Publicité
®
3 - 8
OPERATING INSTRUCTIONS
PM 5135
3.4.6.2
External Start of a Sweep
Set start,
stop frequency and sweep
time
as
described
in
chapter
3 .4. 6. 1 .
Don't press the
switches CONT and TRIG.
Feed external signal
to the
input
socket
TRIGGER
at
the rear panel.
Amplitude:
Pulse
width
:
Frequency
:
>
1
Vpp,
max. ±50
V
DC
;::: 3
µs
max. 180 Hz
The negative going edge* of
the
signal starts the sweep.
During
running sweep the external
signal
is
ignored. Passing the sweep
tim
e
the
sweep
remains at the stop frequency.
The
next
negative going edge of the
signal
sets the sweep to the start
frequency
again
,
the
LED
lights
up. The following negative going edge starts
the
sweep anew
.
*
The positive going edge can also be selected for trigger
by
an
internal
jumper
.
External Signal
Vpp
fSTOP
~
Output frequency
fSTART
I
sweep time
sweep time
Instead of the external signal the sweep can also be started
by
a switch,
re
lay
contact, o
r
similar to ground, at the socket
TRIGGER.
Closing
the
contact
starts the sweep
res
p
.
resets
to the start frequency.
3.4 .6.3
Externa
l
Sweep
I
FM
Feed
external
signal
to
the input socket SWEEP
at
the rear.
Voltage: max. ±20
V
The output
frequency
can
be controlled within the
selected subrange
independent
of
the set
sweep
parameters.
1
Vpp corresponds to
1
frequency decade (sweep
width
/
deviation).
0
V corresponds to the
set
frequency
.
Example:
output
frequency:
external signal:
200 Hz (subrange Ill)
sine
3
Vpp, frequency 0.5
Hz
DC
offset
+O
.
5
V
results in
a frequency deviation
of
+
2
decades
and
- 1 decade
i.e.
20 kHz -
20 Hz
(+2 V)
(-1
V)
The frequency of the
external
signal determines
the rep
etition
frequency
(sweep time
/
modulation
frequency).
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