Manual Fs/BW Ratio (802.16 OFDM)
: See 802.16 OFDM Standard Setups/Presets Table.
Fs/BW is the ratio between 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. 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. sample rate ("Fs" in the standard) and the nominal channel bandwidth ("BW" in the standard). See Nominal Bandwidth. This ratio is referred to as "n" in the standard. The value is generally a number slightly larger than one.
Specific values supported (via radio buttons) are , and .
In addition, arbitrary value between 0.5 and 2 are possible by checking and specifying the value in the text box.
The default is auto-detect based on BW. For auto-detect, the Manual Fs/BW Ratio checkbox is greyed. The image below shows a check in the checkbox. This will manually override the auto-detect setting. The selected value of the manual Fs/BW Ratio shown here is , which is the default manual setting.
To select a Fs/BW Ratio manually:
Check the check box.
Select one of the five preset ratios or and enter a value between 0.5 and 2 in the text box.
Check to see if observing other Trace Data graphs demodulates the signal. The or trace data images are useful. If the signal is demodulated, the Constellation diagram will be correct and the will show low errors.
See Also
