Noise Floor measurements test for receiver (Rx) interference sources that can affect a PIM measurement. In these measurements, transmit (Tx) power is Off, which allows you to check for external interference at the IM frequency being measured. The intermodulation distortion (IM) products of interest are in the same frequency range that is used by mobile equipment to communicate with the base station. Nearby mobiles can generate signals high enough to interfere with a PIM measurement.

The Noise Floor Time View measurement displays the signal level that is received by the MW82119B PIM Master at the IM product frequency as a function of time with TX1 and TX2 turned Off. The PIM Master is in PIM vs. Time analyzer mode during a Noise Floor - Time View measurement, but only the PIM Master receiver is being used. A typical noise floor Time View measurement is approximately –120 dBm, as shown in Figure: Typical Noise Floor (No External Interference, No Limit Line). Refer to Recommended PIM Testing Procedure.

The Noise Floor Spectrum View measurement displays the signal level that is received by the MW82119B over the current Rx band. Because the Spectrum View sweeps across a range of frequencies, you are likely to see bands that are free of mobile traffic and bands with significant mobile traffic. Marker 2 will automatically be set to the current IM product frequency. Other markers can be activated to identify frequencies that are free of traffic. A typical Noise Floor - Spectrum View measurement is shown in Figure: Typical Noise Floor Spectrum View Measurement.

Anritsu recommends that you make a Noise Floor measurement before making a PIM measurement in order to rule out external interference. If external interference is present, change the TX1, TX2, or both test frequencies in order to move the IM product frequency into clear spectrum.