HP 3562A Operating Manual page 318

ENTRY GroUp-this group is used to make numeric entries requested by the instrument.
When the ENABLED indicator is on, the up/down arrows and the knob can be used to
modify the active entry. The keys in this group are not converted in the alpha mode,
and are used to add numbers and punctuation to alpha entries. The YES and
keys are used during previewing; refer to their descriptions for more information.
MARKER VALUE and BACK SPACE are also described individually in this chapter.
(
E X T SAMPLE I N connector
external sampling mode. This signal must be TTL-compatible and not greater than
256 kHz. Refer to the descriptions of the E SMPL ON OFF and SAMPLE FRED soft­
keys in the FRED menu for more inforrnation.
(
E X T TRIGGER
connector
enabled when EXT (in the AVG menu) is pressed and the EXT TRIGGER indicator is
illurninated. The rnaximurn voltage allowed at this input is
external trigger signal level must be at least 200 mVpk. The external trigger signal is
subject to the slope and level conditions; see SELECT TRIG for more information.
(
E X T TRIGGER
indicator
at the EXT TRIGGER input. When external triggering is active, any signal present at
this input is treated as the trigger signal.
FREQ-displays the frequency selection rnenus for all modes. These menus depend on the
rnode selected. All frequency selections must be rnade prior to starting the rneasure­
ment. The linear, log and time capture rnodes have predefined frequency spans
(these spans are a function of the FFT process). The swept sine spans are not pre­
defined.
CENTER FREO-used to select the center of the frequency span, using the Entry
group. In the linear resolution and tirne capture mode, CENTER FRED,
START FRED, and FRED SPAN are interrelated; changing one rnay affect
the other two. In the swept sine rnode, CENTER FRED, START FRED,
FRED SPAN and STOP FRED are interrelated; changing one affects one or
more of the others. It is easiestto use CENTER FRED and FRED SPAN as a
pair or START FRED and STOP FRED as a separate pair.
E SM PL ON OFF-selects external sampling and displays the SAM PLE FRED
soft key. External sarnpling allows you to synchronize the HP 3562A's
data acquisition rate to an external signal, such as a tachorneter pulse. See
SAMPLE FRED for rnore information.
If external sampling is active, you rnust provide a sampling signal to the rear
panel EXT SAMPLE IN connector and enter that frequency with SAMPLE
FRED.
)
-used to input sampling signals when the instrument is in
)
-used to connect an external trigger signal. This input is
)
--this LED indicates that an external trigger signal is expected
LOnapter l�-uperatlng Heterence
ENTRY Group to FREQ
NO
±
10 volts. Note that the
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