DSP Applications and Student Projects - Digital Signal Processing and Applications with the C6713 and C6416 DSK - page 382

FIGURE 10.25. Plot of encoded DSK output using voice as input to the DSK.
that if you do this, you need to change the value of register 4 in the init/comm.
header file (see Chapter 1). Or you can use TheForce.wav as input.
Build this project as BPSK _ ReIN . All the necessary files for this project are on
the CD in BPSK _ ReIn within the folder PSK . Use TheForce.wav or voice as
input to the DSK, with the DSK output to a scope. Verify that a representative
segment of the encoded BPSK output signal from the DSK is as shown in Figure
10.25.
MATLAB Component
The corresponding MATLAB file for this project bpsk_ReIn.m is on the CD.
Verify the resulting MATLAB plots in Figure 10.26. The upper graph shows the
received waveform signal segment of (TheForce.wav) .A .wav file is used to
model the input signal being encoded as a BPSK signal. The plots show successive
samples being encoded and decoded. The .wav sample is decimated to 1 kHz, con-
verted to a bit stream, and then modulated to a BPSK signal that is then plotted.
The upper graph shows which amplitude of the voice signal is being modulated into
a BPSK signal. Note that as the circle moves along the received waveform in the
upper graph, the corresponding BPSK signal and transmitted bits are displayed in
the lower graph and are continuously encoded (updated).