I do not think that it was a misstatement. When you deploy something in a
CRITICAL environment
you need to think at the System level. This will dictate the
cost/performance/reliability trade offs.
We have 2 silicon designs for TEMPEST Class products. So we have some
experience in the
art to bring amorphous silicon to life. I need to tell you, that if you
design HARDRAD without
a look at the environment for it, you are doomed! Your "radiation proofing"
is null and void if it is not protected some how by the System.
Here is an example. There was this IC that has been tested to 6000Rads/Se,
Hard Xray, Gamma, you name it ...
A pretty impressive list. Guess what... It failed in the field as it did not
survive a real life test. At 3000Rads... The System Engineer said sadly
after wards: "If I only turned it off when the rad sensor tripped ...." But
he was young ... He knows better now :)
Integrated Circuits are very vulnerable, even Hardrads, if their limitations
are not incorporated in the total System Design. In the Ham case the
Antenna Field represents a Radiation Hazard for the IC. Thus Hamming is out
of the door and you need start thinking as a "rocket engineer" :)
And I am speaking about the technology of today not of 20 years ago...
Alex
===================================
If we can accept the notion that GUNS are
the killers and not the people, why is it that
we can not accept the idea that CARS are
the speeders and not the drivers?
Alex, trying to understand the world around.
==================================.
----- Original Message -----
From: "Mike Gilmer - N2MG" <n2mg@contesting.com>
To: <towertalk@contesting.com>
Sent: Sunday, December 23, 2001 10:47 PM
Subject: Re: [TowerTalk] Decoding BCD with passive circuit (more)
>
> On Mon, 24 December 2001, "alex" wrote:
>
> > The sensitivity of an IC to it's environment,
> > depends on SYSTEM design and
> > not on the IC itself. Otherwise we would not have
> > Satellites, Deep Space
> > Probes or a Space Shuttle today.
>
> This is a mistatement. Sure there are "system level"
> techniques to render a probe or other complex device
> capable of operating after some cosmic radiation
> damage, but there are definitely technologies of ICs
> that have inherent "radiation proofing" advantages
> over the more standard, off-the-shelf varieties. Even
> the various off-the-shelf technologies vary greatly.
> The old CMOS devices were so highly susceptible to ESD
> that they were essentially banned from military use.
> At one time, anyway, I believe the Shuttle used core
> memory - in large part because it is rad-hard.
>
> There are special "rad hardened" semiconductor devices
> designed SPECIFICALLY to operate in space where they
> are subject to various particles that would never be
> seen by earthbound devices. These devices are by
> their nature less susceptible - and are not "simply"
> some standard IC souped up by some external parts or
> system.
>
> I, too, have pondered the tradeoffs of sticking a PIC,
> 8051 or other device (simple or not) out at the
> antennas, but the low-tech approach (a multi-conductor
> cable) often makes the most sense. Yeah, it's neat
> to whip up something elegant, but since one is likely
> to need a bunch of relays out there anyway, why not
> use them to do the decoding? Elegant or modern alone
> does not make a design better. We aren't talking about
> wiring up an F-16... for most ham installations,
> running cable is cheap or free. Not everyone has
> access to a PIC programmer.
>
> Mike N2MG
>
> ________________________________________________
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>
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>
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