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Both weather stations are Davis Instruments Vantage Pro2 Wireless units running the Ambient Virtual Weather Station software. This software handles the ftp transfers to the web site nicely but the graphics are not top notch - the long term graphs suffer from aliasing and the inability to show high / low values. Also, the Davis / Ambient USB connection can be problematic (the old faithful RS-232 version is much better).

A variety of web cams are in use, but the best are 2 megapixel Logitech Pro 9000 with auto-focus. The Logitech unit handles the high ambient light conditions outdoors very well, better colors and the ability to set a zoom level is convenient. I am currently using any of these free alternatives:
BooruWebCam, - simple, captions, timed capture
Dorgem - bit better picture choices
Wecamfirst - buggy, but more options including 2 cams.

The Davis Vantage Pro2 USB Colorado weather station has been active since 2007. The wind sensor is mounted about 5' above ground. A high ridge to the north and east of the sensor probably reduces the detection of winds from those directions. Internet connection is via radio link WISP, a service provided by Ridgeviewtel to those of us who live beyond the reach of telephone lines. The USB connection is problematic, causing nearly 100% processor ultilization.

The Arizona weather station was activated in October, 2008. The Davis monitor connects to the computer through the faithful RS-232 serial port. The wind speed sensor is mounted on the roof of the house. I suspect that the temperature readings are high in the summer due to the flat roof and protected enclave where the sensor is located.

So what does it take to get a Windows PC to run reliably unattended for months? The obvious answer would be to get an ultra reliable PC, an ultra reliable power source, an ultra reliable internet connection/MODEM/router and ultra reliable software. Right.

My first attempt was to use a laptop. I figured that the primary source of problems would be power supply interruptions and the laptop should handle these seamlessly. The laptop hung twice during 6 months of continuous operation. It should be noted that the VWS software has the ability to restart the PC periodically, but this fix only applies if VWS is running. Next I tried a new desktop with UPS backup. This failed for reasons related to the UPS and transient power surges. A new approach was needed. Besides the cost of the ultra reliable approach, there is the fact that I have a closet full of old computers begging for something to do.

Getting a junk box PC with equally old router / MODEM to operate stand-alone for extended periods of time is a challenge. I have found that the key is to cycle AC power to the system (PC/MODEM/router). This can be done with a programmable AC timer switch. The AC timer switch turns the power off periodically. The timer then turns power back on a short time later. The computer's BIOS is set to turn the PC on upon restoration of power. The freeware application AMP WinOFF schedules a shutdown of the PC at the end of the day (some of the data in the Virtual Weather Station does not get logged until after it has been running for 10 minutes). The sequence of events is;

1) Morning - AC power on, BIOS powers system up, Windows and applications boot
2) AMP WinOFF boots and schedules a shutdown in the evening,
3) data is uploaded to website,
4) AMP WinOFF commands PC system to power down,
5) AC timer shuts power off shortly before turning back on

This approach has worked well, handling such problems as:
• Hard drive boot failure
• PC boot failure ("Keyboard failure - press F1 to continue" - I love that one. The keyboard is dead, dummy!)
• Shutdown failure
• Application software hangups
• MODEM confusion

One failure that this approach did not resolve was a lightening strike that toasted the PC and MODEM. Oh well...