User's Manual Part 2

Test Set Calibration – continued

MAY 2004 1X SC480 BTS Hardware Installation, Optimization/ATP, and FRU 6-69

PRELIMINARY

Prerequisites

S WinLMF computer serial port and test equipment are connected to the

GPIB box.

S Test equipment is turned on and has warmed up for at least 60

minutes.

S Test equipment has been selected in the WinLMF (Table 6-23 or

Table 6-24)

Follow the procedure in Table 6-25 to calibrate the test equipment.

Table 6-25: Procedure for Test Equipment Calibration

Step Action

1 From the Util menu, select Calibrate Test Equipment from the pull–down menu. A Directions

window is displayed.

2 Follow the directions provided.

3 Click on Continue to close the Directions window and start the calibration process. A status report

window is displayed.

4 Click on OK to close the status report window.

Calibrating Cables Overview

The WinLMF Cable Calibration function is used to measure the path

loss (in dB) for the TX and RX cables, adapters, directional couplers,

and attenuators that make up the cable configurations used for testing. A

communications system analyzer is used to measure the loss of both the

TX test cable and the RX test cable configurations. WinLMF cable

calibration consists of the following processes:

1. Measure the loss of a short cable. This is done to compensate for any

measurement error of the communications system analyzer. The

short cable, which is used only for the calibration process, is

connected in series with both the TX and RX test cable

configurations when they are measured. The measured loss of the

short cable is deducted from the measured loss of the TX and RX

test cable configurations to determine the actual loss of the

configurations. This deduction is done so any error in the analyzer

measurement will be adjusted out of both the TX and RX

measurements.

2. Measure the loss of the short cable plus the RX test cable

configuration. The RX test cable configuration normally consists

only of a coax cable with type–N connectors that is long enough to

reach from the BTS RX connector to the test equipment. When the

BTS antenna connectors carry duplexed TX and RX signals, a

directional coupler and, if required by BTS type, an additional

attenuator are also required for the RX test cable configuration.

These additional items must be included in the path loss

measurement.