Introduction to Digital Signal Processing and Filter Design

CHAPTER 8

Hardware Design Using DSP Chips

8.1 INTRODUCTION

In Chapter 7, we used the fdatool to illustrate the analysis and design of a digital filter in which the coefficients of the filter and the input samples are represented by a finite number of bits. We also found the effect of rounding or truncating the results of adding signals or multiplying the signal value and the coefficient of the filter and ascertained that there is no possibility of limit cycles or unstable operation in the filter. In the example chosen we decided that an FIR filter would meet the frequency response specifications of a lowpass elliptic filter, with a wordlength of 8 bits. Very often, however, a digital filter is used as a prominent part of a digital system such as a cell phone, which has other components such as power supply, keyboard, or other I/O interfaces. So we have to simulate the performance of the whole system with all components connected together in the form of a block diagram.

8.2 SIMULINK AND REAL-TIME WORKSHOP

Simulink is the software that is available as a companion toolbox to MATLAB and is used to model and simulate the performance of dynamic systems, under varying conditions. Just as MATLAB works with a number of toolboxes, Simulink has access to a library of many additional tools called blocksets, such as the DSP blockset, fixed-point blockset, communications blockset, and control system blockset, as shown on the left side of Figure 8.1.

The Simulink browser library includes blocksets ...