U need some software to decode,google on that, there is some freeware, connect the scanner on the line-in of the pc, frequencies

131.725 Europe primary (drukste verkeer in nl.)
131.525 Europe secundary
131.825 Europe secundary
136.900 Europe secondary
136.750 Europe (nieuw)
131.850 new European frequency
136.925 ARINC European Channel (active in the uk )
131.550 Primary Channel worldwide
131.550 USA primary
130.025 USA secundary
129.125 USA secundary
136.850 SITA North American Frequency
131.475 Air Canada
131.450 Japan

admin of ACARS servers