code: def get_available_channels(header):
      
  
      chlist_str = header['15_SECONDARY_PRODUCT_HEADER'][
          'SelectedBandIDs']['Value']
      retv = {}
  
      for idx, char in zip(range(12), chlist_str):
          retv[CHANNEL_NAMES[idx + 1]] = (char == 'X')
  
      return retv
docs: Get the available channels from the header information