What the syllabus asks you to cover
Time domain expression, Frequency domain representation of AM, FM & PM signals. Types of AM & FM signals. Modulation, Demodulation and Bandwidth requirement of AM & FM signal. Digital Modulation & Demodulation of ASK, FSK & PSK signal. M-array data communication system.
Start here for the core ideas. A dedicated GitBook topic page was not available; this original guide is introductory. Use the syllabus checklist and references below to study the remaining details.
Put information on a carrier
Amplitude modulation changes carrier amplitude; frequency modulation changes instantaneous frequency; phase modulation changes phase. For a conventional single-tone AM signal, the carrier appears between two sidebands. The information bandwidth and transmitted RF bandwidth are different quantities.
Work with the assumptions
For ordinary double-sideband AM, a message bandwidth occupies approximately of RF bandwidth. For sinusoidal FM, Carson's rule estimates occupied bandwidth as ; it is an engineering approximation, not an exact spectral boundary. Demodulation must match the modulation and receiver assumptions.
Try it
An AM message extending to 5 kHz needs about 10 kHz of double-sideband bandwidth. An FM tone with 5 kHz peak deviation and 2 kHz message frequency gives a Carson estimate of 14 kHz.
Check your understanding
What happens when conventional AM is overmodulated? Compare coherent detection with envelope detection. Study DSB-SC, SSB, FM noise behavior and practical demodulation from the linked materials.
Pause and recall
Without looking back, explain the main idea, recall a key definition or formula, and describe when it applies. Include assumptions and units where relevant. Revisit any step you could not explain.