Result Length (Custom OFDM)

The Result Length parameter and Result Length Selection property are used to specify the amount of acquired time data (in symbols) that is available for measurement analysis. For CustomOfdm, the Result Length data includes both the Preamble and Payload Data symbols beginning at the first preamble symbol within the measurement burst. There are two Result Length Selection modes: Automatic mode and Manual mode. In "Automatic" mode the VSA automatically limits the maximum result length (which also limits the Measurement Interval) to the measurement burst length. In "Manual" mode the measurement result length and Measurement Interval can extend beyond the measurement burst length.

You use the Measurement Interval and Measurement Offset parameters to specify how much and what section of the Result Length that is included in measurement analysis.

The sum of the Measurement Interval plus Measurement Offset must fit within the measurement Result Length.

Result Length Selection

The Result Length Selection parameter is used to select whether the measurement result length is determined automatically or manually; Automatic mode and Manual mode. In general, "Automatic" will limit the maximum measurement result length to the burst length. "Manual" mode will allow the measurement result length and measurement interval to include data beyond the burst length.

In Automatic mode the VSA automatically limits the maximum measurement result length to the measurement burst length. This protects against including non-burst data in the measurement analysis. There are two Automatic mode Result Length conditions:

1) Result Length > Burst Length:
The VSA ignores Result Lengths greater than the burst length and limits the measurement input data to the burst length (in symbols). No input data beyond the first detected burst will be included in the measurement analysis.

2) Result Length ≤ Burst Length
The VSA will use the specified Result Length as the maximum measurement Result Length for Result Lengths less than or to the burst length. Measurement input data can be limited to less than the measurement burst length.

The VSA uses the specified Result Length as the maximum Result Length. All input data specified by the and parameters will be included in the measurement analysis even if the specified Measurement Interval includes data beyond the measurement burst.

Example: The following figures show the difference between Automatic and Manual modes when the Results Length is greater than the measurement burst.

You can view the measurement analysis time date in the Time trace.