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LabVIEW Communications System Design Suite 1.0 Manual

MT Apply Pulse Shaping Filter (Generic)

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Applies a pulse-shaping filter to an input stream comprised of PAM, ASK, QAM, and nonoffset PSK-modulated symbols. Separate nodes are available for offset PSK, FSK, and MSK.

This node first upsamples (zero-insertion) the symbols array by a factor equal to the samples per symbol value, then filters the symbols stream with the pulse-shaping filter that you specify.

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symbols

Array of symbols (comprised of frequency deviations) corresponding to information bits. Wire the symbols parameter of MT Map Bits to Symbols to this parameter.

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pulse shaping filter coefficients

An ordered array containing sample-spaced coefficients for the desired pulse-shaping filter. Wire the pulse shaping filter coefficients parameter of MT Generate Filter Coefficients to this parameter. Ensure that the value of the samples per symbol parameter passed to this node matches the pulse shaping samples per symbol value used to generate the filter coefficients.

Note  

When reset? is set to TRUE, there is a transient response of ½ the filter length at the start of the modulated signal, and the returned data is shortened by approximately ½ the filter length. When reset? is set to FALSE, the node uses data from the previous iteration to eliminate the transient.

You can also specify custom pulse-shaping filter coefficients.
Note  

This node does not verify absence of intersymbol interference in custom filter coefficients before applying the pulse-shaping filter.

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samples per symbol

Number of samples per information symbol in the output complex waveform. Multiply this value by the symbol rate to determine the system sample rate.

Default: 16

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symbol rate

The symbol rate in symbols per second.

Default: 1.0

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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.

Default: no error

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reset?

A Boolean that determines whether the node continues pulse-shape filtering using the previous iteration states.

TRUE Resets the pulse-shape filtering.
FALSE Continues pulse shaping at the previous iteration state on subsequent calls.

Default: TRUE

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output complex waveform

The output pulse-shaped continuous-time I/Q baseband 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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error out

Error information. The node produces this output according to standard error behavior.

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