Measurement Interval and Offset (802.16 OFDM)

The Measurement Interval and Measurement Offset parameters define a specific interval of the Result Length for demodulation and analysis.

These parameters quickly analyze and view specific time intervals of data because the VSA does not acquire new measurement data when the measurement interval or offset is changed. When a new measurement interval or offset is entered, the VSA re-computes the trace data results using the existing measurement data.

The Time trace data shows only time data for the symbol-times specified by Measurement Interval parameter, except when the Measurement Interval is equal to Max Result Length. In this case, the Time trace data also shows the preamble data. See Time trace data for complete details.

The following illustration shows the interrelationship between the Search Length, Result Length, Measurement Interval and Measurement Offset.

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Result Length: Total number of symbol-times included in the acquired and demodulated data.
Max Result Length Sets the maximum number of symbol-times that can be included in the Result Length. Automatic limits the Max Result Length to the number of symbol times within the pulse.
Measurement Interval: Determines what segment of the Result Length data is analyzed and displayed.
Measurement Offset: Sets the start position of the Measurement Interval within the Result Length.
Symbol Time: One OFDM Orthogonal Frequency Division Multiplexing: OFDM employs multiple overlapping radio frequency carriers, each operating at a carefully chosen frequency that is Orthogonal to the others, to produce a transmission scheme that supports higher bit rates due to parallel channel operation. OFDM is an alternative tranmission scheme to DSSS and FHSS. symbol period which includes the IFFT Inverse Fast Fourier Transform/FFT Fast Fourier Transform: A mathematical operation performed on a time-domain signal to yield the individual spectral components that constitute the signal. See Spectrum. period (TFFT) and guard interval period (TGI).