Forum Discussion

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

Inphase (I) and Quadrature (Q) components of signals

Hi All, How to calculate the Inphase (I) and Quadrature (Q) components of signals, such as RF signals? I would like to shift the RF signals to a specific baseband frequency and then derive the ...
Altera_Forum's avatar
Altera_Forum
Icon for Honored Contributor rankHonored Contributor
11 years ago

--- Quote Start ---

As shown in the slides, you can use a NCO at Fs/2 (1, -1, 1, -1, sequence) to flip sidebands, however, that would not apply in your case, since the signal would alias and be corrupted.

--- Quote End ---

Hi Dave,

Can you please explain more about why the signal would alias and be corrupted?

I am trying to replicate the example shown in Figure 36 of your document using "NCO megaCore 13.1 version" but every time I change the 'Desired Output Frequency' value, the Frequency Response plot never changed. I think the version 13.1 NCO has bugs. Have you tried version 13.1 Quartus? I noticed that you used version 12.1 sp1. I might need to use this version instead.

Many Thanks,

Lee