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AD6649 restoring the IQ signal

Category: Hardware
Product Number: AD6649
Software Version: AD6649 Datasheet Rev. C

My AD6649 has been in working condition, and the data output terminal of the chip has been outputting real data. I have obtained the data of two channels A and B from the output real data.

My goal is to recover the unambiguous IQ signal that goes through the FIR filter but not through the fixed fs/4 NCO. Because the phase of the signal is important to me.

For the data of a certain channel (such as the B channel), I decomposed two mutually orthogonal signals (according to the relationship of fs/4), one of which is I and the other is Q (see figure).

But I can't distinguish which one is I and which is Q. I don't know if there is any way to clearly distinguish I and Q, do you have any suggestions? Or can I just choose another device instead?

Thank you.

Parents Reply
  • Hi,

    You are right, it is indeed real output. What my FPGA receives is also a real signal.

    However, since the internal conversion of complex to real in AD6649 uses fs/4 NCO, I can recover IQ signals from the received real signals, but the problem is that I can't distinguish which is I and which is Q.

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