Problem about the value of spectrum_sense's power

i have been studied usrp_spectrum_sense for a while and acquired some
achievements of spectrum sensing. But there is still a problem confused
me,that is the value of my output power spectrum. i use bluetooth signal
as my source signal because of its frequency range. i also look up the
specification of this bluetooth signal’s power, it’s about 20dBm.
However, my received signal from usrp value is large more than 20dBm,
it’s about 70dBm. i do not know what should i modify from Is it the gain control cause? i am now in trouble,any
help would be appreciate.