HP 3562A Operating Manual page 301

nt:11t:1H;:H1{.;t;l
vnapter Jt:: - Uperalmg
(conI) to
AVG BACK SPACE
TM AVG ON OFF-switches between linear and power spectrum quantity averaging.
TIMED PRVIEW-displays the time records for approval before they are included in
B -activates trace B. See the SINGLE, UPPER LOWER and FRONT BACK keys to determine
where trace B is displayed for each olthese formats. The active trace and its annotation
are highlighted. Selection of the active trace is important because the markers, units,
coordinates, math operations, displays and scale affect only the active trace. This key
can also be used to return to a data trace display after a table has been displayed.
(
B
indicator
BA CK SPACE-moves the cursor one space back and deletes the last character or u nits
selection entered. BACK SPACE applies only during alphabetical and nurneric
entries requested by the instrument
12-12
For linear averaging (TM AVG ON), the averaged quantity is the time record.
For power spectrum quantity averaging (TM AVG OFF), the averaged
quantity is the power spectrum, frequency response or correlation,
depending on the measurement Table 12-1 summarizes the advantages
and disadvantages of the two types.
Table 12-1 Linear versus Power Spectrum Function Averaging
Power Spectrum Quantity
Applicable to both pure random and
mixed random/periodic signals
Does not improve SIN ratio
Does not require a synchronized
trigger
the measurement When each time record is displayed, the measurement
pauses for a specified amount of time for you to approve or reject the record
by pressing YES or NO. Any records you do not reject are automatically
accepted at the end of the preview interval.
Press TIMED PRVIEW, then enter the pause in seconds. Timed preview­
ing is deactivated by pressing PRVIEW OFF. When using this feature over
the HP-IB, "ACPT" must be used in place of YES, and "REJT" must be
used in place of NO. Previewing cannot be used with time throughput
)
-this LED indicates when trace B is active.
Linear
Signal must have periodic component
Improves SIN ratio (random compo­
nents average to their mean values
Requires a synchronized trigger in
fixed relation to the signal