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FMCDAQ2 test with iio-oscilloscope

Question asked by yzzhsx123 on Apr 13, 2018

Hello, guys

I am doing some test of Fmcdaq2 through ADI oscilloscope, I have found that the default sampling frequency of both ADC and DAC are set at 1GHz, and the output frequency of DAC is 500MHz. I loaded a file which is a 16QAM signal, and got the constellation diagram like below,

Then I checked the I/Q signal in Time Domain like these, which are irregular waveforms (of course they should be)

Here are my questions:

1. What's the DAC output frequency for each bit data? Is it still 500MHz? Since I counted the bit number,which is 25, each 0.05us.

2. Since the file Ioaded is generated from matlab (attached below), are the waves I checked already added to carrier waveform signals which are cos(wt) for I channel and sin(wt) for Q channel ? (I am sorry this may be a stupid question but wondering the answer.)


Hope anyone with experience can help me or give me a little hint.

Thank you so much!!!!