0
$\begingroup$

We have an adrv9002 that has built in DAC and ADC that takes and gives IQ samples. I did a test to verify functionality but don't understand what I am seeing.

  1. Take a RF tone from a signal generator and feed it to the receiver.
  2. Take this received IQ, and just send the I data to DAC port for output while making the Qs zero.
  3. What I see on spec analyzer is a tone but the time view of the signal looks like a series of camel humps not almost a straight line plus noise.
  4. If I generate my own bpsk signal with just I data and send it through same DAC then it looks fine on spec analyzer.

So my question is, should an I-channel of data show this camel hump periodicity or be more almost constant amplitude? My suspicion is something is not matching in my config but I need a hint on what is wrong.

FYI, the DAC and ADC are set to 25Msps. My bpsk signal is 12.5Mbps interpolated to 25Msps.

enter image description here

i think this output is correct now. since on tx everything is coherent. on receive it isnt so the signal is shift in phase so it needs to be represented in i and q. until its corrected.

duh

$\endgroup$
2
  • $\begingroup$ Welcome to DSP.SE! Normally if configured properly the I data would be a sinusoid for a single tone in unless you are synchronously down-coverting the tone to baseband. Could you update your question to add some more details including: What is the frequency of the RF tone? Is 25 msps the sampling rate of the ADC, or if not what is the sampling rate of the ADC and DAC? What is the LO setting for the DDC (what freq are you translating the input to?). Is the test tone phase locked to the sampling clock or free-running? Can you add a plot of what the output looks like? $\endgroup$ Feb 23 at 3:07
  • $\begingroup$ Can you share the picture of what you are seeing on spectrum analyzer and what you expect to see? $\endgroup$
    – Im Groot
    Feb 24 at 18:07

0

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Browse other questions tagged or ask your own question.