![LeCroy WaveRunner 104MXI Operator'S Manual Download Page 142](http://html1.mh-extra.com/html/lecroy/waverunner-104mxi/waverunner-104mxi_operators-manual_1866369142.webp)
W
AVE
R
UNNER
X
I
S
ERIES
142
WRXi-OM-E Rev B
7. Choose whether to
Truncate
1
or
Zero-fill
2
the trace display.
8. Touch
the
Suppress DC
checkbox if you want to make the DC bin go to zero. Otherwise, leave it unchecked.
9. Touch
inside
the
Output
type field, and make a selection from the pop-up menu.
10. Touch inside the
Window
field, select a window type.
11. Touch inside the
Algorithm
field and select either
Least Prime
3
from the pop-up menu.
ANALYSIS
Pass/Fail Testing
Comparing Parameters
Each Pass/Fail input (
Qx
) can compare a different parameter result to a user-defined limit (or statistical range)
under a different condition.
The conditions are represented by these comparison operators:
At the touch of a button, test results can also be compared to these standard statistical limits:
•
current mean
•
mean + 1 SD
•
mean + 3 SD
1
When the FFT transform size does not match the record length, you can truncate the record and perform an FFT on the shorter record. This
will increase the resolution bandwidth.
2
Zero-fill is useful when the source data for the FFT comes from a math operation that shortens the record. This is commonly encountered in
filtering operations like enhanced resolution. The missing data points are replaced by data values, whose amplitudes are interpolated to fit
between the last data point and the first data point in the record. This guarantees that there is not a first-order discontinuity in the filled data.
Since the data at the end of the record is "filled" data, it is advisable to select a weighting window other than rectangular to minimize the effect
of the fill on the resulting spectrum.
3
The default algorithm is a least primes algorithm that computes FFTs on transform sizes having lengths that can be expressed as factors of
2
N
*5
K
. This is very compatible with the record lengths encountered in the oscilloscope, which are often multiples of 1, 2, 4, 5, or 10. or Power
of 2 The other choice is a power of two algorithm where the record lengths are in the form of 2
N
. The power of 2 algorithm generally runs faster
than the least primes algorithm. The price that is paid is a record length that is not the same as the acquired signal. The power-of-two FFT
uses the first 2
N
points of the record. For example, if you acquire 500 points in your trace, the power-of-two FFT would only use the first 256
points.