- Simon Haykin, Communication Systems. The modern standard. Deep, clear, well-structured. Read chapters 3 (AM), 4 (FM), 5 (noise) carefully.
- B.P. Lathi & Z. Ding, Modern Digital and Analog Communication Systems. Gentler than Haykin, with more worked examples. Excellent treatment of pre-emphasis and the FM threshold.
- Taub & Schilling, Principles of Communication Systems. A long-standing classic; older but still rigorous on superheterodyne design.
- George Kennedy, Electronic Communication Systems. Practical, schematic-rich. Detailed circuit-level coverage of envelope detectors, ratio detectors, Foster-Seeley discriminators.
- Frederick Terman, Electronic and Radio Engineering. From 1955, but if you want to understand why receiver IFs are 455 kHz and 10.7 MHz and why crystal lattice filters look the way they do, Terman has the historical context nobody else does.
- ARRL Handbook. Updated annually, written for radio amateurs. The single best practical reference for everything in this chapter, with hundreds of working circuits.
When the math of this chapter feels comfortable — when you can explain why the FM threshold exists, why SSB needs synchronous detection, why aviation chose AM, and what happens to the spectrum when you increase — you have analog communications under your belt. Onward to Chapter 8: Pulse and Digital Circuits, where we leave continuous waveforms behind and start treating signals as bits.