Conditioning The Test Set For Call Processing - HP 8920A User Manual

Conditioning the Test Set for Call Processing

Using the CALL CONTROL Screen to Test Call Processing Functions
Perform the following steps when first entering the Call Processing Subsystem
(that is, the first time the CALL CONTROL screen is selected during a
measurement session).
1. Zero the RF Power Meter.
Select the RF GEN from the To Screen menu.
a. Set the Amplitude field to off (use the ON/OFF key). This prevent cross-cou-
pling into the power detector while zeroing the power meter.
b. Select CALL CNTL from the To Screen menu.
c. Select CALL CNFG from the To Screen menu.
d. Disconnect any cables from the RF IN/OUT port on the front panel of the Test Set.
e. Select the TX Pwr Zero field.
f. Select the RF Gen from the To Screen menu.
g. Set the Amplitude field to On.
There are two reasons for zeroing the RF power meter:
• When any Call Processing Subsystem screen is displayed (except the ANALOG
MEAS screen) and the Call Processing Subsystem is in the connected state (Con-
nect annunciator is lit), the Test Set constantly monitors the mobile station's trans-
mitted carrier power. If the power falls below 0.0005 Watts, the error message RF
Power Loss indicates loss of Voice Channel will be displayed
and the Test Set will terminate the call and return to the active state. Zeroing the
power meter cancels any inherent dc offsets that may be present within the power
meter under zero-power conditions. This ensures that the Test Set makes the correct
decisions regarding the presence of the mobile stations's RF carrier.
• Zeroing the power meter establishes a 0.0000 W reference for measuring the mobile
station's RF power at the RF IN/OUT port. This ensures the most accurate RF pow-
er measurements of the mobile station's RF carrier at different power levels.
Chapter 6, Call Processing Subsystem
141