Demodulate AM signals on ni-USRP

[Danan]

Hi,

I have  two VIs about AM modulation and demodulation with  ni-USRP, the Tx vi is learned from  the  AM-DSB/SC Tx Example in https://decibel.ni.com/content/docs/DOC-24202, in the RX vi, the signals did not demodulated completly, could anybody tell me why and how to resolve it?

One more question: in the following TX vi, the waveform in graghfic "Tansmiteed Signal"  have no relationship with carrier frequency , does  the USRP hardware do the DUC with carrier signal?  if so ,does it also does the DDC in the  USRP hardware?

[psisterhen]

To answer your second question, there is a DUC in the FPGA that upsamples from the IQ Rate to the DAC rate (100 MS/s on the 292x/293x devices) and also does some digital frequency shifting.  After the DACs, there is a RF mixer that upconverts from baseband to your specified carrier frequency.  

There is a similar setup in reverse (downconverter and DDC) for Rx.