The transmission of bandpass signals and the corresponding channel effects are introduced. Basic single-carrier bandpass modulation schemes – namely, bandpass pulse amplitude modulation, phase-shift keying, and quadrature amplitude modulation – are studied. Lowpass equivalents of bandpass signals are introduced, and the in-phase and quadrature components of a bandpass signal are described. It is shown that bandpass signals and systems can be studied through their lowpass equivalents. The π/4-QPSK and offset QPSK are presented as two practically motivated variations of quadrature phase-shift keying. Coherent, differentially coherent, and non-coherent receivers are described. Differential phase-shift keying is studied in some depth. Finally, carrier phase-synchronization methods, including the use of phase-locked loops, are described.