The received baseband samples as an array of complex, double-precision floating-point data. The real and imaginary parts of this complex data array correspond to the in-phase (I) and quadrature-phase (Q) data, respectively. Because the USRP is not a calibrated device, the units returned by data do not correspond to volts or dB. The Power Spectrum node used in many of the example nodes returns the magnitude spectrum in Vrms^2 or dB relative to 1 Vrms/1 _. If you set the Power Spectrum input to return the spectrum in Vrms^2, you can convert Vrms^2 to volts.