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MT Align To Ideal Symbols (MT Align to Ideal Symbols (Generic)) (G Dataflow)

Version:
    Last Modified: February 7, 2018

    Locates the first occurrence of the ideal symbol timing instant in the matched filtered input complex waveform, then applies phase-continuous resampling to align the first sample of the input complex waveform to the ideal symbol timing instant for PAM, ASK, QAM, and non-offset PSK modulation schemes. The returned waveform is symbol-time aligned such that its first sample corresponds to the optimal (ideal) symbol instant.

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    input complex waveform

    The continuous-time samples of the modulated complex baseband waveform data. Wire the output complex waveform returned from MT Matched Filter to this parameter.

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    Note  

    For this node to function properly, you have to meet the following requirements:

    • The sample rate of the input complex waveform must be an even integer multiple of the expected symbol rate. Use MT Resample (Complex Cluster) to adjust the sampling rate of the input complex waveform if necessary.
    • An appropriate matched filter must be previously applied to the input complex waveform using MT Apply Matched Filter.
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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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    matched filter coefficients

    An ordered array containing coefficients for the matched filter that has been applied to the input complex waveform. Wire the matched filter coefficients parameter of MT Generate Filter Coefficients to this parameter. Ensure that the value of the samples per symbol parameter in this node matches the matched samples per symbol value used to generate these filter coefficients.

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    samples per symbol

    Number of samples per information symbol in the input complex waveform.

    Default: 16

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    error in

    Error conditions that occur before this node runs. Unlike most nodes, this node runs normally even if an error occurs before this node runs.

    Default: no error

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    reset?

    A Boolean that determines whether the node continues to align the input complex waveform to ideal symbol timing instants using the previous iteration states.

    TRUE Resets the node. The node resets on the first call and when reset? is set to TRUE.
    FALSE Continues to align the input complex waveform to ideal symbol timing instants using the previous iteration states.

    Default: TRUE

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    output complex waveform

    The symbol-time-aligned I/Q baseband waveform. Wire this parameter to MT Decimate Oversampled Waveform followed by MT Map Symbols to Bits to obtain the recovered bits corresponding to the modulated waveform.

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    t0

    Trigger (start) time of the Y array.

    Default: 0

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    dt

    Time interval between data points in the Y array. The reciprocal of this value is equal to the system sample rate.

    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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    waveform alignment offset

    Location of the ideal symbol timing instant, in samples, relative to the beginning of the input complex waveform. This offset was applied to the output complex waveform. Multiply this value by the dt element of the input complex waveform to calculate the location of the ideal symbol timing instant in seconds.

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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.

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    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.

    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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