Communication Basics #19 Worked Example: ASK/FSK/PSK Plot (msec)

Instructor: Dr. Süleyman Burak ÇELİK

A worked example in the Communication Basics series. We work through a classic digital modulation problem step by step in light mode. Given an ASK modulated signal with a 1 kHz carrier (sin(2000πt)), we first decode the digital bit pattern (1 0 1 1 1 0 1 1) by reading the on/off envelope, then re-draw the exact same bit sequence as FSK and PSK waveforms. For FSK we use 1 kHz for bit-1 and 2 kHz for bit-0; for PSK we flip between sin and cos (or equivalently a 180-degree phase shift). Along the way we derive the 1 kbps data rate from the bit duration and count the carrier cycles inside each bit interval. Topics covered: - reverse ASK decoding: reading a digital pattern from an amplitude-keyed waveform - Amplitude Shift Keying (ASK): carrier on/off mapping - Frequency Shift Keying (FSK): 1 kHz vs 2 kHz carrier frequencies - Phase Shift Keying (PSK): sin vs cos phase reversal - data rate calculation: 1 ms per bit gives 1 kbps - counting carrier cycles per bit interval Part of the AcEdumy Communication Basics series.