Question

What type of modulation uses discrete values of carrier frequencies to transmit binary data?

(a) Frequency modulation

(b) Amplitude shift keying

(c) Frequency shift keying

(d) Phase modulation

The question was asked in a national level competition.

Origin of the question is Frequency, Phase Modulation, Modulation Index and Sidebands in portion Amplitude & Frequency Modulation of Avionics

Answer 1

Right option is (c) Frequency shift keying

For explanation I would say: Frequency shift keying assigns different values of carrier frequencies for binary digits and transmits data by varying the frequency of the carrier in accordance with the binary data. This type of modulation is widely used in the transmission of binary data in digital cell phones and in some types of low speed modems.