How do ASK and PSK modulation differ in NFC/RFID data transmission?

ASK (Amplitude Shift Keying) varies the carrier's amplitude — simple but noise-prone, used in basic RFID; PSK (Phase Shift Keying) varies the carrier's phase — more complex but more robust and secure, used in 13.56 MHz NFC like bank cards.

Communication between NFC/RFID cards (e.g. credit/bank cards) and readers uses special modulation methods:

• ASK (Amplitude Shift Keying): the carrier's amplitude is modulated to encode data. Easier to implement but more susceptible to interference; used in simple RFID systems.
• PSK (Phase Shift Keying): the carrier's phase is used to encode data. More complex than ASK but more robust against interference and more secure; used in high-frequency NFC systems (13.56 MHz), especially credit/bank cards with higher security needs.

The modulation choice significantly affects the system's range, data rate, and security.

Tip: Amplitude is "how loud," phase is "the timing of the wave." Phase is harder to disrupt with noise, which is why higher-security NFC cards prefer PSK.