How Trentham Weather works


Weather Data

The outdoor sensing instruments are mounted on a 10 metre tall mast at the NRA Offices in Trentham. There are three outdoor sensors, a temperature/humidity sensor, a wind vane/anemometer and a rain gauge which has been modified to record in 0.1mm steps instead of the more usual 1.00mm steps.

The data from these sensors & the webcam is cabled down to a console unit and computer in the office below. The console unit also senses indoor temperature/humidity and barometric pressure.


All console data is sent every minute via a serial cable to the computer (which runs 24/7) running the “Weather Display” software which generates the data and web pages which it uploads to the web server every 15 minutes.

The computer was recently (late 2015) updated from a old desktop tower to a small ex-lease desk-top machine. These are small, low-cost, generally reliable, and use less power. The computer runs Windows and has a UPS to help with short power disturbances.


There are currently 2 cameras on the pole (as at April 2016).

  1. SD composite security camera with manual zoom lens
  2. HD ip camera, fixed wide angle lens

The SD camera is in a standard outdoor housing and connected to the PC via a Easycap composite to USB device. The Weather Display software takes images from the video and gets them up on display. So this updates every 15 minutes.

The HD camera is a standard low cost outdoor IP camera using POE. A script running on the computer requests snapshots every 5 minutes, overlays weather station data and uploads the new image to the web server. So this updates every 5 minutes.

Note: The Easycap accounts for most of the load on the computer. The intention is to replace the SD camera with another low-cost ip camera but with a zoom lens. This will ease the load on the computer and provide a better image.

 Posted by at 12:54 am