Modulation & FSK

  Modulation and Demodulation Technique
There are many modulation techniques available for our requirement, but we have opted to use Frequency Shift Keying (FSK). FSK has much better performance compared to amplitude modulation and frequency modulation, with minimum losses. Although techniques like OFDM would give better performance, but it is out of our scope to implement it as it involves lots of mathematical theories.

 Frequency shift keying

Frequency-shift keying is a modulation technique used by modems in which two different frequencies in the carrier signal are used to represent the binary states of 1 and 0. Using FSK, a modem converts the binary data from a computer into a binary form in which logic 1 is represented by an analog waveform at a specific frequency and logic 0 is represented by a wave at  a different specific frequency .The diagram below represents the phenomenon.

Frequency shift keying is a form of frequency modulation in which the modulating shifts the output frequency between predetermined values. Continuous phase forms of FSK exist in which there is no phase discontinuity in the modulated signal. The example shown below is of such a form. Other names for FSK are frequency-shift modulation and frequency-shift signaling

 Bit representation in FSK