# RSA3408A+ RSA2203A+ RSA2208A+ RSA3303A+ RSA3308A+ WCA230A+ WCA280A: – It takes too long to transfer my spectral data. How do I reduce the number of data points?

### 問題：

RSA3408A+ RSA2203A+ RSA2208A+ RSA3303A+ RSA3308A+ WCA230A+ WCA280A: – It takes too long to transfer my spectral data. How do I reduce the number of data points?

### 答案：

In Auto Resolution BW, there is a large number of frequency points. In a wide span (larger than real time span limits) there are even more points; it can take a long time to transfer the data of a wide sweep. If you reduce the number of points in the spectra, the data will transfer faster.

To reduce the number of points in the spectral data, set the Resolution BW to FFT, and reduce the number of points per section (i.e. from 1024 to 512, 256, 128, or 64).  For example, in very wide spans the RSA3408A takes a snapshot for 20 MHz wide sections, then stitches them together.  Each of the 20 MHz spectra are taken from 1024 IQ sample points, and will create 800 points across each 20 MHz section, so the ratio is 800/1024.

If you use RBW mode set to FFT, and set it to 64 points, you get 50 points per 20 MHz section:

64 points per section x 800/1024 = 50 points per section.

Therefore a 100 MHz span sampled at 64 points per section will have 250 points total:

50 points times 5 sections of 20 MHz each.