LBXXXA Series USB Powe
™
Product Manual PMA (Power Meter Application)
Revision: 08/02/11
- 30 -
Anti-alias Control
The toolbar button is toggle on/off. Enable anti-alias control for input modulation bandwidths greater than 200 kHz.
Disable it for modulation bandwidths less than 200 kHz. This button is used for CW and continuous pulse power
measurements
only
to provide the greatest measurement accuracy. This control feature can best be described as a
low/high pass filter switch and actually relates to the sampling method that is employed for the particular modulation
bandwidth - either narrow or wide.
Normally the sampling is 500 kHz. As the baseband signals approach the Nyquist criteria (realistically about 200 kHz
in this case) problems arise. There are several approaches that can be used to resolve this problem. We use an anti-
aliasing capability that randomizes the sample period. This randomization does have some affect on the rapidity of
acquiring the data.
As a result, the anti-aliasing algorithm is normally turned off. However, if you are measuring signals that have
baseband content greater than about 200 kHz we recommend turning on the anti-aliasing feature.
Anti-alias control enabled (BW >200 kHz)
Anti-alias control disabled (BW <200 kHz)
