Agilent Technologies 4395A - Data Processing; Network Analyzer Basic

Data
Processing
Data Processing
Overview
The
4395A
's receiver
converts the
R, A,
and B
input signals
into useful
measurement
information.
This
conversion
occurs
in
two
main steps
. First,
the high
frequency input
signal
is
translated
to
xed
low
frequency
IF
signals using
analog mixing
techniques (see
the \Theory
of
Operation"
in
the
Service
Manual
for
details). Second,
the IF
signals are
converted into
digital
data
by
an analog-to-digital
converter (
adc ).
From this
point
on,
all
further
signal
processing
is
performed
mathematically by
the analyzer
microprocessor and
digital signal
processor
.
The
following
paragraphs
describe the
sequence of
math operations
and the
resulting
data
arrays
as
the
information ows
from the
ADC to
the display
.
They
provide
a
good
foundation
for
understanding
most
of
the
measurement functions
and the
order in
which
they
are
performed.
The 4395A
has three
data processing
ow
paths:
one
is
for
network
analyzer
mode
,
another
for spectrum
analyzer mode
,and
the
other
is
for
impedance
analyzer
mode
.
The
data
ow
is
automatically
changed
when analyzer
mode is
changed.
Figure
A
-2
,
Figure
A
-3
, and
Figure
A
-4
provide
data
processing
ow
diagrams
that
represent
the
ow
of
numerical
data
from
IF
detection
to display
.
The
data
passes
through
several
math
operations
(shown
as
single-line
boxes).
Most
of
these
operations
can
be selected
and controlled
through
the
front
panel
MEASUREMENT
block
menus
.
The
data
is also
stored in
data arrays
(shown
as
double-line
boxes).
These
arrays
are
places
in
the
ow
path
where the
data is
accessible
via
GPIB
or
using
the
internal
disk
drive
or
the
memory
disk.
Note
While
only
a
single
ow
path
is
shown,
two
identical
paths
are
available
that
correspond
to
channel
1
and
channel
2.
When the
channels
are
uncoupled,
each
channel
can
be
independently
controlled
so
that
the data
processing
operations
for
one
can
be
dierent
from
the
other
.
Data
Processing
for
Network
Measurement
Basic Measurement Theory A-3