Presently, ADS-B messages are broadcast on
- 1090 Mhz Mode S Extended Squitter
- VHF Data Link Mode-4 (VDL-4)
- Universal Access Transceiver (UAT) 978 Mhz
First 2 Frequencies have relevant ICAO standards and third one is predominantly used in America.
Out of the first 2, how to identify in which frequency ADS-B messages are transmitted ?
Also, Presently how many Air Traffic Control around the world use ADS-B messages as means of enforcing surveillance ?.
If installing ADS-B receivers (ADS-B IN) and relevant software are cost-efficient, (Like Flightradar24), Why many ATCs aren't making the switch and if ATC are using ADS-B messages, why do ATC still assign Squawk code ?.