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MT Align To Ideal Symbols (Offset PSK) (G Dataflow)

Last Modified: January 9, 2017

Aligns the first sample of the input complex waveform to the ideal symbol timing instant for an offset PSK (OPSK) modulation scheme. This node returns an output complex waveform (offset removed) with the 1/2 symbol I/Q offset removed. Wire the output complex waveform (offset removed) to MT Decimate Oversampled Waveform to obtain the demodulated soft symbol decisions.

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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. 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 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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output complex waveform offset removed

The matched-filtered continuous-time I/Q baseband waveform with the 1/2 symbol I/Q timing offset removed. Wire this parameter to MT Decimate Oversampled Waveform followed by MT Map Symbols to Bits to obtain the recovered bits corresponding to this offset-removed symbol-time-aligned 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.

Where This Node Can Run:

Desktop OS: Windows

FPGA: Not supported


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