How do missile lock indicators in planes work?
Magic.
Missile acquires target, sends info to computer. Computer tells pilot that missile acquired target. Some work on Infrared, some work on passive radar, some work on active radar. Not sure exactly what you are asking.
Here’s a pdf manual for firing a a stinger missle and it describes how it’s target acquistion system works
"ACQUISITION
When the target provides sufficient IR to the seeker, an acquisition signal is generated. This signal indicates that the seeker has acquired the target. Two conditions are re-quired for the missile seeker to acquire the target’s IR. The weapon must be activated and pointed at the target and the IR from the target must be strong enough to activate the acquisition indicator circuits. Listen for distinct acquisition tone (and discriminate between target and background, if necessary). If the weapon is aimed away from the target when the gyro is caged, the tone should decrease.
UNCAGING
After insuring that the seeker has acquired the aircraft, press the UNCAGING switch with the thumb, hold it in, and con-tinue to track the aircraft. After uncaging, the IR tone usually gets steadier and louder. This lets the gunner know that the seeker has locked onto the aircraft and is tracking it. If the tone does not get louder upon uncaging,
release the UNCAGING switch and continue to track the aircraft in the range ring, allowing it to get closer. Then press the UNCAGING switch again. If the IR tone is weak or distorted, the seeker may be locking on the background instead of the target. When target IR cannot be acquired, or when trying to separate target IR tone from other tones (because of the background radiation), sweeping the target
or the figure eight (8) method should be used. When the target is low on the horizon, sweep the target looking through the front sight ring. Swing the weapon in U-shaped
movements through the target until the IR tone gets stronger. A clear tone should be received when the aircraft enters the range ring on the sweep (see illustration low)."
…and much much more.
Excuse me,
I think you guys missed the question. I think the request was pertaining to how does the plane (ie target) sense that it has been locked on to.
You see it in the movies all the time so it must be true.
I don’t know the answer myself, so I thought I would clarify.
As far as detection, most combat planes have radar receivers in them to detect when they are being illuminated by radar. When a radar sweeps across it, it beeps on seeing the RF energy. With radar locked on, it tells the pilot that it is sensing a steady amount of RF and has been “locked on” by an aircraft or a missle with active radar. Active infrared works in a similar method. Passive IR is a bit trickier.
[sub]must…not…laugh…nnnng[/sub]
BWuuuhHAHAHAHAHA!!!
Sorry. I’m all better now. 
For a specific example the AIM-9 Sidewinder missles acquires the target with its own seekerhead rather than one on the aircraft’s fire control system*. It’s a simple gimbaled sensor that self corrects put it on target. Actually the sensitive area is a circle rather than a center spot as it’s designed not to hit the IR source but miss it slightly. When it senses an IR signal strong enough to lock it on target it sends a tone to the pilots headset I can best describe as a growl. There is no big text display of “MISSLE LOCKED, SHOOT BAD GUY NOW MAVERICK!” but the symbology on the HUD changes to indicate a lock.
*There is an exception called Sidewinder expanded acquisition mode (SEAM) where the missle is slaved to the direction of the RADAR antenna when it has a lock.
Modern flat radar antennas and silent lobing are a bit hard to explain in text so I’ll try to explain the old fashioned parabolic dish and feedhorn system.
A parabolic radar antenna is much like a focused headlight. The feedhorn corresponds to the filament with its energy reflecting off a dish into a focused beam and back the same way. If you are aimed directly at a target most of a pulse of energy will hit the target, reflect back and give a strong return signal into the feedhorn which is processed by the receiver. Fine and dandy, but what if you are a little off target. You can tell that but not which way the target is. To detect direction of error the feedhorn is offset a little, given a little error, then its spun physically or simulated electronically. “Nutating” the feedhorn gives a beam that spins in a narrow cone pattern. If the antenna is aimed say a little below the target the return signal will be strongest when the lobe is at the top of the cone and weakest when at the bottom. This gives an error signal to aim the antenna directly at the target.
Planar array antennas have a different way of lobing, comparing the top/bottom and right/left halves of the array to detect ettor.
Most radar missles are mounted in a way their own antenna’s can’t see the target. They are fed the direction information from the weapons control system so they can aim for the target once they are ejected away from the launcher.
Anyway, that’s the way I learned it when I was an F-14 radar tech in the early eighties.
Yeah, I was wondering how a plane knows when a missile is locked on to it.
Wasn’t there also a difference made between high-frequency/high-accuracy/short-distance (missile) radar and low-frequency/low-accuracy/long-distance (ground-based general) radar?
From the I-HAWK Missile System (Improved Homing All-the-way Killer), there are two basic radars functions, detection and illumination. The detection radars sweep the sky with either Pulse “pings” or a CW (Continuous Wave) sweep, in a 360 deg rotation. The receivers in the target, I mean plane, detect these different sweeps and types of radiation signals, telling the victim, er, I mean pilot, that there is a missile possibly looking to get pumped up his tailpipe.
The Illumination Radar is a high power continuous wave radar that “paints” the target with a much stonger, more powerful and continuous radiation (“Mav, they’ve got a lock on us! Do something!”) When the missile is fired, the high powered illuminator drops it’s signal momentarily so as not to fry the electronics in the missile. The target sensors see this dip, and surmises the missile is launched (“Iceman! We’ve got SAM launch! Bank right… NOW!”). The passive or semi-active receiver in the missile seeker head looks for the reflection of the radiant energy off the target, and goes toward it. (“They killed Kenny! The bastards!”)
As for the Stinger and those passive IR/UV seeker types, the plane MAY have an IR sensor that can detect the heat signature of a launch, but not normally. It takes eyeballs on the smoke plume.
Sorry for going off on that other tangent when your question was a different one.
It’s extrmely easy to know when you’re being painted by a fire control radar. Radar has a distintive signal consisting of short pulses of energy with a delay between them to listen for return signals. The pulse width - time duration of the pulse - and pulse repetition frequency can sometimes be used to identify what kind of radar is tracking you. Some detectio measures are no more sophisticaetd than the early generation of police radar detectors used in card. More sophisticated devices can identify the type of radar and in some cases feed back “false” information to cause it to lose it’s track.
Just an off-handed mention:
The bulges you on the aft control surfaces of combat aircraft are generally RHAW antennae. That’s Radar Homing And Warning. As has been nicely mentioned on this post aircraft don’t get a big warning from IR shit. But the active radar, be they search or targeting, you can smell a fair ways off. And hence the antennae.
Aircraft are always trying to record what frequencies are being used to do this and that, to put it mildly, so that the next guy in gets an easier ride.