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MT Generate PSK System Parameters (M) (G Dataflow)

Last Modified: January 9, 2017

Calculates parameters for use with either MT Modulate PSK or MT Demodulate PSK. This node generates the symbol map for PSK-modulated systems. This node accepts an M-ary value that specifies a predefined symbol map with the number of distinct symbol map values to use as symbols.

Example Symbol Map for PSK

This symbol map corresponds to input symbol values {0, 1, 3, 2} for a quadrature-phase-shift-keying (QPSK) modulation system.

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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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M-PSK

The M-ary number, which is the number of distinct states that represent symbols in the complex baseband modulated waveform. This value must be a positive power of 2.

Default: 4

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differential PSK

A value that indicates how the PSK modulation represents symbols.

Differential operation is used to implement PSK formats such as differential quadrature PSK (DQPSK) and π /4-DQPSK.

Name Description
disable

Symbols are represented as constellation points.

enable

Symbols are represented as the transitions between constellation points.

Default: disable

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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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PSK type

Type of PSK modulation.

Name Description
normal

Sets the modulation type to regular PSK.

shifted

Rotates the constellation by π /M each symbol.

offset

Sets the modulation type to offset quadrature phase-shift keying (OQPSK). This modulation scheme is a form of phase-shift keying in which four different phase angles are used. This scheme is sometimes referred to as staggered quadrature phase-shift keying (SQPSK). For offset PSK, the ideal symbol timing for Q is offset by 1/2 of a symbol period from the ideal symbol timing for I. offset is currently only supported for M= 4.

Default: normal

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PSK system parameters

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

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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.

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symbol map

An ordered array that maps each Boolean symbol to its desired coordinates in the complex plane. The number of PSK states in the array must be 2 N , where N is the number of bits per symbol.

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differential PSK

A value that indicates how the PSK modulation represents symbols.

Differential operation is used to implement PSK formats such as differential quadrature PSK (DQPSK) and π /4-DQPSK.

Name Description
disable

Symbols are represented as constellation points.

enable

Symbols are represented as the transitions between constellation points.

Default: disable

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PSK type

Type of PSK modulation.

Name Description
normal

Sets the modulation type to regular PSK.

shifted

Rotates the constellation by π /M each symbol.

offset

Sets the modulation type to offset quadrature phase-shift keying (OQPSK). This modulation scheme is a form of phase-shift keying in which four different phase angles are used. This scheme is sometimes referred to as staggered quadrature phase-shift keying (SQPSK). For offset PSK, the ideal symbol timing for Q is offset by 1/2 of a symbol period from the ideal symbol timing for I. offset is currently only supported for M= 4.

Default: normal

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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 (for example, for 16-PSK, M = 16).

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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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