Sync Corr (802.16 OFDM)

Sync Corr (Synchronization Correlation) is the correlation coefficient between the measured preamble and an ideal preamble. This can be used as an indication of the quality of the preamble. A value of 1 indicates perfect correlation and a value of 0 indicates no correlation.

Large Frequency Errors and Incorrect Sync Corr Values

Large frequency errors may cause the VSA to show incorrect low Sync Corr values. These values are a result of frequency error and do not necessarily indicate poor signal quality. Therefore, for low Sync Corr values always validate the cause of the low Sync Corr data result.

If the Sync Corr is low and the frequency error is large, check the RCE Relative Constellation Error is the RMS level of the Error Vector Magnitude, averaged over all subcarriers and all detected OFDM symbols. (EVM Error vector magnitude (EVM): A quality metric in digital communication systems. See the EVM metric in the Error Summary Table topic in each demodulator for more information on how EVM is calculated for that modulation format.). If the RCE (EVM) is low, the measured signal data is good and the low Sync Corr value can generally be ignored. To correct for frequency errors, adjust the center frequency so that the Freq Err decreases to approximately 0 Hz. If the Sync Corr increases in value then the contributing factor to the initial low Sync Corr value was the frequency error and not the measured signal.