- Submitted By: Steven-Rawlings
- Date Submitted: 01/17/2016 6:28 PM
- Category: Technology
- Words: 2363
- Page: 10

Objective:

In this lab you will explore:

1. Computing the spectrum of a signal

2. Filtering operations

Required Equipment:

PC and connection to Internet

Access to Matlab at http://lab.devry.edu

Matlab script files: SigSpec.m, LinFiltering.m

Prerequisites:

If you need practice in Matlab basics, you can use Labs-2-3Matlab-Practice.docx (see Doc Sharing) as a guide.

Discussion:

The study of signals and systems in communication systems is facilitated by time-domain (e.g. impulse response and difference/differential equations) and frequency domain representations (e.g. spectrum and transfer function). Filtering is an essential operation in the study of transmission systems. Filters are characterized by impulse response (or difference/differential equations) in time-domain and frequency response (or transfer function) in frequency domain.

In this lab, you will explore spectrum and filtering operations. This knowledge is required in order to understand the transmitter-receiver operation in the next Lab.

Procedure:

1. Calculation of signal spectrum

A signal may be specified in the form of

(i) a mathematical formula (e.g. Acos(2πft+φ) or

(ii) a Matlab function (e.g. randn()) or

(iii) a sequence of values in a file (.e.g. wavread(filename)) or

In all these cases, a signal ends up as a pair of vectors in Matlab, one vector (say, tt1) representing time and the other (say, xx1) representing values of the signal at these times. We can use Matlab plot() function to graph the signal. We can use Matlab dft/fft functions to calculate the spectrum of the signal. We can use the Matlab subplot() command to plot the signal and its spectrum in one figure. The Matlab script file SigSpec.m contains Matlab commands to generate these types of signal data and to compute and display their spectrum. The script is shown below:

%% ECET-375 Lab-2: SigSpec.m %K. Pallegadda, DeVry University

% In this script the number of points should be less than...