It's all about the Software

I see a strong carrier with no antenna connected to the center of the span. How can I get rid of this?
thanks

What happens when you add an antenna and increase the gain?

(Hint, that center screen spur is a feature of all SDRs to one degree or another. It is a sign of two things. First, it is a sign of mismatches in dual A/D converter systems if the pip is large. Even single A/D converter systems will show very subtle timing (phase) and amplitude errors on samples that are supposed to be quadrature timed. This would be due to silly things like "ground isn't ground". A ground plane has different potentials at different places on it. That allows stray signal coupling. This spur will be present but small. Second, that spur is essentially the local oscillator mixing with itself to give a "DC" signal. That DC signal also includes all the oscillator noise. This should be small; but, it will be present. Ask yourself what adding an antenna and adjusting gain distributions if available will do.)

{^_-}

I changed the default resolution to 8-bit and the problem was solved. I went back to 24 bit and the problem did not occur again. Thanks for your feedback.