M-APSK Demodulator Baseband

Signal constellation points per PSK ring, specified as a vector with more than one element. Each element of the vector indicates the number of signal constellation points in the corresponding PSK ring. The first element corresponds to the innermost circle, and so on until the last element, which corresponds to the outermost circle. The sum of the elements in Constellation points per circle determines the modulation order. The element values must be multiples of four, and the modulation order must be a power of two.

Example: [4,12,16] defines a ring signalling constellation of three PSKs with modulation order 32.

The radius of one PSK ring, is given as a vector of the same length as the vector of the Constellation points per circle parameter. Each element of the vector indicates the radius of the corresponding PSK ring. The first element corresponds to the innermost circle, and so on until the last element, which corresponds to the outermost circle. The values of these elements must be positive and in ascending order.

Example: [0.5,1,2] defines the radii for the three rings of the PSK signalling constellation. The inner ring has a radius of 0.5, the second ring has a radius of 1.0, and the outer ring has a radius of 2.0.

The phase offset per PSK ring, is specified as a scalar or vector with the same length as the vector of the Constellation points per circle parameters. Each element of the vector indicates the phase offset of the corresponding PSK ring. The first element corresponds to the innermost circle, and so on until the last element, which corresponds to the outermost circle. The Phase offset of each circle (rad) can only be a scalar if all elements of Constellation points per circle have the same value.

Example: [pi/4,pi/12,pi/16] defines the phase offsets for the three rings of a PSK signalling constellation. The inner ring has a phase offset of pi/4, the second ring has a phase offset of pi/12, and the outer ring has a phase offset of pi/16.

Character Matching. Defined as:

By default, symbol mapping depends on Constellation points per circle and Phase offset of each circle (rad). When all elements of Constellation points per circle are equal and all elements of Phase offset of each circle (rad) are equal, Gray is used by default. In all other cases, Contourwise-gray is used by default.

A custom character mapping specified as an integer vector. This vector shall consist of unique elements with values in the range ], where is Modulation Order for M-APSK. The first element in the Custom symbol mapping corresponds to the signal constellation point in the first quadrant of the inner circle, and subsequent elements are arranged counterclockwise around the PSK rings.

Dependencies

To use this parameter, set the Symbol mapping parameter to User-defined.

Output data type. Defined as:

Demodulation decision type. Defined as:

Refer to [APSK Software Demodulation] for algorithm selection. APSK Software Demodulation for algorithm selection.

Dependencies

To use this parameter, set the Output type parameter to Bit.

The source of noise variance. Defined as:

Dependencies

To use this parameter, set the Decision type parameters to Log-likelihood ratio or Approximate log-likelihood ratio.

The noise variance given as a positive scalar or vector of positive values.

If the noise variance or signal power results in calculations with extreme positive or negative values.

See APSK Software Demodulation for a discussion of the solution type specification.

Dependencies

To use this parameter, set the Noise variance source parameter to Property and the Decision type parameter to Log-likelihood ratio or Approximate log-likelihood ratio.

The data type of the modulated output signal type. Defined as:

Valid values of output data type depend on values of parameters Output type and Decision type.

Dependencies

To use this parameter, set the Output type parameters to Integer or Bit and the Decision type to Hard decision.