Missile Lock

I was reading about the N. Koreal MiGs that intercepted the U.S. spy plane over the Sea of Japan. One article mentioned that the U.S. gov’t. wasn’t yet certain if the jets had used only “acquisition radar” or if they used the more threatening “missile lock” radar.

I recall a scene in Top Gun where there was two jets practicing a dogfight. The fight was considered over when one jet got a missile-lock on the other. How does this missile-lock work? How does the target jet know when it has been locked as a target?

Umm, a bit of dodgy avionics theory follows:

Well you got your passive radar and your active radar.

Your passive just picks up emissions from other sources and your active sends out emissions and picks up the returns from those emissions.

I guess if a radar site (as in Iraq no fly zone) actively tracks a plane, the plane will pick up those transmissions and know that it is being tracked (and may dispense chaff to create false radar signals) - which in that case is considered an agressive action.

As to missile-lock, I only got movie & flight-sim experience to go on.
Long range missiles like AMRAAM use radar guidance as they are pretty long range, like 30 miles or so (total guess). Close range missiles like you would use in a dogfight (like in topgun) I would expect would be heat seeking on the engine exhaust of the target.

The IR tracker in the head of the missile needs to have a track on the heat source to steer (I am probably way out of date here) but I expect modern missiles are ‘fire-and-forget’ and you can shoot’em off and they go looking for a target. I guess you would still have to point them in roughly the right direction though.

More comprehensive answers follow.

That media blurb was vastly oversimplified and is probably meaningless on a technical level.

Without getting too complex fire control radar must track at least the position of the target. In most cases it will aim directly at the target and follow wherever it goes. That signal is easily detected unlike a search radar which only paints a particular target periodically. However modern fire control radar may not need to do this in all situations, particularly at long range. It can behave as a search radar for a small section of the sky and a computer will extrapolate where the target is while the antenna is not aimed directly at it.

With a system that used active or semi-active missles the missle has it’s own radar set. The missle may home in on the return signals from the aircraft radar system or it may have it’s own fully self contained transmit and reciever system.

Many radar systems can be identified by the frequency, pulse width and duty cycle of the transmitted signal. There are also some funky things they can do to fool detection systems or to be resistant to jamming but I’m not sure which have been declassified. There are some complex radar detection systems but to use F-14s as an example they had an auxiliary system that was essentially no more than a “Fuzzbuster” that ran off 28v aircraft power and gave no more indication than a warning light.

That’s the 5¢ lesson in aviation fire control radar. For more information join the United States Navy and spend a year in AFTA shool :smiley: