Agilent Technologies 8960 Series Reference Manual page 487

The RF Interface module provides two identical RF Source path connections to the In/Out port of the
instrument. There is about 25 dB of isolation between the two source paths. There is about 35 dB of isolation
between the source paths and either receiver path. The RFIO module has nominally 23 dB of insertion loss in
the source path. A temperature sensing circuit facilitates compensation for path loss variation with
temperature.
The source signals can be looped back through the input signal path to cross-calibrate the Measurement
Downconverter and the Power Detector.
The sampled input power from the directional bridge can be amplified by as many as two 18 dB range
amplifiers and then can be directed to the fast detector or the thermal detector. The input power to the fast
detector is detected by a diode detector that is part of a feedback loop. The input to the thermal detector is
measured in a bridge using a pair of RMS thermal detectors in a feedback loop.
Signal Downconversion
The test set's downconversion receiver section has two downconversion modules; a Measurement
Downconversion Module for making measurements, and a Demodulation Downconversion Module for
maintaining the radio link.
Demodulation Downconverter Module The Demodulation Downconverter module is used as part of the
demodulation receiver that maintains the radio link.
Measurement Downconverter Module The Measurement Downconverter module provides high quality
(wide dynamic range, spurious free) signals to the Analog To Digital Converter module's measurement
sampler input.
The Measurement Downconverter module is designed for very high performance operation to ensure accurate
and repeatable measurement results. The Measurement Downconverter module contains two downconversion
stages, two local oscillators, and a logarithmic IF envelope detector . Both first and second LO synthesizers are
tunable. The first LO is used when tuning to the RF input frequency, and the second LO is used when setting
second IF frequency, which is fed to the measurement sampler on the Analog To Digital Converter module.
Link Subsystem
The Link Subsystem maintains the radio link for all CDMA formats. The Link Subsystem has two parts:
• Protocol Processor
• Optional Link Subsystem hardware
The Protocol Processor module is responsible for maintaining the radio link between the test set and the
mobile station under test. The primary tasks of the Protocol Processor module are:
• Generating the protocol messaging necessary for the forward channel and sending that protocol stream to the test set's RF
source for transmission to the mobile station
• Decoding the protocol messaging received from the mobile station under test on the reverse channel
• Computing measurement results which are associated with data bits contained within the mobile stations messaging, such
as bit error ratio and frame error rate.
S:\Hp8960\E1963A WCDMA\3.2 release\Reference Guide\Chapters\wcdma_gen_block_diagram.fm
Block Diagram
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