Carrier modulation for passband transmission of digital signal is introduced with BPSK modulation. This is followed by its useful variant DPSK and further improved DEPSK. The bandwidth reduction in QPSK is compared with signal space representation. How far the advantages of QPSK can be extended to MPSK is discussed next. QASK and its extension M-QASK provide interesting alternatives in signal space in terms of distinguishability of a signal. BFSK and MFSK are introduced next and compared with phase shift counterparts. The advantages of MSK and comparison with QPSK come as the final topic of digital carrier modulation technique. The importance of pulse shaping in reduction of inter channel and inter symbol interference is discussed next. Duobinary coding is discussed in detail and comparison with binary, polybinary presented. This is followed by Nyquist criteria for zero ISI, nyquist pulses, cosine filters and partial response filtering that culminates into quadrature partial response encoder and decoder. Regenerative repeater and role of eye diagram, equalizer in digital transmission is discussed at the end.
