What type of modulation is commonly used for VHF packet radio transmissions?

VHF packet radio, including popular networks like the Automatic Packet Reporting System (APRS), is typically transmitted using standard VHF FM transceivers. The data is converted into audio tones via Audio Frequency Shift Keying (AFSK) and fed into the radio's microphone input, which uses Frequency Modulation (FM) or Phase Modulation (PM). Because FM transceivers are inexpensive and ubiquitous, using FM or PM for packet radio made it easy for amateurs to adopt digital networks. While advanced digital modes like PSK exist, they are more common on HF bands, whereas traditional VHF packet relies heavily on FM.