MT Generate PSK System Parameters (map)
- Updated2023-02-17
- 5 minute(s) read
MT Generate PSK System Parameters (map)
Calculates parameters for use with either MT Modulate PSK or MT Demodulate PSK. This node generates the symbol map for PSK-modulated systems. The node accepts an array of symbol values that explicitly specifies the positions of the symbol map.
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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Inputs/Outputs
samples per symbol
An even number of samples dedicated to each symbol. Multiply this value by the symbol rate to determine the sample rate.
Default value: 16
symbol values
An array of symbol values with an order that corresponds to the symbol map. The number of PSK states in the array must be 2N, where N is the number of bits per symbol.
This node expects an array of integers for the symbol values parameter. The integers 0 through (M-1) must all be included only once in the symbol values array, where M is the M-ary number of the modulation. The binary representation (LSB first convention) of the integers represents the bit pattern that is mapped to the corresponding symbol location in the symbol values array. The symbol locations are generated with equal angles between all M-ary symbol locations and a distance of unity from the origin.
For example, in 8-PSK, if you specify symbol values as [5 4 2 7 3 0 1 6], the generated PSK symbol map is [(-0.383 - 0.924i), (0.383 - 0.924i), (-0.383 + 0.924i), (-0.924 - 0.383i), (0.383 + 0.924i), (0.924 + 0.383i), (0.924 - 0.383i), (-0.924 + 0.383i)].
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 /4-DQPSK.
| disable |
Symbols are represented as constellation points. |
| enable |
Symbols are represented as the transitions between constellation points. |
Default value: disable
error in
Error conditions that occur before this node runs.
The node responds to this input according to standard error behavior.
Default value: No error
PSK type
Type of PSK modulation.
| normal |
Sets the modulation type to regular PSK. |
| shifted |
Rotates the constellation by /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 value: normal
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.
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.
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 2N, where N is the number of bits per symbol.
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 /4-DQPSK.
| disable |
Symbols are represented as constellation points. |
| enable |
Symbols are represented as the transitions between constellation points. |
Default value: disable
PSK type
Type of PSK modulation.
| normal |
Sets the modulation type to regular PSK. |
| shifted |
Rotates the constellation by /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 value: normal
bits per symbol
Number of bits represented by each symbol. This value is equal to Log2(M), where M is the order of the modulation (for example, for 16-PSK, M = 16).
error out
Error information.
The node produces this output according to standard error behavior.