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MT Generate System Parameters (MT Generate FSK System Parameters (map)) (G Dataflow)

Version:
    Last Modified: February 7, 2018

    Calculates parameters for use with either MT Modulate FSK or MT Demodulate FSK. This node accepts an input array of symbol values that explicitly specifies the positions of the symbol map.

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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 values

    Array of symbol values with an order that corresponds to the symbol map. The number of FSK levels specified in the array must be 2 N , where N is the number of bits per symbol.

    This parameter expects an array of integers. The integers 0 to (M-1), inclusive, must all be included only once in the symbol values array, where M is the M-ary number of the modulation. The symbol locations (FSK frequencies) are evenly spaced between -FSK Deviation and +FSK Deviation, inclusive, with the binary representation (LSB first convention) of the integers that populate the symbol values array that corresponds to the placement of the M-ary bits on the I/Q constellation.

    For example, for 4-FSK, if you specify FSK deviation as 150k and symbol values as [0 1 3 2], then:

    • 00 (symbol value 0) corresponds to -150k
    • 01 (symbol value 1) corresponds to -50k
    • 11 (symbol value 3) corresponds to 50k
    • 10 (symbol value 2) corresponds to 150k

    Therefore the generated FSK symbol map reads [-150k -50k 150k 50k]. Similarly, if you specify the symbol values array as [0 1 2 3], the generated FSK symbol map reads [-150k -50k 50k 150k].

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    FSK deviation

    Maximum FSK frequency deviation. At baseband frequencies, deviations for individual symbols are evenly spaced in the interval [-f d , f d ], where f d represents the frequency deviation.

    Default: 150,000

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    symbol phase continuity

    Continuity of phase transitions between symbols.

    Name Description
    continuous

    Continuous phase transitions between symbols.

    discontinuous

    Discontinuous phase transitions between symbols, that is, discontinuous phase FSK (DPFSK).

    With discontinuous phase-FSK (DPFSK), modulation consists of selecting the appropriate sinusoid based on the input data. Thus, when switching between symbols, there is a discontinuity in the FSK signal phase. To emulate a hardware-based DPFSK source, this node maintains the phase of each independent sinusoid versus time. Thus, the DPFSK modulator acts like a hardware-based (multiple switched tone generator) FSK modulator.

    Default: continuous

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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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    FSK system parameters

    Parameter values defining the FSK system. Wire this cluster to the corresponding system parameters cluster of MT Modulate FSK or MT Demodulate FSK.

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    samples per symbol

    Number of samples per symbol in the modulated output complex waveform. For error-free operation, the samples per symbol must be an even number. Applying Carson's rule for FSK modulation, the 98% FSK bandwidth is given by the following formula:

    0.5 × (1 + r) × symbol rate + peak frequency deviation

    where 0 ≤ r ≤ 1 is the filter parameter.

    To satisfy the Nyquist criterion, use the following guideline.

    samples per symbol = 2 × ceil(1.5 × bandwidth/symbol rate) to obtain 3× oversampling.

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    symbol map

    Ordered array that maps each Boolean symbol to its desired deviation frequency. The number of FSK levels in the array must be 2 N , where N is the number of bits per symbol.

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    symbol phase continuity

    Continuity of phase transitions between symbols.

    Name Description
    continuous

    Continuous phase transitions between symbols.

    discontinuous

    Discontinuous phase transitions between symbols, that is, discontinuous phase FSK (DPFSK).

    With discontinuous phase-FSK (DPFSK), modulation consists of selecting the appropriate sinusoid based on the input data. Thus, when switching between symbols, there is a discontinuity in the FSK signal phase. To emulate a hardware-based DPFSK source, this node maintains the phase of each independent sinusoid versus time. Thus, the DPFSK modulator acts like a hardware-based (multiple switched tone generator) FSK modulator.

    Default: continuous

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    bits per symbol

    Number of bits represented by each symbol. This value is equal to Log 2 (M), where M is the order of the modulation. Example: For 16-FSK, M = 16.

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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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