The WGN outputs very accurate, high quality white Gaussian noise. The output level can be set as Noise Density or Noise Power in a selectable bandwidth. Factory calibration over the entire frequency range yields 0.25 dB absolute accuracy. The noise power can be varied with 0.015 dB resolution over a 60 dB range. A user-supplied signal can be injected into the instrument to combine with the noise. The instrument utilises dBm's proprietary microprocessor controlled attenuator with 0.015 dB resolution, providing an extremely accurate output.