Monday, January 26, 2015

Barn progress...

Barn progress...  The painters were here today and Friday, taping and (today) starting to prime the OSB.  On Wednesday the texturing guys will be here, probably for two days, making the walls in Debbie's agility court purty.  Once that texturing is done, the entire first floor will be painted.  Woo hoo!

The folks at Agri-Service came down today and picked up my tractor.  It's going into the shop for a 100 hour service (routine) and for some testing to see if they can find the source of a slow (but very irritating!) hydraulic leak.  We timed it so that we had a week's forecast with no snow in it, so I won't be snowed in without a plow...

Progress report...

Progress report...  We did a lot of different things today.

First, we replaced about 15 of those god-forsaken CFL pigtail bulbs with daylight LEDs – far more light, and at a color temperature we find pleasing (the old bulbs were about the amber of a smoky candle, and not much brighter).  Much better in the rooms we fixed.  The main challenge with this process is finding the right LED bulbs to fit the various fixtures.  This danged house must have 15 kinds of light bulbs in it!  And there are another 6 or 7 rooms left to go :)

Then we replaced the broken wine refrigerator with a new one.  The old refrigerator was a conventional compressor-type cooling unit (just like an ordinary kitchen refrigerator).  The new one uses a thermoelectric cooling unit (using Peltier devices), and consequently is completely silent (no moving parts).  Wine refrigerators, it turns out, are not a standard size – they vary in height, width, and depth.  So far as we could tell, there are no two the same.  The new one we bought is about 3/4" wider and 2" shorter than the one we're replacing.  It's under-counter, so that meant I had to cut 3/4" of the cabinet's facing off (there was plenty of room behind the facing).  I clamped a piece of wood in the right place to act as a guide, then used a battery-powered oscillating saw to do the cutting.  This let me cut right down to the floor and right up to the bottom of the cabinet top, and it made a very nice smooth cut.  It was so nice, in fact, that we're not going to put a trim strip up to cover the cut – it looks finished just the way it is.

Finally, we fixed a silly switch arrangement for the light in the walk-in closet in our bedroom.  That closet was originally an office when the house was first built.  The second owner converted it into a closet, installing shelving along the walls, but not changing the location of the switches and outlets.  One (of several) unfortunate consequences of this decision was that the light switch ended up on the inside of the closet, and worse, on the inside of a shelving unit.  To turn the light on, you had to walk into the closet, make a 180° turn, then fumble around in the dark between clothes on the shelf to flip the switch.  This is not what we wanted :)  So I carefully measured and cut a hole for a junction box on the bedroom side of the closet wall, adjacent to where the existing switch box is located.  Then I wired a new switch into that box, connecting it to the existing wiring inside the junction box that the old switch was mounted in.  Then I removed the old switch, and we're covering that old box with a blank plate.  Now we have a switch where it belongs – outside the closet, next to the door – very convenient.

In the process of doing that wiring, I used a tool that was new to me: a circuit breaker tracer.  I found an outlet that I guessed was on the same circuit breaker as the light, and plugged a signal transmitter into it.  That unit sends a low-power radio signal into the wire.  Then I took the tracer unit – the size and shape of a very fat carpenter's pencil – and ran it up and down the circuit breaker panel.  It squawked on one circuit breaker, and when I shut that one off, the outlets and light in the closet were all dead.  That whole process took about 60 seconds, and eliminated the need to shut off one breaker at a time to find the right one.  Very nice!

Bureaucracies are the same everywhere...

Bureaucracies are the same everywhere...  Yes, even in Canada.

   Some assembly required.

Quote of the day...

Quote of the day...  This time from the Ricochet Daily Shot, on the subject of Loretta Lynch, Obama's candidate to replace Eric Holder as U.S. Attorney General:
Barring any last minute revelations of her killing a bunch of hookers or something, she is expected to be confirmed. (Even if she did off the call girls, she'd probably still be better than Eric Holder.)

Broadband Internet everywhere, for cheap?

Broadband Internet everywhere, for cheap?  That's the vision of Elon Musk, CEO of SpaceX and Tesla.  A couple of weeks ago he announced his intent to create a $10 billion network of low earth orbit satellites as the first step in an interplanetary Internet backbone.  These satellites, presumably launched by SpaceX, would provide Internet access to every spot on the planet.  Late last week, he announced a $1 billion round of financing, led by investments from Google and Fidelity – the first step toward realizing that vision.

Current satellite-based Internet distribution is almost entirely done with satellites in geosynchronous orbit, about 26,000 miles above the earth's surface.  At that altitude a radio signal takes about 1/7 of a second to travel between the earth and the satellite, a delay that is the inevitable result of the speed of light.  That delay may seem small, but it adds up very quickly.  The simplest possible web page (with no images or any other non-textual content) requires a minimum of 5 earth-to-satellite-to-earth signal trips (for the geeks: 3 to establish a TCP connection, then one request/response pair).  Each of those trips takes 2/7th of a second, so 5 trips takes 1 3/7ths seconds – and that's the fastest you can get!  There are some tricksy things that can be done to reduce the number of round trips, but the absolute best one can do is still so many trips that browsing the web feels sluggish – a very different experience than one gets with terrestrial Internet connections.  The geosynchronous satellites do have one very compelling advantage, though: a single satellite can service an entire continent (North America, for example).

Musk's vision for satellites in low earth orbits would have quite a different operating characteristic.  First and foremost, they'd be less than about 1,200 miles high – I'm guessing 500 or 600 miles.  Below roughly 500 miles the atmospheric drag limits satellite lifetimes.  Higher satellites increase the speed of light latency, but also increase the “footprint” (the size of the area the satellite can service).  On the other hand, smaller footprints might be desirable, to limit the number of connections that a single satellite must be capable of.  So my guess is Musk will opt for the lower orbital altitudes, to optimize performance and minimize individual satellite size and complexity.  To guarantee global 24x7 coverage, Musk will need hundreds of satellites – even more if there is to be redundancy.  Hence the $10B price tag, even with assumptions about SpaceX drastically reducing the cost of a launch.

Suppose Musk actually pulls this off (and his track record is pretty darned good).  What would that mean for Internet access?  It would mean that no matter where you were – in a city or in Antarctica – you could get 100mbps+, low-latency Internet access.  Broadband for all.  At sufficient scale (not a small constraint, mind you), the $10B price tag will look like peanuts compared to terrestrial methods that require things like digging trenches and burying cables or fiber.  In other words, if Musk gets enough people on the system, it has the potential to be cheaper than existing broadband connections.  Much cheaper.  If the orbits are at 500 or 600 miles altitude, the latency will be very comparable to terrestrial networks – in other words, no performance downside.

Internet distribution could be the killer app for space.  Google and Fidelity are apparently persuaded that that's a good bet.

And Elon Musk will own the world :)

What would Feynman do?

What would Feynman do?  This is an old blog post by Eric Lippert, but I saw it for the first time today.  It speculates on how Richard Feynman might have answered one of the crazy “lateral thinking” interview questions that used to be a fad at many high tech companies, including (most notoriously) Microsoft, Oracle, and Google.  Some of it is quite funny, especially if you're a Feynman fan.  Here's a sample:
Interviewer: Forget about measuring the voltage already! Suppose you can't reach the fixture to measure its voltage.

Feynman: Again, I must point out that it seems very odd to ask a question about diagnosis of an electrical system while not allowing the diagnostician to use common electrical tools. But anyway, you said that I was on the right track, so let's go with that. We know that modern dimmers do not put a variable resistance across the AC signal; rather, they selectively "cut out" a variable-sized portion of the wave and leave the rest of the cycle in its normal size and shape. We could build a device that works analogously to a dimmer, but much slower. The device could have a couple of rotating cams that flip a switch on and off once a second. Now we need not disassemble any of the switches, or cut the power at the panel. We attach the device to the first switch, flip the second switch off, and the third switch on. Since we have already established that the switches are single-location switches that have been wired correctly according to the NEC, we know that the switch in the "up" position is energizing its lamp and the one in the down position is off.  Now we go into the other room. The lamp that is off is controlled by the third switch, the lamp that is on is controlled by the second, and the one that is flipping on and off every second is controlled by the first. This system will work no matter what kind of lamps are in the fixtures, provided of course that they are good lamps, not burned out.
This reminds me of a story I read about Feynman, though I've forgotten where I read it, and why the story was being told.  In the story, someone who knew Feynman wondered out loud why the altimeter in an airplane always seemed to be wrong.  Feynman launched into a learned discussion of how the altimeters worked (bellows-type pressure gauge), the loose correlation between air pressure and altitude (due to humidity, temperature, and wind), and the numerous engineering problems associated with bellows-type pressure gauges (including non-linearity of the spring force in the bellows, thermal expansion and stiffness variation, and the “stiction” effects caused by metal crystals rubbing on each other).  Feynman's companion asked how Feynman came to know all this about how altimeters worked – and it turned out that the only thing Feynman knew was that they used bellows-type pressure gauges.  Everything else he deduced or inferred – classic Feynman...