Data
Processing
Figure A
-2. Data Processing for Network Measurement
Digital Filter
The
digital lter detects the IF signal by performing a discrete F
ourier transform (DFT) on the
digital data.
The samples are converted into complex number pairs (real plus imaginary
, R+jI)
that represent
both the magnitude and phase of the IF signal. The lter shape can be altered
by selecting the IF bandwidth in Hz from the 10, 30, 100,
300, 1 k, 3 k, 10 k, and 40 k choices
.
Changing the lter shape is a highly eective technique for noise reduction.
Ratio Calculations
These calculations are performed if the selected measurement is a ratio of two inputs (for
example, A/R or B/R). This is simply a complex divide operation. If the selected measurement is
absolute (for example, A or B), no operation is performed. The R, A, and B values are also split
into channel data at this point.
A-4 Basic Measurement Theory
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