Eq Impulse Response (802.16 OFDM)

Eq Impulse Response shows the impulse response of the equalization filter. How the Eq Impulse Response is computed depends on the selection for the Equalizer Training parameter MeasSetup > IEEE 802.16 OFDM Demod Properties > Advanced tab. If the Equalizer Training parameter is set to Preamble Only, the Eq Impulse is computed using just the Channel Estimation Sequence portion of the preamble. If the parameter is set to Preamble & Data, the Eq Impulse is computed using both the Channel Estimation Sequence portion of the preamble and the data symbols. The latter option is typically more accurate.

The result length will be four times the 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. length so a total of 1024 points.

This is similar to, but not the same as, the Digital Demod Eq Impulse Response. The differences are:

Digital Demod computes this by comparing the IQ Meas Time and IQ Ref Time data, while 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. digital demod computes it from the preamble/data of the burst.
Digital Demod typically uses a running average to average multiple scans when computing the equalizer impulse response. OFDM demodulation does not average, but computes a new equalizer response for each burst.
The equalization filter is inherent to OFDM Demodulation, it cannot be enabled/disabled like Digital Demod.