LeCroy WaveRunner Xi-A - Page 79

WAVERUNNER Xi-A AND MXi-A SERIES
78 WRXi-A-GSM-E Rev A
10. TouchinsidetheWindow
fieldandselectawindow
type.
11. Touchinsidethe
Algorithmfieldandselect
eitherLeastPrime
*
or
Power2
†
fromthepop‐up
menu.

*
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.
†
The other choice is a power of two algorithm where the record lengths are in the form of 2N.
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 2N 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.