User's Manual

Nexus FT Commissioning
044-05251 Rev B 3-9
Passive Intermodulation (PIM) Testing
PIM is the non-linear effect of passive RF components in a desired RF transmission band. As higher per-
carrier transmit power levels are applied to duplexed passive RF networks, PIM becomes an increasingly
significant factor in potential receiver desensitization. A PIM tester may be used on the RF network prior to
turn-on and commissioning of the unit, but if a PIM tester is not available, the following may be used:
The following equipment is required to test for PIM:
❑ Anritsu Site eMaster or equivilent RF Spectrum Analyzer
❑ Agilent ESG4432B or equivilent Multi-Signal Generator (or commissioned BTS)
❑ Guarateed/calibrated PIM load capable of handling 20W composite power
❑ Low-PIM RF cable adaptors such as N-N female, Din male to N femaile, DIN-DIN, SMA-SMA
female, and N male to SMA female
❑ Installed and operational WRH unit
❑ Installed passive RF network under test
❑ Torque wrenches for DIN and N connectors
Two different types of setup are available, depeding on equipment availability and testing methods.
Figure 3-10 shows PIM testing with two carriers over one WRH, and Figure 3-11 shows PIM testing with one
carrier over each of two WRHs.
Figure 3-10 PIM testing two carriers and one WRH
Figure 3-11 PIM testing one carrier over each of two WRHs
The following PIM test uses the receive sensitivity and gain of the WRH under test to verify that the receive
p
ath is free of PIM n
oise. For PIM to be a problem at a particular site, TX signals must exist such that their
products fall into the RX band using the formulae:
3
rd
order product = (2 * f
1
) - f
2
and
3
rd
order product = (2 * f
2
) - f
1
WRH-V
E4432B
SIG Gen
(
or BTS
)
E4432B
SIG Gen
(or BTS)
Load /
DAS
Σ
OCM
E4402B
Spec. An.
WRH-V
Under Test
E4432B
Sig Gen /
BTS 1
Load /
DAS
OCM
E4402B
Spec. An.
WRH-V
Hybrid
OCM
E4432B
Sig Gen /
BTS 2