Appendix 3-Determining Cable Connection Losses; External Power Meter Method; Using The Agilent 8924C Test Set - Agilent Technologies 8924C Product Notes

Appendix 3—Determining Cable Connection
Losses
In order to obtain accurate power measurements a
few steps need to be taken. First, always calibrate
the channel power on the test set when you have
powered down the test set or if significant changes
have been made to the configuration of the test set
(channel changes, cellular to PCS operation, and so
forth).
Second, you must account for losses that have
occurred through the transmission medium
between the connected devices. Since you are
using a power splitter and two cables, these losses
need to be taken out of the power transmission
process. The test set allows you to enter an RF
level offset. The test set transmits its signal at a
level above or below the entered sector power,
depending on the sign (+ or –) of the attenuation
entered into the RF Level Offset field. (Refer to
Section 6—Setting Up a 20 dB Increment on the
Test Set; and Section 7—Determining Test Set
Trigger Time Delay.)

External Power Meter Method

In order to determine the attenuation of the power
splitter and the two cables, an external power
meter can be used. Listed below are the steps you
need to take to find your RF power compensation:
1. Zero the power meter.
2. Connect the power meter directly to the test
set's DUPLEX OUT port; or, the PCS interface's
RF OUT Only port.
3. On the CONFIGURE screen:
3a. Set RF Level Offset field to Off.
3b. Set the Output Port field to Duplex for cellu-
lar band, or only for PCS.
4. Go to the CDMA CALL CONTROL screen:
4a. If no PCS interface is used, set Sctr A Pwr
field to dBm.
4b. If a PCS interface is used, set to –11 dBm.
5. With the power meter, measure the power out
of the test set.
6. Connect the cables and splitter to the DUPLEX
port, or RF OUT Only for the PCS interface.
Include every connection from the test set up
to but not including the cellular phone. This
includes a car kit or break out box if used.
7. With the power meter, measure the power at
the end of the cables and splitter.
8. Subtract the second measurement from the
first to obtain your RF level offset.

Using the Agilent 8924C Test Set

To determine the attenuation of the power splitter
and the cables, the test set can be used. Refer to
"Determining RF Path Loss" in Chapter 1 of the
Agilent Technologies 8924C Application Guide,
pub. number 08924-90021.
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