The posts of aircraft reminded me of a little known story relevant to this thread: The Royal Australian Air Force's purchase of 72 F-35A fighters was nearly scuttled when the RAAF insisted that Lockheed Martin, the prime contractor, certify that all the wiring in the fighter was oriented in the correct direction. Lockheed Martin finally was able to convince the RAAF that wire direction only mattered in critical applications, such as audio, and was irrelevant to the otherwise mundane systems in the F-35A.
Yes have to flip everything when crossing equator (or fly backward and upside-down).
IIRC, it was Dijkstra who proved that the F15 auto pilot would turn the plane's belly up when crossing the equator.
He also found other defects, like dropping a bomb was inhibited when being on ground. There were other locks when in air. But starting with the knob already pushed would drop it immediately.
regards, Gerhard
I remember hearing that story when I attended a software quality course in the 1980s. I forget the details, but the idea of an aircraft (or cruise missile?) which flips over on passing the equator was a good way of ramming home the point that software quality is important.gerhard said:
Gerhard, unless it was a SW bug in the development stage, it sounds to me like an urban myth.
Any reliable link?
As for violating system “locks” when performing un-thought of sequence of actions, yes sadly it happens.
NTSB accident reports have documented a few.
Pilots reports to OEMs have helped too resolve some of them.
George
I did some searching and the nearest to credible I found was a bug in 'simulator testing'. which makes sense, but that was for the F16 not the 15.
Digital cable direction
Here is a link to Stereophile where they heard and measured a difference in jitter when changing the direction of a digital cable.
A Transport of Delight: CD Transport Jitter Page 4 | Stereophile.com
Here is a link to Stereophile where they heard and measured a difference in jitter when changing the direction of a digital cable.
A Transport of Delight: CD Transport Jitter Page 4 | Stereophile.com
Enough with pictures of graphs already. Let's see the cable.
How about this, after plugging in a couple of ways to first transport the connectors got wiped clean and then it worked normally on the next device? How are we supposed to know how they did the testing? And what about a forensic examination of the cable?
How about this, after plugging in a couple of ways to first transport the connectors got wiped clean and then it worked normally on the next device? How are we supposed to know how they did the testing? And what about a forensic examination of the cable?
Thanks for that link! Between oxidized jacks/plugs and these termination issues I have seen many issues with both SDIF and SPDIF interfaces. Specifically referring to the article, they hypothesized differences in the termination of each end induce asymmetrical impedance which is increasingly important as frequencies rise into the tens or hundreds of MHz regions affecting digital transitions.
To relate this back to discussions here, directionality of the actual bulk wire itself was not in question. It is great to read test results like this which add actual data to the discussion!
Howie
That seems like a simple test to duplicate. A decent sound card plus Arta for analysis is easy to round up. A jtest file can be found on the web or I can provide one if necessary. Or even an fs/4 tone is enough to show problems.
If a cable can be found to consistently show directionality I'll be happy to do detailed testing of both swept and transient measurements of a sample.
I have seen samples of cables where the impedance changes from one end to the other but only a small amount. Usually a manufacturing issue (machine with an out of round roller or tension problems).
If a cable can be found to consistently show directionality I'll be happy to do detailed testing of both swept and transient measurements of a sample.
I have seen samples of cables where the impedance changes from one end to the other but only a small amount. Usually a manufacturing issue (machine with an out of round roller or tension problems).
The funniest one like that I heard about was a torpedo with a software failsafe that if it did a 180 turn it would immediately blow up before inflicting injury on themselves, in trials a torpedo got stuck, so the submarine did a 180 degree turn...
I heard it in the software engineering lectures of the CS curriculum at the TU Berlin in 1979 or so. It was an investigation of existing systems and showed shocking results. Might also have been Donald Knuth or someone else of the very few CS gods.
That was the starting point of the development of the ADA programming language, designed to discipline the programmers. Methinks that did not work.
1979. Were is my bottle of the Gerontol forte?
regards, Gerhard
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You are not alone.
Yesterday I finally packed and sent for recycling 250kg of electronics magazines (1973-1988) and an equal weight of aircraft engineering training manuals.
George
So what? This result, if true, adds nothing whatsoever to the discussion about claims of directionality in analogue audio interconnects, so why mention it? An attempt at confusing newbies, perhaps?Rick Miller said:
Of course interconnects are directional, mostly due to the connectors. Now a piece of wire can also exhibit directional effects. Just try using a piece of insulated wire sideways! 🙂 (Gotcha!)
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