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H
52382-900A
Vol.
1
using
the
Display
keys.
When appropriate, readout
of
numerical keypad entries,
menu selections, prompts, warnings and error messages are also displayed.
The
''preset'^
mode
8.
A
feature which
Is
especially helpful
to
first time users
is
the
''preset'
mode.
When this
mode
is
selected certain keys
are
automatically
set
to
produce an 'initial' display.
These keys
are
identifiable
on
the front
panel;
they have green
lettering.
The
Instrument can however
be set
to
switch
on in any chosen setting according
to
operator preference.
This
is a
feature
of the
store/recall
mode.
The six mode horizontal scale
9.
The frequency scale
of the
display can
be
viewed
in
six different modes
-
full, per div.,
meter,
log,
zero span and FM
DEMOD*
The full span mode
Is
used
to
identify signals.
By
rotating
the REF FREQ
control
a
dashed vertical
line bn the
screen can
be
moved
to
locate
a
required spectral line
and the
frequency
of that
signal
is
then
displayed
at
the
bottom
of
the
graticule
area.
The
'per div.' mode can
be
used to 'zoom' Into that signal
for
a
more
detailed inspection.
It
can
be
displayed
at
the
centre,
at
the left
or at
the
right hand side of the screen
as
required.
When METER
is
selected
the
signal
is
displayed
at
the
centre
of the
screen
in the
form
of
a
vertical
bar-chart readout
10*
In
'log' mode,
frequency
Is
displayed on
a
logarithmic
scale.
One
to
seven decades are available ranging from
100 Hz to
1
GHz.
11.
The 'zero span' mode
is
used for
recovering
modulating signals
or real
time
monitoring
of
a
single signal
- for
settling
tiroes
etc.
In this
mode
the
analyzer acts
as
a
fixed tuned receiver with
selectable bandwldths.
Amplitude
demodulated signals can thereforefbe
displayed
on the screen against
a
time
axis.
The signals can also
be
heard by using
the integral
loudspeaker
or ly
plugging headphones into
a
connector
at the rear of the RF unit.
A
second
function
of
'zero span'
enables
FM
deviation
to be
displayed
and
measured
against
a
time axis in the same way.
12.
For ease
of
operation,
in
the 'auto' mode, filter bandwidth, sweep time
and video bandwidth are
set
automatically
to
give optimum
resolution
at
each
choice
of
frequency
span.
Span can
be varied from
a full 400
MHz down
to
100 Hz;
200 MHz
to 100 Hz in a
1,2,5
sequence.
Resolution bandwldths
are
available from
I
MHz down
to
3
Hz in a 1,3,10 sequence.
The
minimum bandwidth
3
Hz
filter with
a
shape factor
of less
than
11:1
ensures
that line related
sidebands may
be
resolved without being masked by
the
limitation
of the
filter.
Amplitude measurements
13.
High sensitivity
is
achieved
by careful r.f. and i.f.
amplifier design,
the
measurement range being from -150 dBm
to
+30 dBm with an accuracy
of
±1
dB
at
any frequency and
at
all levels.
The vertical scale
is
swltchable
in
1,2,5 steps from
10
dB/dlv.
(a 100
dB display)
down
to
0.5 dB/div. and
amplitudes
can be
resolved
to
0.01
dB.
14.
Facilities
ha'^e
been Included
to
measure
signal levels with respect
to
1
mW,
IV,
1
mV and
I
mV by
changing the vertical scale from
its
preset mode
of
dBm
to
dBV, dBmV, or dBgV.
In
addition relative measurements
in dB
can
be
July
85
Chap.
1
Page
5
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