data-stream clock with just a little doppler shift

[Winfield Hill]

http://www.spectrum.ieee.org/WEBONLY/publicfeature/oct04/1004titan.html


--
Thanks,
- Win

(email: use hill_at_rowland-dotties-org for now)

 

[Paul Hovnanian P.E.]

John Miles wrote:

In article <clben70b2s@drn.newsguy.com>, Winfield_member@newsguy.com
says...
http://www.spectrum.ieee.org/WEBONLY/publicfeature/oct04/1004titan.html


Another good article by the same guy:

http://msnbc.msn.com/id/6301146/

"After all, these switches were reportedly developed as a nuclear
warhead safety device, so one could just assume that they were properly
wired." Um... did the nuke guys make the same assumption?

Randomly select a sample of manufactured units and test them.

Amazing how it's usually the simple stuff that hoses the mission.
Someone mounts the G-sensors upside down (Genesis), conflates metric and
English units (Mars Climate Orbiter), misses a bug in some mundane user-
interface code (Therac-25), or fails to check the specs of reused
software components against the requirements of new hardware (Ariane 5,
and now Huygens).

How do we treat human error as an input to our otherwise-exhaustive
engineering models? That question seems to be worth its own
disciplinary field.

Good question. I wonder to what extent each of the aforementioned goofs
can be traced back to a requirements or design communications error
between the systems level engineering folks and the component or
subassembly design/manufacturing groups.

If you model each component of the design and manufacturing team as a
node on a graph and the data flow between each as a link, an error rate
and latency can be assigned to each link depending on such things as its
length and method (the people in the next cubicle vs. an engineering
group a few time zones away) and the cost each node must incur to
correct errors in the communications channel or time wasted working with
outdated data.

--
Paul Hovnanian mailtoaul@Hovnanian.com
------------------------------------------------------------------
"Si hoc legere scis nimium eruditionis habes."
(If you can read this, you're overeducated.)

 

[Joerg]

Hi Paul,

How do we treat human error as an input to our otherwise-exhaustive
engineering models? That question seems to be worth its own
disciplinary field.



Good question. I wonder to what extent each of the aforementioned goofs
can be traced back to a requirements or design communications error
between the systems level engineering folks and the component or
subassembly design/manufacturing groups.


In this case it seems to boil down to a serious lack of communication

and, consequently, failure to adhere to a proper review process. Quote
from the article:

Quote: "JPL's Horttor admitted that NASA probably could have insisted on
seeing the design if it had agreed to sign standard nondisclosure
agreements, but NASA didn't consider the effort worthwhile,
automatically assuming Alenia Spazio would compensate for the changing
data rate." End of quote.

We see that a lot these days, unfortunately. Especially in the world of
software. Either one party assumes the other party did it all just fine,
or one party decides that a certain information does not need to be
disclosed.

Regards, Joerg

http://www.analogconsultants.com

 

[Rich Grise]

On Fri, 22 Oct 2004 11:00:35 -0700, John Miles wrote:

In article <clben70b2s@drn.newsguy.com>, Winfield_member@newsguy.com
says...
http://www.spectrum.ieee.org/WEBONLY/publicfeature/oct04/1004titan.html


Another good article by the same guy:

http://msnbc.msn.com/id/6301146/

"After all, these switches were reportedly developed as a nuclear
warhead safety device, so one could just assume that they were properly
wired." Um... did the nuke guys make the same assumption?

Ah, what a fantasy! George the Anointed pushes the button, the missiles
all take off, fly their majestic ballistic trajectories, and ten
thousand multiple independently retargetable reentry vehicles go "plop."

My heart wants to sing just thinking about it!

Cheers!
Rich

 

[dd]

In message <clben70b2s@drn.newsguy.com>, Winfield Hill
<Winfield_member@newsguy.com> writes

http://www.spectrum.ieee.org/WEBONLY/publicfeature/oct04/1004titan.html


I believe cellular phone base station receivers have the same

characteristic introduced deliberately.
Max velocity for mobile 280km/sec.
A correspondent in the Science mag New Scientist gave the wrong answer
recently on their back page questions answered as the RF bw and not the
modulation rate was employed to calculate doppler tolerance.
Gave a result orders of magnitude out.
I emailed to point out their error without any response, and so it
goes.

dd

 

[John Miles]

In article <clben70b2s@drn.newsguy.com>, Winfield_member@newsguy.com
says...

http://www.spectrum.ieee.org/WEBONLY/publicfeature/oct04/1004titan.html

Another good article by the same guy:

http://msnbc.msn.com/id/6301146/

"After all, these switches were reportedly developed as a nuclear
warhead safety device, so one could just assume that they were properly
wired." Um... did the nuke guys make the same assumption?

Amazing how it's usually the simple stuff that hoses the mission.
Someone mounts the G-sensors upside down (Genesis), conflates metric and
English units (Mars Climate Orbiter), misses a bug in some mundane user-
interface code (Therac-25), or fails to check the specs of reused
software components against the requirements of new hardware (Ariane 5,
and now Huygens).

How do we treat human error as an input to our otherwise-exhaustive
engineering models? That question seems to be worth its own
disciplinary field.

-- jm

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