Stepped FFT measurements in Scalar mode
The 89400 series analyzers use FFT technology to provide enhanced wideband
measurements. Technological advances in designing analog-to-digital converters
and digital signal processors have been combined with FFT technology to provide
the same results as a swept-tuned analyzer but with additional capability. The
nearby diagrams reflect the differences between swept-tuned technology and
stepped FFT technology.
If you are familiar with swept-tuned analyzers for making high frequency
measurements you will find that the technology used in the 89400 series analyzers
has expanded the capability to make FFT measurements with excellent resolution
at higher frequency ranges. This has been accomplished by translating the highest
frequencies to a lower band, then performing FFTs on separate segments of the
spectrum. These segments are displayed contiguously so that the result appears as
it would with a swept-tuned spectrum analyzer.
If you have previously used FFT Dynamic Signal Analyzers, you will discover that
with the 89400 series analyzers you can select spans and resolution bandwidths
which have previously been unavailable in FFT analyzers.
For low resolution bandwidths, the stepped technology in the 89400 series
analyzers is much faster than swept-tuned analyzers. For each local oscillator step
in a swept-tuned analyzer, time is required for the IF filters to settle on each input
signal. With stepped technology, the largest time constraint is the time required to
collect the data and perform the FFT. This results in speeds up to 1000 times faster
with the new stepped technology.
What Makes this Analyzer Different?
18 - 9
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