The "safe" scaling factor introduced in
7ac54b10d3 is too low and dates back to
the beginning and the move from usrp1->uhd, but the modulator will
exceed +-1 so "proper" scaling leads to overflows. Let's just do what
osmotrx has been doing for many years...
Change-Id: I75a2eba1f7f7b81249c06ce3fc9dfeee08878cb9