1. Quiz: Lead/Lag Network 1.Determine the transfer function V O (s)/V  (s) for the lead-lag network shown. 2.Compute DC Gain, Pole Frequency, and Zero Frequency (r/s). vv vOvO 600  5000  400  7500  VCO PD +-+- +-+- -+-+ 1000  RoRo RiRi RFRF R1R1 R2R2 Ideal Op Amp L 10 mH

3. PCM: Pulse Code Modulation An analog signal, x 1, is sampled at frequency f s1 = 1/T s1. Each sample is A/D converted to an N-bit value, the bits are sent serially over the channel at bit rate f b1 = N f s1. Multiple channels may be multiplexed over a single serial line, and the total required bit rate f b is the sum of the individual Bit Rates: f b = f b1 + f b2 + f b3 + … The required two sided bandwidth for transmission is f b The one sided bandwidth for baseband transmission is f b /2.

4. Delta Modulation “Delta implies” “Difference”. Counters/registers are maintained at the transmitter and receiver which hold an estimate of the digital value representing the input. If the input signal is greater the estimate during one sample time, the registers are incremented; if the input signal is greater the estimate during one sample time, the registers are decremented. Only the Increment/Decrement bit is sent to the remote receiver. D/A Binary Counter U/D’ +-+- Q D Clock x(t) Approximation of x(t) Reproduced at Receiver! 1111101010010 Comparator

5. On the Cheap... +-+- Q D Clock x(t) Approximation of x(t) Reproduced at Receiver! 1111101010010 Comparator Q D Clock Approximation of x(t)

6. Adaptive Delta Modulation Algorithmic encoding involving variable step size (integrator gain) so that a long sequence of ones (zeros) causes the estimate to increase (decrease) faster. Delta Modulation has the shortcoming that it doesn’t track rapid/large changes in the input signal very well.