Chapter 5 127
Setting Measurement Conditions
Setting Measurement Accuracy, Stability, and Time
5. Setting Measurement
Conditions
A
n
= Sweep-to-sweep averaging result (vector value) at the measurement point when
the sweep count is “n.”
S
n
= Current measurement value (vector value) at the measurement point when the
sweep count is “n.”
F = Sweep-to-sweep averaging factor (entered with the
AVERAGING FACTOR key)
Perform the averaging factor setup as follows:
Step 1. Press the
[Bw/Avg] key to display the measurement bandwidth/averaging menu.
Step 2. Press the AVERAGING FACTOR key to display the current setting for the sweep-to-sweep
averaging in the parameter settings located in the upper left area of the screen.
Step 3. Use the keys or rotary knob of the ENTRY block in one of the following ways to specify a
value for the sweep-to-sweep averaging.
• Enter the desired value with the numeric keys (
[0] to [9], [.], and [-]) and then press the
unit key (
[G/n], [M/m], [k/m], or [´1]).
• Turn the rotary knob (m
mm
m) until the desired value is set.
• Press the step keys ([][¯]) to set the desired value.
NOTE The sweep-to-sweep averaging can be set to any natural number from 1 to 256. Setting the
sweep-to-sweep averaging to 1 is equivalent to turning the averaging OFF.
Step 4. Press the AVERAGING on OFF (or AVERAGING ON off) key to turn the sweep-to-sweep
averaging ON or OFF (pressing the key toggles your selection).
NOTE When the sweep-to-sweep averaging is turned ON, the character “Avg” is displayed in the
parameter settings located in the upper left area of the screen. Below the character is also
displayed the value of sweep-to-sweep averaging that has been performed for the trace.
The sweep-to-sweep averaging starts after turning it ON or pressing the
AVERAGING
RESTART
key. When the averaging starts, “0” is displayed for the averaging count because
the number of traces (sweep data) to be swept is always set to 0 at the initial state. Then the
count increases by 1 as each sweeping ends. After the count reaches the number specified
by the
AVERAGING FACTOR key, it stays constant while sweeping continues.
Averaging for each measurement point (point averaging)
Point averaging averages each data point by a user-specified averaging factor. The Agilent
4294A repeatedly measures the same point until the averaging factor is reached. It then
divides the vector summation of the measurement value by the averaging factor and starts
measuring the next point. The sweep time increases in proportion to the averaging factor.
The algorithm used for point averaging is shown in Equation 5-2.
Softkey label Sweep-to-sweep averaging
AVERAGING on OFF Off
AVERAGING ON off On
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