On Mon, Apr 19, 2021 at 11:09 AM Alberto <alberto_gnura...@libero.it> wrote:
> Why a second peak at 2 KHz with same amplitude of 1KHz ? > GNU Radio is designed for working with IQ / complex signals. You are seeing the *symmetric* spectrum that results from treating a real-valued signal as a complex one with a zero quadrature (imaginary) component. The second peak is the mirror image of the first. It is offset on the scale to 2 kHz because you have specified a nonzero center frequency, which offsets the frequency numbers on the scale but does not change the actual data processing.
