FFT Frequency Resolution and Window Length

Fs (Hz) FFT length (samples)

16384	8192	4096	2048	1024	512	256	128	64
8000	0.48	0.97	1.95	3.90	7.81	15.62	31.25	62.50	125.0
11025	0.67	1.34	2.69	5.38	10.76	21.53	43.06	86.13	172.3
16000	0.97	1.95	3.90	7.81	15.62	31.25	62.50	125.00	250.0
22050	1.34	2.69	5.38	10.76	21.53	43.06	86.13	172.26	344.5
32000	1.95	3.90	7.81	15.62	31.25	62.50	125.00	250.00	500.0
44100	2.69	5.38	10.76	21.53	43.06	86.13	172.26	344.53	689.1
48000	2.93	5.85	11.71	23.43	46.87	93.75	187.50	375.00	750.0
64000	3.90	7.81	15.62	31.25	62.50	125.00	250.00	500.00	1100.0
88200	5.38	10.76	21.53	43.06	86.13	172.26	344.53	689.06	1378.0
96000	5.85	11.71	23.43	46.87	93.75	187.50	375.00	750.00	1510.0

Table 10: Effective window duration (ms), depending on sampling frequency (FS), FFT-frame and time window length

Fs (Hz) FFT length (samples)

16384	8192	4096	2048	1024	512	256	128	64
8000	1024.00	512.00	256.00	128.00	64.00	32.00	16.00	8.00	4.00
11025	743.03	371.51	185.76	92.88	46.44	23.22	11.61	5.80	2.90
16000	512.00	256.00	128.00	64.00	32.00	16.00	8.00	4.00	2.00
22050	371.51	185.76	92.88	46.44	23.22	11.61	5.80	2.90	1.45
32000	256.00	128.00	64.00	32.00	16.00	8.00	4.00	2.00	1.00
44100	185.76	92.88	46.44	23.22	11.61	5.80	2.90	1.45	0.72
48000	170.66	85.33	42.66	21.33	10.66	5.33	2.66	1.33	0.66
64000	128.00	64.00	32.00	16.00	8.00	4.00	2.00	1.00	0.50
88200	92.88	46.44	23.22	11.61	5.80	2.90	1.45	0.72	0.36
96000	85.33	42.66	21.33	10.66	5.33	2.66	1.33	0.66	0.33

Table 9: .Frequency bin resolution (DHz) depending on sampling frequency (FS), FFT-frame and time window length.Note 1: in order to obtain the frequency resolution values and window lengths listed above in an STx analysis, specify either the Df-value bandwidth [Hz] or spectrogram frame length [ms]*2 in the Setup dialogue of the spectrogram..Note 2: optional Df-values (such as the bandwidth of exactly 1 Hz) not shown in the table above are available on request applying DFT instead of FFT.