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New scope for snipers

#5
Apparently:

It uses crosswind optics which is a system and method for measuring crosswinds using a laser to send a signal on a signal path, and receiving response signals backscattered off of aerosols or other materials in the atmosphere along the signal path. Wavefronts of the received responses are perturbated by thermal cell turbulence in the atmosphere that perturbs optical wavefront propagation. Signals backscattered by airborne aerosols at different distances from the laser in the wavefront imager arrive at different times at the wavefront imager. Thus the wavefront perturbations vary with range, and data on the perturbed wavefront may be collected by the wavefront imager. Crosswinds cause movements in the optical perturbations over time, as the thermal cell turbulence moves. By comparing wavefronts of signals sent at different times an amount of thermal cell displacement may be determined at a series of ranges away from the laser and the wavefront imager.


- Got that? Good!
 
#6
I've wondered before, somewhat naively I'm sure, why a small scale version of the continuously compacted impact line ( which predicts where fired rounds from an aircraft will land) found on aircraft HUD's can't be reformatted for smaller scale / sniper use.

I expect it's to do with all the software / hardware needed to run it and the fact that as it's a 1000 - 1700 rpm weapon, accuracy doesn't have to be spot on, but still... :D
 
#7
NogBad_the_Bad said:
Apparently:

It uses crosswind optics which is a system and method for measuring crosswinds using a laser to send a signal on a signal path, and receiving response signals backscattered off of aerosols or other materials in the atmosphere along the signal path. Wavefronts of the received responses are perturbated by thermal cell turbulence in the atmosphere that perturbs optical wavefront propagation. Signals backscattered by airborne aerosols at different distances from the laser in the wavefront imager arrive at different times at the wavefront imager. Thus the wavefront perturbations vary with range, and data on the perturbed wavefront may be collected by the wavefront imager. Crosswinds cause movements in the optical perturbations over time, as the thermal cell turbulence moves. By comparing wavefronts of signals sent at different times an amount of thermal cell displacement may be determined at a series of ranges away from the laser and the wavefront imager.


- Got that? Good!
Makes sense, well the basic theory of it.

So, if I have this right, it will fire a laser to 100m, read the return time to apply windage, fire a laser to 200m, read the time, taking in effect the time for the 100m burst, and work out the windage difference bewtween 100m to 200m buy taking the time off the 100m burst? and so on and so on?

Of course I'm using 100m increments but it could be anything
 
#8
Not quite, I think it paints the target, but it paints it with a beam that's contains a signal as opposed to just one thats simply pure coherent (laser) light.

Bits of the signal will be reflected back (hence backscattered) at different points along the signal path and the gadget is clever enough to decode the various bits of the signal that it gets back and how long it's taken.

All this happens thousands of times a second, so it averages everything out and thats good enough to build up a picture of the conditions.
 
#9
It's nice to see Terry Pratchett doing something more worthwhile with his life than writing those crap "Rimmers World" books.
Alzheimers, it's not all bad!
 
#10
NogBad_the_Bad said:
Not quite, I think it paints the target, but it paints it with a beam that's contains a signal as opposed to just one thats simply pure coherent (laser) light.

Bits of the signal will be reflected back (hence backscattered) at different points along the signal path and the gadget is clever enough to decode the various bits of the signal that it gets back and how long it's taken.

All this happens thousands of times a second, so it averages everything out and thats good enough to build up a picture of the conditions.
Oh I see, fair enough.
 
#11
***WAH Shield on

Did you read the article Sandman?

"The project might almost have been dubbed the Discworld-effect generator or similar: it's well known that in Terry Pratchett's magical universe million-to-one shots come off nine times out of ten."

WAH Shield off***
 

Biped

LE
Book Reviewer
#12
It's all very sexy, and the interference system has been on the go as a test-bed for some time. Initially, the problem was that there had to be some distance between two units doing the same job - projecting and receiving to get a decent result on the downrange wind average. The devices had to be something like 50ft apart initially. I'm glad they are resolving this.

Of course, DARPA have got this other idea of a guided .50 calibre bullet (which I hasten to add, I mentioned on here some time ago as an idea) that has control surfaces. Quite simply, it's like a guided bomb, but a lot smaller.

For some time we have had the ability to create very small flexible plastic control surfaces that bend according to a small current passed through them. DARPA is being very cagey regarding the design, but it figures that a perhaps elongated .50 calibre projectile might have enough room for a line-of-sight comms device, power supply, flexible fins and still sufficient space to squeeze in an amount of heavy stuff for terminal smackage effect.

They talk of a .50 calibre bullet still being deadly at 7400m, but the downside is that the comms time back and forth to pass on flight path changes would be far too long at that distance. 14 seconds or therabouts to 'talk' 2 ways between the bullet and firer towards the end of the journey. It might work better for there to be a reflective rear surface on the projectile that allows the firing platform to 'see' the projectile and simply send correction data, rather than the projectile emitting a radio signal, thus cutting in half the time for an in-flight correction to be made. The bullet may not require correcting for the last (furthest) part of the flight as it's own momentum will mitigate the wind for certain distances.
 
#15
Biped said:
It might work better for there to be a reflective rear surface on the projectile that allows the firing platform to 'see' the projectile and simply send correction data, rather than the projectile emitting a radio signal, thus cutting in half the time for an in-flight correction to be made. The bullet may not require correcting for the last (furthest) part of the flight as it's own momentum will mitigate the wind for certain distances.
Thats exactly how the SACLOS system works on the old Rapier system. I would have thought it'd be quite easy to miniaturise something thats been in use for 40-odd years. The operator/sniper would keep an aiming unit aligned on the target (it wouldn't even have to be mounted on the rifle that fires the round); a camera in the unit sees the tracer in the back of the round; computes variance between round and target - and transmits correctional data to steer the round. Presumably you could use either a narrow-beam laser or a radio signal to pass the data.
 
#16
Biped said:
They talk of a .50 calibre bullet still being deadly at 7400m, but the downside is that the comms time back and forth to pass on flight path changes would be far too long at that distance. 14 seconds or therabouts to 'talk' 2 ways between the bullet and firer towards the end of the journey.
Eh?
 

Fronty

Old-Salt
Book Reviewer
#17
Why bother with sending correction data? If you are going to keep aiming at the target, just add small control surfaces like the current crop of LGBs have got and let it home in on something. No need to communicate, same effect.

When it comes to payload though, surely the mass of an enhanced .50 cal projectile would be enough to cause a bit of damage to the mk.1 human head. Failing that, add something on to the anti material rounds. That should do the job.
 
#18
Fronty said:
Why bother with sending correction data? If you are going to keep aiming at the target, just add small control surfaces like the current crop of LGBs have got and let it home in on something. No need to communicate, same effect.
A few guesses, feel free to correct them...

Maybe you could transmit your control signals on other frequencies than near-visible light - because light gets disturbed by atmospheric effects such as mirage.

Maybe it's less prone to problems such as "you're aiming at a bush/tree, and the wind keeps blowing the leaves out of the way and disturbing the laser spot"; or "it's a hot day, and mirage is making the laser spot appear to jump around".

Maybe you want more accuracy than the size of the spot you can generate at that range, from within the footprint of a rifle sight. Perhaps it's the brightness of the spot being sufficient for homing.

My best guess?

Maybe it's easier to put a sensor on the back of the bullet looking backwards, than it is to put a little window on the front of the bullet looking forwards.
 

Biped

LE
Book Reviewer
#19
Vasco said:
Biped said:
They talk of a .50 calibre bullet still being deadly at 7400m, but the downside is that the comms time back and forth to pass on flight path changes would be far too long at that distance. 14 seconds or therabouts to 'talk' 2 ways between the bullet and firer towards the end of the journey.
Eh?
DOH! My mishtake. There I was thinking of sound, not light speed.
 

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