Preamble Freq Error (802.11a/g/j/p OFDM)

Frequency error is the difference between the measured center frequency of the transmitted signal and the VSA center frequency. The Preamble Frequency Error trace shows the total frequency error during the preamble portion of 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. burst. This includes the constant frequency error as displayed in the Syms/Errs trace in addition to any time-varying frequency error.

When Synchronization Reference (on the Advanced tab of the 802.11a/g/j/p Demod Properties dialog box) is set to Short Training Sequence (the default for 802.11a), Preamble Frequency Error covers both the short training sequence and the channel estimation sequence. When the Sync type parameter is set to Channel Estimation Sequence, Preamble Frequency Error covers only the channel estimation sequence.

Preamble Frequency Error is sampled at 64 times the subcarrier spacing, which is 20 MHz Megahertz: A unit of frequency equal to one million hertz or cycles per second. for 802.11a/g and HIPERLAN/2 signals.