"John R Weiss" wrote
"Tarver Engineering" wrote...

As the rest of the thread up to this point indicates, there is a
desire to
redirect a GPS guided munition post launch. The means to reprogram
the munition would require some data link.

Actually, data link is NOT a hard requirement. There have been
several
initiatives in work for many years on autonomous terminal seekers --
TLAM
is
one significant example, though it may not have used GPS. I worked
with
some
relevant JSOW (then AIWS) P3I proposals at TI and a couple other
places
back in '90 and '91.

Irrelevent.

GPS with FOG does all that already.

Fibre Optic Gyro.

GPS with a gyro of any kind does not make for post-launch reprogramming or
retargeting of the weapon.

AMSTE (Affordable Moving Surface Target Engagement) uses a post-release data
link to compensate for the long time of flight of the ballistic weapon used
(JDAM). The current AMSTE test series has demonstrated fair success against
soft targets using JDAM unaided by an imager. An imaging seeker is planned
for use against hard targets like armor. The DAMASK (Direct Attack Munition
Affordable Seeker) imaging seeker is one of the candidates to serve in that
role.

In order to make the DAMASK seeker affordable (a key parameter in the
JDAM-related electronics), several performance parameters were kept modest.
Because the intended application (JDAM) has a small, 10m CEP, the IR Seeker
doesn't need either a wide FOV or high resolution.

If a higher performance IR seeker were used, allowing lock-on prior to
release, then yes a data link would not be needed. But you don't have an
"affordable" weapon then. But the USAF has gotten religion on the
affordability of weapons and within that family, cost is an equal priority
with performance.