to a lot of what happened in late WW2 with regards to radar technology was highly classified and much didn't enter the history books. Pilots shooting and nudging definitely happened but likely other, more advanced stuff happened too. The germans had fully automatic radar controlled flak guns.
  - lupusreal 3y ago
    > Automatic gunlaying (using, among others, the SCR-584 radar) and the proximity fuze played an important part in Operation Diver, (the British operation to counter the V1 flying bombs). Both of these had been requested by AA Command and arrived in numbers, starting in June 1944, just as the guns reached their free-firing positions on the south eastern coast of England. Seventeen per cent of all flying bombs entering the coastal 'gun belt' were destroyed by guns in the first week on the coast. This rose to 60 per cent by 23 August and 74 per cent in the last week of the month, when on one extraordinary day 82 per cent were shot down. The rate increased from one V-1 for every 2,500 shells fired to one for every hundred. https://en.wikipedia.org/wiki/SCR-584_radar#Operational_use https://en.wikipedia.org/wiki/SCR-584_radar#Operational_use > 90mm anti-aircraft guns were normally operated in groups of four, utilizing the SCR-584 microwave computer and being controlled by the M9 Director. The SCR-584 was accurate to about 0.06 degrees (1 mil) and also provided automatic tracking. Direction and range information was sent directly to the M3 Gun Data Computer, and M9 Director, which directed and laid the guns automatically. All the crews had to do was load the guns. https://en.wikipedia.org/wiki/M9_Gun_Director https://en.wikipedia.org/wiki/M9_Gun_Director

WalterBright 3y ago

I'm talking about a land based system to defend military bases from drone attack, not sea borne vessels.