Question about the F-22 and it's radar.

In article , John Cook
wrote:


Just the official reports!!, Lockheed has only purchased enough
processors for 155 F-22's because there out of production, the demand
for Air to ground operations has increased the demand on processing
power, something the original processors are not quite upto hence the
_need_ for the 'upgrade'.

So the processors are obsolete, (too old)... the Avionic architecture
needs to be replaced before the F-22 can become the F/A-22 because the
present system is based on the old processors and rewriting the code
is pointless on an obsolete system, that would only support half of
the F-22 fleet

Methinks there's some confusion there between processors, avionics
architecture, and software.
While it's true that Intel tried to shut down i960 production causing a
chinese fire drill, there are enough assets to get by until a new processor is
ready. That has nothing to do with the avionics architecture, which is
not changing. Plus the whole point of writing all the OS and AS in Ada was
to be as platform independent as possible, so that upgrades to the CIP
could be relatively painless and not force re-flight testing of the A/C.
Ideally, one would not re-write the code, but re-compile the code for
the new platform, then do a LOT of integrity checks, and take it from there...

They have to go with a more COTS based system (similar to, if not the
same as the JSF), which they are working on now, for fielding in (very
optomisticlly) in 2007.

Other than using commercialy available processor chips, what is "COTS"
about it?
Hint - nothing.
Other facts (what a concept in RAM)
The F-22 is also based on commercialy available processor chips (but
not a commercial architecture)
Avionics systems require a much higher level of security and determinism
than any "COTS" package will ever offer.
COTS is not necessarily cheaper when talking avionics

COTS is one of those words that everyone thinks they understand, until
it comes down to brass tacks.


A simple analogy for you, the old 486 computer still works, but when I
wanted to run XP on it the demands of the system increased to the
point where it was useless to try, and you couldn't buy a 486
processor anywhere to support it.

I call that an 'obsolete system', it worked great running win 98.

Your analogy is seriously flawed for several reasons:
A processor does not stand alone, it's part of a system, and many,
many other things affect the system performance besides processor
speed. Backside bus bandwidth, memory architecture, frontside bus
bandwidth, etc.
Plus the system in this case contains MANY processors in parallel.
The system is officially termed a heterogeneous multi-processing system
which means that it has several different kinds of processors as well
as the i960, and all running in parallel. I think someone calculated
the actual processing resources are equal to 2 Cray Y-MP supercomputers.
Software also matters. Comparing avionics software to microS's
bloatware is ludicrous.


Now the Raptor can't run the software to do its air to ground mission
for the same reasons what would you call it?. "processor
challenged???"

I'd say, take a hard look at the above assertation and explain how it
can be true, given that other AESA radars, in service, and with smaller
avionics processors, don't seem to be having these problems.

BTW, I worked on AFT, F-22, and several other current AESA programs,
including airborne processors, and integrated avionics systems.

--
Harry Andreas
Engineering raconteur