HP 8901B Operation And Calibration Manual page 276

Model
8901B
Operation
Peak Hold Mode
When the peak hold mode is selected, the limited rise time of the peak detector circuitry can cause a
slight measurement error for narrow, one-time modulation transients.
T o
prevent this error, repeat the
peak-generating process several times while leaving the peak hold mode active.
If PEAK HOLD is selected while the average or true
rms detector mode
is active, the detector will
switch to the peak detector mode previously selected. If PEAK HOLD is selected while the peak-average
(PEAKf/2) mode is active, the detector reverts to PEAK+ with PEAK HOLD.
HP-IB
In remote operation, new peak-hold cycles can only be initiated by code
D3.
Thus, if the instrument
is in HP-IB Hold mode (code Tl), issue code
D 3
to initiate a peak-hold cycle. Although the display
cannot be updated when in HP-IB Hold, the peak is captured, stored and updated. Upon leaving
HP-IB hold via the triggering codes
(T2
or
T3),
the data output represents the greatest peak captured
since the peak-hold cycle was initiated.
Audio Detectors 3-175