Keeping the Instruments Running

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By Forrest Mims, III

Photo by Forrest Mims.

On March 16-17, 2004, Colorado State University (CSU) installed a USDA UV-B site on the roof of the Moody Science Building at Texas Lutheran University (TLU) in Seguin, Texas. This is one of 34 sites in the USDA network. On January 20, 2012, the entire installation had to be taken down due to replacement of the old gravel roof on the building. The roof contractors were very helpful. They removed all the hardware and wrapped the instrument panel and system board in plastic.


On February 24, 2012, the roof contractors carefully reinstalled all the equipment on the roof parapet (10 inches south of its former location due to an electrical box that had to be raised to accommodate the new roof) and mounted the heavy sensor plate and system equipment securely in place. I reconnected all the system wires and cables to the instruments, but the system could not be placed in operation until the telephone cable was reconnected and power was available.

Meanwhile, TLU installed a new telephone line from the instruments to the roof access port. The termination at the utility room telephone panel was also changed. These changes seem to have reduced previously severe noise on the line. The system was back in operation collecting data on March 6, but the skylight sensor was not sending data. This problem was traced to the replacement data logger board. Today (March 13, 2012) I removed a replacement board that was installed prior to the takedown and replaced it with the original board. Bill Durham at CSU was able to get a good connection, and the system is now 100% in operation. Bill and I think my cell phone might have caused the noise in the original board we reinstalled this morning. Thanks to George Jansen and Bill at CSU for their patient help during this lengthy and sometimes puzzling process.

The photo shows the system as it looked this morning after the latest adjustments. You can find the data from this system at the USDA UV-B site linked below. Look for TX21 and TX22. Data from my personal shadowband radiometer (TX31) is also available. TX31 is the only such instrument to use LEDs as spectrally selective photodiodes instead of optical filters and standard silicon photodiodes. Here’s the main USDA site operated by CSU:

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