Laser guided munitions and targeting

[Basillicus]

Hello!

Once again I got lost to the wonderful world of Wikipedia and started reading about laser guided bombs. However I didn't find all the ansvers. I've always wondered how exactly the targeting works for them.

According to Wikipedia "When a target is marked by a designator, the beam is invisible and does not shine continuously. Instead, a series of coded pulses of laser-light are fired.". This rises some questions:
- Is this sequence of "coded pulses" somehow weapon/system specific so that certain type of munitions require certain type of sequence? Or can it be specified that during one mission certain type of coding is used, and the designator has to set this to the designator?
- If you have two designators and two bombs, can you simultaneously drop both of them over the same area and have them to strike different targets identified by pulse sequences with different coding?
- Is there/does there have to be some sort of datalink between the designator and the munition during the release?

There was also this: "these signals bounce off the target into the sky, where they are detected by the seeker on the laser guided munition, which steers itself towards the centre of the reflected signal"
- How large field-of-view does the seeker typically have? Do you have to release the munition in some specific angle and distance in order to make sure the seeker finds the target, or is it sufficient to fly roughly towards the target and release the munition within its glide range.

Are there anyone with any experience with these?

[StuRat]

How I thought they worked- Person points thingy at target, thingy has GPS therefore it knows where it is, it shoots out a beam, so it knows how far away the target is and in what direction, so it knows where it is too.

Don't know about the pulses, maybe each has its own signature to make sure the right bomb hits the right target


Or I could be completely wrong because I have no experience with any of that weaponry.

[2495]

In a nutshell then.

The laser designator has its own specific frequency and pulse pattern, and this is supplied to the pilot by the target painters. The pilot then keys it in to the bombs seeker chip via his arming panel. The bomb then is target specific, and this way 100 designated targets can be lit up and 100 bombs launched with no errors.

seeker head limits are varied to weapon kit and vary from 10 to 40 degrees.

[Basillicus]

Great, thanks for the info!

[2495]

To clarify though - the weapon would seek laser energy whilst still attached to the aircraft, and when sensing the correct energy it would inform the pilot of this and he would 'see' the designated area in his HUD as targetting ques.

He would then steer and the computers tell him when he is in within release parameters.

The bomb would then launch, fall, aquire target, move towards it, then lock and fall into terminal phase and impact.

[crazyman]

one thing that often gets overlooked: the bomb simply seeks the best laser source with the PRF code...which means if you dont do your planning right, the bomb will seek the designator (which is obviously where the laser is at its most powerfull) not the target. Tis one of the many reasons you want the aircraft coming from behind you, not from the side. Seems like a very common sense factor, but its cost a fair few soldiers and marines.

[2495]

one thing that often gets overlooked: the bomb simply seeks the best laser source with the PRF code...which means if you dont do your planning right, the bomb will seek the designator (which is obviously where the laser is at its most powerfull) not the target. Tis one of the many reasons you want the aircraft coming from behind you, not from the side. Seems like a very common sense factor, but its cost a fair few soldiers and marines.

The designator should not be on in a continued designation. It should 'mark' for the seeker, then be switched off, then the weapon is released into the 'cone' it already has planned to hit within, then the bomb is dropped and in the last 13 seconds of flight, designation is once again started.
.

[highdiver_2000]

IIRC, the seeker has 4 sensors. The sensor outputs will be fed back via control loop to the vanes. Those vanes adjust the glide path of the LGB to make 4 sensors have the same output value.

[crazyman]

you can't turn off the PRF-emitting laser until the round impacts when using most systems. I think you may be refering to copperhead. LGBs operate differently. Also, no matter if you turn it off, on, whatever...if the bomb can see the emitting device, thats where its going