Subset Analysis

Subset analysis uses the Discrete Zak Transform to compute a subset of the baseband FFT. The frequency resolution for spectral measurements computed with the baseband subset analysis equals the frequency resolution for measurements made with the baseband analysis. The acquisition time determines the frequency resolution. The only way to achieve a finer frequency resolution is to increase the length of the time record. In the case of baseband or subset analysis, a longer time record implies a larger block size.

The following consideration can help you decide when to use subset analysis instead of baseband analysis:

• The required block size yields an acceptable frequency resolution.
• The analysis of a narrow subset of the baseband span offers better processing performance than the baseband analysis can provide.