Sync Correlation (DVB-S2/S2X)
is a cross correlation of the preamble synchronization of the measured signal to an ideal signal. It is a figure of merit indicating the quality of the segment of the preamble used for synchronization. The preamble segment used to compute the Sync Correlation is either the short training sequence or the channel estimation sequence as specified by Synchronization Source. 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 (approximately 100 kHz kiloHertz: A radio frequency measurement (one kilohertz = one thousand cycles per second). or more) may cause the VSA to show incorrect low Sync Correlation values. These values are a result of frequency error and do not necessarily indicate poor signal quality. Therefore, for low Sync Correlation values you always need to validate the cause of the low Sync Correlation data result.
If the Sync Correlation 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 Correlation 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 Correlation increases in value then the contributing factor to the initial low Sync Correlation value was the frequency error and not the measured signal.
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