Frequency Selection; Lo Frequency Accuracy And Stability - Agilent Technologies 8719D User Manual

Filtering is required in both ilxed and broadband measurements, but you can implement it more
easily in the fixed situation. Therefore, when configuring broad-band (swept) measurements,
you may need to trade some measurement bandwidth for the ability to more selectively illter
signals entering analyzer's receiver.
the

Frequency Selection

By choosing test frequencies (frequency list mode), you can reduce the effect of spurious
responses on measurements by avoiding frequencies that produce IF signal path distortion.
LO F'requency Accuracy and Stability
The analyzer source is phaselocked to its receiver through a reference loop. In the frequency
offset mode, the mixer under test is inserted in this loop. To ensure that the analyzer
phaselocks correctly, it is important that you use an Lo source that has frequency accuracy
better than fl MHz and residual FM < 20 kHz RMS.
Up-Conversion and Down-Conversion De&&ion
determines which direction the internal source must sweep in order to achieve the requested
IF frequency. For example, to measure the lower sideband of a mixer, where the RF signal
is below the Lo (RF < Lo), the internal source must sweep backwards, See the examples in
Figure 6-90.
Figure 6-90. Examples
E x a m p l e
of Up Converters and Down Converters
w i t h
o f