Friday, February 22, 2013

Weather Station Radio Telemetry at Fabian Garcia

Our office has been operating a weather station at NMSU's Fabian Garcia Science Center for several decades.  Since its installation, we would collect data from the weather station via the telephone network.  The telephone communications served us well, but it became apparent that, in later years, all the experimental changes at the center were disrupting our ability to communicate reliably with the weather station.  The phone line would be accidentally cut and replaced, only to be cut again as another project trenched a nearby experimentation plot.  Something had to be done.

Several months ago I was experimenting with a Campbell Scientific NL200 and a pair of RF401 radios we were going to use at another NMSU science center, and on a lark, decided to try the system on the Fabian Garcia weather station.  While the radios are rated for line of sight communications over several miles, I was skeptical that this would even work.  The distance from the station to our office was around a mile.  Also, some evergreens and an Interstate highway was in the way.

I installed the system anyway, and to my surprise, it worked.  What was even more surprising is that the RF401 radios were using 0dB whip antennas.

My excitement soon evaporated as the system seemed to fail for no reason whatsoever.  The weather station would stop answering comm requests, so we would fiddle with the antennas or change the location of the office RF401 by a few millimeters and it would work again.  After a few days, it would stop working and we would repeat the same process.  Finally, one day we couldn't get it back no matter how much we played with the office RF401.

I took the system apart and checked each device to make sure the hardware was OK.  It was, so we decided that it had to be the antennas.  We bought a 900MHz 9dB yagi antenna for the weather station, and a 1dB dipole window mount antenna for our office. I enlisted the help of Ms. Elizabeth Smith, grad student extraordinaire, and we set a date for the re-installation of the sytem.

On February 6th, 2013, I reconnected the NL200 to the NMSU network, connected one of the RF401 radios to the NL200 and I mounted the 1dB office antenna in the window.  The pictures below show the communications equipment in the office and the new antenna taped to the window.  Because of the angle of the picture, we can't really "see" the trees and Intersate that obscure the Fabian Garcia SC.

Liz and I then went to the Fabian Garcia SC weather station to install the other RF401 and the new 9dB yagi antenna.  Everything went smoothly and after we mounted the antenna, we contacted Dr. Dave DuBois, NM State Climatologist, so that he could check the communications from the office.  It worked!  So now we have a weather station nearly a mile away communicating with our office via a radio system and a network connection.  The Fabian Garcia station joins a list of our other weather stations on RF/Network telemetry and continues our slow communications upgrade of our statewide monitoring network.