Forum Discussion

Altera_Forum's avatar
Altera_Forum
Icon for Honored Contributor rankHonored Contributor
9 years ago

Help needed in VHDl code for calculating the I and Q phase component for a ADC signal

Hello all,

I am designing a DDC in which I need to calculate the In phase(I) and the Quadrature phase(Q) components of my ADC signal. I know how these components are manually calculated from some DSP tutuorials. But what I need to know is how can I represent the same through VHDL code, since I need to synthesise the code on a hardware basis. Just a small introduction on how to preoceed with this is appreciated. Right now, what I have done is I have synthesized the signals from NCO and I have performed the mixer operation (which is basically the multiplication operation of the ADC signal and the synthesizer output) and has completed the decimation by 8 process too. (I read from some tutorials that Decimation is a combo of Fir output + downsampling, and so I have performed it. Also divided the decimation output by 8 since its the decimation factor in my case). I have completed till this, and after this continues the calculation of I and Q phase components. Thanks in advance.

12 Replies

Show More
  • Altera_Forum's avatar
    Altera_Forum
    Icon for Honored Contributor rankHonored Contributor
    9 years ago

    I'm not clear about your problem.

    If you have the decimated output, you have the I/Q components, provided you have already multiplied your ADC signal in the mixer.

    Your ADC should go through Mixer, then through decimation process. IS it the correct order in your implementation?

    I guess that you mean you have no Mixer before decimation.
  • Altera_Forum's avatar
    Altera_Forum
    Icon for Honored Contributor rankHonored Contributor
    9 years ago

    --- Quote Start ---

    I'm not clear about your problem.

    If you have the decimated output, you have the I/Q components, provided you have already multiplied your ADC signal in the mixer.

    Your ADC should go through Mixer, then through decimation process. IS it the correct order in your implementation?

    I guess that you mean you have no Mixer before decimation.

    --- Quote End ---

    Hi, I have a mixer before decimation. But at the output, I have it as a single digital output from which I need to find the I and Q phase components separately. I mean like "111100011101010100..." something like this. I need to decompose this output into I and Q components separately. How to do this in VHDL. Can you suggest me any way of finding this out. Thanks in advance.