Multirate Digital Signal Processing, Oversampling of Analog-to-Digital Conversion, and Undersampling of Bandpass Signals - Digital Signal Processing: Fundamentals and Applications - page 612

ym ()

xn ()

Left Line In
LCI

Left Line Out

Signal
source

TI TMS320C6713
DSP Board

Right Line In
RCI

Right Line Out

xn ()

ym ()

Sampling rate at f s

Update DAC channel
once for M samples to
obatin the sampling
rate at f s /M

FIGURE 12.46

Downsampling using the TMS320C6713.

ym ()

xn ()

Left Line In
LCI

Left Line Out

Signal
source

TI TMS320C6713
DSP Board 2

Right Line In
RCI

Right Line Out

xn ()

ym
Sampling rate set as f s L

()

Acquiring x(n) once
for L samples

FIGURE 12.47

Upsampling using the TMS320C6713.

lc ¼ (float) (AIC23_data.channel[LEFT]);

(float) (AIC23_data.channel[RIGHT]);
// Insert DSP algorithm below
Lcount þþ ;
for(i ¼ 66; i>0; i--) // Update input buffer with zeros
{ x[i] ¼ x[i-1]; }
x[0] ¼ 0;
if (Lcount ¼¼ L)
{
x[0] ¼ lc; // Load new sample for every L samples
Lcount ¼ 0;
}
y[0] ¼ 0.0;
for(i ¼ 0;i<67;i þþ ) // FIR filtering
{ y[0] ¼ y[0] þ x[i]*b[i]; }
y[0] ¼ (float) L*y[0]

rc ¼