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Installation
Determining the Test Set to Site Equipment Connections
Chapter 2
37
Installation
Figure 2-8 Transmitter Output Path Simplified Diagram
If you are uncertain of the exact coupling factor, the Test Software contains a utility to
measure the coupling factor (see “TX Test Port Calibration Test” on page 77).
NOTE
If you are uncertain of the Specified Output Power for the transmitter at the Base
Station TX Antenna Port, the Test Software must measure the power to calculate the
coupling factor. This requires that you take the Base Station out of service to connect the
Test Set directly to the Base Station TX Antenna Port during the calibration routine.
One disadvantage to using the Base Station TX Test Port to make measurements is the
possibility that its coupler is malfunctioning and therefore will cause erroneous
measurements. If TX power measurements fail by a large amount, but you suspect the
actual transmitted power is correct, take the Base Station out of service and make
measurements directly at the Base Station TX Antenna Port to verify the failing
reading. If the Test Software is correctly configured, TX power measurements using the
Base Station TX Test Port and TX Antenna Port should not differ significantly.
Out-of-Service Testing Using the Base Station TX Antenna Port
Disconnecting a TX antenna feed line and connecting the Test Set to the Base Station TX
Antenna Port (see Figure 2-8) requires that you first take the Base Station out of service
(disable call processing and turn off all transmissions to that TX Antenna Port).
The Base Station may be taken out of service (and turned back on to make
measurements) in two ways:
1. Access the MSC using a PC and the BTS Laptop Utility program to control the Base
Station through its maintenance software.
2. Call the MSC and have switch personnel control the Base Station for you.
One benefit of testing directly at the Base Station TX Antenna Port is the confidence
that the measurement will reflect the true output power of the Base Station at the point
at which the antenna feed line connects to the Base Station. This verifies the operation
of the full transmission path inside the Base Station. It also provides an opportunity to
perform transmission line and antenna testing while the antenna is disconnected from
the Base Station.
Antenna
Directional
Coupler
Base Station
Linear
Amplifier
TX Test Port
TX Antenna Port
Coupling Factor is the loss through the
directional coupler to the TX Test port.