These gauges are sampled at approximately 1 Hz.

  Sample file format:
  yr mm da hhmm pos vis     lum ALv ALl pts
2008  4 17 1554  1    5039      0   0   6  145
2008  4 17 1600  1    5038      0   0   6  293
2008  4 17 1606  1    5903      0   0   6  303
2008  4 17 1612  1    5568      0   0   6  304
2008  4 17 1618  1    5579      0   0   6  294

where:
   yr = year
   mm = month
   da = day of month
   hhmm = time (UTC/GMT)
   pos = instrument position on concrete slab
   vis = visibility (m)
   lum = background luminance (cd/m^2)
   ALv = alarm status of visibility sensor
   ALl = alarm status background luminance
   pts = number of points averaged in 6-minutes