R&S®Power Viewer Plus Software Manual - Rohde & Schwarz

R&S Power Viewer PlusUncertainty Calculation5.2 Measurements at –50 dBmThis example calculates the absolute uncertainty for the R&S NRPZ11when used for measuring a CW signal at 2 GHz and at a very lowpower level of –50 dBm. The temperature shall be 30 ºC.All values marked with an arrow (►) are taken from the R&S NRPZxxPower Sensor Specifications that are available from theRohde & Schwarz website.Power level in W10 nW► Used path 1► Uncertainty for absolutepower measurements 0.081 dB► Zero offset after zeroing 104 pW 0.045 dB► Zero drift after zeroing 35 pW 0.0015 dB► Measurement noise65 pWMultiplier for 1.28 s integrationtime is sqrt(10.24s/T) x 2.8= 182 pW 0.078 dBTotal expanded uncertainty 0.12 dB2.8 %After zeroing, the absolute accuracy is 0.12 dB when using anintegration time of 1.28 s. This integration time can be achieved with anaverage filter count of 32 and a measurement window of 20 ms. Furtherimprovement of the uncertainty is possible by increasing the averagingfilter count.The total integration time is twice the aperture time multiplied by theaveraging filter count.Manual 18