Measurements

The low level interface allows to load measured MPI data via the measData function. The returned data is exactly how it is stored on disc. This has the disadvantage that the user needs to handle different sorts of data that can be stored in the measData field. To cope with this issue, the MDF also has a high level interface for loading measurement data. The first is the function

function getMeasurements(f::MPIFile, neglectBGFrames=true;
                frames=neglectBGFrames ? (1:acqNumFGFrames(f)) : (1:acqNumFrames(f)),
                numAverages=1,
                bgCorrection=false,
                interpolateBG=false,
                tfCorrection=measIsTFCorrected(f),
                sortFrames=false,
                spectralLeakageCorrection=true,
                kargs...)

that loads the MPI data in time domain. Background frames can be neglected or included, frames can be selected by specifying frames, block averaging can be applied by specifying numAverages, bgCorrection allows to apply background correction, tfCorrection allows for a correction of the transfer function, interpolateBG applies an optional interpolation in case that multiple background intervals are included in the measurement, sortFrames puts all background frames to the end of the returned data file, and spectralLeakageCorrection controls whether a spectral leakage correction is applied.

The array returned by getMeasurements is of type Float32 and has four dimensions

1. time dimension (over one period)
2. receive channel dimension
3. patch dimension
4. frame dimension

Instead of loading the data in time domain, one can also load the frequency domain data by calling

function getMeasurementsFD(f::MPIFile, neglectBGFrames=true;
                  loadasreal=false,
                  transposed=false,
                  frequencies=nothing,
                  tfCorrection=measIsTFCorrected(f),
                  kargs...)

The function has basically the same parameters as getMeasurements but, additionally, it is possible to load the data in real form (useful when using a solver that cannot handle complex numbers), it is possible to specify the frequencies (specified by the indices) that should be loaded, and it is possible to transpose the data in a special way, where the frame dimension is changed to be the first dimension. getMeasurementsFD returns a 4D array where of type ComplexF32 with dimensions

1. frequency dimension
2. receive channel dimension
3. patch dimension
4. frame dimension