How to center the bandwidth for carrier frequency?

[IKnowNada]

I have a baseband signal in IQ form. I have a method to calculate the carrier offset and estimate the carrier bin. I want to center the carrier to the middle of the bandwidth. How do I do so? Do I simply multiply the IQ data by the exponential with the carrier offset, but doesn't that shift the carrier frequency to bin 1?

 

[Baluncore]

Sorry about the delay.

I have a baseband signal in IQ form. I have a method to calculate the carrier offset and estimate the carrier bin.

How can a baseband signal have a carrier? Is the “bin” one analysis frequency of many from a DFT?

I want to center the carrier to the middle of the bandwidth. How do I do so?

The base bandwidth or the RF bandwidth? Are you modulating or demodulating up or down converting frequency?
You can translate a frequency by multiplying by a sinewave from a local oscillator. That will give two sidebands either side of the LO frequency.
If the carrier is also an IQ signal you can reject the image frequency without needing a filter by doing two multiplies and an add or subtract.
https://www.electronics-notes.com/articles/radio/rf-mixer/image-rejection-mixer.php

 

[sophiecentaur]

How can a baseband signal have a carrier?

It depends on how you look at it but a Manchester Coded signal would normally be regarded as a baseband signal and yet it basically uses a clock that's at twice the data rate so the spectrum sits about a notional carrier. Manchester coding is a simple example of a coding system that has no DC component. Handy for passing through many kinds of transmission channel or recording system.