TBS 5925 Maximum SNR at 20db?

[mcelliotg2]

Hi everyone, a quick question!
What is the maximum SNR that can be shown using TBS 5925? I have the card running on my Enigma2 receiver and I see that the reading stops at 20db while on my windows PC it can go above 22db on the same frequency! So why is there a limitation on db for Enigma2 or is it something else involved? Theoritically there should be no max reading in db!