The sensors collect weather data and send it to an in-home console that looks like this. The console then sends the data via serial port to a PC running the Linux operating system and wx200d server software. The server software logs the data and makes it available on the internet here on my page and at wunderground.com as KCACITRU2.
The station was first installed in late 1997. As I do not own any
Microsoft(TM) software, I developed wx200d quickly thanks to
reverse engineering of the protocol by Mike Wingstrom and others on
the internet. The software has been very stable ever since, running
for literally years on end, never missing a beat.However in February, 1998 the hardware console failed. It was sent in for repair and returned about a month later. This is the widest gap seen in the historical graphs. A few months later, in November, the host PC began having intermittent lockups. This caused more data loss until the Pentium 100 machine was replaced by a Celeron 300A with more memory. This is the second gap in the data. Ever since, the station has been rock solid (cross-fingers).
Due to physical limits on where the station could be installed at my
tiny little property, the sensors had to be located between two willow
trees to the south. The wind sensor is installed on a mast several
feet above the peak of my roof. But, the trees slowed the wind,
especially from the south. By November 2001, the willow trees had
dried up and died. A wind storm knocked one over, so I cut it up and
cut the other one down too. Now the anemometer is unblocked by trees,
except a healthy non-Willow one 20 feet to the west.I believe you can actually see the average wind speed increase in the graphs. It still seems to read lower than the local airports. Maybe all the suburban obstructions around here slow down the surface wind that much compared to a wide open airport. I notice most personal stations read low compared to airports.
In July 2002 I finally got around to building this Stevenson Screen to shade the temperature sensor. It was installed on the 20th and located about 5 feet from the house. It appears to be very successful, immediately removing 7 degrees on the day that it was installed:
| Time | Temp | July 20, 2002; actual high 99 degrees |
|---|---|---|
| 16:00 | 109 | beginning temperature as sensor is removed from roof eave and left hanging against house in direct sunlight |
| 16:05 | 113 | peak reverses as sensor is moved into new shade box |
| 16:30 | 103 | temperature begins to stabilize 6 degrees lower than the eave position |
| 16:45 | 102 | stable at 102 degrees until 17:50 when it drops to 101 |
Specifications are typical; individual units might vary. Specifications are subject to change and improvement without notice.
| WX200 | Operating Measurement | Accuracy | Resolution | Sampling Frequency | |
|---|---|---|---|---|---|
| Temperature | -40° to 140°F -40° to 60°C | -40° to <32°F -40° to <0°C | ±4°F ±2°C | 0.2°F 0.1°C | 10 seconds |
| >32° to 105°F >0° to 40°C | ±2°F ±1°C | ||||
| >105° to 122°F >40° to 50°C | ±4°F ±2°C | ||||
| >122° to 140°F >50° to 60°C | ±6°F ±3°C | ||||
| Relative Humidity | 10 to 97% | 25 to 90% | ±8% | 1% | 10 seconds |
| Dew Point | 32° to 133°F 0° to 56°C | 25 to 40% RH | ±16°F ±8°C | 2°F 1°C | 10 seconds |
| 40 to 90% RH | ±12°F ±6°C | ||||
| Barometric Pressure | 23.48 to 31.01 inHg 795 to 1050 mb | 32° to 123°F 0° to 50°C | ±.21 inHg ±7 mb | .03 inHg 1 mb | 15 minutes (trend: 1 hour) |
| Wind Speed | 0 to 125.3 mph 0 to 56 m/s | 4.5 to <44.7 mph 2 to <20 m/s | ±2.2 mph ±1 m/s | 0.4 mph 0.2 m/s | gust: 5 seconds |
| 44.7 to 125.3 mph 20 to 56 m/s | ±5% | average: 1 minute | |||
| Wind Direction | 0 to 359° | 0° to 347° | ±6° | 1° | 5 seconds |
| <0° or >347° | ±8° | ||||
| Wind Chill | -121° to 140°F -85° to 60°C | 4.5 to 125.3 mph 2 to 56 m/s | ±16°F ±8°C | 2°F 1°C | 5 seconds |
| Rainfall Daily & Total | 0 to 394 in 0 to 9999 mm | <.6 in <15 mm | ±.04 in ±1 mm | .04 in 1 mm | 24 hours |
| .6 to 394 in 15 to 9999 mm | ±5% | ||||
| Rainfall Rate | 0 to 39.32 in/hr 0 to 9999 mm/hr | <.6 in/hr <15 mm/hr | ±.04 in/hr ±1 mm/hr | .04 in/hr 1 mm/hr | varies: 1 / mm |
| .6 to 39.32 in/hr 15 to 998 mm/hr | +4% or -7% | ||||
Do you have a question about my station that is not answered here? Let me know!