Extra exam question E2E01

WhyData emissions below 30 MHz commonly use frequency shift keying (FSK) as their modulation. Data emissions below 30 MHz commonly use frequency shift keying (FSK), where the transmitter shifts between two discrete frequencies to represent binary data, the basis for modes like RTTY and many other HF digital modes, answer B. DTMF-modulated FM, pulse modulation, and spread spectrum aren't the modulation types typically used for HF data emissions.