Product Card

Cable Calibr ation Chapter 3: LMF Oper ation

Cable Calibration

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Calibrating Cables Overview

The cable calibration function measures the loss (in dB) for the TX and RX cables that are to be

used for testing. A CDMA analyzer is used to measure the loss of each cable conﬁguration (TX

cable conﬁguration and RX cable conﬁguration). The cable calibration consists of the following:

• Measuring the loss of a short cable – This is required to compensate for any

measurement error of the analyzer . The short cable (used only for the calibration process)

is used in series with both the TX and RX cable conﬁguration when measuring. The

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

cable conﬁguration to determine the actual loss of the TX and RX cable conﬁgurations.

The result is then adjusted out of both the TX and RX measurements to compensate for

the measured loss.

• Measuring the short cable plus the RX cable conﬁguration loss – The RX cable

conﬁguration normally consists only of a coax cable with type -N connectors that is long

enough to reach from the BTS RX port of the test equipment. Refer to Figure 3 -31 ,

Figure 3 -32 , Figure 3 -33 , or Figure 3 -34 for speciﬁc cable and connection requirements for

each type of communications system analyzer .

• Measuring the short cable plus the TX cable conﬁguration loss – The TX cable

conﬁguration normally consists of two coax cables with type N connectors and a directional

coupler , a load, and an additional attenuator (if required by the speciﬁed BTS). The total

loss of the path loss of the TX cable conﬁguration must be as required for the BTS (normally

30 or 50 dB). Refer to Figure 3 -31 , Figure 3 -32 , Figure 3 -33 , or Figure 3 -34 for speciﬁc

cable and connection requirements for each type of communications system analyzer .

Cable Calibration Set–up Diagrams

Figure 3 -31 and Figure 3 -32 show the cable calibration set–up for various supported test sets.

The left side of the diagram depicts the location of the input and output connectors of each test

equipment item, and the right side details the set up for each test.

Calibrate Test Cabling using Communications System Analyzer

Cable Calibration is used to calibrate both TX and RX test cables.

3 -64 68P09283A63 -5

FOA A UG 2007