The Station

The weather station is a Davis Vantage Pro Wireless Integrated Sensor Suite. 'Integrated' means it has a raingauge, anemometer, windvane, thermometer and hygrometer all in one unit. The station is now outdated, having been replaced with the Vantage Pro2 in 2006, not long after the unit was installed. While it would have been nice to have the latest and greatest, the consolation was in being able to purchase extra equipment (like the soil moisture and temperature station) from Davis at bargain-basement prices during their end-of-model sale.

Being completely wireless, the station relies on solar power to operate and has its own little solar cell. A supercapacitor keeps it running overnight. There is also a lithium battery for backup, although it seems to be only drawn upon late at night after a few cloudy days have prevented the capacitor from charging.

Rain is measured using a 'tipping bucket'. Effectively two little cups of precise volume sitting on each end of a see-saw. When a cup fills, it tips the see-saw causing a magnet to momentarily close a reed switch, sending a signal that 0.01 inches of rain has been measured. The cup empties as it tips down, and the other cup is positioned under the funnel ready to catch more rain. The anemometer also uses a reed switch, triggered by a magnet passing on each rotation of the wind cups.

The station constantly transmits weather data to a console in the kitchen of the house. The signal is also picked up by a second receiver connected to the computer. The new Pro2 wireless is supposed to be more reliable, but this station was rather fiddly to get set up for reliable reception. Even a repeater station (bought in the half price sale) actually made the reception worse! While the reception is pretty good now, we intend moving the station to a more suitable location - out of the cold hollow and away from a tree. Hopefully this will make reception better and not worse. 

The Console

The console provides constant updates on the current weather conditions as well as attempting short- and medium-term forecasting. Perhaps it is a legacy of its North American heritage, but it doesn't always get the forecast right! Historical data is also recorded so we can quickly look up, say, the maximum and minimum temperatures for the day or the week or the daily rainfall for each day this month. At the end of each month, however, all the figures are totaled and we can only see the monthly totals, maximum and minimum for the month and so on. To store any more detailed long-term records means recording on the computer where the storage space is virtually unlimited.

Soil Temperature Station

One of the extra units purchased in the end-of-model sale was a wireless soil temperature and moisture station. This unit also records leaf wetness. The soil thermometer is buried at 100mm depth, but the moisture sensor is yet to be connected as we have been unable to find an Australian standard for its placement. Both soil moisture and the leaf wetness sensor seem to be aimed at irrigators as a means of optimising water use.

Weather Envoy and Logger

A Davis weather Envoy is a secondary receiver with logging facilities built in. It receives the same data as the console, but makes a complete and permanent snapshot every 5 minutes (this time is user-adjustable) that is then downloaded to the computer for permanent storage. It is these snapshots that are uploaded to the website every 5 minutes. The logger is capable of storing weeks or months of data (depending on the recording interval), ready or periodic downloading to computer if required. Davis supplies software with the logger to download and process the data as well as producing an interactive screen display. In this setup it spends most of its time running as a service to produce the graphs and data for the website. There are other packages out there that can interact with the Davis stations, but there hasn't been any real need to abandon the manufacturers software yet.