Tektronix 492 Operator's Handbook

As stated in the preceding CAUTION , too much power
can
cause signal
compression
or if
excessive
, it can
destroy the
1st
mixer .
Signals
greater
than -30
dBm or
-20
dBm in
MIN
NOISE mode ,
should be
attenuated by
the RF ATTENuator . Signals above the safe input level
(
+30
dBm )
must be
attenuated by
external
attenuators
.
Ensure that
the
frequency
range
of external
attenuators is
adequate
.
Signal
levels of -10 dBm
or more
( -28 dBm
Option 1 ,
for 1.7 to 1.8 GHz range , see Specifications ) may be
compressed .
This
may degrade
signal
reference
level
measurements and generate spurious responses .
RESOLUTION BANDWIDTH ,
FREQUENCY
SPAN , AND
SWEEP
TIME
Resolution is the ability of a spectrum analyzer to
display
discrete frequency
components within
a
frequen
cy
span .
This ability
is a
function
of the
analyzer
bandwidth ,
sweep
time
, frequency
span , and
incidental
FM
. Frequency
span and sweep
time are
normally
selected
to provide the minimum resolution bandwidth setting for a
particular
cw
signal .
Bandwidth
also has
an
effect on
noise
level . As the bandwidth decreases , signal - to - noise ratio or
sensitivity increases . Maximum sensitivity is therefore
attained at the narrow resolution bandwidth settings .
3-2
As
the
analyzer
sweep
rate
is
increased
, a
critical
rate is
reached
where
both sensitivity
and
resolution are
degrad
ed
.
Therefore ,
sweep time
for a
calibrated
display
is
dependent
on
resolution
bandwidth
and the
frequency
span .
In
spans
other
than
MAX
SPAN ,
frequency span
is
symmetrical
about
the
center
frequency . In
MAX
SPAN
the
display
represents the
full
frequency
range
of the
selected
band
. A
frequency
dot
above the
display
in
dicates the
location on
the
spectrum of
the
FREQUENCY
readout . The
frequency
span used
depends on the
application .
Wide
spans
are
normally
used to
monitor
a
frequency
spectrum
for
spurious signals
,
check
harmonic
content
, etc.
Narrow
spans
are
used to
identify
the
characteristics
around a
particular
signal , such
as
modulation side
bands ,
bandwidth , power
line related
distortion , etc. When wide spans are used , sweep rate on
non
-
store
displays is
usually
increased
to
eliminate
flicker . This
requires
wider resolution
bandwidths .
Narrow
spans ,
used to
observe
signal
phenomenons
, usually
call
for
narrow
resolution
bandwidths
and
therefore
slow
sweep
speeds
.
The 492 features microcomputer circuitry that selects
sweep
rate and
resolution
bandwidth
to correlate
with
the
selected
frequency
span .
When
both TIME /
DIV and
RESOLUTION are in the AUTO mode , the display is
492
Operator's
Handbook

Tektronix 492 Specifications

General

Brand	Tektronix
Model	492
Category	Measuring Instruments
Language	English