R&S ESCI Analyzer - Traces
1166.6004.12 4.105 E-1
AVERAGE
The AVERAGE softkey activates the trace averaging function. The average is
formed over several sweeps. Averaging can be performed with any of the
detectors available. If the detector is automatically selected by R&S ESCI, the
sample detector is used.
Depending on the setting of AVG MODE LOG / LIN, the logarithmic level
values or the measured power/voltage values are averaged.
Averaging is restarted every time the AVERAGE softkey is pressed. The
trace memory is always cleared.
IEC/IEEE-bus command DISP:WIND:TRAC:MODE AVER
Description of averaging
Averaging is carried out over the pixels derived from the measurement samples. Several measured
values may be combined in a pixel. This means that with linear level display the average is formed over
linear amplitude values and with logarithmic level display over levels. For this reason the trace must be
measured again when changing between LIN and LOG display mode. The settings CONT/SINGLE
SWEEP and running averaging apply to the average display analogously.
There are two methods for calculating the average. For a sweep count = 0 , a running average is
calculated according to the following formula:
TRACE
9* TRACE meas. value
10
=
+
Due to the weighting between the new measured value and the trace average, past values have
practically no influence on the displayed trace after about ten sweeps. With this setting, signal noise is
effectively reduced without need for restarting the averaging process after a change of the signal.
If the sweep count is >1, averaging takes place over the selected number of sweeps. In this case the
displayed trace is determined during averaging according to the following formula:
Trace
1
n
(T ) meas
ni n
i1
n1
=+
=
−
∑
.value
where n is the number of the current sweep (n = 2 ... SWEEP COUNT). No averaging is carried out for
the first sweep but the measured value is stored in the trace memory. With increasing n, the displayed
trace is increasingly smoothed since there are more single sweeps for averaging.
After the selected number of sweeps the average trace is saved in the trace memory. Until this number
of sweeps is reached, a preliminary average is displayed.
After completion of averaging, ie when the averaging length defined by SWEEP COUNT is attained, a
running averaging is continued with CONTINUOUS SWEEP according to the following formula:
where Trace = new trace
Trace
old
= old trace
N = SWEEP COUNT
The display "Sweep N of N" does not change any more until a new start is triggered.
In the SINGLE SWEEP mode, the number of sweeps is triggered with SWEEP START. The sweeps are
stopped when the selected number of sweeps is attained. The number of the current sweep and the
total number of sweeps are shown on the display: "Sweep 3 of 200".
Trace
(N 1) Trace meas
N
old
=
−⋅ + .value
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