ELEC 241 Lab

Introduction

We've actually been doing digital signal processing for quite some time now. But for the most part it has been more of a measurement tool than a system component. In this Lab and in Lab 8 we will look at how we might use the computer alongside (or instead of) op amps as part of an overall signal processing system. We will look at some processing functions (e.g. filtering) which are direct "analogs" of analog processing, as well as some that would be difficult or impossible to implement in an analog circuit.

So far all our digital signal processing has been done in Labview. Labview has the advantage that it allows us to see and hear the processed signals immediately, just like an analog circuit. However, it has two shortcomings (actually, one is a limitation of the PC itself): there is a limit on the complexity of processing it can perform and still meet the real time requirement of keeping up with the input signal; and it has a rather arcane programming language. So in this lab and the next, we will use Matlab to do most of our signal processing.

Matlab has a more conventional programming language, and it allows us to circumvent the real time constraint by using "batch" processing: we record a signal on disk, process it (taking as long as we need), write the resulting output to disk, and then play back the output signal. This has the additional advantage of allowing us to perform different processing functions on exactly the same input (reference) signal and compare the results.