Pulse modulation techniques can encode an analog signal for transmission. This document discusses several techniques including: - Pulse-amplitude modulation (PAM) which varies pulse amplitudes based on sample values of the message signal. - Pulse code modulation (PCM) which assigns a binary code to each analog sample. PCM is commonly used in digital communications systems. - Delta modulation which transmits one bit per sample indicating if the current sample is more positive or negative than the previous. It requires higher sampling rates than PCM for equal quality.

7. Block diagram of PAM generation System for recovering message signal m(t) from PAM signal s(t).

13. Pulse Code Modulation

17. Figure The basic elements of a PCM system. Pulse Code Modulation

18. Encoding

20. Noise in PCM Systems

22. Quantization Process

23. Two types of quantization: ( a ) midtread and ( b ) midrise.

24. Illustration of the quantization process. (Adapted from Bennett, 1948, with permission of AT&T.)

31. Delta Modulation (DM)

32. DM System: Transmitter and Receiver.

33. The modulator consists of a comparator, a quantizer, and an accumulator. The output of the accumulator is Slope overload distortion and granular noise

34. Adaptive delta Modulation

35. Adaptive delta modulation system: ( a ) Transmitter. ( b ) Receiver.

36. Waveforms resulting from the computer experiment on delta modulation: ( a ) Linear delta modulation. ( b ) Adaptive delta modulation.

37. Differential PCM (DPCM)

38. Figure 3.28 DPCM system. ( a ) Transmitter. ( b ) Receiver.