Searching for a Bandwidth
The analyzer can automatically calculate and display the -3
dB
bandwidth (BW:), center
frequency (CENT:), Q, and loss of the device under test at the center frequency. (Q stands for
“quality factor,”
defined
as the ratio of a circuit’s resonant frequency to its bandwidth.) These
values are shown in the marker data readout.
1. Press
m
and turn the front panel knob, or enter a value from the front panel keypad to
place the marker at the center of the filter passband.
.,..,;
:
,,
,.
::
..%..
.i/.
,..
3.
Press
~:~~~~~
(
MarkerF
ctn)
‘~~~~~~~
to access the marker search menu.
*
..*..
,/
,,,,.,...........,
s
. . . . .
,......,,,,...
.::
:..
:::...
. . .
..i.
~..:........;../
3.
Press
~%&XRl&fl!&
to calculate the center stimulus value, bandwidth, and the Q of a
T.
.i
.:
:
,.,........ . . . . . . . .
i
/.i
..i
i ‘,,
bandpass
or band reject shape on the measurement trace.
4. If you want to change the amplitude value (default is -3
dl3)
that defines the
passband
or
“’
_
i
rejectband,
press
~~~~~~~.
and
enter
tie
new
value
from
*e
front
panel
keypad*
i................../
.:::::..
........................i
Figure
Z-27.
Example of Searching for a Bandwidth Using
Markers
Tracking
the Amplitude that You Are Searching
1. Set up an amplitude search by following one of the previous procedures in
“To
Search for a
Specific Amplitude.
n
“::IxE:5~~~~
.‘?g
.:Fj.::<~/:.::
. . . . .
.:t
:<::.
..c,:;,
:e,
:.~
.~.,.~.~.~.~,~,~,~,~,~
;,.,;...
,..
.,
2.
Press
(MarkerFctn)
~~~~~~~~
,~~~~~~~~~~
to track the specified amplitude
search
:.i..:::
.
..A
.;::..::::
:...........
.A..
.a:
. . . . . . . . . . . .
ii
>u..;..>
..A..
.;:
. . . . . . .
.:.::..:
.__.
v~::..:::
,...
.
.li
. .
..A
..L
..i
. . . . .
.A....
.~;;...~..~::.:::..:..l.i
:..
with every new trace and put the active marker
on that
point.
When tracking is not activated, the analyzer
IInds
the specified amplitude on the current
sweep and the marker remains at same stimulus value, regardless of changes in the trace
response value with subsequent sweeps.
Making Measurements 236
To Next Page
Loading...
