Noise Floor Time View measurement displays the signal level that is received by the PIM Master at the IM product frequency as a function of time with TX1 and TX2 turned Off.

The Noise Floor Measurement in Figure: Typical Noise Floor (No External Interference, No Limit Line) shows no external interference. A good noise floor that will not interfere with a typical PIM test is below –120 dBm. After verifying that no interference is present, begin PIM testing. Note that units of dBc are not applicable to Noise Floor measurements.

 

In the example shown in Figure: Noise Floor Measurement with External Interference, external interference is seen that is higher than the –97 dBm PIM test limit. This external signal level would be high enough to prevent an accurate PIM test. The test frequencies must be changed to find an IM product frequency without external interference (see Figure: Typical Noise Floor Spectrum View Measurement).