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MT Decimate Oversampled Waveform (G Dataflow)

Version:
    Last Modified: February 7, 2018

    Decimates the input complex waveform and returns the decimated output complex waveform. Use this node to decimate the matched filtered waveform at the output of MT Matched Filter to recover the symbols corresponding to the ideal symbol timing location.

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    input complex waveform

    The modulated complex baseband waveform data.

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    t0

    Trigger (start) time of the Y array.

    Default: 0.0

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    dt

    Time interval between data points in the Y array.

    Default: 1.0

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    Y

    The complex-valued signal-only baseband modulated waveform. The real and imaginary parts of this complex data array correspond to the in-phase (I) and quadrature-phase (Q) data, respectively.

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    decimation factor

    The extent to which the input complex waveform is decimated. This parameter is ignored on subsequent calls when reset? is set to FALSE.

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    Tip  

    If you are recovering the ideal symbol timing instant, ensure that this input value matches the samples per symbol parameter to MT Matched Filter.

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    offset

    The starting index of the Y array within the input complex waveform cluster from which decimation is performed. This parameter is ignored on subsequent calls when reset? is set to FALSE. Samples prior to the specified offset are discarded. Use this parameter to specify the first sample containing an ideal symbol timing instant.

    Default: 0 (no samples discarded)

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    error in

    Error conditions that occur before this node runs.

    The node responds to this input according to standard error behavior.

    Standard Error Behavior

    Many nodes provide an error in input and an error out output so that the node can respond to and communicate errors that occur while code is running. The value of error in specifies whether an error occurred before the node runs. Most nodes respond to values of error in in a standard, predictable way.

    error in does not contain an error error in contains an error
    If no error occurred before the node runs, the node begins execution normally.

    If no error occurs while the node runs, it returns no error. If an error does occur while the node runs, it returns that error information as error out.

    If an error occurred before the node runs, the node does not execute. Instead, it returns the error in value as error out.

    Default: No error

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    reset?

    A Boolean that determines whether stored state information is cleared at subsequent calls to this node.

    TRUE Decimation begins at the starting point specified by offset.
    FALSE The specified offset and decimation factor values are used on first call only, and computed on subsequent calls to ensure continuability from one iteration to the next.

    Default: TRUE

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    output complex waveform

    The decimated I/Q baseband waveform sampled at a rate 1/(decimation factor × dt) seconds/sample.

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    t0

    Trigger (start) time of the Y array.

    Default: 0

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    dt

    Time interval between data values in the Y array.

    Default: 1.0

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    Y

    The complex-valued signal-only baseband modulated waveform. The real and imaginary parts of this complex data array correspond to the in-phase (I) and quadrature-phase (Q) data, respectively.

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    error out

    Error information.

    The node produces this output according to standard error behavior.

    Standard Error Behavior

    Many nodes provide an error in input and an error out output so that the node can respond to and communicate errors that occur while code is running. The value of error in specifies whether an error occurred before the node runs. Most nodes respond to values of error in in a standard, predictable way.

    error in does not contain an error error in contains an error
    If no error occurred before the node runs, the node begins execution normally.

    If no error occurs while the node runs, it returns no error. If an error does occur while the node runs, it returns that error information as error out.

    If an error occurred before the node runs, the node does not execute. Instead, it returns the error in value as error out.

    Advantages of Using MT Decimate Oversampled Waveform

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    Note  

    Although MT Resample (Complex Cluster) can be used to downsample a complex waveform, MT Decimate Oversampled Waveform is sometimes a more suitable choice because it does not apply filtering during the decimation process. Compared to MT Fractional Resample, this node has the following characteristics:

    • Does not introduce any additional phase shift (other than any specified nonzero offset)
    • Does not introduce transient effects associated with filter application
    • More computational efficiency and speed

    Where This Node Can Run:

    Desktop OS: Windows

    FPGA: Not supported

    Web Server: Not supported in VIs that run in a web application


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