Sync Corr (Custom OFDM)
is a cross correlation of the preamble of the measured signal to an ideal signal. It is a figure of merit indicating the quality of the preamble. A value of 1 indicates perfect correlation and a value of 0 indicates no correlation.
All subcarriers specified as preamble subcarriers in the Resource Map are used to compute Sync Corr. The ideal signal is constructed based on the values in the Preamble Values array. If there are no subcarriers specified as preamble subcarriers in the Resource Map, then the demodulator will attempt to use pilots (but not Unknown Pilots) for synchronization, and the Sync Corr value is the cross correlation of the measured pilot subcarriers to an ideal signal constructed from the Pilot Values array.
Large Frequency Errors and Incorrect Sync Corr Values
When the Synchronization Mode is set to , large frequency errors (approximately 1/3 subcarrier spacing or more) may cause the VSA to show incorrect low SyncCorr values. These values are a result of frequency error and do not necessarily indicate poor signal quality. Therefore, for low Sync Corr values you should validate the cause of the low Sync Corr data result. If the Sync Corr is low and the frequency error is large, check the 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 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.
See Also
Available Error Summary Results
