WavePro 7 Zi and Zi-A Oscilloscopes
123
WP7Zi-GSM-E RevB
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.
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
or
Power of 2
from the pop-up menu.
Least Prime
- 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.
Power of 2
- The other choice is a power of 2 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 2 FFT
truncates to the nearest power of 2 less than record length (if
truncate is chosen) or fill data to nearest power of 2 greater
than the record length (if zero fill is selected).
12.
If the
Phase
Output Type is selected during Step 9 (previously), a
Group Delay Shift
field is available for use. Provide the desired
value for your FFT.
