The PIM Master User Guide describes the connection and operation of the PIM Master and also the PIM Analyzer and Distance‑to‑PIM Analyzer modes that are associated with supported Anritsu handheld instruments.
This chapter provides a general overview of PIM analysis and the Anritsu PIM Master. It also includes instructions on care and user maintenance, describes frequency range pairs, illustrates a typical PIM analysis setup, and reviews updating the PIM Master firmware.
PIM Analyzer provides an instrument overview, parameter setup, and connection setup for PIM analysis. It also includes a comprehensive review of the menus that are available in the PIM Analyzer mode on Anritsu handheld instruments.
Distance‑to‑PIM™ (DTP) provides an instrument overview, parameter setup, and connection setup for Distance‑to‑PIM analysis. It also includes a comprehensive review of the menus that are available in the Distance‑to‑PIM Analyzer mode on Anritsu handheld instruments.
Programming Commands lists available SCPI commands for remote setup of the PIM Master and PIM Analyzer mode through the remote control of the Anritsu handheld product.
Images of measurement results and display screens that are shown in this manual are typical examples. Images on your instrument may differ.
Why Test for PIM?
Lack of linearity can limit the receive sensitivity of a cellular system. This limits the reliability, data rate, capacity, coverage, and return on investment of the system. The PIM test is an excellent indicator of linearity and construction quality.
PIM results from two or more strong RF signals mixing in a non‑linear device. These non‑linear devices, or junctions, occur in improperly tightened, damaged, or corroded connectors or in damaged antennas. Rusty components, such as mounts and bolts, are also suspect when hunting for sources of PIM.
Many common frequency combinations can produce PIM in a cell receive band. PIM signals in the cell receive band will:
• Raise the receive noise floor
• Increase the bit error rate
• Decrease the coverage area
• Cause early handoff
• Increase dropped calls
• Increase early termination
• Require the mobiles in the cell to increase Tx power (increase battery drain)
Avoiding PIM begins with quality construction methods. Increasing capacity, new services, and aging infrastructure, however, are all working against this strategy, and PIM testing is becoming more important every day.
Proper care and maintenance of connectors is essential to keeping PIM low. Inspection and cleaning is a central part of good performance. Proper torque is important, because the seals and interface areas are designed for this pressure.
PIM testing is becoming more important as cellular systems age and as the carrier count is increased. A test that was not as important when cellular systems were lightly loaded is becoming a critical part of modern cellular maintenance.
A cell site that is constructed with PIM in mind will cost less to maintain over time. This same site will show cleaner performance than similar sites that were not PIM tested.