S-DSP/Noise: Difference between revisions

Revision as of 04:20, 14 June 2023

Noise clock table

Hardware noise on the SNES is generated by a 15-bit Fibonacci linear feedback shift register. [1] Note that the noise sampling frequency is the perceived pitch (due to overtones) even though it is double (Nyquist) that of the fundamental. The Gaussian interpolator does not operate on the hardware noise generator.

Value	Sampling Frequency	Pitch
00	0 Hz	off
01	16 Hz	C0 - 38¢
02	21 Hz	E0 + 33¢
03	25 Hz	G0 + 35¢
04	31 Hz	B0 + 7¢
05	42 Hz	E1 + 33¢
06	50 Hz	G1 + 35¢
07	63 Hz	B1 + 35¢
08	83 Hz	E2 + 12¢
09	100 Hz	G2 + 35¢
0A	125 Hz	B2 + 21¢
0B	167 Hz	E3 + 23¢
0C	200 Hz	G3 + 35¢
0D	250 Hz	B3 + 21¢
0E	333 Hz	E4 + 18¢
0F	400 Hz	G4 + 35¢
10	500 Hz	B4 + 21¢
11	667 Hz	E5 + 20¢
12	800 Hz	G5 + 35¢
13	1.0 kHz	B5 + 21¢
14	1.3 kHz	E6 - 24¢
15	1.6 kHz	G6 + 35¢
16	2.0 kHz	B6 + 21¢
17	2.7 kHz	E7 + 41¢
18	3.2 kHz	G7 + 35¢
19	4.0 kHz	B7 + 21¢
1A	5.3 kHz	E8 + 9¢
1B	6.4 kHz	G8 + 35¢
1C	8.0 kHz	B8 + 21¢
1D	10.7 kHz	E9 + 25¢
1E	16 kHz	B9 + 21¢
1F	32 kHz	B10 + 21¢

References

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 Noise clock table
-Hardware noise on the SNES is generated by a 15-bit Fibonacci [https://www.eetimes.com/tutorial-linear-feedback-shift-registers-lfsrs-part-1/ linear feedback shift register]. [1]  Note that the noise sampling frequency is the perceived pitch (due to overtones) even though it is double (Nyquist) that of the fundamental.  The [[S-DSP/Gaussian Filter|Gaussian interpolator]] does not operate on the hardware noise generator.
+Hardware noise on the SNES is generated by a 15-bit Fibonacci [https://www.eetimes.com/tutorial-linear-feedback-shift-registers-lfsrs-part-1/ linear feedback shift register]. [1]  Note that the noise sampling frequency is the perceived pitch (due to overtones) even though it is double ([https://www.techtarget.com/whatis/definition/Nyquist-Theorem Nyquist]) that of the fundamental.  The [[S-DSP/Gaussian Filter|Gaussian interpolator]] does not operate on the hardware noise generator.
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