SymClkErr (802.11a/g/j/p OFDM)

SymClkErr is the symbol clock frequency error, which is the difference between the ideal and actual symbol clock frequency in ppm. A symbol clock frequency that is less than ideal will make the 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. symbol time to take longer than required and cause the OFDM subcarrier spacing to decrease. A symbol clock frequency that is greater than ideal will make the symbol times take less time than required and cause the OFDM subcarrier spacing to increase. In either case this creates subcarrier interference and increases the signal's 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.. The resultant error value is a unitless fraction, which is multiplied by 1,000,000 to obtain SymClkErr in ppm.

The 802.11a/j/p and HIPERLAN/2 standards require the symbol clock frequency error tolerance to be ± 20-ppm maximum. The 802.11b/g standards require the symbol clock frequency error tolerance to be ± 25-ppm maximum. The transmit center frequency and the symbol clock frequency shall be derived from the same reference oscillator.