1. PAM Pulse Amplitude Modulation Professor: Dr. Miguel Alonso Jr.

2. Outline Description Bandwidth Requirements Signal Reconstruction Types of PAM LABVolt Module 2: PAM

3. Description PAM is a type of pulse modulation A PAM signal consists of samples of the analog signal, in which the amplitude of each pulse is proportional to the analog signal at that point Pulses have a fixed width

4. Bandwidth Requirements Sampling Rate of the PAM pulses should be twice that of the analog signal to be transmitted. Nyquist But what about the bandwidth of the PAM signal itself? Bandwidth of the PAM signal is roughly computed as

5. Where B T is the transmission bandwidth τ is the pulse width K 1 is a constant that depends on the spacing between adjacent pulses, the level of acceptable adjacent pulse crosstalk, the sharpness of the cutoff rate, and other factors Typical values range from 0.5 to 1

6. Example An analog signal is sampled at a rate of 5kHz. The width of each sample is 40 us. Compute the approximate bandwidth for K1=0.5 and K1 = 1 What is the duty cycle of the sampling pulse? Answer: 12.5kHz and 25kHz What is the bandwidth requirement for a K1 = 1 and a sampling width of 15us?

7. Signal Reconstruction Reconstruction of the PAM occurs through the use of a low-pass filter

8. Types of PAM Flat-top Natural PAM

9. LAB Volt Module Labvolt Module 2: PAM Exercise 2-1 and 2-2