Agilent Technologies 83236B, Operating Manual, Page: 73 / 164

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Chapter 3, Programming the PCS Interface using GPIB Control
Overview of Programming Issues
Temperature
Compensations
Power measurement accuracy and signal level accuracy in the PCS Interface are
affected by temperature. The PCS Interface has an internal temperature sensor
which is used during compensations which are necessary to ensure that the
accuracy specified is achieved. Temperature compensations, which use a
temperature sensor in the PCS Interface, are used to re-calibrate the PCS Interface
when the temperature variations exceed an acceptable value. Default temperature
changes are 1°C. This default value is required to maintain the performance
specifications shown in chapter 5, "Specifications".
The two compensations
1. DC offset temperature compensation
This compensation procedure removes the dc drift of the power detector to provide
accurate power measurements of signal levels less than 0 dBm. During this procedure
the UUT connected to the PCS Interface’s RF IN/OUT port is disconnected from the
analyzer path so the zero power condition can be measured. This process updates the
dc drift compensation factor used in power measurements.
Before making a transmitter power measurement, the dc offset temperature
compensation should be performed using a single GPIB command.
Since the UUT is internally disconnected from the Test Set during dc offset
compensation, it should be performed before an active traffic/voice channel link is
established if over-the-air protocol is used. Otherwise, the active call may be dropped.
NOTE: Over-the-air protocol - The Test Set can essentially simulate a cellular base station and
use over-the-air protocol to establish and maintain an active voice/traffic channel. This
protocol can be used with a subscriber unit UUT connected to the Test System.