Table of Contents
Advertisement
120
Table 9.1: Examples of FFT Bin sizes
TIME BASE
FFT SIZE (SWEEP LENGTHS)
MAIN = 1.024
256
MHZ
SMP/S
DIVI-
FFT BIN SIZE IN HZ
SOR
1024000 1
4000
512000 2
2000
256000 4
1000
204800 5
800
128000 8
500
102400 10
400
51200
20
200
40960
25
160
25600
40
100
20480
50
80
12800
80
50
1024
100
40
5120
200
20
4096
250
16
2560
400
10
2048
500
8
1280
800
5
1024
1000
4
Additional information
The Nyquist frequency (f/2) is the maximum frequency that can be accurately
measured by a digitizer sampling at a rate of (f). Otherwise stated: a digitizer
sampling at a rate of (f) cannot measure an input signal with bandwidth
components exceeding f/2 without experiencing "aliasing" inaccuracies.
Nyquist's theorem determines the range of frequencies that can be measured.
They range from DC to one half the sampling rate at which the data was
captured. An FFT of a sweep of N points produces N/2 frequency domain data
points within the range of frequencies between DC and the Nyquist frequency.
So the frequency resolution is:
512
1024
2048
2000
1000
500
1000
500
250
500
250
125
400
200
100
250
125
62.5
200
100
50
100
50
25
80
40
20
50
25
12.5
40
20
10
25
12.5
6.25
20
10
5
10
5
2.5
8
4
2
5
2.5
1.25
4
2
1
2.5
1.25
0.625
2
1
0.5
GEN5i
4096
8192
250
125
125
62.5
62.5
31.25
50
25
31.25
15.625
25
12.5
12.5
6.25
10
5
6.25
3.125
5
2.5
3.125
1.5625
2.5
1.25
1.25
0.625
1
0.5
0.625
0.3125
0.5
0.25
0.3125
0.0156
0.25
0.125
(EQ 2)
I2679-4.0 en
Advertisement
Table of Contents
Troubleshooting
