Tektronix SPECMON3 Manual page 257

OFDM Analysis
Advanced Params Tab – OFDM
The Advanced Params tab contains parameters that control the analysis of the input signal.
Settings
Constellation determination
Symbol analysis offset
Channel Estimation
Preamble
Preamble + Data
Pilot tracking
Swap I & Q
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Description
Specifies the method used to detect the constellation. Automatic analyzes the
signal to determine the appropriate constellation, Manual allows you to specify
the constellation type. Manual choices are: BPSK, QPSK, 16QAM, and 64QAM.
Specifies the analysis offset in the symbol interval. This value is a percentage
of the Guard Interval. The allowable range is -100% to 0%. -100% positions
the FFT to start at the beginning of the Guard Interval, 0% positions it to start
at the end of the Guard Interval. Default value is -50% which usually gives
the best measurement results.
Specifies the method used to estimate channel frequency response and
equalization. This control can be used to diagnose changes in frequency
response over the signal packet.
When you select Preamble, the instrument uses only the Preamble to estimate
channel frequency response. This response is then used to equalize the entire
signal packet.
When you select Preamble + Data, the instrument makes an initial channel
frequency response estimate from the Preamble. Then estimates the channel
response for each data symbol using the decoded data content to derive
equalization for each symbol individually. This allows compensation for
time-varying channel response over the packet.
Specifies if pilot subcarriers should be used to correct amplitude, phase, and
symbol timing variations over the packet. The choices available are Phase,
Amplitude, and Timing. The default setting is Phase.
Select the checkbox to swap the I and Q components of a signal. This
compensates the input signal for spectral inversion.
Advanced Params Tab – OFDM
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