I’ve read that during World War II, some radar sets were capable of detecting the signature of a submarine periscope. Pretty small target in some hellacious interference, right? So could a modern radar set with a small enough wavelength detect a firearm, something on the order of an AK-47? What about larger small arms, like an RPG-7 or a Stinger? Crew-served MGs? Ammunition caches? From what range?
While I find your firm commitment to National Security laudable, Mr. Duality, when the American military will happily talk to television programs about complex sytems like JSTARS and Missile Defense, and weapon camera footage is replayed endlessly (revealing both the capabilities of weapons and thermal imagers), I cannot help but find such statements misplaced, as well as purposefully and singularly unhelpful.
I agree, something that small would most likely disappear in the ground clutter. The big difference here is that a sub periscope is a nice metal object sticking straight up from the water. Unless you have a nasty sea state, you really don’t get very much of a return from water, since your signal is mostly absorbed and whatever reflection there is bounces at an oblique angle off the surface (like a stone skipping across the water) and away from your receiver. The periscope would show up as a bright spot in the middle of a dark screen and would actually be a fairly easy target.
In Viet Nam, the Army played around with man-detecting radar. It was used for monitoring perimeters and other such security work, and as I recall, wasn’t all that useful, even though it sometimes actually worked.
I suppose, it you weren’t worried about putting a big 'ol E-M emmitter out where everyone could see it, that today’s better processors and antennae could make it work somewhat efficiently.
I’m entertained by the “10km (personnel) / 20km (vehicle)” specification for the propsed AN/PPS-5 upgrade. I find it had to believe that there are very many enviroments where that kind of detection range would actually be useful. You’d have to be on a billard-table flat plain in order to use much more then half that range, and in many circumstances, you’d be better off going thermal.
I do believe the AN-PPS-5A and the bullet tracker TurboDog mentioned are both CW (Continuous Wave) radars that track movement (phase shift of signal emitted compared to phase of signal sent). I have snuck up on the AN-PPS by moving vewy vewy qwietwy and slowly. The radar to find the periscope or Stinger would be a Pulse radar, where phase shift isn’t a big thing. It just finds the “ping” return and gets an azimuth, then the time of the “ping” sent to the “ping” returned to get range. Needs multiple returns to find speed and heading of target. Good for stationary hard stuff. Artillery folk have counter-battery radar (CW) that can lock onto an incoming round, and have the gun position located before the shell lands. Then they send a big nasty note to the gun that fired on them.
Cool… puter crashed as I was typing and posted some of it. That’s a new one.
Anyway, most of the tracking was on 20mm, but occasionally I used it on 7.62 and 5.56. It could track outgoing and incoming at well over 2000 meters and would get data such as range, velocity, azimuth, and more depending on how the software and frequencies were set up. As Bill mentioned, CW Doppler is what it used. It is not classified and many units can be purchased by the general public if you have the cash to burn.