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I appreciate any help: I wanna convert IQ data to its RF data, representing an image. The centre frequency and sampling rate are available. What I do is:

First I do up-sampling in MATLAB by applying interpolation along the depth. So, the new data has a new sampling frequency higher than the first one.

My questions are:

  1. Do I need to do low-pass filtering before multiplying the data by the exponential term (that converts IQ to RF)?

  2. What is the exponential form that I need to multiply the IQ data by ( specifically, I am asking about the frequency or frequency ratio in the exponential term used to do the conversion, which I mentioned in the first question) Thanks

Could someone guide me through the detail one more time? I read the documentation I copy here and it is confusing for me: (Page 8 and afterwards)

http://folk.ntnu.no/htorp/Undervisning/TTK10/IQdemodulation.pdf

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    $\begingroup$ Could you try to ask a precise question? Asking for a complete guide is not really appropriate for the format of this platform (which is pretty strictly Q&A). $\endgroup$ – Marcus Müller Feb 20 at 21:33
  • $\begingroup$ @MarcusMüller: Sure, My questions are: 1) do I need to do low-pass filtering before multiplying the data by the exponential term (that converts IQ to RF)? 2) what is the exponential form that I need to multiply the IQ data by ( specifically, I am asking about the frequency or frequency ratio in the exponential term used to do the conversion, which I mentioned in first question) Thanks, $\endgroup$ – Jill Feb 25 at 16:25
  • $\begingroup$ hm, you're skipping steps if you're directly multiplying the IQ samples you get with a complex sinusoidal. Think about what the Nyquist bandwidth of these samples is! $\endgroup$ – Marcus Müller Feb 25 at 20:22

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