Table Of Contents

MT Generate Synchronization Parameters (MT Generate PAM Synchronization Parameters (bit array)) (G Dataflow)

Version:
    Last Modified: February 7, 2018

    Generates synchronization parameters for PAM demodulation using a synchronization sequence directly represented by the sync bits input array. The generated synchronization parameters cluster avoids phase ambiguity at the demodulator, thus allowing recovery of the actual message bits.

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    PAM system parameters

    Parameter values defining the PAM system. Wire the PAM system parameters cluster of MT Generate PAM System Parameters (M) or MT Generate PAM System Parameters (map) to this cluster. Do not alter the values.

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    samples per symbol

    An even number of samples dedicated to each symbol. Multiply this value by the symbol rate to determine the sample rate.

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    Note  

    The demodulation and detector nodes use timing recovery, which is optimized for four or more samples per symbol.

    Default: 16

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    symbol map

    An ordered array that maps each symbol to its desired level. The number of PAM levels in the array is 2 N , where N is the number of bits per symbol. The vector length for the symbols farthest from the origin is 1.

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    sync bits

    An array of synchronization bits used to generate the PAM synchronization parameters cluster. For example, if you specify a preamble word of 1111 1111 1111 1110 for symbol synchronization, you can wire a 16-bit array with the above entries to the sync bits parameter. For reliable symbol synchronization, specify an array of length (10 × bits per symbol).

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    Note  

    To prevent false synchronization, select a bit pattern with low correlation to non-synchronized portions of the data stream.

    Default: 0

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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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    expected sync location

    The expected location of the synchronization parameters in symbols. Set this value to -1 to search the entire waveform for the synchronization symbols.

    Default: -1

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    sync location uncertainty

    Number of symbols before or after the expected sync location where the first symbol of the sync sequence may be located. The node ignores this parameter if the expected sync location parameter is set to -1.

    Default: 10

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    sync indent

    Distance that the sync sequence is indented into the information block.

    The distance is the number of demodulated symbols preceding the sync sequence. For example, a value of 10 indicates that the output bit stream consists of 10 data symbols, followed by the sync sequence, followed by the remaining data symbols.

    Default: 0

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    PAM synchronization parameters

    Synchronization parameters to pass to the demodulation node.

    If the synchronization parameter passed to the demodulation node is left empty, the constellation of the demodulated waveform has a 90° carrier phase ambiguity for two-dimensional modulation schemes (QAM, QPSK, and higher order PSK) and a 180° carrier phase ambiguity for one-dimensional modulation schemes (PAM/ASK/BPSK).

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    expected sync location

    The expected location of the first symbol of the sync sequence.

    This value is an index to the input complex waveform. A value of -1 searches the entire input complex waveform and ignores the sync location uncertainty parameter.

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    sync sequence

    The mapped symbol array from the specified synchronization bits or synchronization numbers.

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    sync location uncertainty

    Number of symbols before or after the expected sync location where the first symbol of the sync sequence may be located. The node ignores this parameter if the expected sync location parameter is set to -1.

    Default: 10

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    sync indent

    Distance that the sync sequence is indented into the information block.

    The distance is the number of demodulated symbols preceding the sync sequence. For example, a value of 10 indicates that the output bit stream consists of 10 data symbols, followed by the sync sequence, followed by the remaining data symbols.

    Default: 0

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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.

    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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