View Full Version : What's a "lock?" (fighter planes)
02-23-2001, 06:15 PM
So you're at an anti-aircraft radar site and you're searching the sky for a plane. How does that plane know when you've got a "lock" on it? Is it the same as a fighter plane getting a "lock" on another plane? (IIRC, Top Gun had some gunner shouting to his pilot, "He's got a lock on us!" Is it the same as the "painting" with radar that happend in Iraq?
02-23-2001, 06:27 PM
Yup. Same principle. Basically, an RWR (Radar Warning Receiver) picks up the radar signal and lets you know the strength and direction of the source. By intelligence, research, trial and error, etc... enemies collect radar signatures and characterize them to use in the RWR technologies. That's why "frequency hopping" is such a big deal. By constantly changing radar frequencies, it can confuse an RWR of it's strength, search pattern and if lucky, whether or not it's a friendly source. In the case of attacking ground radars, the HARM missile locks onto the radar on the ground and basically, follows it to the source. The faster you can make the missile break it's lock, the better your chances of survival, as the HARM has a "memory" and will travel to it's best possible source that it has determined.
02-23-2001, 06:35 PM
Radar sends a distinctive signal that is usually pulsed to get range information. Fire control radars are designed to find a target then follow it, that's a "lock." There are several ways radar sets will lock onto a target, the most simple being to offset the feedhorn slightly and spin it, this is called lobing. The return signal from the target is processed to know where the antenna should move to stay on the target. The target also gets this information from passive detection systems and can easily tell when it's being tracked. Countermeasure systems can send back a slightly stronger signal that can easily fool an unsophisticated rader set and make it look elsewhere or break the lock. More sophisticated systems have "silent" lobing that is more resistant to jamming.
Painting a target usually means the signal has covered the target enough to get a return but it hasn't locked on. A PPI (plan position indicator) radar, search radar like in the dome of an AWACS or E2 Hawkeye) doesn't attempt to lock onto targets with the signal.
02-23-2001, 07:21 PM
Thanks Turbo & Padeye.
So the target can tell when the transmitter is following it, and that's a 'lock'?
02-23-2001, 07:36 PM
Poster, it all depends on the sophistication of all the equipment involved. When I was a fire control tech working on F-14s, one of the radar detection systems was literally a form of a fuzzbuster made to work in the appropriate band and run on 28VDC aircraft power. The plane had more sophisticated countermeasures but that wasn't my specialty.
As a general rule if you can tell a radar antenna is pointed at you by a strong and reasonably steady signal and it stays pointed at you, your being tracked but newer technology doesn't have that limit. Some radar antennas "move" the energy lobe electronically rather than physically moving the antenna. The lobe can be moved so rapidly that enough information can be gathered to have an effective compter track on multiple targets without out having to stay locked on a single one of them.
02-23-2001, 07:41 PM
A simple explanation is like this. You are flying a plane. Imagine a radar sweeping the sky looking for you. As the radar sweeps over you and hits your plane, your RWR gives you a beep. The radar starts narrowing it's scan and it now hits you more frequently, and you hear a beep each time it hits you, eventually, the radar locks on to you and rather than scanning, it just keeps radiating on you (aka illuminating) so your RWR emits a steady tone to let you know that it is receiving a steady pulse of radar. You are no longer being "looked for", but are located and targeted. Does that help?
02-23-2001, 08:13 PM
I think I've got it. :)
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