Frequency Domain Processing

The frequency domain processing components provide builders for operators that handle frequency-domain filtering, correction, and processing operations in VLBI fringe fitting.

MHO_NotchesBuilder

Class	MHO_NotchesBuilder
Primary Functionality	Builds a notches (frequency cut) operator
Key Features	Constructs and adds MHO_Notches operator to toolbox Implements frequency domain filtering/cutting Returns bool indicating construction success Removes specific frequency ranges from data

The MHO_NotchesBuilder class builds a notches operator that performs frequency domain filtering by removing specific frequency ranges from the data. This is essential for eliminating radio frequency interference (RFI) and other unwanted signals that can contaminate VLBI observations.

The builder constructs the MHO_Notches operator and provides boolean feedback on the success of the construction process.

MHO_PassbandBuilder

Class	MHO_PassbandBuilder
Primary Functionality	Builds a passband (frequency chunk excision) operator
Key Features	Constructs and initializes passband operator Handles frequency domain filtering/excision Returns bool indicating construction success/failure Defines usable frequency ranges

The MHO_PassbandBuilder class builds a passband operator that defines the usable frequency ranges for fringe fitting by excising frequency chunks that should not be used in the analysis. This is complementary to the notches operator and helps define the clean frequency ranges for processing.

The builder provides boolean feedback on the success or failure of the operator construction process.

MHO_DCBlockBuilder

Class	MHO_DCBlockBuilder
Primary Functionality	Builds a DC block operator
Key Features	Constructs and adds MHO_DCBlock operator to toolbox Inherits from MHO_OperatorBuilder Implements DC blocking functionality Removes DC component from frequency domain data

The MHO_DCBlockBuilder class builds a DC block operator that removes the DC component from frequency domain data. This is important for eliminating DC offsets that can affect the quality of fringe fitting and correlation analysis.

The builder constructs the MHO_DCBlock operator and adds it to the processing toolbox for frequency domain DC removal.

MHO_LSBOffsetBuilder

Class	MHO_LSBOffsetBuilder
Primary Functionality	Builds a LSB (lower side band) offset operator
Key Features	Constructs and initializes MHO_LSBOffset operator ExtractStationIdentifier() method for station identification Handles lower side band offset corrections Compensates for frequency-dependent effects

The MHO_LSBOffsetBuilder class builds a lower side band (LSB) offset operator that handles frequency-dependent corrections for the lower side band in heterodyne receiver systems. This correction is essential for maintaining proper frequency calibration in dual-sideband VLBI observations.

The builder includes station identification capabilities to ensure corrections are applied to the appropriate station’s data streams.