Amplitude phase shift keying (APSK) modulation

performs APSK modulation on the input data, `y`

= apskmod(`x`

,`M`

,`radii`

)`x`

, based on the
specified number of constellation points per PSK ring, `M`

, and
the radius of each PSK ring, `radii`

. For a description of APSK
modulation, see Algorithms.

apskmod specifically applies to multiple ring PSK constellations. For
a single ring PSK constellation, use `pskmod`

.

specifies an initial phase offset for each PSK ring of the APSK modulated
signal.`y`

= apskmod(`x`

,`M`

,`radii`

,`phaseoffset`

)

specifies options using one or more name-value pair arguments using any of the
previous syntaxes. For example, `y`

= apskmod(___,`Name,Value`

)`'OutputDataType','double'`

specifies the desired output data type as double. Specify name-value pair arguments
after all other input arguments.

The function implements a pure APSK constellation.

A pure M-APSK constellation is composed of *N*_{C}
concentric rings or contours, each with uniformly spaced PSK points.
The M-APSK constellation set is

where

The modulation order is equal to the sum of all

*M*_{l}for*l*= 1, 2, ... ,*N*_{C}.*N*_{C}is the number of concentric rings.*N*_{C}≥ 2.*M*_{l}is the number of constellation points in the*l*th ring.*R*_{l}is the radius of the*l*th ring.*θ*_{l}is the phase offset of the*l*th ring.

[1] Corazza, Giovanni E.
*Digital Satellite Communications*. New York: Springer Science
Business Media, LLC, 2007.

[2] Liu, Z., Q. Xie, K. Peng, and
Z. Yang. "APSK Constellation with Gray Mapping." *IEEE Communications
Letters*. Vol. 15, Number 12, December 2011, pp. 1271–1273.