spectrum of 5640

[david uang]

Hi all,

   I generate a 1M sine wave in the fpga baseband and then upconverted to carrier frequency 20M using the DUC embeded in Ni5640R card. However, this is what I get, as depicted in the picutre. My questio is why I get 17M and 23M frequency signal.
   thanks.

David

[david uang]

I did not solve it, but this disappears. I do not know what happened. Excuse me for bothering.