Thursday, October 30, 2008

LOTW troubles


Steve K9ZW has a point.

LoTW bad news: Way too complicated to set up, especially compared with other "secure" services like e-banking. (And, I might add, poorly supported under Linux.)

LoTW good news: Works well once set up.

Saturday, October 18, 2008

Fedora - poof!

Faced with the decision to upgrade my Fedora 8 installation to Fedora 9 or the forthcoming Fedora 10, I made my decision.

I am off the Fedora treadmill now! We have become an Ubuntu 8.04 household. The "Long Term Support" feature of this release (until 2011!) was very appealing.

In the long term, this should mean less update & compatibility hassle. In the short term, there is an amazing amount of stuff that has to be ported over. Somehow, I can't live with the "vanilla" out-of-the-box configurations for very long...

Sunday, October 12, 2008

More important than Amateur Radio?

Yes, my oil usage, my carbon footprint, and ways to evade the financial meltdown. All these have taken me away from ham radio for the moment.

All these, plus one other. I won a little applications contest being held by a company called Plat'Home. They have a line of tiny Linux servers called the OpenMicroServer (OMS 400). These are headless, diskless Linux platforms, based on the RMI Alchemy au1550 chip -- a MIPS architecture device that runs at 400 MHz. A Compact Flash chip can be installed to serve as a hard drive. I use a 2 GB device. Plat'Home supplies a minimal Linux distribution called SSD/Linux, but you can also install Debian. (I haven't gone to Debian yet, but may do so.)

My application was a "Home Utility Support System" - a combination of hardware and software that would monitor operation of the home heating and hot water systems with an eye toward analyzing operations and reducing heating costs.

A prelimary report is available here as a PDF. The installation is shown in the photo at left. (Click on photos for high res.) Physical I/O is through Ethernet connected to a WiFi bridge that hooks into the household LAN, and through the USB to an inexpensive DLP-IO8-G 8-channel data acquisition and control module from DLP Design.

I built a number of interface devices that monitor the state (on/off) of the oil burner, the hot water circulator, and our three heating zone circulators. (Our hot water is supplied indirectly through a heat exchanger that receives hot water from the furnace "boiler".) The DLP interface also supports DS18B20 digital temperature sensors. I use two of these to monitor outside ambient temperature and hot water outlet (pipe) temperature.


The software is all developed in Python to log data every 30 seconds and to do analysis and data plots once a day. A sample run is shown here, as produced by gnuplot software running on the OMS400. The computer also runs the standard Apache web server to make data available to any authorized user anywhere on the Internet.

The work is still in progress, but I have a preliminary interesting, if depressing, result. The idle cycle of boiler (when no heat or hot water is demanded) is about one burst of several minutes every 3 hours. This just maintains the boiler's water temperature in its operating range. At a nominal 1.65 gallons per minute burn rate and with the current price of heating oil, that amounts to some $3.00 a day every day of the year!

Furnace people tell us never to let the system cool down, because of the thermal/mechanical cycling and because of possible corrosion problems, but paying ~$1,000 per year to idle is excessive. (I do dial down the operating temperature in the summer months, but we can't go too far or the domestic hot water will not come to full temperature.)

So there is some incentive to continue this project, potentially saving money (for ham work, of course), saving the environment, and having a little fun by the way.

Many thanks to Plat'Home for their support.

Friday, October 03, 2008

NYT: Sunspots Are Fewest Since 1954, but Significance Is Unclear


See New York Times article. The prospects for "Cycle 24" are especially interesting for hams who use the "high frequency" (HF) bands, 3 - 30 MHz. We need those sunspots!

Wednesday, October 01, 2008

A "perfect" gadget

This is an Encore ENRXWI-G "Wireless LAN Extender". I needed to extend my home Ethernet into the basement, for a project I'll describe later. For about $30 (newegg.com), this box saves me an hour or two struggling in my crawlspace for CAT 5 installation. That's a fair trade, I'd say! I bought two of them, with one as a spare.

In addition, it turns out this is a Linux box. (If you're up to it, you can reverse engineer the system and flash it with your own OS. But I will let that exciting project go for now...) And it can actually be used as a full-blown WiFi access point and in a couple of other modes. The only limitation is its single 10/100 baseT Ethernet connection.

I did try the "Repeater" mode with the second unit. Maybe this would help me get a better signal to the basement ENRXWI-G? My main WiFi access point happens to throw a shadow into the basement area that I am using, probably because of an intervening brick chimney. Moving my AP a foot or two seems to cure the problem, but could the repeater function do the same? I set it up according to instructions, and it seemed to help on the basement-to-AP route, but if anything hurt the performance (lost packets, etc) AP-to-basement. (puzzling) In any case, no joy.

A WiFi repeater is probably more appropriate when your client and AP are truly separated by long distances, and the signal strength directly from client to AP is really weak. The AP-to-basement path here is relatively short. My transmission errors may be due more to multipath reflections than to weak signals.

The only downside of this box, shared with most WiFi devices, is that there is a lot of setup required. The supplied documentation is about average, but many people will scratch their heads at some point when setting things up.

In summary, score one for cheap Internet appliances.

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