Agilent Technologies E4406A, User Manual

Page: 85 / 230

Chapter 4 85
Making Measurements
Preparing for Measurements
accurate results. There will be an increase in the time taken to make
a measurement if the number of averages is increased.
• Avg Mode - Selects between an
Exp
(exponential) or a
Repeat
mode
of averaging. This selection only affects the averaging after the
number of N averages is reached (set using
Avg Number
). Normal
(linear) averaging is always used until the specified number of N
averages is reached. When
Measure
is set to Single, data acquisitions
are stopped when the number of averages is reached. Therefore
Avg
Mode
has no effect on single measurements.
Exponential averaging: When
Measure
is set at Cont (continuous)
data acquisitions will continue indefinitely. After N averages,
exponential averaging is used with a weighting factor of N (the
displayed average count stops at N). Exponential averaging
weights new data more than old data, which facilitates tracking
of slow-changing signals. The value of N is set through use of the
Average
key or the Avg Bursts key.
Repeat averaging: When
Measure
is set at Cont, data acquisitions
will continue indefinitely. After N averages is reached, all
previous result data is cleared and the average count is set back
to 1. This is equivalent to pressing
Measure
,
Single
and then
pressing the
Restart
key each time the single measurement
finishes.
• Avg Type - Allows you to select type of averaging. Only the types of
averaging that are appropriate for the current measurement are
available in that measurement. The following average types are
available:
Pwr Avg - Averages the power, which is equivalent to the rms of
the voltage. This is the default type of averaging.
Log-Pwr Avg - The log of the power is averaged. This is also
known as video averaging.
Voltage Avg - The voltage is averaged.
Maximum - The maximum values are retained.
Minimum - The minimum values are retained.
Trigger Source
Changing the
Trig Source
alters the trigger source for the current
measurement only. Not all of the selections are available for all
measurements. Note that the
RF Burst
,
Video
,
Ext Front
, and
Ext Rear
menu keys found in the
Trigger
menu enable you to change settings to
modify the delay, level, and slope for each of these trigger sources (as
described on
page 79 . Choose one of the following trigger sources:
• Free Run - Triggers at the time the data is requested, completely
asynchronous to the RF or IF signals.