Offset Freq; Port/Sweep - HP 8921A User Manual

Chapter 21, Spectrum Analyzer Screen
Field Descriptions

Offset Freq

Port/Sweep

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Frequency offset (RF Generator) sets the difference between the instantaneous
frequencies of the Tracking Generator and the center frequency of the Spectrum
Analyzer.
Operating Considerations
The offset can be a positive or negative value. When set to zero, the Tracking
Generator produces a sweeping signal that matches the Spectrum Analyzer's tune
frequency.
This control performs two functions:
• The upper field specifies the output port of the Tracking Generator.
• The lower field specifies whether the Tracking Generator sweeps from low-to-high fre-
quencies (Norm), or from high-to-low frequencies (Invert). (The Spectrum Analyzer
always sweeps from low to high frequencies.) The swept frequency range is determined
by the Span setting in the Spectrum Analyzer's Main Menu.
Operating Considerations
When using the Tracking Generator, if the output port is set
menu is set to
Input Port
the best isolation between the Tracking Generator and the Spectrum Analyzer, use
for the output, and
Dupl
For measurements on high-power devices, such as amplifiers, use the RF IN/OUT
port for the input.
, internal instrument coupling can occur. For
RF In
for the input.
Ant
, or the main
RF Out