SCOPE DATA ACQUISITION, data becomes not SMOOTH suddently

[aynor007]

Hi, I use ni fgen to generate single pulse, and obtain the data by scope. After filtering, the data is saved as txt file. But the data is not consistent, and suddently becomes not smoth as shown in attached picture. 

The VI is also attached.

Could you help me to solve this problem?

[aynor007]

The pulse is tone bust, center frequency is 250khz, cycle is 5. The filter cut frequency is 500Hz and 2MHz SCOPE samples is 50Mhz, 5 chs, fgen sample rate is 20Mhz

[aynor007]

PXI 1042: 5412 for FGEN, and 5402 for scope

[AndyCandy]

Hi aynor007,

I can't see anything in your code immediately sticks out at troublesome.  I would recommend isolating the problem to the software by testing other synchronization examples like the one found here--http://www.ni.com/example/26535/en/

It may be possible that the Write to Measurement Express VI isn't able to keep up with the fast acquisition times, in which case you could try the lower level VIs for saving data.