Table Of Contents

MT Demodulate PM (G Dataflow)

Version:
    Last Modified: February 7, 2018

    Performs phase demodulation on the incoming I/Q signal.

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    PM modulated waveform

    The baseband (downconverted) time-domain data for demodulation.

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    t0

    The trigger (start) time of the acquired signal.

    Default: 0.0

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    dt

    Time interval between data points in the acquired signal.

    Default: 1.0

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    Y

    The complex-valued time-domain data array. 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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    phase deviation

    A value that indicates how to scale the PM demodulated waveform. You can set this value to 1.0 or to the expected phase deviation of the incoming PM signal for demodulation.

    • Set this value to 1.0 to return a PM demodulated waveform in degrees with no scaling. In this case, the maximum amplitude of the PM demodulated waveform is equal to the actual phase deviation of the incoming PM signal.
    • Set this value equal to the expected phase deviation of the incoming PM signal to divide the PM demodulated waveform by this value. You can use the resulting scaled PM demodulated waveform to quantify the degree of error between the expected phase deviation and the actual phase deviation.
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    carrier correction?

    A Boolean that determines whether to enable carrier correction.

    TRUE Determines a linear correction to the carrier frequency estimate and compensates for it in the FM demodulated waveform.
    FALSE Carrier correction is not enabled. Use this option when performing continuous acquisition.

    Default: FALSE

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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 initialization of an internal node state tracks the ending phase.

    TRUE The node clears the state information about each call.
    FALSE The node uses the final phase from the previous call as the starting phase for the next call, ensuring phase continuity between calls.

    Default: FALSE

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    PM demodulated waveform

    The phase-demodulated information signal.

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    carrier offset

    The offset, in hertz (Hz), between the incoming modulated carrier frequency and the estimated carrier frequency. The offset is returned whether carrier correction? is TRUE or FALSE. If the carrier frequency drifts as a function of time, this node calculates the offset by performing a weighted linear fit on the phase information in the I/Q signal, and then taking the slope of this linear fit. You can use this slope to monitor drift in the carrier frequency.

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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.

    PM Demodulation

    This node computes the information signal as a result of the demodulation and returns the data in the PM demodulated waveform.

    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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