Frequency Estimation & Equalization & Synchronization (Flex Frame)

The Frequency Estimation & Equalization & Synchronization parameter group configures the measurement controls that relate to frequency estimation, equalization and synchronization.

Synchronization Source determines which allocations are used for initial synchronization.

Default: Auto

Choices: Auto, Customized

Frequency Estimation Mode determines whether the frequency error is estimated and compensated. Having an incorrect carrier frequency estimate can lead to significant errors during the demodulation process. The carrier frequency estimate is indicated in the Carrier Aggregation tab, where each component carrier has an absolute center and offset from that center frequency.

Default: Normal

Choices: Off, Normal

Phase Tracking Mode determines how phase tracking and offset is performed.

Default: Off

Choices: Off, Interpolate with Pilot, Moving Average Over All

Phase Tracking Interpolation Mode (enabled when Phase Tracking Mode is set to Interpolate with Pilot) determines the type of interpolation used.

Default: Average And Nearest

Choices: Average And Nearest, Linear Interpolation

Phase Tracking Filter BW (enabled when Phase Tracking Mode is set to Moving Average Over All) determines the moving filter length (bandwidth) by multiplying the value entered in this field by the Symbol Rate.

Default: 0.01

Equalization Mode determines which mode to use when estimating the best possible equalizing FIR Finite Impulse Response filter taps that will compensate for variations in the IF.

Default: Zero-forcing

Choices: Least Mean Squares, Zero-forcing, XCorrelation

Cost Function Criteria - (only available when Equalization Mode is set to Least Mean Squares) specifies the type of the optimizer used in the LMS equalizer.

Default: Minimize EVM at Decision Points

Choices: Minimize EVM at Decision Points, Minimize Entire Error Vector

Channel Estimation Source determines which allocations are used to estimate the frequency response of the channel. The selection made will determine the state of the Chan Estimation column of checkboxes in the Overall Allocation Control grid.

Default: None

Choices: None; Preamble Only; Pilots Only; Preamble and Pilots; Preamble, Pilots, and Data; Allocations with Known Sequences, Customized

Initial Equalization (Least Mean Squares and Zero-forcing Equalization Modes only) is used to enable or disable the first round channel estimation and compensation. When unknown data is included in the channel estimation, and when the channel response is not flat, Initial Equalization uses a known sequence to do the first round of channel estimation and compensation. Initial Equalization usually leads to more accurate restoration of unknown data, which results in better final channel estimation.

Default: Cleared

Range: Selected, Cleared

Normalized Channel Delay Spread sets the expected delay spread of the channel in units of symbols. The actual equalization filter length is 2 * Normalized Channel Delay Spread + 1.

Default: 10 symbols

EQ Tracking determines which impairments are tracked for equalization impulse response.

Default: Off (Track when Equalization Mode is set to XCorrelation)

Choices: Off, Track, Hold

Reset (only available when Equalization Mode is set to XCorrelation) resets the adaptive equalization coefficients as a single point impulse response for the carriers. This makes the initial estimate transparent, causing no frequency response shaping to the channel.

Tracking Convergence (only available when Equalization Mode is set to XCorrelation) controls the rate of convergence of the adaptive equalizer of the digital demodulation measurement. Convergence determines how quickly the equalization filter coefficients converge to the estimated values for each measurement. Larger values converge faster but might not be as consistent, based on noise in the data. Smaller values converge more slowly but provide a more consistent equalization filter for a given channel. This provides a trade-off in the number of measurements required for convergence of the equalization filter taps, and the stability of those taps. For more information, see Convergence (Digital Demod).

Default: 1E-07

See Also

Measurement Control Tab