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^
/|\
|
|
0 db |____
| \
| \ Filter response
| \
-30 db |_______\_________________________________\
| | | | | | /
05 10 15 20 25 30
KHz
Filter passes all frequencies below about 5KHz
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= 16KHz
12-4= 8KHz
^ Filter response
/|\
| 12 KHz sampling frequency
| |
0 db |____ |
| \ Diff. | Sum
| \ | | |
| 4| \ | | |
-30 db |____|__\_|___|_____|_____________________\
/ | | | | | | /
/ 05 10 15 20 25 30
/ KHz
/
Desired output frequency
Figure 5-6: Noise-free Output (No Aliasing Distortion)
You can see in Figure 5-7 that is unacceptable to use a 10 KHz sampling rate to produce a
4 KHz waveform. One of the beat frequencies (10 - 4) is within the range of the filter,
allowing some of that undesirable frequency to show up in the audio output.
- Audio Hardware 151 -
Содержание Amiga A1000
Страница 1: ...AMIGA HARDWARE REFERENCE MANUAL 1992 Commodore Business Machines Amiga 1200 PAL...
Страница 20: ...Figure 1 1 Block Diagram for the Amiga Computer Family Introduction 11...
Страница 21: ...12 Introduction...
Страница 72: ...Figure 3 12 A dual Playfield display Playfield Hardware 63...
Страница 87: ...Figure 3 24 Horizontal Scrolling 78 playfield hardware...
Страница 101: ...92 Playfield Hardware...
Страница 199: ...Figure 6 9 DMA time slot allocation 190 Blitter hardware...
Страница 203: ...Figure 6 13 Blitter Block Diagram 194 Blitter Hardware...
Страница 229: ...220 System Control Hardware...
Страница 246: ...Figure 8 8 Chinon Timing diagram cont Interface Hardware 237...
Страница 265: ...256 Interface Hardware...
Страница 289: ...280 Appendix A...
Страница 297: ...288 Appendix B...
Страница 298: ...APPENDIX C CUSTOM CHIP PIN ALLOCATION LIST NOTE Means an active low signal Appendix C 289...
Страница 302: ...APPENDIX D SYSTEM MEMORY MAP Appendix D 293...
Страница 343: ...334 Appendix F...
Страница 351: ...342 Appendix G...
Страница 361: ...352 Appendix H...
Страница 367: ...358 Appendix I...