Operation Model 8642A/B
Amplitude Sweep (cont'd)
HP-IB
Keys
START AMPTD
STOP AMPTD
SWEEP TIME
AUTO
MANUAL
SINGLE
OFF ON
Codes
AA
AB
ST
AASA
AASM
AASG
AAOF,
ABOF
AAON,
ABON
Keys
dBm
V
mV
MV
s
ms
EMF
SPCL
Codes
DM or DB
VL
MV
UV
SC
MS
EMON,
EMOF
SP
Comments Sweep Time Is Common to All Sweeps
Sweep time is common to amplitude sweep and frequency sweep. If sweep time is not
specified, the Signal Generator assumes the value last selected for either amplitude or
frequency sweep. If this last-selected sweep time value is below the minimum setting
allowed under current conditions, the message "SWEEP TIME ADJUSTED .C21" is
displayed and sweep time is automatically set to the minimum allowed setting.
Changing End-Point Values During the Sweep
During auto or single sweep, the Knob, Step keys, and Data keys can be used to change
the start and stop end-points and sweep time values. During manual sweep, the Knob
and Step keys can only be used to perform the manual sweep.
HP-IB. How to Manually Sweep
In the manual sweep mode, HP-IB codes "UP" and "DN" can be used to step manually
by one step (each time the code is sent). Knob rotation is not possible via HP-IB.
How to Tell if the Start and Stop Amplitude Entries Are Accepted
If the amplitude values entered are accepted, both values will appear in the display.
If the amplitude values entered are not accepted, a message will either be queued up or
displayed to direct you to the entry error.
Modulation Types Not Possible During Amplitude Sweep
AM and pulse modulation are not possible during amplitude sweep.
Limitations on Display Resolution When Manually Sweeping in Volts Units
During manual sweep, when the end-points are set in volts, it may seem like the Signal
Generator is not reaching the selected end-points. Also, when Linear Amplitude
Sweep (Special Function 122) is selected with a sweep set in volts, the display may
seem to change more coarsely than the actual output is changing. The display operates
in these ways because the displayed value is always rounded internally in 0.1 dB units
and then converted to volts.
Converting Amplitude Units
Refer to Amplitude Units Conversion on page 3-205 for information about changing
amplitude values from one unit to another.
Zero Span for Amplitude Sweep
To calculate the number of X-axis steps automatically selected for zero span, refer to
calculation #1 on page 3-86. To calculate a sweep time that could be selected for a
desired number of X-axis steps, refer to calculation #3 on page 3-87. The maximum
number of X-axis steps is 1023 (or 1024 points).
3-92
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