I recently ran across the Davis Vantage Vue compact weather station in the latest AES amateur radio catalog and decided to buy it to replace my old Scientific Oregon WMR-968, a station in total disrepair.
Putting the new station together turned out to be easier than taking the old one apart. Besides being a huge spider convention, the bolts on the old station were so badly rusted onto the mast that I finally had to hammer the old hardware off into pieces.
Despite the Vantage Vue’s low cost, connecting it to a USB port ends up adding an extra $150. That’s for the hardware adapter and a software package. A standalone Ethernet-connected version is also available for $250. The WeatherLink software appears to be from the Windows 95/98 era, which is good enough to confirm that the station’s data transfer is working, but that’s about it.
I had used wx200d on Linux with the old WMR-968 station. It provided a reliable daemon and included everything needed to graph data, report to Weather Underground and CWOP, and send packets out over the local APRS network via RF on 144.39 MHz. I had to do some extra perl scripting to glue it all together, but that was part of the fun.
The next task was to find something similar that would work for the Vantage View. “wview” seemed promising at first, but I could feel the inevitable time sink of dependencies and troubleshooting that a lot of Unix based projects become. Then I found a modest sounding package called weewx that was almost too easy to overlook. It’s a thoughtful system written in Python by Tom Keffer. I put it in place, set a few variables, installed the init.d script, and that was that. It provides a comprehensive page of data that can be used in place or automatically FTP’d to a remote server. It reports to Weather Underground, CWOP (APRS-IS), and PWS Weather. It’s also well templated and object oriented – all very extensible in general.
APRS – Back to Radio
The only thing left was how to get it onto the local APRS ham radio network. I got my old Kenwood TH-D7AG working again, hooked it up to the server using a serial-to-USB adapter, and put it in standard TNC mode where it’s bypassing the built in APRS and simply receives regular TNC commands.
Because the CWOP routine in weewx already creates the same packet needed for APRS, it seemed silly to rewrite anything. My first instinct was to use the perl script I’d written for wx200d and have it read directly from weewx’s SQLite database. It was immediately clear that this was a kludgy workaround and not a true solution, so I put a message on the weewx Google Groups forum. I immediately received direction from Tom on how it might be best integrated and it only took a few hours to get it working. I’ve made it available on github in case anybody else can make use of it.
Okay, it’s actually more of a view-of-sky-somewhat-obstructed-by-trees-cam, but I really wanted to do a real time view of the sky this time. It’s the Foscam FI8918W wifi camera in an upstairs window. It has a built in web server that provides live images and video, and the ability to remotely pan and tilt from any Internet connected device. It also makes a nice way to continue watching a storm long after nearby lightning chases everybody inside. (Edit: There are now three weather cams in place.)
The old weather station lasted three or four years, and I hope this one will last longer. But either way, it will definitely be easier to replace when the time comes.
– Brad N8QQ