Before testing for PIM, ensure that line sweeping has been performed so that you can be confident that the insertion loss and return loss data are at acceptable levels. These results ensure that the PIM test signals actually reach all components at the correct signal level, and therefore offer the most accurate indication of true PIM performance.
Typically, a PIM versus Time test is used to certify PIM performance. Anritsu recommends that you perform a Noise Floor measurement before you begin PIM testing. Refer to PIM versus Time and Noise Floor Measurements for setup and measurement procedures.
The Noise Floor measurement reveals external signals from mobile subscribers that might interfere with your PIM measurement. If high interference is found, then adjust your F1 or F2 test signals. This will shift the IM3 frequency and may provide you with a clear IM3 frequency for the PIM versus Time measurement. See Figure: PCS Band PIM Testing.
After the IM3 frequency has been verified to be clear of interference, perform a PIM versus Time measurement to search for any static PIM sources.
If static PIM sources are found that exceed the pass / fail criteria, then use Distance‑to‑PIM (DTP) to locate and eliminate these static PIM sources. If DTP identifies multiple PIM sources, then correct the largest magnitude fault and repeat the DTP measurement. Repeat this process until magnitudes of all reported PIM faults appear acceptable.
Return to PIM vs. Time and perform a dynamic PIM test to verify that all RF connections and components are robust. A dynamic PIM test involves lightly tapping on all RF connections and components in the system while measuring PIM versus Time. If the peak PIM observed during the dynamic test is below the customer's pass/fail threshold, then save the measurement.
A PIM Master equipped with Option 331 is able to perform all site PIM tests and Sweep tests using a single instrument.
