Lengths, Intervals, and Offsets (MB-OFDM)

Menu Path: MeasSetup > MB-OFDM Demod Properties > Time tab

This topic describes the relationships between Search Length, Result Length, Measurement Interval, and Measurement Offset. It is the Measurement Interval and Measurement Offset parameters that define a specific interval within the Result Length for demodulation and analysis, where the Result Length pulse appears within the search time of the Search Length. These parameters allow quick analysis and viewing of specific time intervals of data because the VSA does not acquire new measurement data when the Measurement Interval or Measurement Offset is changed. When a new Measurement Interval or Measurement Offset is entered, the VSA re-computes the trace data results using the existing measurement data.

Search Length: Search Length specifies the length of time to acquire the input signal, which defines the length of time that the pulse search is performed. When this value is changed, the VSA must be restarted (Control > Restart).
Result Length: Result Length displays the total number of symbol-times included in the acquired and demodulated data. This is the value that determines the packet length for the packet traces.
Measurement Interval: Measurement Interval determines what portion of the Result Length data is demodulated for the demodulation trace results.
Measurement Offset: Measurement Offset sets the start position of the Measurement Interval within the Result Length.
PayLoad Octets: PayLoad Octets displays the resulting payload, in octets, for the Result Length and Data Rate settings.

The following illustration displays the interrelationship between the parameters Search Length, Result Length, Measurement Interval, Measurement Offset, and PayLoad Octets. The Preamble plus the Result Length form the Packet Length, which is used for the Packet Time and Packet Spectrum traces. For more information, see MB-OFDM Packet.