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• Editor's Notes
• Quotes and Thoughts
• Tools and Tips
• More on Patents
• Eternal Tool Support
• Anachronisms
• Failure of the Week
• Jobs!
• Joke for the Week
• About The Embedded Muse

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I have always found that plans are useless, but planning is indispensable. Dwight Eisenhower

Please submit clever ideas or thoughts about tools, techniques and resources you love or hate. Here are the tool reviews submitted in the past.

Jim Kneale had some thoughts about high-speed probes:

Jim Kearns passed this along:

Jonathan Bruneau wrote:

Dave Telling wrote:

Peter Nink sent this:

An engineer recently sent me a collection of emails between himself and the support desk of a large test equipment provider.  He had identified a bug in his scope’s firmware and wanted a fix, or at least a workaround, though the latter seemed unlikely.

The dialog proceeded as you’d expect: he clearly described the problem, and the support tech told him to check the instrument’s settings. That iterated a couple of times with the engineer asking – pleading, really – for the technician to at the very least attempt to duplicate the error condition. Eventually the admission came: there was indeed a bug that made one bit of functionality rather useless.  The fix was to toss the very expensive unit and buy the new model. At the advanced age of four years the scope was obsolete and essentially unsupported.

I suspect the company lost a customer.

But this story is part of a larger issue, one engendered by software. How long should a tool be supported? Forever? Or, just until next year’s model hits the streets?

In some cases companies have taken a pretty reasonable approach. Microsoft (dare I say something nice about them?) supported XP for many years, and gave a clear and long warning when the OS would enter the twilight of life. And, that’s a relatively inexpensive product (other than for enterprises which may buy thousands of copies). Further, consumers’ expectation of longevity for these sorts of products is relatively short. Other consumer products seem to have useful lives measured in microseconds so long-term support is probably not important. Mobile phones are practically fashion items, discarded as soon another version appears. (Though my wife’s iPhone 3G is about four years old, and she has no interest in an upgrade. Happily on a dinghy ride this week it took a wave, so there’s a Siri in her future).

But a scope or similar tool, which might cost tens of thousands, could reasonably be expected to perform for a couple of decades.  I had a Tek 545 thirty years after it was discontinued and it continued to perform well for low-speed applications. But that device, which was comprised of about 100 vacuum tubes and not a single bit of digital, was simple enough that feature perfection was expected and not terribly hard to achieve. A modern scope that boots a desktop OS is comprised of millions of imperfect lines of code.  Features are very complex and interact in ways that are very difficult to test exhaustively. Probably most of these units are shipped with at least a few quirks.

So how long should the vendor be on the hook for fixes? Forever, and “till the check clears” are both unreasonable ends of the spectrum.

I think that with the long expected lives of these sorts of devices, coupled with their chilling complexity and high costs, a vendor could gain substantial competitive advantage by offering bug fixes for very long periods of time. Such a policy can be expensive, which means wise managers will work even harder to insure that version 1.0 functions properly.

Which will make their customers even happier.

Every four years the Royal Western Yacht Club of Plymouth, England runs the OSTAR, a single-handed sailboat race from the UK to Newport, Rhode Island. In 1992 I participated with my, at the time, 30 year old wooden 35-footer. And three decades ago this week I abandoned that vessel, climbing onto a German container ship 350 miles from Newport after 29 days alone at sea. Right now, we're on our sailboat in Bermuda, so I'm reminded of this story.

But where, exactly, was Amber II in July of that year? It’s hard to say.

The previous year a friend and I sailed her to Newfoundland and thence to Plymouth. At the time GPS was hideously expensive. No one really knew where anything was. Bermuda was reported to be three miles SW of its charted position. Newfoundland’s sailing directions warned that the island might be as much as 10 miles away from the location plotted on the chart. We had borrowed a GPS, one with military precision (pre-Clinton commercial GPSes had downgraded accuracy) from special friends in the government, but it took 20 minutes to compute a position. We didn’t have enough AAs on board to run the thing very often, so navigated by sextant with only the occasional GPS fix.

1992 saw the collapse of the price of GPS – for $1000 ($1600 today) one could buy a unit which would report positions accurate to a couple of hundred meters. In the week prior to the race all but one of the 67 skippers bought a GPS in Plymouth via a special deal offered to the racers. My finances were at the breaking point, and a GPS was out of the question.

Celestial navigation has been used for centuries to determine position. The idea is simple: measure the angle between the sun (or star, planet or moon) and the horizon, and, if you know the time it’s possible to calculate where you are. Think of it this way: At any given instant the heavenly object is directly above one location on Earth. That means the angle you measure puts you on a circle some distance from the object’s ground position. Observe two bodies and your location is at the circles’ intersection. (The circles generally intersect at two points thousands of miles apart; one presumably at least knows what ocean you’re in).

The reality is a bit grittier. An observation error of one minute of arc (one sixtieth of a degree) induces an error of a mile. Yet at 50 degrees north the ocean is always rough, so the navigator is being tossed about violently while getting soaked in cold spray. It’s impossible to sight two objects at the same time, so corrections are needed. Get the time wrong by four seconds and another mile of error creeps in. The sextant has errors, as does the clock, and the bodies in the sky don’t move in quite the way predicted by the ephemeris tables, so correction after correction has to be applied, and the results carefully plotted carefully despite heavy seas.

Or, today, one merely looks at the screen and records GPS coordinates accurate to a handful of feet. In a single generation the entire history of navigation has been tossed overboard, replaced by cheap electronics with unprecedented accuracy.

In 1992 the Canadian P3 Orion located Amber II by homing in on my distress beacon. They found a ship but could not supply them an accurate vector to Amber II as their navigational tools weren’t much better than mine. Today, one wouldn’t bother to read off all of the digits of latitude and longitude from the electronic box as the precision far outstrips that required.

(In fact, most GPS users are clueless about the units’ precision. An app on my iPhone displays coordinates to one-thousandth of a second of arc, which is about an inch, far exceeding the GPS’s capabilities.)

The microprocessor has displaced all of traditional navigation techniques. Many sailors today barely know how to read a chart. One acquaintance navigated from below as his boat approached Virgin Gorda, reading data off the instruments. The crew on deck warned about the rocks clearly visible ahead, but they weren’t shown on his display.

They hit the rocks.

Voyager, my current boat, is a 32 foot ketch, which is quite small for ocean sailing. But in that tiny envelope we carry three GPSes. And RADAR. Then there’s the AIS which has a RADAR-like screen that displays the position of all ships within 30 miles, using data packets they all transmitted several times a minute on VHF frequencies.  The RADAR detector alarms when it picks up a signal. A network connects the GPS to the AIS, the RADAR and the marine radio. A panic button will cause the radio to broadcast the boat’s unique identification code and position to any nearby vessel. It’s possible to add the autopilot to the network so it will automatically change course as needed, but that seems a silly feature to me.

Voyager is not a high-tech boat and does not even have a chart plotter, but she fairly bristles with electronics that sense ocean temperatures, ship positions and much more. None cost much and all are astonishingly reliable. And all are made possible by microprocessors.

But we also still carry my sextant, which I clutched while scrambling up the ship’s cargo net. Today that Tamaya would cost around $2000, ten times what I paid for it 40 years ago, and the price of about twenty GPSes. It’s not particularly accurate, by today’s standards, but tradition still has value. So every year I take some sights to stay in practice. There’s a certain satisfaction in repairing a diesel engine, fixing the rigging, and figuring position without the aid of millions of transistors.

But yesterday, at a West Marine store, my wife lovingly eyed a 12” full-color touch screen chart plotter. I told her we just don’t have room for the thing.

She suggested making room by getting rid of the sextant.

(For the complete story of the 1992 OSTAR see https://www.ganssle.com/jack/ostar1.html).

Have you submitted a Failure of the Week? I'm getting a ton of these and yours was added to the queue.

Here's a twofer from Mark Peterson:

Let me know if you’re hiring embedded engineers. No recruiters please, and I reserve the right to edit ads to fit the format and intent of this newsletter. Please keep it to 100 words. There is no charge for a job ad.

These jokes are archived here.

From Clive Souter:
Thought for the day:

Okay, let’s say we have a second.

1/1000 of a second in a millisecond

1/1000 of a millisecond is a microsecond

1/1000 of a microsecond is a nanosecond

1/1000 of a nanosecond is a picosecond

1/1000 of a picosecond is a femtosecond

And lastly, 1/1000 of a femtosecond is an attosecond..

So, an attosecond is an insignificant amount of time.

Then does this mean that when your boss gives you an attoboy, you are getting an insignificant amount of praise?

The Embedded Muse is Jack Ganssle's newsletter. Send complaints, comments, and contributions to me at jack@ganssle.com.

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