For ADS-B decoding, dump1090 is an RTL-SDR compatible program that is commonly used. In order to provide information about the aircraft being detected (e.g. icao24 hex address, registration/tail number and sometimes the type of aircraft like A380), dump1090 uses an offline database. Unfortunately this database has not been maintained in a very long time, so it is now out of date, and so cannot display information about many aircraft.
Recently Thierry had the idea to use the data from VDL2 aircraft transmissions to update his dump1090 database. VDL2 is a short data messaging system used by aircraft that will eventually replace the older ACARS messaging system. With an RTL-SDR and vdlm2dec decoder, the VDL2 signal which broadcasts at around 136 MHz can be received and decoded.
Contained within the data is the icao24 hex address and registration/tail number. By collecting this VDL2 data over a number of days, a new database can be generated which can then be imported into the dump1090 database. It however, doesn’t seem to acquire aircraft type data.