[ibis-macro] Re: SATA: Why 14 sigma?
- From: Mike Steinberger <msteinb@xxxxxxxxxx>
- To: ibis-macro@xxxxxxxxxxxxx
- Date: Wed, 18 Apr 2012 15:50:52 -0500
David-
You need to be looking at the Q function, not the erfc function. The two
functions are closely related, but they're not the same. Q(7)=1e-12.
From Wozencraft and Jacobs, pg 83, Q is the area of the tail of a
Gaussian function:
Q(a) = 1/sqrt(2pi) * integral from a to infinity exp( -b^2/2) db.
and for relatively large values of a
Q(a) ~ 1/(sqrt(2*pi)*a) * exp( -a^2/2 )
Mike S.
On 04/18/2012 03:26 PM, David Banas wrote:
Hi experts,
Does anyone know why the SATA committee chose to add 14 sigma to Dj,
in order to determine Tj at an effective BER of 1e-12?
I'm looking at a table of the erfc function, and it's telling me that
erfc(14) = 3.0372e-87!
(I would've expected that they would've chosen `n', such that erfc(n)
= 1e-12.)
Thanks!
*David Banas*
/Sr. Member Technical Staff/
Altera <http://www.altera.com/>
+1-408-544-7667 - desk
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