# 27 Communication System Model

**Objective: **

To investigate the response of a communication channel to a pulse signal.

**Procedure:**

1 . Using Matlab write the code to model the following impulse response (h(t)) of the channel in terms of step function. Note that T_{h}=1 second

2. Plot the impulse response in Matlab.

3. Signal x_{1}(t) with T_{p}=2 seconds goes through the communication channel with impulse response h(t). Using Matlab find the output signal of the communication channel.

4. Apply x_{2}(t) signal with T_{p}=2 seconds to the communication channel with impulse response h(t). Use Matlab to sketch the output signal of the communication channel. If the response of the positive and negative portions of x_{2}(t) are represented by “1” and “0” symbols respectively, do you see inter-symbol interference when the signal x_{2}(t) passes through the communication channel? What solution can you suggest to avoid the symbol interference?

5. Cascade two communication channels as shown in the figure below and apply the input signal x_{1}(t) . Plot the output signal z_{1}(t).

6. What will be the output if three communication systems with impulse response h(t) are cascaded and the signal x_{1}(t) is applied to the input? What if there are 4 cascaded systems?

7. Can you guess what will happen to the output if cascade more number of communication systems with impulse response h(t) and apply the signal x_{1}(t) ?