String: D075YYMM.FIT
Pattern:
   D -> Data version:
         'X' GOES X-ray
         'M' GOES Magnetometer
         'P' GOES Electrons, Protons & Alpha particles.
   07 -> GOES-7, 91 = SMS-1, 92=SMS-2, etc.
    3 -> 3-second values
   YY -> year
   MM -> month