[Ground-station] Radiation Susceptibility

[Bruce Perens]

We're going to have to pull the cap off of some of those 74AC chips and
make sure they're still fabricated the old way, if we end up using them.
The hacker community has deep expertise in uncapping chips, and I know just
who I'd ask.

Vorago has some technical papers regarding their prototype Cubesat
controller, below.
They are using ferroelectric RAM for storage.

https://www.voragotech.com/products/rhobc1
https://www.voragotech.com/sites/default/files/RH-OBC-1_Flyer_rev_1.1.pdf
https://www.voragotech.com/sites/default/files/RH-OBC-1_schematic.pdf
http://smallformfactors.mil-embedded.com/articles/designing-rad-hard-cubesat-onboard-computer/
http://www.pumpkinspace.com/store/p199/Vorago_Rad-hard_OBC_%2F_C%26DH_Avionics_Kit.html

On Sun, Jun 3, 2018 at 6:41 PM, Tom Clark <tom.k3io at gmail.com> wrote:

>
> On 6/1/2018 2:19 PM, Bruce Perens via Ground-Station wrote:
>
>> Bdale,
>>
>> Do you happen to know where there's a copy of Karl's old proposal?
>>
>> Finding a viable part is important. There are consumer or industrial
>> parts that we may choose to trust based upon someone else's testing and our
>> understanding of their architecture. The most common seems to be a
>> Microsemi (formerly Actel) part that is reported upon here:
>> https://www.hevs.ch/media/document/1/20130612_cof_igloo-for-cubesat_1.pdf
>> This goes to 40 krad.
>> Parts that are specified as rad-hard seem to start in the $2000s and go
>> up from there. Do you know of less expensive ones?
>>
>> I learned from Jan King (W3GEY) way back in the Microsat (i.e. AO-16) era
> some 30 years ago that 74AC logic was intrinsically good for ~200+ kRad
> total dosage and 74HC parts were good to around 100 kRad. The manufacturing
> processes also rendered plastic 74AC/HC parts to have good intrinsic
> vibration & thermal reliability.
>
> Anything that used a charge pump in it went bad at 20-25 kRad, including
> DRAM and the clock circuitry in a number of small microprocessors.
>
> We (AMSAT) also did a lot of testing on radiation susceptibility using
> medical x-ray machines cranked up to levels associated with "the patient is
> already dead so lets make certain that the remains are sterile";  this
> including using x-ray machines associated with large animal veterinarians.
> As I recall some of the testing was done by Stacey  Mills, W4SM and some by
> Paul ???, VE6???.
>
> Jan King was a font of information on a lot of Co60 testing done by
> industry (especially @ Orbital Sciences). That's how we learned about the
> "magic" of 74AC logic.
>
> 73 de Tom, K3IO
>
>
>
> ---
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>


-- 
Bruce Perens K6BP - CEO, Legal Engineering
Standards committee chair, license review committee member, co-founder,
Open Source Initiative
President, Open Research Institute; Board Member, Fashion Freedom
Initiative.
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