Figure 5-5 Frequency Domain Plot Of Low-Pass Filter; Figure 5-6 Noise-Free Output (No Aliasing Distortion) - Commodore Amiga Hardware Reference Manual

o
db 1---,",
Filter response
-30 db
5 kHz 10 kHz 15 kHz 20 kHz 25 kHz 30 kHz
Filter passes all frequencies below about 5 kHz.
Figure 5-5: Frequency Domain Plot of Low-Pass Filter
Figure 5-6 shows that it is permissible to use a 12 KHz sampling rate to produce a 4
KHz waveform. Both of the beat frequencies are outside the range of the filter, as shown
in these calculations:
12
+
4
=
16 KHz
12 - 4
=
8 KHz
Filter response
Odb 12 kHz sampling frequency
~D;ff'
Sum
4 kHz
-30db
LI
I
I
I
5 kHz 10 kHz 15 kHz
20 kHz
Desired output frequency
I
I
25 kHz 30kHz
Figure 5-6: Noise-free Output (No Aliasing Distortion)
Audio Hardware 155