We are testing the fmcomms1-ebz using the reference design(edk_14_4_3013_04_04 reference design).Here is two points I don't understand.
(1) When the SDK project is running with nothing changed from the reference design, everything seems to be ok and the sine wave on chipscope is perfect. But there will be a noise clutter for about 1 second every 13 seconds, and it is very regular. When we changed to use dac_dma_setup() instead of dds_setup() (want to send DDR sine data in test.c) in main.c, it is the same as what described above.
The normal sine wave is:
The noise clutter for about 1 second every 13 seconds is
(2) As above, we changed to use dac_dma_setup() instead of dds_setup() in main.c, and change Xil_Out32((dac_baseaddr+0x04), 0xf) to Xil_Out32((dac_baseaddr+0x04), 0x7) at line 331 of test.c in order to disable the interpolation. In my opinion, now the data in DDR (dac_dma_data) should be transmitted in the order by DAC. But the fact seems not to be that. What we received is not sine wave as below.
(The key parameter is: adcsampling 100M, dacsampling 100M, rx gain 5dB, tx and rx center frequency 2.2GHz.)
Can any one explain this?