LeCroy WaveRunner Xi series Operator's Manual page 130

W R X S
AVE UNNER I
S A
UMMED VERAGING
Summed Averaging is the repeated ad
stable trigger is available, the resulting a
record. Whenever the maximum number of swee
An even larger number of records can
other parameters must be left unchang
averaging by changing the trigger mod
you change the trigger mode back to N
You can reset the accumulated averag
parameter such as input gain, offset, co
current averaged waveforms of the fun
averaging is performed, the display is u
events per second).
C A
ONTINUOUS VERAGING
Continuous Averaging, the default setti
waveforms. It is particularly useful for r
most recently acquired waveform has m
is dominated by the statistical fluctuatio
in the continuous average gradually ten
weight increases.
The formula for continuous averaging is
new average = (new data + weight *
This is also the formula used to compute summe
weight that is assigned to the old avera
For example, for a sweeps (weight) val
st
1 sweep (no old average yet): new a
nd
2 sweep: new average = (new data +
rd
3 sweep: new average = (new data +
th
4 sweep: new average = (new data +
th
5 sweep: new average = (new data +
th
6 sweep: new average = (new data +
th
7 sweep: new average = (new data +
In this way, for sweeps > 4 the importa
Note: The number of sweeps used to compute the average will be displayed in the bottom line of the trace
descriptor label:
130
ERIES
diti on, with
verag e ha
ps is reached, t
be acc umu
ed or a ne
e from NO RM/AUTO to STOP.
OR M/AUT
e by push ing the
upli ng, tri gger c
ction , or it s zoom
pda ted at
ng, is t he r
edu cing no
ore w eig ht than
ns of th e most re
ds to zero
old ave rag
d averag
ge onc e th
ue of 4
:
verag e =
1*old average)/(1
2 * old average)/(2
3 * old av erage)/(3 + 1) = 1/4 new d
4 * old av erage)/(4
4 * o ld av erage)/(4 +
4 * old av erage)/(4 + 1
nce of the
equal weight, of successive source waveform records. If a
s a random noi se component lower than that of a single-shot
he averaging process stops.
lated simply by c hanging the number in the dialog. However, the
w averaging calculat ion will be started. You can pause the
The instrument resumes averaging when
O.
CLEAR SWEEPS button or by changing an acquisition
ondition, timebase, or bandwidth limit. The number of
, is shown in the acquisition status dialog. When summed
a red uced rate to increase the averaging speed (points and
epea ted addition, with unequal weight, of successive source
ise on si gnals that drift very slowly in time or amplitude. The
all the previously acquired ones: the continuous average
cently acquired waveform. The weight of 'old' waveforms
(followi ng an exponential rule) at a rate that decreases as the
e)/(weight + 1)
ing. But by setting a sweeps value, you establish a fixed
sweeps is reached.
e number of
(new data +0 * old average)/(0 + 1) = new data only
+ 1) = 1/2 new data +1/2 old average
+ 1) = 1/3 new data + 2/3 old average
+ 1) = 1/5 new data + 4/5 old average
1) = 1/5 new data + 4/5 old average
) = 1/5 new data + 4/5 old average
old average b egins to decrease exponentially.
ata + 3/4 old average
WRXi-OM-E Rev C