Software-based Solution for Analysis and Decoding of FSK-2 Modulated, Baudot-coded Signals

Abstract

In the present-day scenario, digital communication has become predominant choice over
analog communication worldwide. Digital modulation schemes form the main block of the digital
communication. Among these, frequency shift keying (FSK-2) is a widely used technique employed
for Baudot-coded english text transmission. A Baudot-coded-FSK-2 modulated signal was
simulated corresponding to an english text file. A technique has been developed for its analysis
and decoding in the MATLAB environment. This technique does the signal analysis, its parameter
extraction, and then digital demodulation, to retrieve its corresponding composite bit-stream. An
efficient method for edge detection using the number of zero-crossings has been devised and
implemented successfully. From the composite bit-stream, overhead bits were removed and
decoding was performed to get back the text output.