Commodore Amiga - Chapter 6: BLITTER HARDWARE

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